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With so many colors, traits and patterns to choose from, it's easy to see why a single bearded dragon ( Pogona vitticeps) quickly leads to a collection. These medium-sized lizards are easy to care for, personable and often bond with their keepers.

Keep Them Separated

Even if you purchase a sexed bearded dragon, re-sex it as it grows. Some males drop hemipenes later than others, so they can be mistaken for females early on. Male bearded dragons typically measure 18 to 23 inches long, and females measure 17 to 21 inches.

Bearded dragons have many morphs, including red-orange (top) and super citrus (bottom).

Never place male bearded dragons together; they can injure or even kill one another. They pace the cage and puff out their "beards," which turn black during a dominance display. Face cages in the same direction, and use a sheet between racks to calm excitable males.

Female bearded dragons exposed to males too early may produce a clutch of infertile eggs. This can drain a female's calcium resources and also can create egg-binding, which could kill the female.

Bearded dragon egg production requires a great deal of calcium.

We at Fire and Ice Dragons keep males and female bearded dragons separate as they mature to allow them to reach full growth potential before breeding. Weight is a more accurate measure of maturity than length. Female bearded dragons should be approximately 350 grams before breeding. Males should be at least 300 grams.

Feeding Bearded Dragons to Breed

We give our bearded dragons a variety of foods. Fresh, high-calcium collards, mustard greens, endive and escarole are daily staples. These are left in the cage until the next morning and then replaced. Insects such as silkworms, superworms or Phoenix Worms are also provided. Depending on the dragon's body weight, three times a week we dust about five superworms with Zoo Med Repti Calcium With D3. Fresh vegetables, including green beans, butternut or acorn squash, and okra, are fed every other day. Fruit, such as papaya, kiwi, raspberries and cantaloupe, is provided once a week and sprinkled with a supplement.

Supplement the female's diet to ensure that her health and that of her eggs are not at risk.

Extra calcium is important for breeding female bearded dragons. Egg production requires a lot of calcium, and without it a female can develop a crippling bone condition known as nutritional secondary hyperparathyroidism. A calcium-deficient female lays clear or semiclear eggs, and these eggs may result in egg binding. These eggs also burst as the embryo grows, which kills the offspring.

Warm, Clean Bearded Dragon Housing

We house a breeding pair, or two females and one male bearded dragon, in an enclosure measuring 4 feet long, 2 feet wide and 2 feet tall. A Zoo Med ReptiSun 10.0 fluorescent tube provides UVB, and an incandescent bulb, basking bulb or mercury vapor bulb can be used for heat.

In nature, bearded dragons live in the arid woods and deserts of central Australia. Captive adults breed best with a basking temperature between 110 and 115 degrees Fahrenheit, and a cool side between 80 and 90 degrees.

Leaning 1-foot-square cardboard egg-crate flats against the wall, we create climbing areas and a hide on the cool side. Egg crate allows us to continually change the internal structure of the cage, which offers the bearded dragons mental stimulation.

We soak our bearded dragons twice a week for 15 to 30 minutes in a container long enough for them to stretch out, and we mist them from head to tail every night. Providing a water bowl is fine, but misting keeps the cages clean and allows us to monitor which dragons drink. Renal (kidney) failure is possible if a dragon becomes dehydrated.

A clean enclosure is imperative. After removing the bearded dragon, we use a solution of 30 parts water to one part bleach to weekly clean the cage. We use the anti-microbial, anti-viral agent Nolvasan for daily cleaning.

Breeding Bearded Dragons

Introduce one female bearded dragon at a time into the male's enclosure with a week or so between the next introduction. Observe the two lizards' interaction, and make sure everyone gets along. The courting male puffs out his "beard" and bobs his head rapidly. If a female is not ready, she scratches at the walls or door to signal she wants out. Remove her, and try her again in a few weeks. A receptive female raises and lowers her head slowly. The male then jumps on her back, bites her neck, swings his tail under hers, and locks onto her by using his back legs.

Copulation takes less than a minute. Some bearded dragons are so secretive that copulation is never witnessed. Remove the female after three clutches or if she is slow to recover her pre-laying weight.

In 14 to 21 days, the female bearded dragon scratches the substrate to indicate her need to lay eggs. We then place the female in an 18-gallon Rubbermaid nestbox with a 16-inch-deep mix of two parts horticultural vermiculite, which can be found in nurseries or garden centers, to one part water. The covered bin should be about 80 degrees. Place a clear 25-watt bulb over one side of the egg-laying box. The female will dig a hole, turn around and lay her eggs. The typical clutch has 18 to 23 eggs, but first clutches can have as few as seven. After the female lays her eggs, return her to her enclosure.

Carefully dig out the bearded dragon eggs, and place them in egg boxes for incubation. Keep the embryo side up. The embryo can be seen as a pink dot inside fertile eggs, which are white and puffy. Infertile eggs are smaller and yellow.

We place fertile bearded dragon eggs in a covered plastic shoebox measuring 14 inches long, 6 inches wide and 5 inches tall with holes around the top-third of the container. It is filled halfway with the same vermiculite-and-water mix used for the nestbox. Cover eggs two-thirds of the way with the mix.

Our incubators are set at 84 to 86 degrees. Fan bearded dragon eggs every other day by opening the container to let in fresh air and release gasses from the developing eggs. As the eggs incubate, slight condensation around the edges of the egg box is good. If an egg box isn't showing mist, add a few drops of water to increase humidity. After 65 to 70 days, the eggs will sweat to indicate the onset of hatching.

Baby Beardie Care

Neonate bearded dragons are placed in a misted shoebox measuring 14 inches long, 8 inches wide and 6 inches tall with paper towel for substrate. We do not give them lights yet, but ambient temperatures are maintained between 80 and 85 degrees.

After 24 hours, baby bearded dragons are placed in rearing bins measuring 26 inches long, 13 inches wide and 10 inches tall, and heat and UVB lighting are provided. Keep the basking spot at 100 degrees. Each bin can hold three hatchlings.

By the time baby bearded dragons are 6 inches long, they each have a bin. This prevents tail- and toe-nipping, and keeps babies stress-free. Hatchlings kept alone grow faster than those kept with many competing, dominating siblings.

Hatchling bearded dragons actively hunt for food, and they eat within 48 hours. We offer three-eighths-inch-long crickets and small Phoenix Worms two to three times a day. They get as many as they'll eat. One meal a day is dusted with Repti Calcium With D3. Three times a week crickets are dusted with Rep-Cal Herptivite.

Bearded Dragon Success Tips

Have a veterinarian check bearded dragon fecal matter for intestinal worms and coccidia before pairing, especially during times when dragons are weak and more susceptible to parasitic overload.

Also trim nails if needed. A female bearded dragon's long, sharp nails can puncture eggs as she covers the clutch.

Explore the Options

With some traits, such as hypomelanism, clear nails, leatherbacks and some translucent lines, the results of your breeding decisions can be seen at hatching. With color traits, the results are typically assessed after juvenile bearded dragons have had their first or second shed at 4 to 6 weeks of age.

With so many colors, traits and combinations cropping up each year, breeding bearded dragons is an exciting, wide-open field for both novice and experienced lizardkeepers.

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With so many colors, traits and patterns to choose from, it's easy to see why a single bearded dragon ( Pogona vitticeps) quickly leads to a collection. These medium-sized lizards are easy to care for, personable and often bond with their keepers. Even if you purchase a sexed bearded dragon, re-sex it as it grows.

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There is a lot of debate about whether rabbits and guinea pigs should be kept together.

Some textbooks say there is no problem with this. For example, 'Diseases of Domestic Rabbits' by Lieve Okerman says: 'Pet rabbits can be kept together in the same space with different animals (for example, dogs), as long as the other animals adapt to the rabbits. Cohabitation with guinea pigs is never a problem'.

Other sources say that rabbits can bully guinea pigs so they don't eat properly. In addition, their different nutritional requirements, cage space and exercise needs mean that they are not ideally suited to live together.

If you do decide to keep a rabbit and guinea pig together you must always feed them separately.

If kept outdoors, they are often considered as company for each other, as the guinea pig can get warmth from the larger rabbit.

However, a rabbit has very powerful back legs which often does great harm to the more fragile guinea pig.

Rabbits will also burrow, and if placed on grass outdoors will soon escape by burrowing under the hutch. Guinea pigs do not have this burrowing instinct, but will be quite happy to use any tunnel provided by a rabbit.

Because of their different dietary requirements, I would suggest you try and get a copy of 'Small Animal Nutrition' by Sandie Agar (ISBN 0-7506-4575-X) published by Butterworth Heinemann. This gives a good idea about the diets of small furries, as well as other pets.

Keeping a rabbit and guinea pig together needs a lot of thought, care, preparation and observation and there's no real hard and fast rule.
Remember Elaine cannot replace the vet who normally looks
after your pet and they should always be the first point of contact. If you

are concerned your pet may be ill, don't delay contacting your own vet.

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Can a rabbit and a guinea pig live together?

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There is a lot of debate about whether rabbits and guinea pigs should be kept together. Some textbooks say there is no problem with this. For example, 'Diseases of Domestic Rabbits' by Lieve Okerman says: 'Pet rabbits can be kept together in the same space with different animals (for example, dogs), as long as the other animals adapt to the rabbits.

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Abstract

A key theoretical tool in many branches of behavioral and conservation biology is the Ideal Free Distribution and its many elaborations (see Tregenza, 1995 for an overview). This describes the distribution of individuals across a range of habitats in situations where the success rate of one individual in an environment is affected by the number (and possibly identity) of those sharing the habitat with it. Dominance relations are common in the natural world and have been included in several such models (e.g., Houston and Lang, 1998; Parker and Sutherland, 1986; Stillman et al., 1997, Sutherland and Parker, 1985; van der Meer, 1997). These models make different assumptions about how the foraging performance of an individual will be based on its own competitive ability relative to the competitive abilities of its competitors, and hence how prey encounter rates will vary with group size and composition (reviewed by van der Meer, 1997; Weber, 1998). For example, Sutherland and Parker's ( 1985) model incorporates an individual's competitive ability by comparing it to the average competitive abilities of individuals in a patch. An individual's relative competitive ability is calculated as its competitive ability divided by the average competitive abilities of all animals in the patch. The prey encounter rate E of individual j is proportional to

where p is the number of predators present in the patch, R is the inverse of individual j's relative competitive ability, and m is the interference constant. The negative sign in this relationship means that if p, m, or R increase, encounter rate E decreases. However, unless all animals are of equal competitive ability, arrival of additional animals in a patch will cause both p and R to change. For most realistic arrival scenarios, the increase in p will compensate for decreases in R caused when the new arrivals are of below-average competitive ability. However, if the number of dominants or there relative competitive ability is large, an influx of poor competitors may increase an original individual j's relative competitive ability (reducing R). If this effect is sufficient to offset the increased number of animals p in the patch, will increase.

The likelihood of such an outcome has been challenged in recent work, and has sparked several alternative methods of modeling competitive differences ( van der Meer, 1997). The main difference between these models and that of Sutherland and Parker ( 1985) is that an animal's feeding rate is calculated not in terms of the number of competitors present in the patch, but the number of `effective competitor units' present in the patch. is proportional to

where the parameter gives the number of effective competitor units (ecu's) that competitor k contributes to the interference that individual j experiences. Van der Meer ( 1997) describes a number of general models which make assumptions about how the dominance relationship between individuals j and k influence . They illustrate examples where is dependent on the ratio between the competitive abilities of j and k, or has unit value only if k is dominant over j. However, Sutherland and Parker ( 1998) suggest that if such general rules cannot be supported, it may be necessary to establish empirically the whole matrix of values for all individuals or phenotypes visiting patches.

So far, the mechanism by which dominance affects interference and hence foraging rate has received only very limited comparisons with empirical data ( Ruxton, 1999; Sutherland and Parker, 1998; Weber, 1998). Hence, here we will use a wild population of European blackbirds Turdus merula feeding on seminatural resource patches to explore the relationship between dominance and feeding rates. We present data from small feeding groups where the presence of others (social foraging) may allow an individual to spend a greater fraction of its time foraging, because of the antipredatory advantages of risk dilution ( Hamilton, 1971) or collective detection (see Elgar, 1989 for review; Lima, 1990). However, this is a particularly appropriate study species because interference affects on feeding rates are known to reduce the benefits of social foraging, even in small groups where dominance effects are likely to be most marked (Cresswell, 1997, 1998a, b).

The rate of food finding considered in these models is a combination of the intensity of foraging activity and the success rate per unit effort. It seems quite possible that the presence of other birds could have differential effects on these two processes. For example, risk dilution and collective predator detection may allow an individual to spend a greater fraction of its time foraging, but its success rate per unit effort might decline because its use of the full extent of a resource patch may be limited by interference with conspecifics (e.g., Cresswell, 1997). The potential costs and benefits that each individual accrues from group foraging will vary, however, because individuals will differ in foraging ability, susceptibility to interference and dominance. Individuals that have high absolute foraging abilities (foraging rate when alone) but that are highly susceptible to interference competition will have much lower feeding rates in groups. Any benefits of increased time available for feeding because of vigilance/dilution effects may not be sufficient to outweigh any interference-mediated losses of feeding time. In contrast, a dominant individual may suffer little interference competition and may actually increase its success rate in a group because of its ability to displace or kleptoparasitize subordinates, as well as gaining extra feeding time from the association due to dilution/vigilance trade-offs (e.g., Ens and Goss-Custard, 1984; Goss-Custard and Durell, 1988). Most previous empirical and theoretical works have simply subsumed foraging intensity and success rate per unit effort into overall intake rate. However, in view of the argument above, we will treat these processes separately, investigating the effects of group size changes for birds of contrasting dominance in relation to both foraging effort and success.

Last, the effects of "public information" on foraging success have attracted recent theoretical (e.g., Beauchamp et al., 1997; Valone, 1993), and empirical study ( Livoreil and Giraldeau, 1997; Smith et al., 1999; Templeton, 1998; Templeton and Giraldeau, 1995, 1996). The suggestion here is that individuals can use information on the position and behavior of other individuals in order to improve their own intake rate. While intuitively appealing, the importance of this effect has not previously been demonstrated in a situation which closely mimics natural foraging conditions. Hence, as our study fits this criterion, we will also examine the effects (if any) of this on the foraging success of our blackbirds.

METHODS

We studied the feeding behavior of a population of wintering blackbirds in the grounds of Hopetoun House, near Edinburgh between 23 January and 6 February 1998. This population was individually color-marked and had been the subject of previous foraging research in the previous three winters (Cresswell, 1997, 1998a, b). Birds were offered patches of shredded suet covered in a layer of autumn leaves. The locations of our experimental suet patches, as opposed to natural leaf litter, were made distinctive by clearing the surrounding area of fallen leaves (up to approximately 5 m), and inserting white pegs into the ground at the corners of the patches. After a short period of training, birds appeared to preferentially recognize these patches, and tossed the leaves aside to uncover the suet. Both our subjects, and other blackbird populations ( Cramp, 1988), have been noted uncovering items from below natural leaf litter in the same way.

We spread suet shreds uniformly throughout each 1 × 2 m rectangular patch, at two different densities, either 150 shreds or 30. Five sites were used in an area of approximately 1 ha of parkland, comprising areas of mixed woodland, mown lawn, and dense mature bushes. Although the sites were only 30-110 m apart they each consistently attracted different individual blackbirds, perhaps dependent on each bird's range. Our five sites were chosen from a larger number of training sites because they suffered only low levels of overt aggression from territorial resident blackbirds, and consequently tended to attract larger numbers of birds per presentation. Our blackbirds were therefore "free" to visit these neutral sites, and were only occasionally driven away by despotic behavior. As well as the territorial residents, the patches attracted neighboring territory holders and nonterritorial individuals and was typical of blackbird populations in other winters and other parts of our site. Forty individually identifiable birds fed at the patches during the experiment, 35 of these feeding at only 1-2 patch sites, and the remaining five birds fed at three. Each patch attracted up to 12 feeders during a given trial, and between eight and 19 birds over the entire set of experimental trials.

Individual blackbirds would typically take between 10 and 30 pieces of suet before retiring to cover, and up to seven birds were noted foraging simultaneously, although 1-4 birds were most frequent. Although the number of foragers was usually highest early in the trial, there were often breaks in feeding activity and subsequent arrival of "new" individuals. We continued the trial until feeding activity had stopped, most of the expected resident feeders had fed, or the feeding rates of the remaining feeders suggested that the densities of suet remaining were much reduced. Presentations lasted between 13 and 69 min (mean 35.1 min ± 12.6 SD). Few individuals fed more than once during a given trial. At least 1 h passed before we carried out a succeeding trial at the same patch location. Up to four trials were conducted at the same site each day, and up to nine trials at all sites in a day.

All trials were filmed on a portable camcorder, allowing us to ascertain which blackbirds fed simultaneously, and when they found suet. Although it was not uncommon for birds to curtail feeding movements for several seconds or more while visiting a patch, these interruptions were usually associated with periods of vigilant head-raising or conspecific aggression rather than comfort behaviors. Before and after feeding, blackbirds moved swiftly between our patches and protective cover, and rarely moved outside the patches unless competition at the patches was high. This suggests that our birds felt vulnerable in open feeding situations, and that the sole purpose of visiting our patches was to feed. We therefore calculated feeding rates throughout the entire time that a bird was present in a leaf patch. However, we obtained similar results in an analysis that omitted periods when birds did not feed for 5 s or more.

Our birds fed using a series of similar head movements into the leaf litter, which functioned to either toss leaves aside, or peck at (i.e., consume) exposed suet. Although a bird's head and bill were sometimes obscured, preventing us from seeing suet or directly counting swallowing motions, we were still able to distinguish pecks from tosses by the lack of leaf movement, and the slightly shorter duration of pecks compared to leaf tosses (averages of 0.9 s versus 1.4 s). Suet was swallowed as the head was lifted, so handling time was considered to be negligible. The accuracy of our observed number of suet pecks was confirmed by counting the number of suet shreds remaining after a patch presentation was completed.

Pecks and tosses were combined as total head movements when calculating feeding rates. Our patches were small and prone to patchy depletion as birds fed, and therefore feeds were not always long enough to allow proper compensation of periods of good and bad luck when searching for suet. Therefore, to avoid including the added variability of whether or not birds actually find suet while foraging, our main measure of foraging rate was foraging effort, that is, the number of head movements per minute (HM min⁻¹) that the bird was present in a patch. However, we also calculated foraging success (the number of suet pecks per hundred peck/toss head movements; P HM⁻¹ × 100). Although intake rates are the traditional currency of foraging models, intake rate is actually the product of foraging effort and foraging success. Our analyses are able to examine how these separate feeding components may be modified when feeding in different social situations. We calculated feeding rates for birds which spent at least 10 s feeding at constant flock size, resulting in a total of 1621 time budgets, lasting between 11 and 461 s (median = 38 s).

Inevitably, foraging success increased with suet density. To minimize the variance in suet peck rates associated with pecking at low suet densities, we confined our analysis of foraging success to time budgets starting when at least 20% of the initial suet density was still present. Foraging success was linearly related to the density of suet remaining in a patch at the start of a time budget (mean of 8.3 P HM⁻¹ × 100 when 30 suet shreds present, 30.6 P HM⁻¹ × 100 when 150 shreds present, r ₁₄₄₄ =.73, p <.001, quadratic term not significant). As suet handling times were short, and feeding pecks closely resembled leaf tosses, the relationship between foraging effort (pecks plus tosses per minute) and suet density was less predictable. The mean foraging effort across all time budgets was 44.9 ± 10.1 SD HM min⁻¹, decreasing slightly from 48.1 HM min⁻¹ in patches where 150 suet shreds were initially present, to 43.8 HM min⁻¹ when there were 30 suet shreds initially ( r ₁₆₁₉ =.18, p <.001). Therefore, as suet density affected both feeding measures, we calculated the values for foraging effort and foraging success after controlling for suet density, and used these residual values throughout this article.

As expected, despite controlling for the effects of suet density, variation in foraging success was still much larger than variation in foraging effort (standard deviation of each residual measure expressed as a percentage of the original mean: foraging success 54%, foraging effort 22%). This was partly because feeds were short in relation to the time taken to find successive suet shreds, and partly because successive suet pecks were likely to occur in the same part of the patch as an individual foraged, causing suet distribution within the patch to become uneven. Only the first blackbird to arrive in a new patch would encounter a relatively even suet spread. The foraging success of its successors would depend on how long they were able to spend in relatively undepleted parts of the patch. Our measure of feeding effort does not suffer this additional stochasticity, so we were more likely to detect differences in feeding effort within individuals in different social situations. An additional problem with foraging success, but not foraging effort, was that its variance increased (at a declining rate) with suet density (correlations of absolute magnitude of feeding residual versus suet density: foraging effort, r ₁₆₁₉ = -.01, p =.75; foraging success, r ₁₄₄₄ =.34, p <.001). We therefore stabilized the variance of foraging success in relation to suet density by dividing it by the square root of suet density, and used transformed residuals for foraging success throughout this article.

All other things being equal, increases in either foraging effort or foraging success will be reflected by increases in intake rate. Our measure of foraging effort was least affected by sampling limitations. Moreover, it is likely that animals searching for hidden prey will have more control over their foraging effort than their ultimate success, so it is this variable which will suffer directly from increased conspecific or predator vigilance. Consequently, we have concentrated on foraging effort throughout much of this article.

We also recorded rates and outcomes of aggression in each patch, allowing us to establish individual dominance. On average, birds were involved in 2.5 ± 1.5 SD ( n = 35 individuals) aggressive encounters per competitor minute. Most encounters were simple noncontact displacements. Most dominance relationships were unambiguous and linear, permitting calculation of dominance hierarchies. Individuals in triangular relationships (where A succeeded against B and B beat C, yet C won encounters with A) were given equivalent rankings unless their relative success with other individuals indicated that they merited higher or lower ranking. A bird's dominance in a patch hierarchy was then calculated as the number of other individuals which it ranked higher than in a patch divided by the number of birds which it either ranked higher or lower than (i.e., codominants were excluded from the ratio). Unless otherwise stated, the influence of dominance rank and group size on feeding rates was examined by comparing mean feeding rates of individuals in contrasting situations (e.g., as dominants versus as subordinate in dyads) using matched pairs t tests. All probabilities quoted are two-tailed.

RESULTS

We recorded the outcome of a total of 842 encounters between 39 individually identified blackbirds. Our within-patch dominance rankings correctly classified the outcome of 89% of encounters. A further 6% of encounters were between birds which were given codominant status, and 42 (5%) were reversals. For 24 of these reversals, there were a similar or larger number of victories in the dominant birds favor, indicating that the assigned direction of dominance was correct. Dominance was unrelated to age ( t test: adult versus first winter birds, t ₂₄ = 1.24, p =.23) or sex ( t test: t ₃₀ = 0.93, p =.36), but, within individuals, was similar in different patches ( r ₁₁ =.48, p =.097).

Feeding rate versus dominance in dyads

The residual feeding rates of each bird were compared when they fed alongside a dominant competitor as opposed to a subordinate competitor. Foraging effort, but not foraging success, was higher when feeding with a more subordinate individual than with a more dominant individual (Table 1).

Significance levels derived from paired t tests, n = 11 individuals. Individuals were omitted unless they were observed feeding at least twice with single subordinates and at least twice with single dominants. For foraging success, residuals were transformed to equalize variance as suet density increased; value given is therefore mean difference in foraging success in a patch containing 50 suet shreds.

However, does the magnitude of the difference in dominance between two competitors further affect foraging effort? Subtracting the dominance of the competitor from the dominance of the focal bird gave a dominance difference score between -1 (when the competitor dominated all birds in the patch and the focal bird was entirely subordinate) to 1 (focal bird dominant, competitor entirely subordinate). The dominance difference score was not constant for each focal individual, but varied according to the dominance of its paired competitor. Hence, the individual which was most subordinate in a patch could have dominance difference scores between -1 and 0, depending on the competitive ability of its paired feeding partner, while the top dominant bird could have dominance difference scores between 0 and 1. Intermediate dominance birds had intermediate scores, with a maximum range of 1. We looked at the effect of dominance difference score on residual foraging effort in a general linear model ( SPSS Inc, 1997) which also controlled for the focal bird's identity. We selected individuals for which there were at least five time budgets. There was no evidence for individual variation in the manner in which residual foraging effort was influenced by dominance difference score (interaction between bird identity and score, F 23,381 = 1.18, p =.26). After removing this term from our model, both bird identity ( F 23,404 = 2.96, p <.001) and dominance difference score ( F 1,404 = 6.07, p =.014) explained significant variation in overall foraging effort.

However, such a result could also be obtained if foraging effort increased when feeding with a subordinate and declined when feeding with a dominant, but is not influenced by the magnitude of the feeding partner's dominance or subordinance. Hence, we repeated our analysis, splitting our data into whether the focal bird was dominant or subordinate. Again, within dominance classes, there was no evidence for individual variation in the relationship between residual foraging effort and dominance difference score (interaction term for subordinate focal birds, F 10,148 = 1.23, p =.28; for dominants, F 11,148 = 1.44, p =.16). After removing this term, there was still significant individual variation in residual foraging effort (for subordinate birds, F 10,158 = 2.98, p =.002; for dominants, F 11,159 = 2.23, p =.015), but this was unaffected by dominance difference score (subordinates, F 1,158 = 0.13, p =.72; for dominants, F 1,159 =.46, p =.50). This indicates that, after determining which bird was dominant, the magnitude of the difference in dominance between two individuals explained little additional variation in foraging effort.

Feeding rates in dyads compared to solitaires

The residual feeding rates of focal birds feeding with one other bird were then compared to the same bird's feeding rate when feeding alone. Interference could cause solitary feeders to suffer reduced feeding rates when joined by a competitor, while group foraging benefits could enhance their feeding rates.

Overall, restricting analysis to birds which were time budgeted at least three times both when alone and with one other bird, foraging effort was higher when with one other bird than when alone (paired t test, difference = 1.9 HM min⁻¹, t ₂₅ = 2.30, p =.030). However, foraging effort was not independent of a competitor's dominance status. Birds feeding with a more subordinate competitor still had a higher foraging effort than when they fed alone, but birds feeding with a more dominant competitor tended to have lower foraging effort than when feeding alone ( Figure 1). We did not detect significant differences in foraging success of birds feeding with either a dominant or subordinate competitor compared to when they fed alone ( Figure 1).

How do feeding rates change when a third bird is present?

Three or more time budgets were obtained from nine individuals when solitary, when in groups of two and when in groups of three. Although average residual feeding effort of these birds were slightly higher in groups of three than when solitary (paired t test, difference = 3.4 HM min⁻¹, t ₈ = 1.50) or when in pairs (paired t test, difference = 2.0 HM min⁻¹, t ₈ = 1.52), the differences, although exceeding those in the previous section, did not reach significance (both p =.17).

Again we compared foraging effort of birds in groups of three with the residuals of the same birds when solitary in relation to dominance rank. Top dominants had higher effort when feeding in groups of three than when feeding alone, but bottom subordinates had slightly but not significantly lower effort when foraging in groups of three ( Figure 1). Repeating this analysis for foraging success gave similar but subtly different results ( Figure 1). Residual foraging success was slightly but not significantly greater in groups of three than when solitary in dominants, but subordinates had substantially lower foraging success when feeding in tryads ( Figure 1). In contrast to the results for foraging effort, the change in foraging success of middle-rank birds was slightly lower than that of dominants.

To look at whether interference affects were multiplied or diluted on the addition of birds of different status, we compared the residual feeding rates of a bird when in a group of two with those when it was with the same competitor plus one other. One hundred time budgets were available where the feeding rate of a bird in a group of three could be compared with its feeding rate with the other individuals when in groups of two; the majority (84%) of these budgets had unique combinations of individuals undertaking the three roles (focal bird, second competitor, and third joiner). As the number of potential comparisons was large (each of three ranks joined by each of the other two, i.e., six), and as we considered some birds to have the same dominance rank (effectively making 12 comparisons, thereby reducing sample sizes), we analyzed the data using four different groupings (Table 2).

The difference ( d) for each feeding residual is the residual feeding rate when in the threesome minus the rate in the twosome. Differences were compared using paired t tests. The differences given for foraging success are standardized for patches containing 50 suet shreds.

The foraging effort of any dominant (i.e., the top dominant or middle-rank individual) with a subordinate was higher when another dominant joined the system (Table 2), possibly due to the shared advantage of feeding in groups. Such shared increases in residual effort were not obvious in the other three groupings. As with residual effort, the foraging success of any dominant with a subordinate, was significantly higher if another dominant was present. In contrast to foraging effort, the foraging success of two other groupings showed significant changes when a third bird was present. First, top dominants had higher foraging success when any other subordinate was present. Second, and somewhat complementarily (though based on an independent set of time budgets), bottom subordinates had lower foraging success when any other dominant was present.

Such a difference in success, but not effort, might be expected if dominants displaced subordinates from less depleted areas within our patches. We tested this in birds that displaced a competitor during a time budget, by comparing their feeding rates before and after the displacement. We selected data where at least 10 s were spent in the patch before and after the displacement, and, for birds which made more than one displacement during a time budget, selected only the first such displacement in the time budget. Foraging effort was similar before and after displacements (paired t test, mean increase of 1.5 HMmin⁻¹, t ₂₈ = 0.49, p =.63), indicating that dominants did not change effort following an interaction. However, the foraging success of dominants increased after they had displaced a subordinate (mean increase of 6.0 P HM⁻¹ × 100, t ₂₈ = 2.48, p =.019), despite the slightly reduced suet densities, supporting the idea that dominants use subordinates as food finders.

DISCUSSION

It is clear that there was a dominance hierarchy in our birds, birds could identify whether a foraging partner was higher or lower in the hierarchy than them, and that birds modified their behavior in the light of this information. It is perhaps unsurprising that our birds were able to do this as blackbirds show age, sex, and individual variation in plumage ( Cramp, 1988) and they interact with a relatively small number of other blackbirds repeatedly throughout the winter, affording them plenty of opportunity to assess the characteristics of others. This information has a strong influence on their behavior: birds feed at a greater rate with subordinate individuals than they would do if alone, but, when in the presence of an individual that is dominant to them, feed at a lower rate than when alone. The first result could occur in two ways. First, group vigilance may allow dominants to increase foraging effort without a corresponding increase in predation risk. Blackbirds in the study area are attacked by both avian (sparrowhawk Accipiter nisus) and terrestrial (Mustelid) predators. Our artificial food patches required them to feed away from cover, in situations where they were likely to perceive an increased threat of predation ( Bednekoff, 1996). There are many observational studies of reduced vigilance rates in passerines as group size increases ( Elgar, 1989). This reduced vigilance requirement could therefore liberate time for increased foraging effort. Second, dominant birds may be able to use subordinates as food-finders ( Rohwer and Ewald, 1981; Wiley, 1991), taking advantage of information gleaned from subordinates to forage in parts of the patch where depletion is least.

It is likely that some antipredatory benefits of foraging with other individuals holds for all birds regardless of their place in the dominance hierarchy. It might therefore seem surprising that foraging effort decreases for subordinate birds in the presence of a dominant individual. There is clearly an interference cost paid by the subordinate which supercedes any antipredatory vigilance advantages which the dominant might bring. Our understanding of how dominance relationships might affect feeding rates through interference has largely depended on studies of oystercatchers Haematopus ostralegus feeding on mussels Mytilus edulis and cockles Cerastoderma edule. When mussel-feeding, dominant oystercatchers may increase their feeding rate with increasing competitor density because kleptoparasitism opportunities increase ( Ens and Goss-Custard, 1984; Goss-Custard and Durell, 1988; Stillman et al., 1996). However, dominant oystercatchers did not have higher feeding rates than subordinates when feeding on cockles at lower competitor densities ( Sutherland and Koene, 1982), perhaps because subordinates were able to make behavioral adjustments to reduce the probability of kleptoparasitism without reducing their intake rate greatly ( Norris and Johnstone, 1998). Interference is, however, found in cockle-feeding oystercatchers at higher densities, especially when cockles are rare ( Triplet et al., 1999). In comparison to these studies, group-feeding subordinate blackbirds showed reduced foraging effort compared to dominants, but were never seen to be kleptoparasitized. Therefore, the cost of interference in blackbirds may largely result from a need to monitor the aggressive behavior of more dominant individuals (see Cresswell, 1997). Our data show that dominance is a very good predictor of the outcome of aggressive interactions and that such interactions occur frequently. Hence, in contrast to dominant individuals, subordinates may have to reduce foraging effort in order to be vigilant for possible attack by dominants.

However, whatever the mechanisms involved, our results show that the presence of other conspecifics at a feeding site does affect foraging effort, and that the effect on an individual will depend both on its own place in the dominance hierarchy and those of its competitors. As with oystercatchers, this gives important empirical support to ideal free distribution models which allow for individual differences in competitive ability, such as Sutherland and Parker ( 1985) and van der Meer ( 1997). However, an important caveat to this is that in the simple situation when birds fed in pairs, there was no evidence that an individual responded to the magnitude of the difference in dominance between it and a competitor (only on whether they were higher or lower in the hierarchy). This stands in direct contrast to almost all the commonly used models of the effect of interference in systems where individuals differ in dominance (but see Stillman et al., 1997; linear hierarchy model of van der Meer, 1997). This may be a real effect. Alternatively, additional costs involved with feeding with a highly dominant competitor may increase comparatively slowly in comparison to the initial cost of feeding with a dominant competitor of any magnitude. As this relationship is key to a great deal of the existing literature on the effects of interference on foraging decisions, there is a clear need for further experimental and theoretical effort focused on this assumption.

When two foraging birds are joined by a third, the affects on foraging are complicated. We might predict foraging effort should increase due to the antipredatory benefits of collective vigilance. However, mean food intake rate commonly increases at a reducing rate with group size, and sometimes drops in larger groups ( Beauchamp, 1998). Our results were mixed. An original subordinate individual did not increase its effort, regardless of the newcomer's place in the hierarchy. However, there was some evidence that original dominant birds did increase their foraging effort when a newcomer arrived, although the effect was not universal ( Table 2). Foraging success followed a more intuitively appealing pattern. If the newcomer was subordinate, the dominant bird's foraging success (but not that of the original subordinate) increased. In contrast, if the newcomer was a dominant bird, then the success rate of the original subordinate, but not the original dominant, decreased. This suggests that dominant individuals benefit from the presence of subordinates, perhaps by supplanting them from good foraging areas within the patch (as found, e.g., in several seed-eating passerines, Baker et al., 1981; Rohwer and Ewald, 1981; Theimer, 1987; Wiley, 1991). To examine this, we looked at a dominant bird's foraging pattern before and after supplanting a subordinate. There was no detectable change in foraging effort after displacing a subordinate, but an increase in foraging success. This suggests that dominants do obtain useful public information (sensu Valone, 1989) to improve their ability to exploit a food resource.

Recently, there has been considerable interest ( Ruxton, 1999; Sutherland and Parker, 1998) in comparing experimental data to the underlying assumptions of the models of Sutherland and Parker ( 1985) and van der Meer ( 1997). The latter make the prediction that an individual's return from foraging will be reduced as more competitors arrive, dependent on the number of effective competitor units they contribute to its interference. This contrasts with Sutherland and Parker's ( 1985) model which predicts that although an individual's foraging rate will usually decrease as more competitors arrive, there will be times when the feeding rates of the original foragers will increase as more subordinates arrive. Such circumstances arise when the difference between the competitive abilities of dominant and subordinate birds is high, and the increase in an original forager's relative competitive ability more than compensates for the increased number of foragers competing for food. Although this outcome was not expected when the original model was put forward, Sutherland and Parker ( 1998) suggest that it is plausible that additional subordinates could divert dominant animals' attention from the original subordinates, diluting the frequency of attacks or the vigilance invested in avoiding attacks. It is not, however, so easy to explain why the feeding rates of the original dominants might also increase without invoking benefits arising from group size, such as predation risk dilution or faster food finding. Our data cannot directly address the question of what happens when additional competitors are present without first accounting for the beneficial effects of social foraging. Furthermore, we have not measured relative competitive ability, only the linear dominance hierarchy, where increases in dominance between adjacent members of the hierarchy may not always reflect similar-sized increases in relative competitive ability. However, our observation that feeding effort depended more on the direction of dominance, rather than on the magnitude of the dominance difference, suggests that in blackbirds feeding encounter rate does not increase with an individual's relative competitive ability (as modeled by Sutherland and Parker, 1985). Instead, encounter rate may depend more on how many competitors are dominant (as in the linear hierarchy matrix, V ₃, Van der Meer, 1997). However, the high yet variable values of foraging effort and foraging success seen in birds of intermediate dominance in tryads ( Figure 1) suggests that in some cases the presence of a subordinate may shelter the intermediate-dominance individual from interference from the dominant bird. Indeed, the increase in foraging effort with group size observed in intermediate birds may exceed that seen in dominant birds, perhaps because intermediate birds are prepared to take larger risks in profitable foraging situations. Intermediates may locate themselves in parts of the patch which take advantage of the position of subordinates to dilute the possibility of aggression from dominants. If so, it is possible that such opportunities would disappear in larger groups containing dispersed dominants, so that encounter rate would again increase with an individual's competitive ability, perhaps in the fashion employed by Van der Meer's ( 1997) V ₄ interference matrix (interference constant m acts on the sum of the ratios between competitive abilities of competitors in the patch).

Clearly, average foraging effort did increase as group size increased from one to at least three birds, and may have increased further in large groups. Yet, in our study, larger groups were rare. It is possible that this was driven by the departure of subordinate birds, whose foraging effort declined in groups in comparison to when solitary. Departure of subordinates from tryads may increase the level of interference experienced by intermediate-dominance birds, instigating their ensuing departure (perhaps to join subordinates). Indeed, in more general terms, when or where groups occur, as well as maximum group sizes or densities, may depend on the shape of the cost-benefit curve for subordinates rather than dominants. Reduced feeding rates in groups may be offset against greater predation risk when feeding alone, especially if alternative patches are of lower quality. Nevertheless, it is likely that as group size antipredation benefits are hindered by interference costs, switching to forage solitarily in less rich patches may become a viable option for animals in large groups, especially if the probability of being joined quickly by other animals is high. Such benefits may give rise to small groups of foragers taking advantage of lower predation risk (than when solitary) but low interference costs (than when in a larger group). Invasion of such groups by dominants may give rise to a dynamic distribution of small groups of animals. Such situations could be explored by including group size benefits in future ideal free models.

In summary, our results suggest that foraging on a shared resource is constrained in a complex fashion by conspecific competitors, dependent on the relative dominance and aggression of the individuals involved. Further, when we divided foraging into effort and success we found that both were affected by dominance relations but not in exactly the same way. Our results therefore suggest that some assumptions of models which seek to describe the distribution of a group of individuals of different competitive abilities between a range of resources in a very simple way (e.g., Sutherland and Parker, 1985) are too simplistic. However, our results also suggest that more complex models (such as that of van der Meer, 1997 which requires input of matrices of interindividual interference effects) can be somewhat generalized if intraspecific dominance-interference patterns are measured. Current models also generally assume that interference is the main influence of group size on foraging, whereas we have shown that, at least for our system, the effects of safety in numbers and public information may also be important. If we are to improve the predictive ability of these models, then a more detailed description of such effects will be required. This represents a major challenge to empiricists and theoreticians, who must be aware of all the difficulties of disentangling a large range of dominance effects which together act to modify foraging behavior.

We thank Paul Normand, Tom Weaver, the Marquis of Linlithgow, and all at Hopetoun House for practical help. This manuscript was greatly improved by the contributions of three anonymous referees. Our work was carried out under a Natural Environment Research Council (NERC) research grant to Glasgow University.

References

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Dominance and feeding interference in small groups of blackbirds | Behavioral Ecology | Oxford Academic

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Dominance and/or interference parameters play a pivotal role in most ideal free distribution models, but there has been scant empirical study of the exact manner in which they jointly operate. We investigate how foraging effort and success varied amongst individuals of different dominance rankings in groups of 1-3 wild blackbirds (Turdus merula) attracted to patches of hidden food.

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The Bearded Dragon Manual provides the essential information all devoted bearded dragon owners need to meet the demands of these beautiful, naturally tame reptiles. Since reptiles are cold-blooded creatures, most humans don't instinctively understand their requirements the way they understand the needs of a cat or dog.

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View of Effect of post-gut loading time on the macro-nutrient content of three feeder invertebrate species

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Return to Article Details Effect of post-gut loading time on the macro-nutrient content of three feeder invertebrate species

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Aspinall's Complete Textbook of Veterinary Nursing E-Book

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The third edition of Aspinall s Complete Textbook of Veterinary Nursing is the ideal text for both student and qualified veterinary nurses as it covers the entire veterinary nursing syllabus. Now written in the main by veterinary nurses this book comprehensively covers all aspects of the veterinary nursing role from client communication to nutritional support.

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Trade Literature

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There is a lot of debate about whether rabbits and guinea pigs should be kept together.

Some textbooks say there is no problem with this. For example, 'Diseases of Domestic Rabbits' by Lieve Okerman says: 'Pet rabbits can be kept together in the same space with different animals (for example, dogs), as long as the other animals adapt to the rabbits. Cohabitation with guinea pigs is never a problem'.

Other sources say that rabbits can bully guinea pigs so they don't eat properly. In addition, their different nutritional requirements, cage space and exercise needs mean that they are not ideally suited to live together.

If you do decide to keep a rabbit and guinea pig together you must always feed them separately.

If kept outdoors, they are often considered as company for each other, as the guinea pig can get warmth from the larger rabbit.

However, a rabbit has very powerful back legs which often does great harm to the more fragile guinea pig.

Rabbits will also burrow, and if placed on grass outdoors will soon escape by burrowing under the hutch. Guinea pigs do not have this burrowing instinct, but will be quite happy to use any tunnel provided by a rabbit.

Because of their different dietary requirements, I would suggest you try and get a copy of 'Small Animal Nutrition' by Sandie Agar (ISBN 0-7506-4575-X) published by Butterworth Heinemann. This gives a good idea about the diets of small furries, as well as other pets.

Keeping a rabbit and guinea pig together needs a lot of thought, care, preparation and observation and there's no real hard and fast rule.
Remember Elaine cannot replace the vet who normally looks
after your pet and they should always be the first point of contact. If you

are concerned your pet may be ill, don't delay contacting your own vet.

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Can a rabbit and a guinea pig live together?

# data[].attributes.attachment_link.description
There is a lot of debate about whether rabbits and guinea pigs should be kept together. Some textbooks say there is no problem with this. For example, 'Diseases of Domestic Rabbits' by Lieve Okerman says: 'Pet rabbits can be kept together in the same space with different animals (for example, dogs), as long as the other animals adapt to the rabbits.

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Journal

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Introduction

Amphibians and reptiles differ in many respects from the mammals and birds most commonly used in biomedical research. These differences affect the physical and biological requirements of amphibians and reptiles in captivity. In this contribution, some basic biological characteristics of these animals are described that are relevant to their husbandry. My goal is to help members of institutional animal care and use committees appreciate the requirements of amphibians and reptiles in captivity, and to make suggestions that will be helpful in designing housing and providing day-to-day care.

I will focus on amphibians and reptiles used for research and teaching in colleges and universities. In the sense that amphibians and reptiles are exotic animals in a biomedical context, there are parallels between their use in academic settings and in zoos and aquariums. However, the facilities and resources available at colleges and universities are more limited than those of most zoos and aquariums. These recommendations address the limitations and opportunities of small-scale husbandry.

The husbandry practices suggested here are compatible with the Health Extension Act (PL-99-158), with the National Research Council's Guide for the Care and Use of Laboratory Animals ( NRC, 1985 ) with the Canadian Council on Animal Care's Guide to the Care and Use of Experimental Animals ( Canadian Council on Animal Care, 1980 ) and with the Guidelines for Use of Live Amphibians and Reptiles in Field Research ( American Society of Ichthyologists and Herpetologists et al., 1987 ).

Amphibians and Reptiles in Research and Teaching

Understanding the husbandry requirements of amphibians and reptiles begins with understanding why these animals, rather than traditional biomedical species, are being studied. Studies of amphibians and reptiles often have different perspectives and goals than those using traditional biomedical species. These differences are reflected in the housing and care that is appropriate for the animals. In addition, the physical and biological needs of amphibians and reptiles differ from those of mammals and birds, and are often more difficult to provide in an artificial setting. Both of these factors must be appreciated by investigators working with these animals, and by the individuals responsible for evaluating protocols and husbandry practices.

The Context of Study

Many studies of amphibians and reptiles have an organismal perspective. That is, the focus of study is the intact animal and the context is the species as it functions in its natural environment. This approach differs from the traditional biomedical use of mammals and birds to illustrate general biological phenomena or to serve as models of specific human diseases or genetic defects. In organismal research, behavior, ecology, physiology, and morphology are studied in the context of phylogenetic relationships and environmental specializations. Husbandry must consider the entire biology of an organism so that normal behavior, physiological response, and morphogenesis can be assured. Much research in organismal biology is currently directed to comparative studies that investigate the evolution of physiological, morphological, and behavioral characteristics by studying a series of species (see Brooks and McLennan, 1991 ; Harvey and Pagel, 1991 ; and Huey, 1987 for examples of this approach). Studies of this sort rely upon measuring the same phenomenon (e.g., thermoregulation, parental care, or feeding mechanics) in several species. Reviewers of protocols must understand that the study of multiple species of known phylogenetic relationship is an essential element of the comparative approach, and is not unnecessary duplication.

Practical Considerations

Providing environments suitable for amphibians and reptiles can be difficult. Domestic animals used in biomedical research have been bred to prosper under conditions that can easily be maintained in an animal room. Amphibians and reptiles, on the other hand, are wild animals, and the husbandry methods applied to them must take this into account. Housing, food, and care must match the physical and behavioral needs of each species. Carefully designed physical and biological environments are often needed, especially when the goal of husbandry is to facilitate studies of complex responses such as hormonal cycles, reproductive and social behavior, or water and temperature regulation. The welfare of the animals must have the highest priority in the design of animal rooms, cages, and cage furnishings. This effort must not be frustrated by the application of inappropriate standards based on domestic species.

Because most species of amphibians and reptiles are not available on short notice or from commercial breeding colonies, they are usually either collected from the wild by the investigators themselves, or obtained by gift from other researchers, zoos, or agencies such as the U.S. Fish and Wildlife Service. The availability of a species is likely to be affected by its seasonal activity cycle, the opportunity to collect in an exotic locality, and the provisions of national laws and international treaties. An investigator who plans to travel thousands of miles cannot predict in advance exactly how many individuals of which species will be collected. As a consequence of this uncertainty, investigators may have to submit protocols that include several taxa, only a few of which will actually be used. Furthermore, unusual species that have been successfully acclimated to laboratory conditions have a scientific value that transcends the project for which they were originally collected, and they may be kept indefinitely in expectation of further use. Animal care and use committees must understand these practical aspects of working with amphibians and reptiles and evaluate protocols accordingly.

The Biology of Amphibians and Reptiles

In order to design appropriate environments for amphibians and reptiles, one must have an appreciation for their unique biological characteristics. Some practices and materials that are suitable and desirable for the care of birds and mammals are unimportant or even deleterious for amphibians and reptiles. Conversely, considerations that have little relevance for birds and mammals can be crucial for successful husbandry of amphibians and reptiles. A large literature shows that husbandry practices that are appropriate for mammals are not suitable for amphibians and reptiles, but the pertinent references are scattered. Recent sources of general information about amphibians and reptiles include Bellairs (1969 ), National Academy of Sciences (1974 ), Hatless and Morlock (1979 ), Stewart (1984a , b ), Duellman and Trueb (1986 ), Halliday and Adler (1986 ), Seigel et al. (1987 ), Norris and Jones (1987 ), and Pough et al. (1989 ) and the references therein.

Distinctive Characteristics

Two attributes of amphibians and reptiles underlie all aspects of their care: Ectothermy and diversity.

Ectothermy.

Amphibians and reptiles are ectotherms, that is, they do not ordinarily generate enough metabolic heat to raise their body temperatures above the ambient temperature. However, ectotherms are not literally 'cold blooded.' Under normal conditions, terrestrial ectotherms regulate body temperature by behavioral means, often at high levels and within narrow limits. Several important implications for their care follow from this aspect of their biology. Most importantly, they require environmental conditions quite different from those appropriate for birds and mammals.

Ectothermy is an energy-efficient mode of thermoregulation because metabolic energy is not used to warm the body. As a result, the resting metabolic rates, aerobic capacities, and overall energy needs of ectotherms are nearly an order of magnitude lower than those of endotherms (birds and mammals) of similar size ( Figure 1 ).

The thermoregulatory mechanisms employed by amphibians and reptiles are by no means simple. Many ectotherms regulate their body temperatures during activity at levels that are similar to those of birds and mammals (35°C-42°C). The regulated temperature may change in response to internal and external conditions. Changes in thermoregulatory behavior include differences between daytime and nighttime temperature, elevation of body temperature following feeding, increase or decrease in body temperature during pregnancy, behavioral fever mediated by prostaglandin release during bacterial infection, and muscular thermogenesis during egg brooding ( Hutchison et al., 1966 ; Regal, 1966 , 1967 ; Lillywhite et al., 1973 ; Vaughn et al., 1974 ; Van Mierop and Barnard, 1976 , 1978 ; Kluger, 1977 , 1979 ; Hutchison and Erskine, 1981 ; Bartholomew, 1982 ; Beuchat, 1986 ; Sievert, 1989 ). Humane care of amphibians and reptiles requires conditions that facilitate their complex thermoregulatory responses.

Diversity.

Living ectothermal tetrapods include nearly 4,000 species of amphibians and 6,000 species of reptiles. These 10,000 species display an enormous array of lifestyles, and it is this diversity that makes them attractive for research at the cellular or molecular level, as well as for studying organismal, ecological, and evolutionary questions ( Deuchar, 1975 ; Greenberg et al., 1989 ; Pough, 1989 ; Elinson et al., 1990 ). For example, an investigator studying hormonal control of reproductive behavior can choose from some 3500 species of anurans (frogs and toads). Among these are species that retain an ancestral amphibian life cycle (terrestrial adults, aquatic eggs, and aquatic larvae); terrestrial species in which either males or females carry developing eggs and/or young on the back, in vocal pouches, and even in the stomach; species in which females feed their tadpoles unfertilized eggs; and species that give birth to live young, either with or without some form of matrotrophic contribution to the fetus. Moreover, anurans run the gamut from totally aquatic frogs to species that live in deserts. Reptiles show still greater diversity in habitats and specializations. Because the ecological characteristics and husbandry requirements of the animals are so diverse, it is impossible to formulate specific guidelines for groups larger than a few species. In fact, broad application of specific guidelines would inhibit rather than promote humane care.

Sources of Information

The husbandry requirements of amphibians and reptiles in an academic setting are similar to those in zoos and aquariums ( Gans and Van den Sande, 1976 ; Gans, 1979 ; Murphy and Campbell, 1987 ; Murphy and Chiszar, 1989 ), and research in zoos has been a fruitful source of information about amphibians and reptiles ( Sajdak and 1983 ). Publications for herpetological hobbyists often provide useful guides for care of ectothermal vertebrates (e.g., Mattison, 1982 , 1988 ; Obst et al., 1988 ; de Vosjoli, 1989 , 1990a , b ; and journals like Lacefta, Reptile & Amphibian Magazine, Salamandra, and Vivarium). Herpetological Review, published by the Society for the Study of Amphibians and Reptiles, has a section called 'Herpetological Husbandry.' The International Zoo Yearbook usually contains sections about amphibians and reptiles, and much of Volume 28 (1989) of this series was devoted to their care. Symposia, newsletters, and special publications of herpetological societies are also helpful sources of information (e.g., Bowler, 1977 ; Murphy and Armstrong, 1978 ; Ferner, 1979 ; Murphy and Collins, 1980 ; Gray and Bumgardner, 1984 ; Gray, 1985 ; Gowen, 1987 , 1989 ; and the Bulletin of the Association of Amphibian and Reptilian Veterinarians). The professional staff at zoos and aquariums can often provide advice about the husbandry requirements of a particular species. Such advice may be particularly helpful in establishing breeding programs. Slavens (1989 ) publishes an annually-updated inventory of reptiles and amphibians in zoos and private collections; this volume can lead to an appropriate source of information about a particular species.

The diversity exhibited by amphibians and reptiles presents problems for husbandry that are not encountered with domestic and laboratory birds and mammals. Husbandry conditions must match the needs of the species being kept. Three factors are essential to achieve that goal:

1. Knowledge of the natural history of each species, obtained from field observations or from the literature;

2. Duplication of the features of the animals' natural microhabitats that are crucial for normal behavior and physiological function; and

3. Awareness and sensitivity on the part of caretakers to the unique requirements of these animals and the ways in which they manifest ill-health.

General Recommendations For the Care of Ectothermal Vertebrates

The following generalizations apply to the care of most amphibians and reptiles, but caution must be employed in their use. The taxonomic categories included are broad, and substantial variation exists within them. Some lizards, for example, are heliothermic and regulate their body temperatures between 38 and 42?C, whereas others live beneath the canopies of tropical forests with body temperatures that fluctuate between 25 and 30?C. Still others are nocturnal and active at body temperatures below 20?C. Similarly, some amphibians are entirely aquatic, whereas others may never see a body of water larger than a pool of raindrops on a leaf. While these guidelines emphasize the factors that are likely to be important for husbandry and point to general categories of problems and solutions, information about the ecology and physiology of the species being kept is indispensable.

The Physical Environment

Housing conditions must provide appropriate temperature, moisture, and light regimes. In general, these include visible and ultraviolet light controlled on a daily and seasonal cycle, water for drinking or bathing, and high relative humidity. High rates of air flow are not usually required in animal rooms housing amphibians and reptiles. Limiting the number of air changes per hour greatly simplifies the task of maintaining high humidities. In most cases the key to successful care of amphibians and reptiles lies in providing a gradient of conditions within the cage that allows animals to select combinations of environmental factors needed.

Temperature.

The thermoregulatory requirements of amphibians and reptiles are different from those of birds and mammals and are more difficult to satisfy in captivity. As endotherms, birds and mammals have continuously high rates of metabolic heat production, and ther-moregulation consists primarily of adjusting the insulating value of hair or feathers to equalize the rates of heat production and loss. Endotherms accomplish this regulation over a broad range of air temperatures. The radiative environments of the animal room and their cages normally have little significance.

In contrast, amphibians and reptiles balance heat uptake from the environment with heat loss to the environment ( Tracy and 1976 , 1982 ). Control of the radiant environment of the cage (in both the infrared and visible wavelengths) is especially important, because this is usually the major pathway of heat gain and loss. The thermo-regulatory behaviors of many species, especially reptiles, are based on adjusting position, posture, and reflectivity in response to radiant flux. These animals may be unable to respond appropriately to a uniform temperature or to a substrate temperature gradient. Lizards can be confused by unnatural combinations of temperature and light intensity. For example, lizards controlled their body temperatures more effectively in gradients that provided the normal stimulus of bright light and heat at the same end of the gradient than they did in gradients that were uniformly lighted or in those that combined bright light with low temperatures ( Sievert and Hutchison, 1991 ).

Photothermal gradients employing incandescent bulbs that produce both heat and light are probably the best choice for long-term care ( Regal and 1980 ). These gradients must provide cool retreat sites as well as warm basking spots for the animals. Because the body temperatures that many species of lizards maintain during activity are only a few degrees below their lethal temperatures, overheating is a substantial risk if gradients are poorly designed. The cage must be large enough so that one end always remains cool, and cages that incorporate photo-thermal gradients should never be covered with solid lids that prevent the escape of heat. Shelters should be placed along the length of the gradient so that animals are not forced to choose between thermoregulation and security. In most cases, a variable temperature regime is necessary ( Regal and 1967 , 1971 ). Animals kept continuously at the warm body temperatures they select voluntarily during activity may show deleterious physiological changes ( Licht and 1965 ). Transient exposure to high temperatures may suppress the immune system of reptiles (Elliott Jacobson, personal communication).

Choosing the range of temperatures that should be provided for a particular species requires information about its phylogenetic affinities and ecology. The thermoregulatory characteristics of groups of reptiles have been summarized ( Avery and 1982 ). In particular, Ford (in press) suggests appropriate temperatures for snakes. In general, amphibians are less heliothermic than reptiles, and the high rate of evaporative water loss characteristic of amphibian skin counteracts radiant heat uptake ( Lillywhite, 1975 ; Tracy, 1976 ). Nonetheless, adult and larval amphibians bask in the sun or use temperature gradients to regulate body temperatures. A thermophilic response after feeding and behavioral fever mediated by pros-taglandin E l have been reported for amphibians ( Lillywhite et al., 1973 ; Hutchison and Erskine, 1981 ). Substrate temperature gradients produced by heating elements beneath the cage floor may be more effective than photother-mal gradients, especially for nocturnal or secretive amphibians. The thermoregulatory characteristics of amphibians have been summarized ( Brattstrom, 1979 ; Hutchison, in press), and information about salamanders can be found in Feder et al. (1982 ) and the references therein.

Water.

A shallow container of water is appropriate for many amphibians and reptiles. However, some tropical species require daily spraying, and some desert reptiles never drink. Amphibians do not drink; terrestrial species absorb water through the skin and anurans have an area of skin in the pelvic region that is specialized for this function. Shallow water dishes, moist substrates, and spraying are appropriate for terrestrial amphibians. Chlorinated water should be avoided, especially for aquatic amphibians, and water bowls should be changed as often as practical because Pseudomonas populations increase rapidly in stagnant water (Etliott Jacobson, personal communication).

Humidity and Air Flow.

Most amphibians and reptiles are much smaller than laboratory mice ( Pough, 1980 , 1983 ). An adult white mouse weighs about 20 g, while nearly 80 percent of the species of lizards and frogs and 95 percent of the salamanders have adult body masses smaller than 20 g ( Figure 2 ). Indeed, 8 percent of lizards, 17 percent of frogs, and 20 percent of salamanders weigh less than 1 g as adults! These very small body sizes have important implications for husbandry (Pough, in press). In their natural environments, most amphibians and reptiles spend their time at the ground surface, under leaf litter, or in burrows. As a result they are exposed to microclimates (especially humidities and rates of air movement) that are very different from those perceived by large animals like humans. Even desert species spend much of their time in burrows or buried in loose sand. Relative humidity approaches saturation in these microhabitats, and the low humidities characteristic of heated and air-conditioned buildings can be stressful even for desert reptiles. Relative humidities should be maintained above 70 percent (preferably at 80 percent) for nearly all species of amphibians and reptiles. However, most reptiles develop skin lesions when they are kept on wet substrates for long periods.

Amphibians can often be kept in cages with lids to keep humidity high, but many reptiles require photothermal gradients. Putting a lid over a photothermal gradient quickly leads to lethal overheating of the animals inside. Instead, it is necessary to maintain high relative humidity in the entire animal room. Room air flow can be limited to a maximum of one or two changes per hour to maintain the humidities these animals require.

The large number of incandescent lights required in a room that houses 20 or 30 cages of lizards or snakes may produce more heat than the air-handling system can exhaust, especially when the number of air changes per hour is restricted to keep the relative humidity high. It is wise to incorporate thermostats to turn off the lights when room temperature approaches a level that is stressful for the least heat-tolerant species.

Light.

Quality and quantity of light may both be important to amphibians and reptiles. An annual cycle of day length is usually critical, especially for breeding colonies. Windows or skylights that admit bright sunlight without overheating the room are ideal, but are rarely included in animal rooms. In lieu of natural daylight cycles, timers can be used to control photoperiod on an annual cycle.

The wavelengths of light provided to captive amphibians and reptiles also require attention, but little is known about the effects of different light intensities and of varying ratios of wavelengths. A trial-and-error approach has been adopted by zoos and individuals who maintain these animals, and this body of anecdote constitutes nearly all the information currently available for most species.

Providing the proper amount and quality of ultraviolet light is probably the most difficult aspect of lighting. Some species of amphibians and reptiles appear to require ultraviolet light for calcium metabolism, normal behavior, and reproduction ( Cole and Townsend, 1977 ; Laszlo, 1969 ; Moehn, 1974 ; Townsend, 1979 ; Townsend and Cole, 1985 ; Regal, 1980 ). Middle-wavelength ultraviolet light (UVB) penetrates the epidermis and converts provitamin D ₃ to previtamin D 3. Synthesis of the active form of the vitamin (1,25-dihydroxyvitamin D3) by birds and mammals has been studied, but the process is not well understood for amphibians and reptiles, some of which have as many as six types of provitamin D ₃ in their skins ( Holick and 1989a ).

Some diurnal reptiles from open habitats have layers of melanin in the skin that block penetration of ultraviolet light ( Porter and 1967 ). These animals might require higher intensities of light than do species with more translucent skins. Preliminary information from work at the National Zoo suggests that green iguanas (Iguana iguana) cannot use dietary vitamin D 3, and must receive ultraviolet light for maintenance of blood levels of 1,25-dihydroxyvitamin D ₃ (Mary Allen, personal communication). Similarly, birds and mammals synthesize two types of vitamin D 3, and dietary 1,25-dihydroxyvitamin D ₃ would not substitute for cutaneous synthesis of 24-dehydrovitamin D ₃ ( Holick and 1989b ). However, several species of lizards have been raised successfully without ultraviolet light, in some cases for two or more generations, using dietary supplementation to provide vitamin D ₃ (Larry Talent, personal communication; Gehrmann et al., 1991 ).

We do not know exactly what wavelengths of light are required for vitamin D ₃ synthesis by amphibians and reptiles, nor do we know whether the ratio of middle-wavelength (290 to 315nm) to long-wavelength (315 to 400nm) ultraviolet light (UVA) is important. Gehrmann (1987 ) presented information about the spectra of several bulbs used in animal husbandry. Broad-spectrum fluorescent bulbs such as Vita-Lite? (Duro-test) and Chroma 50? (General Electric) may be effective ( Regal and 1980 ), although these lights, especially the Chroma 50 bulb, emit little energy in the middle-wavelength ultraviolet portion of the spectrum. (Note that, contrary to common misconception among hobbyists, Gro-Lux? bulbs do not emit much ultraviolet light, and they are not appropriate for UV supplementation, although they may be used in displays to support plant growth without harm to animals) ( Roberts and Gehrmann, 1990 ). Fluorescent BL (black light) bulbs provide long-wavelength ultraviolet light (UVA). Bulbs designated BLB (black-light blue) have a filter that passes only ultraviolet wavelengths; they are more expensive than BL bulbs, but no more effective for animal husbandry. Neither a twelve-hour daily exposure to Vita-Lite? nor a half-hour exposure to a Sylvania BL bulb was sufficient for normal calcification of young chickens ( Bernard et al., 1989 ), and the authors recommended that these bulbs not be used for captive animals.

Middle-wavelength ultraviolet light (UVB) is provided by fluorescent sunlamp bulbs of the sort sometimes used in treating psoriasis. In addition to the familiar tubular fluorescent sunlamps, self-ballasted reflector mushroom-type mercury lamps emit UVA and UVB radiation (William H. Gehrmann, personal communication). They are manufactured in 160 and 250 watt sizes by Philips Lighting Company and Iwaski Electric Company. National Biological Corporation (1532 Enterprise Parkway, Twinsburg, OH 44087) is a source of UVA and UVB bulbs. Middle-wavelength ultraviolet light can injure the eyes of animals and caretakers, and precautions should be taken to limit exposure. Species of reptiles differ substantially in the UV exposure they require ( Townsend and Cole, 1985 ; Gehrmann, 1987 ), and a conservative approach is advised. Exposure periods of 30-45 minutes at a distance of 50 cm from a UVB lamp may be satisfactory for reptiles from open habitats ( Moyle and 1989 ). UV irradiance at the midpoint of tubular bulbs is about twice as intense as irradiance at the ends ( Gehrmann and 1987 ). Breaking the daily UVB exposure into 10-15 minute periods at hourly intervals may help to ensure that all the individuals in a community cage have access to the light.

Snakes may normally satisfy their vitamin D ₃ requirements from their diet of whole animals (Ford, in press). Reptiles from forests, and amphibians in general, are probably more sensitive to UV light than are desert reptiles, and UVB bulbs are probably not appropriate for these animals. Early signs of UVB toxicity include failure to eat, lethargy, diminished activity, and a gray or smokey skin color that turns progressively darker (William Gehrmann, personal communication). All of these symptoms appear to be reversible when exposure ceases. Considering the potential risk posed by UVB bulbs to reptiles and their caretakers, a combination of broad-spectrum fluorescent bulbs and long-wavelength (UVA) bulbs is probably the most practical starting point for husbandry of a species with unknown requirements ( Townsend and Cole, 1985 ). The bulbs should be as close as possible to the tops of the cages, preferably within 15-20 cm of the animals. However, if symptoms of vitamin D ₃ deficiency are observed, it may be wise to consider providing a source of UVB radiation.

Because glass does not transmit middle-wavelength ultraviolet light and greatly attenuates longer wavelengths, it should not be used for cage tops. Wire mesh and some acrylic plastics and fluoroplastics transmit short-wavelength ultraviolet light and are suitable for cage tops ( Gehrmann and 1987 ).

The ultraviolet output of fluorescent bulbs decreases substantially after a few hundred to a few thousand hours of use. Unfortunately, this change is not apparent to the human eye, and can be easily overlooked until the animals' health is affected. Manufacturers can provide information about the useful life of their bulbs, and a regular schedule of changing bulbs will ensure that the animals are receiving ultraviolet light ( Townsend and Cole, 1985 ).

The Biological Environment

Most amphibians and reptiles are secretive. They live in close association with their structural microenvironments, and subtle cues--scent, texture, contact--are important aspects of their behavior. Animals of this sort do not thrive in barren steel cages or in plastic boxes filled with wood shavings; their husbandry requires housing that combines the animals' need for environmental cues with effective care and sanitation. Providing hiding places is of paramount importance for nearly all species.

Cage Furnishings.

Cage and aquarium props (e.g., branches, rocks, and substrate) should complement the normal lifestyle of the animal. A varied cage environment may be necessary for normal behavior; for example, the thermoregulatory and foraging behaviors of Lacerta vivipara break down in the absence of spatial diversity (Roger A. Avery, personal communication). Many species of amphibians and reptiles require materials that duplicate their natural settings for breeding. Terrestrial frogs such as Eleutherodactylus, Dendrobates, and Colostethus breed in captivity when they are given suitable nest sites. In nature these species deposit their eggs in smooth-surfaced fallen leaves, which should be included in the cage. Nearly all animals require a hiding place; opaque plastic boxes with small entrance holes make good retreat sites, and have the merit of being easily cleaned. Thigmotaxic stimuli may be nearly as important as the darkness that opaque shelters provide. Cobras used transparent plastic boxes as regularly as they used opaque boxes for hiding places when the two kinds were tested sequentially. However, in simultaneous presentations, the snakes always chose the opaque box ( Chiszar et al., 1987 ). It can be advantageous to be able to see an animal when it is in its retreat, and some situations may warrant the use of transparent shelters.

Amphibians and reptiles often ingest bedding material with food, and cage substrates should be chosen with this possibility in mind. Several substrates commonly used for bird and mammal cages are harmful for amphibians and reptiles. Appropriate substrates keep the animal dry, such as newspaper, indoor-outdoor carpet, sand (only for species that normally live in sand), gravel (smooth particles that are fine enough to pass through the digestive tract), crushed oyster shells (especially good for tortoises, large lizards, and snakes), hardwood mulch and bark chips, and peat and sphagnum moss. Materials that swell when they are swallowed, such as ground corn cobs, kitty litter, the pine shavings used in rodent cages, and cocoa shells, should not be used ( Demeter and 1989 ). Cedar shavings have neurotoxic properties and should not be used (Elliott Jacobson, personal communication). Aspen shavings (Animal Bedding #2, American Excelsior Co., Arlington, TX) have proven satisfactory for snakes (Ford, in press).

Many animals press their snouts against the walls of their cage as they explore, and rough or sharp surfaces may injure them.

Behavioral Interactions.

Many amphibians and reptiles are territorial in the field, and in captivity often form dominance hierarchies. Initially the establishment of these dominant-subordinate relationships is likely to involve fighting and the risk of injury, especially because the loser is unable to leave the cage. After hierarchies have stabilized, low-ranking individuals may be excluded from feeding, basking, or retreat sites ( Regal and 1971 ). Aggressive behavior often waxes and wanes seasonally. For example, courtship can lead to injury of a female that rejects a male's advances but is unable to escape from him. Caretakers must be alert to subtle departures from normal behavior that indicate incipient problems, as well as to the appearance of wounds and new scars.

Caretakers must also be aware of the sensory worlds of the animals and the stimuli that are important to them. For example, it is stressful for a plethodontid salamander to be moved into a cage that bears the scent of another individual, or to have pheromones from another salamander deposited on its body during handling (Jaeger, in press). Ovarian development of female lizards (Anolis carolinensis) has been reported to be accelerated by the sight of male lizards giving courtship displays, and retarded by watching aggressive interactions between males ( Crews and 1975 ).

Social interactions may be important components of the biology of some amphibians and reptiles. Crocodilians appear to be the most social reptiles, and parental care for young after hatching is probably universal among crocodilians ( Lang and 1987 ). Sibling groups of young crocodilians remain with one or both parents for extended periods--as long as 24 months for the American alligator ( Garrick and Lang, 1977 ; Hutton, 1989 ). Young American alligators spend the day together, basking on land or moving back and forth between land and water. At night the individuals disperse to forage, reassembling in the morning ( Deitz and 1979 (quoted in Lang, 1987 )). Vocalizations by juveniles and adults assist in maintaining these groups, and a distress call from a juvenile brings an adult to the rescue. Juvenile and adult crocodilians may continue to associate in social groups, sometimes segregated by age and sex. These social interactions have implications for management ( Lang and 1987 ), and the behavioral consequences of raising and maintaining crocodilians in isolation have not been studied. The possibility that behavioral imprinting of juveniles occurs during their association with their parents should be considered in husbandry programs.

Some lizards and snakes employ communal defecation, hiding, or egg-laying sites. Several lizards and a few snakes remain with their eggs, and prolonged association between mother and offspring has been reported for the Solomn Islands prehensile-tailed skink, Corucia zebrata (John Groves, personal communication). Parental care by some species of frogs extends to association between an adult and its tadpoles or hatchlings (see Duellman and Trueb (1986 ) for examples). I suspect that social interactions are more widespread among amphibians and reptiles than we currently realize, and in some cases may be components of successful husbandry.

Food.

The type of food and the rate of feeding should, at a minimum, ensure normal growth or maintenance of weight. (The nutritional requirements of breeding animals may be different from those only being maintained.) The low metabolic rates and high conversion efficiencies of ectotherms means that overfeeding of captive animals is more common than underfeeding. The food requirements of amphibians and reptiles vary widely; some species require nearly daily feeding, whereas others do best on three, two, or even one feeding per week. Very large snakes may benefit from still longer intervals between meals. In general, if a healthy animal that has adjusted to captivity does not accept food soon after it is offered, the food should be removed and the animal allowed to fast until the next feeding time. In salamanders, crocodilians, snakes, and lizards emaciation is first visible as concavity at the base of the tail and prominence of the lateral processes of the caudal vertebrae. The pelvic girdle of emaciated frogs is clearly outlined. While turtles exhibit fewer conspicuous signs of emaciation, with experience it becomes easy to recognize a turtle that feels too light for its size.

The foods that can be provided to amphibians and reptiles in captivity rarely resemble their natural diets, and the nutritional requirements of amphibians and reptiles are poorly understood. A varied diet is likely to be more nutritious and more readily accepted than a diet consisting of only one kind of food. Providing balanced nutrition for amphibians and reptiles is challenging, and a variety of opinions can be found in the literature. The following paragraphs emphasize points of agreement, but the references should be consulted for additional information and dissenting views.

Vitamins and Minerals.

The routine use of supplementary vitamins and calcium is often advised for amphibians and reptiles ( Campbell and Busack, 1979 ; Allen et al., 1986 ; de Vosjoli, 1990a; Staton et al., 1990 ), but generalizations about the quantities needed are difficult to formulate. Studies of lizards have revealed substantial interspecific and geographic variation in vitamin and mineral requirements, and the symptoms of vitamin deficiency or excess are similarly variable (Larry Talent, personal communication). Many multivitamin supplements don't state nutrient levels on their labels. Using a product without knowing whether it has, for example, 5000 or 50,000 IU of vitamin A per gram is dangerous (Mary Allen, personal communication).

As with UVB supplementation, we remain largely at a trial-and-error stage, and a conservative approach to vitamin supplementation is probably the best starting point for a species with unknown requirements. Selective supplementation of particular nutrients is preferable to a shotgun approach. For example, a calcium:phosphorus ratio of 1.5:1 promotes normal bone growth.

Food items can be dusted with a vitamin-mineral mixture just before they are offered to the animals; uneaten items should be removed from the cage. Most insects have low levels of calcium, and dusting them with a calcium/phosoporous mixture that adjusts the ratio is desirable. D-Ca-Fos? (Fort Dodge Labs, Fort Dodge, IA 50501) is a finely powdered mixture of vitamin D, calcium and phosphorus that can be applied to insects as small as fruit flies and pinhead crickets. Beta-carotene and vitamins C and E may also be beneficial, but excessive vitamin and mineral supplementation can cause problems (de Vosjoli 1990a). Feeding a balanced diet is preferable to supplementing an inadequate one.

The diets of anurans can be supplemented by putting slow-moving insects, such as mealworms and wax moth larvae in shallow dishes with powdered vitamins and minerals. When the frogs catch the insects, some of the powder adheres to their tongues and is ingested with the prey. Many lizards will eat a mixture of dry vitamin and mineral powders and fine silica sand from a dish (Larry Talent, personal communication).

Live Food.

Many amphibians and reptiles respond to movement and will ignore even their favorite prey if it is motionless. Live food is required for these animals, and husbandry of amphibians and reptiles often requires maintaining colonies of insects as well.

Insects.

Diets that alternate different kinds of live food are desirable, and a diet consisting solely of mealworms is notoriously unsatisfactory (e.g., Demeter, 1989 ). A combination of crickets (Acheta), mealworms (Tenebrio larvae), flour beetle larvae (Tribolium) and wax moth (Galleria) or fly larvae (Sarcophaga) is suitable for insectivorous lizards and amphibians. Roaches (Blaberus), king mealworms (Zoophobias), and fruit flies (Drosophila) are also standard food items for captive amphibians and reptiles. The insects must be healthy and well-fed if they are to be nutritious food. Insects that are not eaten promptly should be removed from cages, because they may attack the animals. Suggested diets and instructions for care of insects and other invertebrates are available in The Encyclopedia of Live Foods ( Masters and 1975 ), the Carolina Arthropods Manual ( Anonymous and 1982 ), and The Right Way to Feed Insect-eating Lizards (de Vosjoli, 1990a). Mary Allen (National Zoo) recommends monkey chow and dog kibble as a stock cricket diet.

The material in the gut of insects is an important source of nutrients for amphibians and reptiles, and insects can be nutrient-loaded to increase their food value. A high-calcium diet for crickets (Cricket diet #39-390) is available from Ziegler Bros., Inc. (PO Box 95, Gardners, PA 17325). This diet is intended for calcium-loading crickets before they are fed to amphibians and reptiles; it is not suitable for rearing crickets. The gastrointestinal tracts of crickets contained detectable quantities of calcium and phosphorus after 48 hours on the high-calcium diet (see Allen and Oftedahl, 1989 for details and suggestions).

Birds and Mammals.

Mice, rats, and hatchling chickens or quail should be euthanized by an approved method that does not leave a toxic chemical residue before they are fed to captive amphibians and reptiles. Asphyxiation with carbon dioxide is a satisfactory method of killing animals for this purpose.

Prepared Diets.

Although many amphibians and reptiles have narrow dietary preferences, some species can be trained to accept prepared foods that incorporate vitamin and mineral supplements. Good candidates for such dietary shifts are lizards and snakes that rely on scent to identify food. Skinks (Eumeces, Chalcides, and many other genera), tegus and dwarf tegus (Tupinambis and Callopistes), monitor lizards (Varanus), and natricine snakes (Thamnophis, Nerodia, and related genera) wilt often learn to accept canned cat and dog food. The odor of a fish-based food is sometimes particularly attractive, even to species that never see a fish in their natural state. Dietary shifts can be facilitated by introducing them gradually, a time-honored technique among reptile keepers (Weldon et al., in press). For example, a lizard that eats mice can initially be given mice with progressively more cat food spread on the fur, then cat food in a dish garnished with portions of a mouse carcass, and finally plain cat food. Not all of the commercial foods for reptiles and amphibians that are sold in pet stores provide a well-balanced diet, and advice about specific products should be sought from a qualified source. Many of the major zoos now have nutritionists who can provide helpful information.

Herbivorous Reptiles.

Many species of reptiles include some plant material in their diets. The most specialized of these are folivores (leaf-eaters). Prominent in this group are large lizards such as chuckwallas (Sauromalus), green iguanas (Iguana), ground iguanas (Cyclura), the Galapagos marine and land iguanas (Amblyrhynchus and Conolophus), Fijian iguanas (Brachylophus), mastigures (Uromastyx), the East Indian water lizard (Hydrosaurus), and the green sea turtle (Chelonia mydas). These species rely on fermentative digestion and show characteristic morphological and physiological specializations of the gut ( Iverson, 1982 ; McBee and McBee, 1982 ; Troyer, 1983 , 1984a ; Bjorndal, 1985 ; Bjorndal and Bolten, 1990 ). Food particle size, the ratio of fruit to foliage, and the ratio of plant to animal material can affect digestibility and the assimilation of energy and nutrients by herbivorous reptiles ( Bjorndal and 1989 , 1991 ; Bjorndal et al. 1990 ).

Nutritionally complete diets for herbivorous reptiles are commercially available. Ziegler Bros., Inc. (PO Box 95, Gardners, PA 17325) makes 15 percent and 25 percent crude protein meal-type diets for iguanas, and a variation of that diet in small pellets for desert tortoises. Marion Zoological (Marion, Kansas) makes an extruded diet of very small diameter for herbivorous reptiles. A mixture of 10 parts by weight of leafy greens to one part soaked dry dog food is a good alternative. The dog food should be soaked just enough to soften it because excess water can leach out nutrients (Mary Allen, personal communication). Chopped alfalfa hay is also accepted by tortoises, especially when it is mixed with greens.

The specializations of folivorous reptiles extend beyond morphology and physiology to include behavior and ecology, and these phenomena must be considered in husbandry. Like all folivores, reptiles are selective about the species and the parts of plants they eat. Juvenile iguanas choose leaves with low fiber and high protein content, and they accelerate digestion by maintaining body temperatures higher than those of adults ( Troyer, 1984b , 1987 ). Social behavior probably also contributes to folivory for iguanas. Newly hatched green iguanas spend a short time in the tropical forest canopy where adult iguanas live before returning to the forest-edge vegetation where they remain during their growth as juveniles. Apparently this brief association of hatchlings with adults facilitates the transfer of the gut symbionts responsible for fermentative digestion of plant matter ( Troyer, 1982 , 1984c ). Thus, juvenile folivores hatched in captivity and isolated from sources of normal symbi-onts probably do not have their species' typical complement of fermentative microorganisms. Although these individuals may grow and prosper on diets that do not require fermentation of plant cell walls, their digestive physiology is probably not typical of free-ranging individuals. This observation has important implications for laboratory studies that assume their subjects to be in a normal physiological state, and for husbandry programs that rear juveniles for release. In situations when digestive physiology is important, husbandry of folivorous reptiles should probably include a method of inoculating hatchlings with the species' typical gut symbionts. This may be a matter of substantial applied significance, because many folivorous species of reptiles are threatened or endangered, and captive breeding programs for some of them are planned or in progress ( Bjomdal, 1981 ; Burghardt and Rand, 1982 ; Miller, 1987 ; IUCN, 1989 ; Swingland and Klemens, 1989 ).

Housing and Sanitation.

Housing conditions should inhibit the presence and spread of disease. However, sanitation protocols should not frequently disturb the animals nor require complete removal of feces because many ectothermal vertebrates use pheromones, including constituents of feces, for intraspecific communication. Snakes kept in clean cages spend more time attempting to escape than do individuals in cages where a small amount of fecal matter is left each time the cage is cleaned ( Chiszar et al., 1980 ). Similarly, plethodontid salamanders mark their cages with pheromones in their feces, and salamanders in freshly cleaned cages make more attempts to escape than do salamanders in cages they have marked with their own scent ( Jaeger and 1986 and references therein). Thus, excessive cleaning or sterilization of cages can be deleterious to the well-being of the animals. The human nose is the most appropriate guide to cleanliness: No odor of waste products should be perceptible in the air of a room housing ectothermal animals. Application of this criterion is practical and effective because unsanitary conditions are readily detected when the number of changes of room air per hour is limited to maintain the high relative humidities amphibians and reptiles require.

Through-flow aquatic systems are less likely to spread pathogens than are recirculating systems. Chlorine should be removed from incoming water, which should be heated or cooled to the appropriate temperature before it is introduced to the animals' tanks. If a recirculating water system is necessary, each tank should have a self-contained system to minimize the chances of cross-contami-nation. A sterilization process may be a desirable component of recirculating aquatic systems.

Separate quarantine facilities are highly desirable for amphibians and reptiles, and newly arrived animals should be kept in cages isolated from long-term stock for at least 90 days (Elliott Jacobson, personal communication). Checks for parasites should be routine. These tests contribute to the health of the caretakers as well as to the welfare of the animals.

Marking Individuals

The ability to recognize individuals is critical to many studies, and methods of marking amphibians and reptiles were reviewed by Ferner (1979 ). In many instances individual variations in pattern allow even large numbers of animals to be distinguished without artificial marks. When this is not possible, several techniques can be employed, depending on whether long-term or short-term marks are needed. Clipping off portions of toes or scales has traditionally been used to mark individuals, but toe clipping in particular is painful and may affect locomotor ability, especially for arboreal species. Furthermore, some individuals regenerate the clipped toes or lose additional toes in fights. Freeze-branding appears to produce a mark that lasts one or two seasons. Passive integrated transponders (PIT tags) have been used successfully to mark amphibians and reptiles, and this appears to be the best method of permanently marking species that are large enough to accommodate the tag ( Camper and Dixon, 1988 ).

Breeding

The reproductive cycles of amphibians and reptiles are closely linked to their physical and biological environments, and effective breeding programs employ manipulation of these factors (e.g, Crews and Garrick, 1980 ). Case-studies are published in the newsletters and symposia of herpetological societies, the International Zoo Yearbook, and hobbyist literature. As with most other aspects of herpetological husbandry, we are at the stage of trial and error, and investigators should seek information about the species of interest to them from those publications and from the staffs of zoos and aquaria, many of which have successful breeding programs for several species.

Some generalizations will provide a starting point for establishing breeding programs. For example, manipulating temperature, humidity, and photoperiod on an annual cycle has been effective for many species. A period of 1 to 4 months of low temperature stimulates breeding for a variety of reptiles and amphibians, including some tropical species. This method has been applied successfully to snakes (e.g., Scheidt, 1984 ; Tryon and Whitehead, 1988 ), as well as to lizards, turtles, and amphibians. Animals must be allowed to fast before they are cooled, and a gradual reduction in temperature over a period of days is preferable to an abrupt change. Environmental temperatures can be lowered to 10°C for species from temperate zones, whereas warmer temperatures (18°C-20°C) are appropriate for tropical species. Most animals do not become torpid under these conditions, but emerge from their hiding places during the day and retreat at night. A short photoperiod is more natural than continuous darkness, and a daily temperature cycle may be desirable. Dehydration is a risk in environmental chambers that regulate temperature by passing air over refrigerating coils. The cages must prevent excessive water loss without allowing the continuous contact with wet substrates that is likely to produce skin lesions. As the end of the cool period approaches, the photoperiod should be lengthened and the temperature gradually increased. Animals undergoing this treatment are not in any sense in cold storage or suspended animation, and water dishes should be cleaned and refilled daily.

Seasons in some habitats, particularly in the tropics, are distinguished more clearly by rainfall patterns than by temperature cycles. Animals from these habitats may be induced to breed by simulated rain showers. This method was used by the Metropolitan Toronto Zoo to breed Puerto Rican crested toads (Peltophryne lemur) ( Paine et al., 1989 ). The breeding schedule is keyed to environmental conditions in the toads' natural habitat. In December, which corresponds to the late part of the rainy season in Puerto Rico, feeding is increased, and females receive newborn mice dusted with vitamin D ₃ and calcium supplements. In late January, when the dry season is beginning, the toads are put into a cage that has been filled with a water-soaked mixture of peat and sphagnum mosses. Ambient temperature is about 22°C, and the relative humidity is 50 to 70 percent. The toads burrow into the substrate, which dries slowly during the next month. A shallow water dish in the cage allows the toads to rehydrate when they emerge from the substrate at night. The toads are dug out of the moss and fed weekly. Feeding ceases at about the time the moss dries completely. The toads are kept for another month in the dry substrate, and checked regularly to see that they remain hydrated.

At the end of 60 days of dryness, a time that corresponds to the usual onset of the Puerto Rican rainy season, water is added gradually for two days until the moss is saturated with water, and the air temperature is raised to 27°C. On the morning of the third day, the males are transferred to tanks of water in which cultures of algae have been established. A spray of water simulates rainfall, and tape recorded mating calls of the toads are played to both sexes. The males are left in the breeding tanks for two days before the females are added. The presence of a group of toads appears to contribute to the formation of amplexing pairs, and amplexus normally begins very soon after the females are introduced. The simulated rainfall and recordings of mating calls are continued for another three or four days.

The Toronto Zoo's program illustrates the effectiveness of techniques that initiate the physiological changes associated with breeding by manipulating the physical and biological conditions that stimulate breeding in nature. Another approach is to administer exogenous hormones to initiate reproduction. This method has been widely used by embryologists to induce breeding by amphibians (e.g., Rugh, 1962 ; National Academy of Sciences, 1974 ), and the process is so simple that amphibian reproduction kits can be purchased from biological supply houses. Pituitary glands from amphibians or human chorionic gonadotropin have traditionally been employed for this purpose, but Goncharov et al. (1989 ) advocated the use of synthetic analogues of luteinizing hormone-releasing hormone. Caution in the use of these techniques may be desirable, because larvae produced by the administration of exogenous hormones might differ in morphology, growth rate, behavior, or viability from those obtained from breedings that result from endogenous endocrine cycles. An extensive literature of life-history studies testifies to the importance of maternal effects that are controlled by environmental variables such as temperature and energy intake during vitellogenesis (e.g., Kaplan, 1987 ). These interactions might be affected by interruption of normal reproductive cycles, and if exogenous hormones are to be employed, their use should be coordinated with the breeding cycle so that hormones are administered after gametes have matured ( Goncharov et al., 1989 )

The nutritional status of a female reptile during oo-genesis or pregnancy and the environment in which eggs are reared can affect characteristics of the clutch and of the offspring. In laboratory studies of viviparous and oviparous snakes the ratio of clutch mass (eggs or embryos) to female body mass remained constant under different feeding regimes, with the result that absolute reproductive effort (grams of offspring per female) was proportional to energy intake ( Ford and Siegel, 1989 ; 1991 ). That is, females that were well fed during oogen-esis produced larger litters than did females that received less food. In these experiments, only the number of offspring responded to maternal nutritional status, but in some species of reptiles the size and viability of the offspring might be affected. Viviparity has evolved at least 45 times among lizards, and another 35 times among snakes ( Blackburn and 1982 , 1985 ). Modes of fetal nutrition among viviparous reptiles encompass a spectrum from lecithotrophy (nutrients deposited in the yolk during vitell-ogenesis) to matrotrophy (nutrients supplied throughout development via a placenta). The skink Mabuya heathi, a Brazilian lizard, exhibits a nearly mammalian level of matrotrophy ( Blackburn et al., 1984 ). The newly ovulated egg is only I mm in diameter, and placental transport accounts for more than 99 percent of the dry mass of the fetus at birth. Another skink, Chalcides chalcides, a species that is used in biological studies, may also rely primarily on matrotrophy during embryonic development: the ova of C. chalcides are less than 3 mm in diameter at ovulation ( Blackburn et al., 1984 ). For these skinks, and for other reptiles with high levels of maternal input to the fetus, the nutrition of a female during embryonic development may influence the size and viability of the young she produces.

Temperature is an important factor in the embryonic development of reptiles. Normal morphogenesis is limited to a narrow range of egg temperatures for some species of reptiles, whereas others tolerate ranges as large as 10°C ( Packard and Packard, 1988 ). Temperatures outside those ranges may be lethal to the embryos, or may produce hatchlings with abnormal skeletons, scale patterns, or pigmentation ( Vinegar and 1973 ), as well as differences in post-hatching survival ( Whitehead et al., 1990 ). Snakes hatched from eggs that had been incubated at intermediate temperatures performed better in several behavioral tests than hatchlings from higher and lower incubation temperatures ( Burger and 1989 , 1990 ), and alligators from eggs incubated at intermediate temperatures grew faster and survived better than those from higher or lower temperatures ( Joanen et al., 1987 ). Temperature-dependent sex determination has been demonstrated for species in seven families of turtles, for crocodilians, and for a few lizards (summarized by Paukstis and Janzen, 1990 ).

The wetness of the substrate on which reptile eggs are incubated affects the length of the incubation period and the size and robustness of the hatchlings ( Packard and Packard, 1988 ). The same phenomenon has been demonstrated for one species of frog ( Taigen et al., 1984 ). The largest and most vigorous turtle hatchlings are usually produced by incubating eggs in wet substrates (water potentials of-100 to -200 kPa) at the lowest tolerable temperatures (Gary C. Packard, personal communication). However, this advice must be modified for species that display temperature-dependent sex determination to avoid producing hatchlings of only one sex. As a rule of thumb, temperatures that produce incubation periods similar to those observed in the field are likely to be satisfactory ( Miller and 1987 ). Unlike the eggs of birds, reptile eggs should not be turned during development.

Environmental Conditions and Medical Care

A discussion of the veterinary requirements of amphibians and reptiles is beyond the scope of this review, but the importance of environmental conditions, particularly temperature during illness and following surgery should be noted. The role of temperature in reptilian health management was reviewed by Mader (1985 , 1991 ). Fishes, amphibians, and reptiles maintain elevated body temperatures when they are injected with pathogens, and this behavioral fever is associated with increased survival compared to animals that are prevented from raising their temperatures ( Vaughn et al., 1974 ; Kluger, 1977 , 1979 ). The immune response of reptiles is temperature-sensitive ( Evans and Cowles, 1959 ; Evans, 1963 ; Cohen, 1971 ; Elkan, 1976 ), and antibiotic therapy also may be most effective at high temperatures ( Mader et al., 1985 ). Because behavioral fever is a normal response of reptiles and amphibians to endogenous pyrogens, it may be desirable to allow the animals to control their febrile response during antibiotic treatment and following surgery by keeping them in thermal gradients so they can warm themselves several degrees above their normal activity temperatures.

Health Precautions for Release of Animals

The release of amphibians and reptiles that have been held in captivity is potentially damaging to the health and the genetic composition of wild populations. It should be prohibited in almost all cases. Cross-contamination of animals with pathogens is nearly unavoidable in captivity, and amphibians and reptiles that are obtained from dealers have been exposed to a wide range of microorganisms that they would not encounter in their natural habitats. If these animals are released, the pathogens they carry can spread to the wild population with potentially disastrous results. From 1987 to 1990 an outbreak of upper respiratory distress syndrome (an infection by Pasturella testudinis and Mycoplasma spp.) reduced the population of desert tortoises at the Desert Tortoise Natural Area in California from an estimated 1000 individuals to 30 survivors. The outbreak may be associated, at least in part, with the release of captive tortoises by well-meaning individuals (Elliott Jacobson, personal communication).

Even in the absence of disease, the introduction of individuals from a distant part of a species' range can change the genetic composition of local populations, and exotic species may establish populations that compete with native species. A recent summary lists more than 20 exotic species of reptiles and amphibians that have become established in the United States ( Conant and Collins, 1991 ).

Under some circumstances the release of animals does not pose a risk, or the risk can be justified. If animals are rigorously isolated from any contact with other species while they are in captivity and are returned to their sites of capture, no harm is likely to result. Work with threatened or endangered species may require the release of animals after they have been in captivity. In this case, the animals should be kept isolated from other species, and from individuals of other populations of their own species. They should be thoroughly screened for parasites and pathogens before they are released. Institutional animal care and use committees must be alert to the dangers associated with releasing animals. Committee members must expand their view of animal welfare to consider impacts on wild, as well as on captive populations. Unfortunately, the only possible option for animals that do not meet the criteria for release may be euthanasia.

Health Precautions for Animal Caretakers

Most amphibians and reptiles pose no greater risks for caretakers than do birds and mammals. Normal precautions include washing the hands after working with the animals or their feces. A dust mask should be worn when cages containing dry fecal material are cleaned. Salmonella is frequently associated with reptiles, and its presence should be assumed unless several cultures of fresh feces have given negative results.

Some amphibians have potent skin toxins, and a few species can be dangerous to humans (e.g., Phyllobates terribilis; see Myers et al., 1978 ). Venomous snakes are potentially dangerous to caretakers, as are the two species of venomous lizards (the gila monster and Mexican beaded lizard, Heloderma suspectum and Heloderma horridum). Dangerously venomous snakes are not limited to vipers, elapids, and sea snakes; many colubrid snakes are venomous and some of these can be dangerously toxic to an animal as large as a human. Gans (1978 , appendix 2) lists more than 40 species of venomous colubrids.

Husbandry of dangerously venomous snakes is a specialized activity involving legal and ethical responsibilities that are beyond the scope of these general recommendations. Most research programs do not require venomous snakes, and they should not be kept in an academic institution without a compelling reason to do so. Gans and Taub (1978 ) discuss the precautions that are necessary for housing venomous snakes, as well as the daunting legal implications of keeping these potentially dangerous animals.

Summary

Successful husbandry of amphibians and reptiles must be based on an understanding of the ways in which they function as intact organisms. That is, one must know what physical and biological factors are important to them, how they interact with their environments, and how they exhibit signs of good or poor health. While the same principle applies to the care of a laboratory mouse, amphibians and reptiles are sufficiently different from mammals that our intuitive sense of what makes a suitable environment is not a satisfactory guide. Standards based on mammalian husbandry are likely to be detrimental to amphibians and reptiles. Intuition must be replaced by an understanding of the unique characteristics of ectothermal vertebrates and how these characteristics affect husbandry. Amphibians and reptiles are wild animals and we must adapt our laboratory techniques to their needs; we cannot expect them to adjust their biology to suit our convenience.

Fred Quimby and Larry Carbone of the Center for Research Animal Resources at Cornell University first encouraged me to prepare this review and provided assistance in many ways. I am grateful for their help, and for their commitment to providing the best possible care for animals at Cornell. The topics covered here extend far beyond my personal experience and rely on the contributions of colleagues at many institutions who read drafts of the manuscript in various stages of its preparation, pointed out references, and provided general information and specific details of their work. Mary Allen and B~la Demeter (National Zoological Park); Robin Andrews (Virginia Polytechnic Institute and State University); Roger Avery (University of Bristol); Cynthia Carey (University of Colorado); Jay Cole (American Museum of Natural History); Lloyd Dillingham, Gabriel Foo, Jessica Geyer, Nell Heinekamp, Paula Hintz, Barbara Lok, and Jennifer Weinheimer (Cornell University); Katherine Graubard and Ellen Smith (University of Washington); Robin Green-lee and Charles Radcliffe (San Diego Zoo); Neil Ford (University of Texas at Tyler); William Gehrmann (Tarrant County Junior College); John Groves (Philadelphia Zoological Garden); Elliott Jacobson (University of Florida); James Murphy (Dallas Zoo); Gary Packard (Colorado State University); Larry Radford (Buffalo Zoo); Richard Shine (University of Sydney); Larry Talent (Oklahoma State University); and Katherine Troyer (U. S. National Museum of Natural History) generously shared their experience and opinions. The development of techniques for husbandry of amphibians and reptiles in my laboratory has been supported by a series of grants, including funding from the National Science Foundation and the National Institutes of Health. The most recent sources of support have been grants from the Hatch (Project NYC 183-412) and McIntire Stennis (Project NYC183-572) programs.

References

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Recommendations for the Care of Amphibians and Reptiles in Academic Institutions | ILAR Journal | Oxford Academic

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© Institute for Laboratory Animal ResearchAmphibians and reptiles differ in many respects from the mammals and birds most commonly used in biomedical research. These differences affect the physical and biological requirements of amphibians and reptiles in captivity. In this contribution, some basic biological characteristics of these animals are described that are relevant to their husbandry.

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Magazine

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By Margaret A. Wissman, DVM, DABVP

My box turtle is peeling his skin, and I read in the book I got about them that that is not ok for them to do. It says that he is getting too much vitamin D3 and not enough vitamin A. Do you know what fruits and vegetables contain that vitamin? I've tried strawberries, but he doesn't like them.

Can you put chameleons and tree frogs in the same cage together? I've also heard that you're not supposed to hold chameleons all that much. Is that true? Also my dumb boyfriend is wanting to buy a bearded dragon, and he wants to keep it at my house. The only problem is he is trying to put it in the same cage as the chameleons and tree frogs. Even though the cage is big enough, I want to know if it is OK to do.

I am so glad you wrote in to ask me about this. While it is very cool to have a mixed herpetarium with different species, one must always ensure that those reptiles and/or amphibians are compatible and that the environmental conditions are suitable for the different creatures.

Unfortunately, this is not the case for a tree frog, box turtle, chameleon and bearded dragon. Bearded dragons are from arid desert areas in Australia. They require high heat and low humidity, and their daytime temperature range is 75 to 85 degrees Fahrenheit with a focal hot spot of 110 degrees F. Being amphibians, tree frogs require higher humidity and a cooler environment. If you tried to keep the temperature range high enough for the beardie, you would end up dehydrating your tree frog, resulting in its untimely demise. I don't know what kind of tree frog you have, so I cannot offer more specific recommendations. It would be safest to house your chameleons and tree frogs in separate habitats.

Chameleons are happiest -- if we can use that term -- and do best when housed as solitary creatures. For the most part, chameleons are only combined for breeding purposes, yet for convenience, many breeders house hatchlings and juveniles together. This is a temporary situation. When I read your letter, you said "chameleons," so I wonder if you are housing more than one chameleon per enclosure. If so, you should consider other options. It may be possible to house several juvenile chameleons in a large habitat with dense plants. This provides them with hiding spots, visual barriers and places of escape, but this should still be considered a temporary fix. Chameleons should be housed separately as they mature.

Even though chameleons appear gentle and tame, it is generally believed that handling is very stressful to them. When stressed, some creatures will lash out, bite, kick, whip their tails or hiss, but many chameleons won't show any outwards signs of stress when handled. That doesn't mean they are not affected by it. Handling should be kept to a minimum. It is possible to injure a chameleon by pulling it off a branch. A claw could get damaged or even ripped off. The injury often becomes infected and causes soft tissue and/or bone infections, which can be very serious.

I also don't recommend purchasing a new reptile and just plopping it into an enclosure with other established residents. It is very important that new acquisitions should be quarantined to prevent the introduction of disease to the animals already in residence. Also, during quarantine, new herps should be examined and tested by a qualified herp vet to ensure they are healthy. This way any necessary treatments can be administered during quarantine.

Now onto your box turtle questions. All reptiles lose their skin periodically. Chelonians (turtles, terrapins and tortoises) continually shed their skin in pieces or sheets, so the peeling you describe may be normal.

If you have any concerns about your box turtle, schedule an appointment with a herp veterinarian in your area to have him examined. As for feeding him, your box turtle will benefit from consuming a commercial box turtle pelleted diet, which should provide a balanced variety of nutrients. Also add nutritious vegetables, a small amount of fruits and a few insects (snails, slugs, mealworms, crayfish, frogs, tadpoles, lizards, fish, earthworms or crickets) several times per week.

You didn't say what kind of box turtle you have, so I can't give you specific help regarding husbandry and the like. If the peeling skin is see-through and coming off in little chunks, then that is probably normal. However, if the skin underneath is red, thickened or abnormal in any way, or if your turtle has an odor to it, then a herp veterinarian should examine him as soon as possible.

Box turtles usually exhibit vitamin A deficiency with swollen eyes. Box turtle pellets should contain adequate amounts of either vitamin A or beta carotene, which turtles convert into vitamin A. I doubt your box turtle is suffering from an overabundance of vitamin D3. Unfortunately, you can't trust everything you read. Beta carotene can be found in dark green leafy vegetables, orange vegetables (sweet potato, carrots, bell peppers) and green, red and orange fruits.

Please don't let your boyfriend attempt to house a new baby bearded dragon with chameleons and tree frogs. It's a bad combination because they all require different habitat temperature and humidity parameters.

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Keeping Different Herps And Reptiles In The Same Cage

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By Margaret A. Wissman, DVM, DABVP My box turtle is peeling his skin, and I read in the book I got about them that that is not ok for them to do. It says that he is getting too much vitamin D3 and not enough vitamin A.

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Our position

A rabbit's best companion is another friendly rabbit. A guinea pig's best companion is another friendly guinea pig. Keeping rabbits and guinea pigs together is not an ideal combination.

Historically, rabbits and guinea pigs were kept together, providing companionship for each other when neutering rabbits was considered unsafe. Now rabbits of both sexes and male guinea pigs are routinely neutered safely. Therefore rabbits may more appropriately, be kept with other rabbits, so it's unnecessary to keep them with guinea pigs.
We advise against keeping rabbits and guinea pigs together as:

They have different needs (e.g. dietary). Unlike rabbits, guinea pigs cannot synthesise vitamin C which must be provided adequately within their diet.

Rabbits may injure guinea pigs, intentionally or unintentionally:
-by kicking them with their powerful back legs,
-trying to mate with them (e.g. could injure the guinea pig's back).

Rabbits may bully guinea pigs, which can make them stressed if they cannot get away. The bacteria, Bordetella bronchiseptica,is the most common cause of respiratory disease in guinea pigs. Rabbits, cats and dogs can carry this bacteria which can pass to guinea pigs and cause disease. Therefore, guinea pigs shouldn't be housed with rabbits, and should be kept away from dogs and cats.

Rabbits behave and communicate in very different ways to guinea pigs, so if kept together they won't understand each other's behaviour and therefore do not make ideal companions.

What if rabbits and guinea pigs currently live together?

If they get on well, it's best not to separate them as this could cause welfare problems. This advice should help ensure the welfare needs of both are met:

Guinea pigs must have constant access to safe hiding places to escape to; with an entrance large enough for the guinea pig, but too small for the rabbit to enter.

They need different diets, so may need feeding separately, to ensure both get the correct nutrients.

Neuter the rabbit; otherwise they may stress/injure the guinea pig with mounting behaviour/bullying.

Your vet will provide further advice about meeting animals' welfare needs.

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Keeping rabbits and guinea pigs together - RSPCA

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A rabbit's best companion is another friendly rabbit. A guinea pig's best companion is another friendly guinea pig. Keeping rabbits and guinea pigs together is not an ideal combination. Historically, rabbits and guinea pigs were kept together, providing companionship for each other when neutering rabbits was considered unsafe.

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A Guide To Buying, Keeping, Breeding And Selling Domestic Rabbits

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A Guide to Buying, Keeping, Breeding and Selling Domestic Rabbits by Chantelle Saunders

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First published in 1953, Animal Behaviour is a leading international publication and has wide appeal, containing critical reviews, original papers, and research articles on all aspects of animal...