Contributor: Tim Moore

At an odontocete (toothed whales, a parvorder of Cetacea) rehabilitation center in the Netherlands, researchers observed white-beaked dolphins engaging in mutually beneficial cooperation with humans and altruism towards harbor porpoises. The first instance of mutually beneficial cooperation involved a juvenile dolphin cooperating with staff by helping to herd the porpoise towards the corner of the pool where the staff could tube feed it and give it medication.

The second instance of observed altruism occurred on a separate date when a male harbor porpoise was placed into the same pool as two juvenile female white-beaked dolphins, who would flank him on either side while swimming. When a second juvenile male porpoise was added to the pool, each dolphin would swim flanking the left side of each porpoise, creating a shield between the porpoises and the concrete walls of the pool.

A proposed explanation for this is that perhaps the dolphins had mistaken the porpoises to be infant dolphins. However, this explanation was deemed unlikely given the very different vocalizations of dolphins and porpoises. Another proposed explanation is that the behaviors exhibited by the dolphins ultimately benefited themselves by creating a less stressful situation.

These observations are interesting as cooperation with other species is a rare occurrence among animals, and altruistic behavior towards other animals is even more so. The observations are however limited in that the samples were very small, with there only being two observed groups containing only one and two dolphins in them, respectively.

Contributor: Tracy HooSang

Humpback whales are known to interfere with attacking killer whales. What causes this to happen? Researchers looked at 115 descriptions of encounters between humpback whales and killer whales to figure out why. Killer whales regularly attack the young and juveniles of other species resulting in high mortality. Humpback whales rely on their bulk, power, and oversized appendages to ward off attackers. Humpback whales are categorized as fight species, for example, they exhibit a defensive fight style as a group to ward off killer whale attacks (Pitman, et al., 2017). 

The researchers compiled published and unpublished observations of interactions between humpback whales and killer whales, recorded over a sixty-two-year period from 1951 to 2012. The researchers analyzed the data and compiled 115 interactions from various locations, but the majority came from the eastern North Pacific Ocean. Interactions between humpbacks and killer whales were often agonistic and occasionally lengthy, although which species acted offensively and which defensively depended heavily on the killer whales' ecotypes and which species approached the other first. 103 out of 115 interactions humpback whales approached killer whales more often when mammal-eating was occurring or attacking. When humpback whales approached or were approached by killer whales they always displayed offensive and defensive behaviors. Researchers also found that when lone humpback calf pairs were attacked, the mother was sometimes able to drive off the killer whales by herself. Killer whales would try to separate the humpback calf from its mother, so the humpbacks would take specific countermeasures. Other humpbacks would guard the mother and calf and escort them to their desired location (Pitman, et al., 2017). 

Researchers found that humpback whales not only interfere when their own species are being attacked but when other species are being attacked as well. For example, a gray whale calf with its mother, seals, or sunfish. Humpbacks face little risk of serious injury, and they gain no obvious benefits for their time and energy spent. If this behavior included an increase in fitness, involved kin selection, or reciprocity it would have more benefits (Pitman, et al., 2017). 

Killer whales approaching humpbacks were virtually entirely mammal-eating species, and they appeared to be on the lookout for calves or juveniles to attack. When humpback whales approached killer whales, they were picky about which killer whales they interacted with since there was a cost. Humpback whales exhibited antipredator behaviors, which are all of an organism's actions aimed at avoiding being captured, harmed, or killed by another organism. They also exhibited cooperative defense behaviors to protect young and other species. Altruistic behaviors of cetaceans have only been found when responding to calves or when other cetaceans are injured (Pitman, et al., 2017). 

The observations were very interesting and were useful in advancing our understanding of altruistic behaviors in cetaceans. Altruistic behaviors are not common for cetaceans. The study had a large sample size allowing in-depth analyses of all areas, which include mobbing behavior, kin selection, reciprocity, and altruism. 

Future research questions are needed to explain this altruistic behavior. 

Potential Future Research Questions (Group 6):

Kastelein, R. A., Jennings, N., & Huijser, L. A. (2022). White-beaked dolphins (lagenorhynchus albirostris) cooperating with humans and showing altruism toward harbor porpoises (Phocoena phocoena). Aquatic Mammals, 48(1), 75–82. https://doi.org/10.1578/am.48.1.2022.75

Nowbahari, E., & Hollis, K. L. (2010). Rescue behavior. Communicative & Integrative Biology, 3(2), 77–79. https://doi.org/10.4161/cib.3.2.10018

Pitman, R. L., Deecke, V. B., Gabriele, C. M., Srinivasan, M., Black, N., Denkinger, J., Durban, J. W., Mathews, E. A., Matkin, D. R., Neilson, J. L., Schulman, J. A., Shearwater, D., Stap, P., & Ternullo, R. (2017). Humpback whales interfering when mammal-eating killer whales attack other species: Mobbing behavior and interspecific altruism? Marine Mammal Science, 33(1), 7–58. https://doi.org/10.1111/mms.12343