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This article talks about "Aquarium of the World", or in other words the gulf of California  in Northwestern Mexico and the harmful impacts that have occurred to it. These islands and areas are home to a great biodiversity of marine life. keeping these islands maintained and safe could lead to great economical development.

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This article talks about "Aquarium of the World", or in other words the gulf of California  in Northwestern Mexico and the harmful impacts that have occurred to it. These islands and areas are home to a great biodiversity of marine life. keeping these islands maintained and safe could lead to great economical development.

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Outstanding Universal Value
Brief synthesis
The Gulf of California in Northwestern Mexico, once famously dubbed the "Aquarium of the World", is recognized as an area of global marine conservation significance. Less known but equally spectacular are the terrestrial conservation values of the islands and coastal areas most of which are part of the Sonoran Desert. As a serial property, Islands and Protected Areas of the Gulf of California includes representative components of all major oceanographic zones of the biogeographically diverse Gulf, thereby capturing a broad spectrum of landscapes and conservation values. Extending from the Colorado River Delta in the north to 270 kilometres southeast of the tip of the Baja California Peninsula, the property includes 244 islands and islets clustered in eight major groups and another nine protected areas with coastal and marine zones. The total area is 1,837,194 hectares, of which about one quarter are terrestrial and the remainder marine.

The rugged islands and coastal desert contrasting with the surrounding turquoise waters are of striking natural beauty. Speciation both on land in the many islands and in the Gulf has resulted in a notable diversity of life forms with a high degree of endemism. The productivity of the Gulf also leads an extraordinary natural abundance of many marine species. There are some 900 species of fish, around 90 of them endemic, and roughly one third of the World's marine mammals occur within the property. The islands and islets are mostly of volcanic origin. There are numerous species of succulents, including some of the World's tallest cacti, exceeding 25 meters in height. Overall, some 700 species of vascular plants have been recorded. There are many species and impressive numbers of resident and migratory birds with some small islands hosting major proportions of the global population of Heermann's Gulls, Blue-footed Booby and Black Storm Petrel.

Criterion (vii): The serial property is of stunning landscape beauty with dramatic contrasts between the rugged and seemingly inhospitable islands, coastal deserts and the brilliant reflection from the surrounding turquoise waters. High rocky cliffs and sandy beaches in countless forms and colours rim the islands and coasts. The beauty of the desert landscape is complemented by the fascinating and highly diverse desert vegetation and the ubiquitous birds. To the south, the islands are covered with deciduous vegetation and stand out from the vast blue sea. The diversity and abundance of marine life associated with spectacular submarine terrain and unusual water transparency turn the underwater seascape into a globally renowned diver's paradise.

Criterion (ix): A major foundation of the Gulf of California's phenomenal marine productivity are nutrient-rich upwelling oceanic currents supporting abundant phytoplankton and zooplankton, which in turn provide nurseries for larval reef fish. However, many other oceanographic processes, such as wind-driven currents, tidal mixing and thermohaline circulation, occur in the property, giving it extraordinary importance for conservation and the study of marine and coastal processes. The Gulf of California is notable for containing ecologically distinct bridge islands, populated across past land bridges, and oceanic islands populated by sea and air. The multitude and diversity of islands in terms of origin, size, environmental conditions and distance to the mainland has enabled an ongoing evolutionary speciation and endemism of major significance for conservation and science. The many components of the property are both part of a vast landscape and distinctive in many ways, ranging from a variety of pelagic and benthic environments to coral reefs, as well as mudflats, coastal wetlands and various types of desert and deciduous forest.

Criterion (x): The diversity of terrestrial and marine life in the property is extraordinary and constitutes a global priority for biodiversity conservation. On land, the close to 700 species of vascular plants are notable within a desert environment. There are 115 species of reptiles, almost half of them endemic, in some cases even to individual islands. 154 land bird species have been recorded and the property is of particular importance to migratory species. Almost 900 species of fish have been documented with some 90 species occurring exclusively in the Gulf of California or parts of it. These include the critically endangered species Black Sea Bass and Totoaba, as well as the vulnerable Basking Shark. The serial property provides habitat for roughly one third of the world's total number of marine mammals, sometimes in impressive numbers, for example huge colonies of California Sea Lion. The five species of dolphin include the critically endangered Gulf Porpoise or "Vaquita". Eleven species of whale visit the northern Gulf, such as the endangered Blue Whale and Fin Whale and the vulnerable Sperm Whale. The coral reef at Cabo Pulmo is one of the most important in the Gulf of California and in the eastern Pacific. The marine habitats also harbour large concentrations of macro-invertebrate life with many endemic species, especially in the intertidal zones.
Integrity
All of the marine area and most of the 244 islands of the serial property are federally owned with only very few in private hands. Private owners typically do not live on the islands and the majority of the islands have no inhabitants, with some containing small settlements and camps of fishermen. Isla Maria Madre has been a state penitentiary since 1905. One particularity is the uninhabited Isla Tiburon (Shark Island), which is communally owned by the Seri indigenous peoples. The Seri consider the island a sacred site and carry out ceremonies. Overall, the past human impacts on land, for example from guano extraction and egg collection, are moderate. The serial approach is an adequate reflection of the biogeographic range and diversity of the Gulf of California and its islands. The great challenges to the integrity of the marine and coastal areas mostly stem from developments outside the protected areas, most importantly excessive fisheries, tourism and coastal development. Further extensions, including of vulnerable coastal areas and additional islands is an explicit element of the regional conservation strategy and would help consolidate the integrity of the property and the entire Gulf of California.
Protection and management requirements
The vast serial property has a step-wise formal conservation history going back at least to the 1950s. All of the islands within the property have a formal protection status under Mexican environmental legislation. While all of the marine area and most of the islands are federally owned, even the privately owned islands are bound to conservation and management requirements determined for each protected area at the time of its declaration and refined in management plans. All islands are protected and managed by the National Commission for Natural Protected Areas (CONANP), a specialized agency of the Mexican Ministry of the Environment and Natural Resources cooperating with several other involved governmental agencies. CONANP being a decentralized agency, management activities are implemented by the pertinent regional branch and their local operational units. Conservation, management and research are financially and technically supported by a number of local, national and international non-governmental organisations. There is an Integrated Management Program guiding conservation and management activities in the entire serial property and co-management arrangements with local communities are sought. Major challenges in the operational management are the securing of long-term funding, as well as coordination and cooperation across five different states and differing formal conservation status of components.

The coasts of the Gulf of California and the larger islands close to the shore were historically settled before imported diseases severely decimated the indigenous cultures. More recently, guano and egg collection, hunting of sea lions and whaling occurred in the Gulf of California. Most such activities have long been phased out leaving the affected areas to recover naturally. Threats today include, on land, alien invasive species with herbivores and predators menacing the delicate small island systems. The biggest, ongoing impact on the marine conservation values stems from artisanal, industrial and sport fishing. Fisheries and shrimp trawling play an important role in the local economy but put ever more pressure on the resources. Management responses are needed to ensure that harvesting levels are adapted to the productivity in the entire Gulf. Looming potential threats include plans for large-scale tourism development. While adapted forms of tourism can have important benefits in terms of awareness-raising and conservation funding, some proposed projects appear incompatible with long-term conservation and local development objectives. From the coasts pollution from agriculture, industry and sewage are increasing. The Gulf of California is a global conservation gem, invaluable to science and as a resource for local economic development, namely fisheries and tourism. Investing in the property's conservation is an investment in the maintenance of its productivity and economic potential.

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Islands and Protected Areas of the Gulf of California

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The site comprises 244 islands, islets and coastal areas that are located in the Gulf of California in north-eastern Mexico. The Sea of Cortez and its islands have been called a natural laboratory for the ...

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Documentary about the local people of Mexico (Baja California) being dedicated to protecting their natural wonders.

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Documentary about the local people of Mexico (Baja California) being dedicated to protecting their natural wonders.

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Baja California: the opposite of beach tourism | WIDE

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This is a picture of the Black Sea Bass. The Black Sea Bass is an endangered marine life species in the gulf of California. 

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This is a picture of the Black Sea Bass. The Black Sea Bass is an endangered marine life species in the gulf of California. 

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 The Sea of Cortez is one of the most important seas for studying these marine mammals. It is also popular for its beautiful light blue color.

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 The Sea of Cortez is one of the most important seas for studying these marine mammals. It is also popular for its beautiful light blue color.

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scuba diving kayaking beach sea kayaking fish map sharks sailing coral reef la paz

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This is a picture of a Basking Shark, an endangered species in Baja California. The basking shark is the second-largest living shark and fish.

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This is a picture of a Basking Shark, an endangered species in Baja California. The basking shark is the second-largest living shark and fish.

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The Gulf Porpoise or "vaquita" is a dolphin that is facing imminent extinction in Baja California. It is also the smallest porpoise species.  

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The Gulf Porpoise or "vaquita" is a dolphin that is facing imminent extinction in Baja California. It is also the smallest porpoise species.  

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drawing endangered cute rare animal fish national geographic vaquita marina phocoena sinus the vaquita dolphin

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This is a picture of a Blue-Footed Booby, an endangered species located in Baja California. These birds do a special dance to attract their mates. 

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This is a picture of a Blue-Footed Booby, an endangered species located in Baja California. These birds do a special dance to attract their mates. 

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red high resolution dance bird sleeping green little einsteins happy galapagos island clipart

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This article talks about how there has been a new protected area added in Baja California. This article shows that there is an effort being made to save the gulf and all of the live it holds.

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This article talks about how there has been a new protected area added in Baja California. This article shows that there is an effort being made to save the gulf and all of the live it holds.

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The Monte Ceniza Nature Reserve was certified as a Natural Protected Area, in the category of Area Voluntarily Destined for Conservation, that certification was managed through SEMARNAT and CONANP, environmental authorities in Mexico.

"We have worked on different protection projects in the peninsula of Baja California, and the idea is that we continue to collaborate and strengthen these projects together with our allies", said the National Commissioner of Natural Protected Areas in Mexico, during the opening ceremony in Ensenada, México.

The commissioner mentioned that the Monte Ceniza Nature Reserve is part of the 10 areas protected in that category in Baja California, of 379 that currently exist in the country.

The Monte Ceniza Nature Reserve has an area of 1984.26 acres and it is located in San Quintín Bay, this reserve is protected and managed by Terra Peninsular together with CONANP.

The reserve is home to a significant number of mammals, reptiles and amphibians, some of the species are catalogued as endangered or threatened by the Mexican norm NOM-059-SEMARNAT-2010.

Some of these species are: Baja California Whiptail ( Aspidoscelis labialis), Baja California Rattle Snake ( Crotalus enyo) and the Black Brant ( Branta bernicla nigricans).

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New Protected Area in Baja California | Terra Peninsular

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The Monte Ceniza Nature Reserve was certified as a Natural Protected Area, in the category of Area Voluntarily Destined for Conservation.

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This is a article about how Baja California is a safe place for seabirds. We can also infer from this article that it is important that we maintain these areas because they're home to many animals.

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This is a article about how Baja California is a safe place for seabirds. We can also infer from this article that it is important that we maintain these areas because they're home to many animals.

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Map of the Baja California Pacific Islands, a seabird hotspot where breeding populations have been systematically monitored for almost two decades. Photos of Coronado Archipelago and San Roque islands are shown-being the extremes in geographic location-to show the heterogeneous physiography of the region's islands. Arrows depict the southerly flow of the California Current, which has significant influence on the region's marine productivity and thus the seabird populations. Map design: © GECI / Gabriela Fernández Ham. Photos: © GECI / J.A. Soriano. Credit: PLOS ONE (2022). DOI: 10.1371/journal.pone.0258632

Seabirds are the most threatened group of birds and the one with the greatest and fastest decline globally. A study published on October 7th in PLOS ONE shows that a holistic conservation approach, including the creation of protected areas, the eradication of invasive alien species (the primary cause of biodiversity loss on islands), active restoration with social attraction techniques, and long-term monitoring, has a cumulative positive effect on seabird populations on islands in the Mexican Pacific off the Baja California Peninsula.

The study, titled "Population trends of seabirds in Mexican Islands at the California Current System," is the most comprehensive and recent assessment of the breeding status and population growth trends of seabirds in the Baja California Pacific Islands, a recognized seabird hotspot that supports 129 breeding populations of 23 species, many of which are shared with Canada and the United States of America.

Its conservation is a trinational priority. This study found that 17 islands support between 400,000 and 1.4 million breeding individuals annually of 19 of the 23 seabird species in this region, and more than half of the breeding populations (31 out of 61) are significantly increasing.

"Our study demonstrates that collective action, an overarching and long-term vision, and science-driven restoration actions have important positive outcomes for seabird populations and island ecosystems," said Federico Méndez Sánchez, lead author of the paper and Executive Director of Grupo de Ecología y Conservación de Islas, A.C. (GECI). "Our findings are a testament to Mexico's commitment to protect and restore its seabird islands for present and future generations."

North American seas and islands support nearly half of all seabird species globally, mostly due to the high productivity associated with the California Current System, one of the most productive marine ecosystems in the world. In particular, the Baja California Pacific Islands-a corridor of around 30 islands, all within Protected Areas managed by Mexico's federal government-are home to a fifth of the world's 368 seabird species, including fourteen threatened with extinction according to the IUCN Red List of Threatened Species.

This region is more important because it hosts colonies of 10 of the 12 species of seabirds endemic to Mexico, meaning that their global breeding populations reproduce within the country in just a few islands. Examples are the Ainley's and Townsend's Storm-Petrels which only nest on Guadalupe Island and its surrounding islets.

The multidisciplinary and interinstitutional team draws its conclusions from analyzing over two decades of monitoring data that was collected while conducting restoration efforts on ten island groups. The data sample included 61 colonies of 19 seabird species, from surface nesting species such as cormorants and pelicans to less-known burrow nesting species such as petrels and murrelets.

"The backbone of this study was the biggest and most important seabird restoration project ever formulated and implemented in the world, funded by the Montrose Settlements Restoration Program and the S.S. Jacob Luckenbach Trustee Council," said Alfonso Aguirre Muñoz, co-author and former GECI's Executive Director 2002-2017 and current member of the Board of Directors. "This initial significant funding leveraged other national and international support from the Fundación Carlos Slim in Mexico and the National Fish and Wildlife Foundation in the U.S."

"This regional analysis complements previous findings where we documented that 23 out of 27 (85%) historically extirpated seabird colonies from the Baja California Pacific Islands have been restored and 12 new colonies recorded," said Yuliana Bedolla Guzmán, joint senior author on the paper and Marine Birds Project Director at GECI. "We knew seabirds were returning thanks to our conservation efforts, but we were interested on knowing details on their populations' numbers and trends. Now we have a good perspective, and it is a positive and encouraging one."

The findings of the research build upon bold conservation actions taken in Mexico through the collective work of government agencies like the National Commission of Natural Protected Areas (CONANP), the National Commission for the Knowledge and Use of Biodiversity (CONABIO) and the Ministry of the Navy (SEMAR), civil society organizations such as GECI, academic institutions like the Centro de Investigaciones Biológicas del Noroeste (CIBNOR) and the Cornell Lab of Ornithology, and local island communities. Such actions include the legal protection of Mexico's 4,500 islands, the eradication of invasive mammals from 39 islands and the restoration and long-term monitoring of seabird populations.

"Sustained and long-term monitoring is crucial to understand how wildlife populations respond to both anthropogenic and environmental stressors, but also to assess the outcomes of conservation and restoration interventions," said Alfredo Ortega Rubio, co-author, and Emeritus National Researcher at the Centro de Investigaciones Biológicas del Noroeste (CIBNOR). "This kind of regional and multi-year studies are only possible when working collectively and joining forces between managers, practitioners, local communities and academia."

The key findings of the study suggest that the Baja California Pacific Islands support healthy and growing populations of seabirds that have shown to be resilient to extreme environmental conditions and persistent anthropogenic impacts, and that such resilience has been strengthened thanks to conservation and restoration actions.

"The results in our study are an important message of hope and proof that conservation works in light of the recent BirdLife International's State of the World's Birds report that asserts that nearly half of the planet's bird species are in decline, with just 6% of bird species globally increasing," said Alfonso Hernández Ríos, co-author, and Conserva Aves Program Manager at BirdLife International Americas Partnership. "The conservation milestones achieved for seabirds on the Baja California Pacific Islands are an encouraging example for other regions in the world facing the same threats."

More information: Federico Méndez Sánchez et al, Population trends of seabirds in Mexican Islands at the California Current System, PLOS ONE (2022). DOI: 10.1371/journal.pone.0258632

Provided by Grupo de Ecología y Conservación de Islas, A.C.

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Mexican Pacific islands are safe havens for seabirds thanks to conservation and restoration actions

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Seabirds are the most threatened group of birds and the one with the greatest and fastest decline globally. A study published on October 7th in PLOS ONE shows that a holistic conservation approach, including the creation of protected areas, the eradication of invasive alien species (the primary cause of biodiversity loss on islands), active restoration with social attraction techniques, and long-term monitoring, has a cumulative positive effect on seabird populations on islands in the Mexican Pacific off the Baja California Peninsula.

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This article is talking about a marine reserve that has been created in Baja California. This reserve is to attempt to save al of the endangered species in the gulf, such as coral reefs, fish, and whales.

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This article is talking about a marine reserve that has been created in Baja California. This reserve is to attempt to save al of the endangered species in the gulf, such as coral reefs, fish, and whales.

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(Sachi Cunningham / Los Angeles Times)

Mexican President Enrique Peña Nieto has established a new marine biosphere reserve covering a broad area that includes the Coronado Islands near the U.S. border and Todos Santos Island, site of a famed surfing spot off the coast of Ensenada.

The Pacific Islands Biosphere Reserve, formally established last week and located along the Baja California peninsula, is one of three new marine biosphere reserves decreed as Mexico hosted the United Nations Biodiversity Conference in Cancun.

The area provides critical habitat for many species of marine birds, said Alfonso Aguirre Muñoz, director of the Ensenada-based Islands Conservation and Ecology Group, which has worked with local fishing communities to promote the designation.

"The decree now legitimizes the hard work done by civil society during so many years, with already tangible and relevant results," Aguirre said. He was honored this month with the Midori Prize for Biodiversity for his work in protecting the islands.

The reserve, operating under Mexico's National Commission of Natural Protected Areas, "is a protected area that is already operating, the [opposite] of a paper park," Aguirre said. The effort to restore the area's marine bird habitat has involved private organizations and government agencies in the United States and Mexico, he said, including the U.S. Fish and Wildlife Service, the Cornell Lab of Ornithology, and the Audubon Society.

"Conservationists around the world are very happy," said Serge Dedina, mayor of the San Diego County border city of Imperial Beach and executive director of the environmental group Wildcoast. "Traditionally, conservationists have focused on the Gulf of California, but what we're learning is that the Pacific is equally important."

The Pacific Islands Biosphere Reserve covers more than 2.7 million acres, an area that comprises 21 islands and 97 islets and the surrounding marine areas that serve as a habitat for marine mammals and seabirds, as well as commercially important fish and shellfish.

Biosphere reserves promote sustainable growth and protect ecosystems through the establishment of strongly protected core zones, together with as buffer zones and transition zones.

The Pacific Islands Biosphere Reserve complements protections already in place off the California coast. "Now we have a chain of island conservation that extends from the U.S. all the way to Mexico," Dedina said.

A separate designation was made for the Pacific Biosphere Reserve, a 143-million-acre area that includes the Revillagigedo Archipelago off the tip of Baja California Sur.
Dibble writes for the San Diego Union-Tribune. ALSO A top Danish chef plans to open at $600-per-dinner pop-up in Mexico, and it's already fully booked More Central Americans are giving up on the U.S. and looking instead to a Mexican dream 'Mexico is one big cemetery': The search for the secret graves of 'the disappeared'

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Mexico establishes a vast marine reserve surrounding islands off Baja California

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Mexican President Enrique Peña Nieto has established a new marine biosphere reserve covering a broad area that includes the Coronado Islands near the U.S. border and Todos Santos Island, site of a famed surfing spot off the coast of Ensenada.

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This is an article about the extinction/population number about the animals in Baja California. This is a good way to track how much life is left in Baja California. It also a good way to see how we can better things depending on the numbers. 

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This is an article about the extinction/population number about the animals in Baja California. This is a good way to track how much life is left in Baja California. It also a good way to see how we can better things depending on the numbers. 

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Federico Méndez Sánchez,

Yuliana Bedolla Guzmán,

Evaristo Rojas Mayoral,

Alfonso Aguirre-Muñoz,

Patricia Koleff,

Alejandro Aguilar Vargas,

Fernando Álvarez Santana,

Gustavo Arnaud,

Alicia Aztorga Ornelas,

Luis Felipe Beltrán Morales

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Abstract

The Baja California Pacific Islands (BCPI) is a seabird hotspot in the southern California Current System supporting 129 seabird breeding populations of 23 species and over one million birds annually. These islands had a history of environmental degradation because of invasive alien species, human disturbance, and contaminants that caused the extirpation of 27 seabird populations. Most of the invasive mammals have been eradicated and colonies have been restored with social attraction techniques. We have recorded the number of breeding pairs annually for most of the colonies since 2008. To assess population trends, we analyzed these data and show results for 19 seabird species on ten island groups. The maximum number of breeding pairs for each nesting season was used to estimate the population growth rate (λ) for each species at every island colony. We performed a moving block bootstrap analysis to assess whether seabird breeding populations are increasing or decreasing. San Benito, Natividad, and San Jerónimo are the top three islands in terms of abundance of breeding pairs. The most widespread species is Cassin's Auklet ( Ptychoramphus aleuticus) with 14 colonies. Thirty-one populations of 14 species are significantly increasing while eleven populations of seven species are decreasing. We did not find statistical significance for 19 populations, however, 15 have λ>1 which suggest they are growing. Twelve of the 18 species for which we estimated a regional population trend are significantly increasing, including seven surface-nesting species: Brandt's Cormorant ( Phalacrocorax penicillatus), Brown Pelican ( Pelecanus occidentalis), Caspian Tern ( Hydroprogne caspia), Double-crested Cormorant ( P. auritus), Elegant Tern ( Thalasseus elegans), Laysan Albatross ( Phoebastria immutabilis) and Western Gull ( Larus occidentalis), and five burrow-nesting species: Ainley's ( Hydrobates cheimomnestes), Ashy ( H. homochroa) and Townsend's ( H. socorroensis) Storm-Petrels, and Craveri's ( Synthliboramphus craveri) and Guadalupe ( S. hypoleucus) Murrelets. The BCPI support between 400,000 and 1.4 million breeding individuals annually. Our results suggest that these islands support healthy and growing populations of seabirds that have shown to be resilient to extreme environmental conditions such as the "Blob", and that such resilience has been strengthen from conservation and restoration actions such as the eradication of invasive mammals, social attraction techniques and island biosecurity.

Citation: Méndez Sánchez F, Bedolla Guzmán Y, Rojas Mayoral E, Aguirre-Muñoz A, Koleff P, Aguilar Vargas A, et al. (2022) Population trends of seabirds in Mexican Islands at the California Current System. PLoS ONE 17(10): e0258632. https://doi.org/10.1371/journal.pone.0258632

Editor: Vitor Hugo Rodrigues Paiva, MARE - Marine and Environmental Sciences Centre, PORTUGAL

Received: October 1, 2021; Accepted: September 24, 2022; Published: October 7, 2022

Copyright: © 2022 Méndez Sánchez et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Data Availability: All relevant data are within the paper and its Supporting Information files.

Funding: This research was funded by The David and Lucile Packard Foundation, Marisla Foundation, National Fish and Wildlife Foundation, the Montrose Settlements Restoration Program and the S.S. Jacob Luckenbach Trustee Council, Fundación Carlos Slim, Fondo Mexicano para la Conservación de la Naturaleza, The Cornell Laboratory of Ornithology, Global Environment Facility and Programa de las Naciones Unidas para el Desarrollo México. This research was partially funded by the Red Temática de Investigación en Áreas Naturales Protegidas (RENANP) of the Consejo Nacional de Ciencia y Tecnología (CONACyT), the CONACyT Basic Science project 251919, and the Centro de Investigaciones Biológicas del Noroeste (CIBNOR). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Competing interests: The authors have declared that no competing interests exist.

Introduction

Of all the birds in the world, seabirds are the most threatened group and the one with the greatest and fastest declines [ 1- 4]. Invasive alien species are the prevalent threat to seabirds, followed by fisheries bycatch, climate change and severe weather, pollution, and human disturbance [ 2, 5]. North American seas and islands support nearly half of all seabird species globally [ 2, 6], mostly due to the high productivity associated with the California Current System (CCS) [ 7- 10]. This highly productive upwelling ecosystem is a hotspot for seabirds, where their abundance and population trends have been long and well-studied in the Canadian and United States portions of the CCS [ 9- 12] but not further south in Mexico in a comprehensive and systematic manner. For the Mexican portion of the CCS there is no exhaustive assessment of at-sea seabird abundances while the last regional multispecies population estimates for colonies in the Baja California Pacific Islands (BCPI; from Coronado Archipelago in the north to the Magdalena Bay islands in the south) are from the period 1999-2003, when the BCPI harbored half (2,433,000) of the breeding individuals and 22 out of 37 taxa that occurred in the whole CCS [ 13].

The BCPI are home to a fifth of the world's 368 seabird species [ 2, 5, 14]. Fourteen (18%) of the 80 seabird species in the BCPI are threatened: two species as Critically Endangered, three as Endangered, and nine as Vulnerable on the IUCN Red List of Threatened Species (IUCN 2021), while 23 (29%) are federally listed in Mexico's Official Norm for species at-risk ( NOM-059-SEMARNAT-2010) [ 14, 15]. In terms of endemism (i.e., endemic and semi-endemic species) [ 16], the BCPI host colonies of 10 of the 12 species endemic to Mexico: Craveri's Murrelet ( Synthliboramphus craveri), Guadalupe Murrelet ( S. hypoleucus), Ainley's Storm-Petrel ( Hydrobates cheimomnestes), Black Storm-Petrel ( H. melania), Guadalupe Storm-Petrel ( H. macrodactylus), Least Storm-Petrel ( H. microsoma), Townsend's Storm-Petrel ( H. socorroensis), Elegant Tern ( Thalasseus elegans), Heermann's Gull ( Larus heermanni), and Black-vented Shearwater ( Puffinus opisthomelas) [ 15, 17].

Most of the seabird populations on the BCPI were severely reduced during the 20th century [ 13, 18], with 27 seabird populations extirpated due to the combined negative effects of invasive alien mammals and direct human disturbance [ 13, 17, 19]. Much has changed for seabird conservation in Mexico during the last couple of decades, particularly in the southernmost region of the CCS (i.e., the Pacific Ocean off the Baja California Peninsula). From an almost complete lack of knowledge and inaction by the late 90's, where little was known about seabird populations [ 19, 20] and no protection of their colonies existed [ 13, 21], Mexico has taken bold conservation actions, including the legal protection of its nearly 4,500 islands [ 22], the removal of invasive mammals from 39 islands [ 18, 23], the restoration and long-term monitoring of seabird populations [ 17, 24, 25], and the formulation of a National Action Program for Seabird Conservation ( PACE Aves Marinas) [ 15].

Benefits derived from the eradication of invasive mammals on the biodiversity of the world's islands have been greatly documented [ 26- 29], and many studies have focused on the recovery of seabird populations [ 30- 32]. Mexico is among the countries that have successfully carried out the most eradications of invasive mammals globally with 60 populations from 39 islands [ 18, 23, 27, 33]. It is also some of the few that actively conduct pre- and post-eradication monitoring [ 34, 35] to assess ecological outcomes [ 17, 18, 24, 36] as well as active restoration such as seabird social attraction [ 37- 39] once invasive mammals are removed to maximize conservation gains. Benefits to seabird populations in Mexico from both passive and active restoration have also been documented, with the encouraging outcome that to date 23 out of 27 (85%) historically extirpated seabird colonies have been restored, and 12 new colonies have been recorded [ 17].

Beyond updating the number of breeding individuals at their island colonies [ 13, 17, 24, 40- 43], there have not been any attempts to understand the dynamics of the BCPI seabird populations and to assess recovery or decline trends at the subpopulation and metapopulation level [ 44, 45]. Therefore, building upon our long-term monitoring of the seabird populations on the BCPI for nearly two decades, in this paper we aim to answer two questions: (1) What is the current abundance of the seabird populations on the BCPI? and (2) What are their population trends? By doing so, we expect to highlight the importance and the contributions of these populations and their habitats-islands and the surrounding marine environment within the CCS-in the context of seabird conservation in the central eastern Pacific and the world.

Methods

Study area

The Baja California Pacific Islands (BCPI) are in the southern California Current System, off the Baja California Peninsula ( Fig 1). In this region, there are around 30 islands, all within Protected Areas managed by Mexico's Federal Government through the National Commission for Natural Protected Areas (CONANP): El Vizcaíno Biosphere Reserve; Guadalupe Island Biosphere Reserve; and Baja California Pacific Islands Biosphere Reserve [ 22, 46]. They are key reproduction sites for 133 species of vertebrates: 41 amphibians and reptiles, 69 birds, 19 mammals and four pinnipeds [ 47]. We focus our analyses on the ten islands and archipelagos described in Table 1. Due to their relevance for birds, all these islands are Important Bird and Biodiversity Areas (IBAs) [ 48]. The size of the islands where we conducted our work ranges from 35 to 24,171 hectares, with maximal altitudes ranging from 10 to 1,298 meters. Except for San Martín and Guadalupe islands, which have a volcanic origin, the rest are an unsubmerged extension of the continental shelf [ 49]. Most of them are within proximity to the Baja California Peninsula, between 1.8 to 72 km, with Guadalupe Island and Morro Prieto and Zapato islets being the most oceanic at 260 km. This region is characterized by a Mediterranean climate, with hot and dry summers and cold and wet winters, a regional average annual temperature of 18-23°C, and an average annual cumulative precipitation of ca. 200 millimeters. The dominant plant communities are maritime desert scrub, although Guadalupe Island sustains a temperate forest because of its high elevation and an almost permanent fog system [ 50].

To conduct our fieldwork, we obtained permits from all relevant Mexican authorities: (1) Ministry of Interior (Secretaría de Gobernación-SEGOB) to visit the islands; (2) General Directorate of Wildlife from the Ministry of Environment and Natural Resources ( Dirección General de Vida Silvestre-DGVS, Secretaría de Medio Ambiente y Recursos Naturales-SEMARNAT) for scientific collection, including the handling of seabirds and biological samples collection; and (3) National Commission for Natural Protected Areas ( Comisión Nacional de Áreas Naturales Protegidas-CONANP) to conduct fieldwork on islands within natural protected areas. In some cases, particularly for Guadalupe Island, we had the logistical support of the Mexican Navy ( Secretaría de Marina-SEMAR) for transport of personnel and equipment.

Monitoring of seabird colonies

We have been monitoring seabird populations on Guadalupe Island since 2003 [ 24, 52], on Asunción and San Roque islands since 2008 [ 17, 23], and from 2014 expanded to the rest of the islands in the region (except Magdalena Bay islands) [ 17, 18]. For this study, our data sample includes 61 colonies of 19 seabird species: 5 Procellariiformes, 9 Charadriiformes, 4 Suliformes, and 1 Pelecaniformes, on ten islands and archipelagos ( S1 Table).

For surface nesting-species (i.e., cormorants, pelicans, terns, and gulls), we surveyed active nests from land-based vantage points, complemented with surveys around the islands (boat counts), every 15 days during the whole breeding season. For burrow-nesting species (i.e., shearwaters, petrels, auklets, and murrelets), we conducted an exhaustive and intensive search of active burrows in all potential breeding sites. Burrow occupancy was determined either by recording apparently occupied burrows (i.e., with signs of activity such as guano, feathers, clear entrances, and footprints) or by directly confirming burrow content (i.e., adult, egg, or chick). On islands with accessible nesting sites and small size (i.e., Asunción and San Roque), we conducted a census (i.e., counted all available burrows) across the whole island, and either recorded apparently occupied burrows or checked burrow content using a hand-lamp or a burrowscope. Pairs nesting on artificial colonies installed on all the islands for social attraction [ 17] were included on our counts.

For those species with high nest density, such as the Western Gull ( Larus occidentalis) on the Todos Santos Archipelago, Cassin's Auklet ( Ptychoramphus aleuticus) on San Jerónimo Island, Black-vented Shearwater ( Puffinus opisthomelas) on Natividad and Guadalupe islands, Townsend's Storm-Petrel ( Hydrobates socorroensis) on Morro Prieto islet, and Guadalupe Murrelet ( Synthliboramphus hypoleucus) on Zapato and Morro Prieto islets, we estimated nest or burrow densities during peak incubation by counting nests or burrows within circular or square plots that were randomly distributed and georeferenced [ 53, 54]. We performed non-parametric resampling [ 55] of the density of either nests or burrows with apparent activity. This bootstrapping procedure does not include any assumptions about the data distribution. The algorithm we implemented to resample the data was proposed by [ 56]. We took a sample of n random observations with the possibility of replacement based on the original set of observed density data of burrows with activity, σ obs. We calculated the average for the bootstrapped version of the density, σ*, repeated the previous steps B = 2000 times, and obtained the bootstrapped distribution of the average nest and burrow density. With this, we obtained the 95% percentile bootstrap confidence interval (CI) for the average density of nests and burrows . To calculate the total number of nests and burrows ( N) per island, we multiplied the CI for the average density of nests and burrows by the nesting surface area A. The nesting surface area A was calculated using two different approaches: (1) based on an estimation done by field staff and confirmed every year on site. This only affected the Black-vented Shearwater on Natividad Island, the Cassin's Auklet on San Jerónimo Island and the Western Gull on Todos Santos Island; (2) using the Gaussian kernel density estimation method, in which each georeferenced point contributes a Gaussian component to the total density. The result is a kernel density estimate derived entirely from the historical data (exhaustive searches) and serves as a non-parametric model of the distribution of nests and burrows. We defined the nesting area A as the 95% contour of the kernel density estimate. This only affected the Black-vented Shearwater on Guadalupe Island, the Townsend's Storm-Petrel on Morro Prieto islet and the Guadalupe Murrelet on Zapato and Morro Prieto islets. In both cases, the field staff confirmed that the nesting area did not change and was the same throughout the breeding seasons of the data series. For most of the populations we did not need to estimate an area because we performed censuses instead of sampling.

Population growth trends

Model and moving block bootstrap.

We used the maximum number of breeding pairs for each nesting season on each island or archipelago to estimate the population growth rate (λ, lamda) for each of the 19 seabird species ( S2 Table) using moving block bootstrap [ 57] and the relationship described in Eq ( 1): 1) where N( t) is the number of breeding pairs in year t, N 0 is the number of breeding pairs at the time of the first count of the period, and λ is the annual population growth rate. We tested that trends are approximately log-linear by plotting the yearly values of the logarithmic number of breeding pairs for each species at the different islands (Fig A in S1 Appendix). From the moving block bootstrap regression analysis, we were able to assess whether the seabird breeding populations are increasing, decreasing, or show no significant change (i.e., undetermined).

Moving block bootstrap makes no assumptions of the data distribution, and sampling is done with replacement [ 57]. We generated a bootstrap set N* by randomly sampling k blocks of l = 3 consecutive records with replacement from our data set of maximum number of breeding pairs ( S2 Table), N obs. We chose the number of blocks k so that n≈ k× l, where n is the total number of records (i.e., monitored breeding seasons; e.g., n = 5 for Brandt's Cormorant on Natividad Island) and l is the length of each block. We used moving block bootstrap to account for the autocorrelation in the time series [ 57]. We then calculated the bootstrap version λ*, of the population growth rate λ, by fitting Eq ( 1) to the bootstrap sample N*. We repeated these last steps b = 2000 times. After this, we calculated the 95% bootstrap percentile interval for λ*. Finally, we tested the following null hypotheses: increasing population, H ₀: λ≤1, p< α = 0.1 and decreasing population, H ₀: λ≥1, p< α = 0.1.

With results from Eq ( 1), we calculated the percent of change in the population using Eq ( 2): (2) where N 0 is the number of breeding pairs at the time of the first count of the period and N(t) is the number of breeding pairs in year t.

The regional population growth rate ( λ R) and its percent of change were then calculated using Eqs ( 1) and ( 2), respectively. These population parameters were calculated for species with at least three consecutive years of data for all their colonies on different islands (18 of the 19 monitored species; Royal Tern was not included). We used the sum of the breeding numbers for all colonies for common years as the number of breeding pairs at the time t. For instance, for Brandt's Cormorant we only have data for all its colonies in the period 2016-2018, although we have monitored some of its colonies since 2012 (e.g., Asunción and San Roque).

In order to summarize our findings, we performed a hierarchical bootstrap analysis [ 58] to calculate the average population growth rate of each seabird order (Charadriiformes, Pelecaniformes, Procellariiformes, and Suliformes). This analysis allowed us to account for the nested or multi-level structure of the data, as each species is associated with specific islands.

Results

Status of the seabird breeding populations

The BCPI current seabird assemblage is 23 species and a total of 129 colonies on 17 islands. Table 2 contains the most recent and updated information to date on the number of breeding pairs per seabird species per island on the BCPI. On average for the period 2014-2019, the BCPI supported breeding pairs at 61 colonies of 19 species (48% and 83% of the total, respectively). This means that considering just half the colonies (61 vs 129), at least between ca. 400,000 and 1.4 million individuals breed on this important seabird hotspot every year. San Benito, Natividad, and San Jerónimo are the top three islands in terms of abundance of breeding pairs (2014-2019 average): , and , respectively.

The most widespread species is Cassin's Auklet with 14 colonies, followed by Brandt's Cormorant with 13, Western Gull with 12 and Scripps's Murrelet with 11. The less widespread species are Blue-footed Booby, Brown Booby, Caspian Tern, Elegant Tern, Hermann's Gull and Royal Tern with two colonies each (Fig B in S1 Appendix).

The San Benito Archipelago hosts the greatest seabird assemblage with 13 breeding species, followed by the Coronado Archipelago and San Jerónimo Island (11 species), and San Martín Island (10 species) (Fig C in S1 Appendix). It stands-out the number of species on San Jerónimo and San Martín despite their relatively small size (48 and 265 hectares, respectively). We are reporting one new record, the Blue-footed Booby on Asunción Island, and one new recolonization of a previously extirpated species, the Cassin's Auklet on Coronado Norte ( Table 2).

The island with the lowest number of breeding species is Guadalupe (5 species), despite being the biggest (24,171 ha) although the most oceanic island (Figs C and D in S1 Appendix). Two species are extirpated from this island due to predation by feral cats: Black-vented Shearwater and Cassin's Auklet, which are restricted to the nearby cat-free Zapato and Morro Prieto islets ( Table 2).

Seabird population trends

We were able to assess the population growth rates of 61 colonies of 19 species of the BCPI. Estimated population growth rates and the percent of change of the populations over the monitored timeframes are shown in S1 Table. Thirty-one (50.8%) populations of 14 species are significantly increasing while eleven (18.0%) populations of seven species are decreasing ( Fig 2 and Table 3). We did not find statistical significance for 19 (31.1%) populations thus were unable to determine an increasing nor decreasing trend. We also found that all taxonomic groups evaluated are growing, and that populations of murrelets, auklets, gulls, and terns (Charadriiformes) show the fastest growth ( Fig 3). The median growth rate for all seabird populations in the BCPI was λ = 1.19.

Cassin's Auklet and Brown Pelican are the species that have the most populations-six each-with a positive growing trend, while Brandt's Cormorant has the most decreasing populations with four colonies. Three species stand out for their fast population growth rates: Elegant Tern on San Roque Island ( ; 249,900% population change 2017-2019), Brown Pelican on San Jerónimo Island ( ; 507% population change 2015-2017), and Guadalupe Murrelet on Guadalupe Island ( ; 10,044% population change 2015-2019) ( Fig 2 and S1 Table).

For the period 2014-2019, twelve (66.7%) of the 18 species for which we estimated a regional population trend are significantly increasing, including seven surface-nesting species (Brandt's Cormorant, Brown Pelican, Caspian Tern, Double-crested Cormorant, Elegant Tern, Laysan Albatross and Western Gull) and five burrow-nesting species (Ainley's, Ashy and Townsend's Storm-Petrels, and Craveri's and Guadalupe Murrelets). Four species are restricted to the remote Guadalupe, Morro Prieto and Zapato: Ainley's and Townsend's Storm-Petrels, Guadalupe Murrelet and Laysan Albatross ( Fig 4). Other two species (Black-vented Shearwater and Pelagic Cormorant) have a population growth rate λ>1, which suggests a positive growth despite not statistically significant. This suggests that 78% (14) of the assessed species (n = 18) on the BCPI show a positive regional growth trend.

Discussion

We provide the most comprehensive and recent breeding status of this region's seabirds, including the first multi-colony and multi-species evaluations of population growth trends. Seabird populations in the BCPI have been showing an improvement both in number of species, colonies and breeding pairs as has been demonstrated by [ 17] and our own present work. Our estimation of ca. 400,000-1,400,000 breeding individuals is like the estimates by [ 11] from aerial at-sea and coastal surveys for seabirds off southern California (from Cambria, California, USA, to the Mexican border) in 1999-2002, and below the estimate of 2.4 million breeding pairs for the BCPI region done by [ 13] from a literature review and censuses in 1999-2003. We argue this is not because the seabird abundance has decreased in the region but more to the fact of how [ 13] calculated such figure from bibliographical population estimates combined with few population censuses between 1999 and 2003. Also, we consider our estimation conservative since our analyses only considered nearly half (61) of the 129 colonies that currently occur within the BCPI, and we are not including breeding numbers from colonies on the islands of Magdalena Bay (i.e., Santa Magdalena, Santa Margarita and Creciente).

The San Benito Archipelago, Natividad and San Jerónimo remain to be the three islands with the greatest abundance, with the former and the latter hosting the greatest number of breeding seabird species of all the BCPI. The case of San Jerónimo stands out given that it doubled its species richness in a couple of decades, from four species reported by [ 13] to eleven species at present time ( Table 2). This reveals the importance of this small island for the seabirds in the BCPI and thus the relevance to prevent and mitigate threats such as guano mining-still a latent danger since there exists an active lease to exploit it although it has been demonstrated that seabird guano is more valuable if retain in the ecosystem for aiding in nutrient deposition from the marine to the terrestrial environment [ 60]-and the introduction of invasive alien species both of which severely affected the seabird populations on this island for many decades. This increase in species might be related to the fact that the island is free from invasive mammals since 1999 [ 18] and that it has been protected since 2016 as part of the Baja California Pacific Islands Biosphere Reserve [ 22]. But also, to the existence since 2014 of community-led marine reserves to protect habitat and restore populations of abalone ( Haliotis spp.) as well as to increase fish recruitment, which have already proven to have an indirect positive effect on marine mammals such as the California Sea Lion ( Zalophus californianus) [ 61], plus the fact that San Jerónimo lies within an upwelling center making its surrounding environment highly productive [ 62].

Specie richness not only remained high on the BCPI but it increased during the past couple of decades, with the number of colonies increasing twofold, from 62 [ 13] to 129-partly because we surveyed all islands and islets and provide disaggregated information for each island within archipelagos in Table 2-, and with the number of species increasing from 19 [ 13] to 23.

No previous evaluation of the trends of this seabird populations existed, particularly at a regional scale. We found that 46 out of 61 seabird populations on the BCPI are growing, which means that a third of all known breeding populations (N = 129) have a positive population growth trend. In contrast, 15 out of 61 seabird populations are declining, which represents just 12% of the whole breeding populations. The median growth rate of λ = 1.19 for all assessed seabird populations is similar to that found by [ 32] of λ = 1.119 for 181 seabird populations of 69 species on islands around the world. It is also similar to the population growth rate recorded by [ 24], λ = 1.10, and [ 63], λ = 1.35, for a steadily expanding Laysan Albatross population on Guadalupe Island. Currently, this breeding population has a λ = 1.1, just barely higher than almost a decade ago, and it remains to be higher than λ observed for other species of albatross [ 64].

We found a high, atypical λ = 35.74 for the Elegant Tern on San Roque Island. This is explained because it is a newly established colony where the species recolonized the island in 2017 with one breeding pair, this after a decade of a systematic seabird social attraction program [ 17]. For the following years, the colony has significantly increased in breeding numbers, which is must probably the result of immigration playing an important role in the formation of the new colony [ 32]. A contrasting example on this same island is that of the Royal Tern that had been extirpated for almost a century, with a λ = 0.78 despite also being a newly formed colony in the same year as that of Elegant Tern [ 17]. For this species we suggest that the decreasing trend is mostly related to the short timeframe since the colony formation and thus would suggest keeping monitoring further years to reevaluate such trend. It might also be related to what [ 32] point out about growth rate declining over time because immigrant birds become a smaller fraction of the breeding population. The results obtained for this tern species can also be related to the low philopatry known for gulls and terns, where local population dynamics are influenced by emigration and immigration processes that can produce annual variations in breeding numbers [ 1]. Environmental factors have also an influence in the distribution of Elegant Tern since it has been proved that this species adapts to changing oceanographic conditions and fish availability, which makes it migrate from the Gulf of California to Southern California searching more productive waters [ 65].

At a regional scale, 14 out of 23 species on the BCPI show growing populations. It stands out that four of these species occur on the Guadalupe-Morro Prieto/Zapato cluster. This is not surprising because the islets are seabird havens where no pressing threats exist and no perturbations such as the existence of invasive mammals have ever occurred, and Guadalupe Island has been subject to a comprehensive and long-term restoration program, which has had a positive effect on the Laysan Albatross population [ 52] and very recently on the Guadalupe Murrelet thanks to the protection of its potential nesting habitat from the presence of feral cats with an exclusion fence since 2014 and with the four-year eradication program that is being carried out on the island. The case of the Guadalupe Murrelet can be explained as a rapid population growth rate following a successful invasive mammal eradication by immigration from the nearby islets [ 32].

The BCPI region has been subject to variable and extreme environmental conditions that are known to negatively affect seabird populations. The "Blob" occurred in 2013-2015 and reached the coasts of the Baja California Peninsula in May 2014, lasting until April 2015 [ 66]. It was followed by strong ENSO conditions, "Godzilla", that lasted until the end of 2016 [ 67]. This extreme conditions severely affected the CCS and its species, including massive die-offs of seabirds, such as Cassin's Auklets in the central CCS in the western coast of the United States [ 68]. For the BCPI region, the 2014-2016 marine heatwaves have been the most intense and persistent events recorded to date [ 69]. For instance, we recorded a 38% and 50% nest abandonment for the Brown Pelican and Brandt's Cormorant, respectively, in 2015, between the "Blob" and "Godzilla" marine heatwaves. Nonetheless, despite these severe environmental conditions in recent years, the seabird breeding abundances and population growth rates that we report here indicate that the BCPI seabird populations are resilient to environmental variations [ 70]. Such resilience has and can be further strengthened from conservation actions such as the eradication of invasive mammals [ 18, 23] and social attraction techniques [ 17].

Supporting information

S1 Table. Population trends for 19 seabird species at their colonies on 10 islands/archipelagos in the Mexican Pacific off the Baja California Peninsula.

A 95% bootstrap interval was calculated for population growth rates (λ) using moving block bootstrap; central value, lower and upper limits are given. Percent change was estimated using Eq ( 2) for the period described. aIsland/archipelago ordered North to South. bN indicates the most recent count of breeding pairs with the year in parentheses. c Increasing (+); Decreasing (-); Not Determined (ND).
https://doi.org/10.1371/journal.pone.0258632.s001
(XLSX)

Acknowledgments

We would like to thank the local fishermen cooperatives and their regional Baja California federation (FEDECOOP), and the Comisión Nacional para el Conocimiento y Uso de la Biodiversidad who over the years have supported this research alongside conservation and restoration work for the benefit of the seabirds in the Baja California Pacific Islands. We are also grateful for the institutional support of the Mexican federal authorities in charge of the islands: Secretaría de Gobernación, Secretaría de Marina, Secretaría de Medio Ambiente y Recursos Naturales, and Comisión Nacional de Áreas Naturales Protegidas. The work that allowed this research was done under permits from the Unidad de Gobierno-Secretaría de Gobernación, Dirección General de Vida Silvestre-Secretaría de Medio Ambiente y Recursos Naturales, and Direcciones de Áreas Naturales Protegidas-Comisión Nacional de Áreas Naturales Protegidas. We thank Gabriela Fernández Ham for the graphic design of the figures, and Guillermo Olvera Guerrero and Mario Villasante Barahona from GECI's Data Science Department for their assistance with analysis during the review process of this paper. A very special and hearted thank you to Annie Little and Jen Boyce for their trust and support before, during and after the Montrose-Luckenbach project. We thank all individuals that throughout these years participated in fieldwork phases. Finally, we are grateful to the two anonymous reviewers and the third reviewer, Dr. Moritz Mercker, whose comments and suggestions greatly improved this manuscript.

References

1. 52. Hernández Montoya JC, Juárez-Rodríguez M, Méndez-Sánchez F, Aguirre-Muñoz A, Rojas-Mayoral E, Íñigo-Elias E, et al. Sexual Dimorphism and Foraging Trips of the Laysan Albatross (Phoebastria immutabilis) on Guadalupe Island. Animals. 2019;9(6):364. pmid:31212935

2. 56. Carpenter J, Bithell J. Bootstrap confidence intervals: when, which, what? A practical guide for medical statisticians. Statistics in Medicine. 2000;19(9):1141-64. https://doi.org/10.1002/(SICI)1097-0258(20000515)19:9<1141::AID-SIM479>3.0.CO;2-F. pmid:10797513

# data[].attributes.attachment_link.title
Population trends of seabirds in Mexican Islands at the California Current System

# data[].attributes.attachment_link.description
The Baja California Pacific Islands (BCPI) is a seabird hotspot in the southern California Current System supporting 129 seabird breeding populations of 23 species and over one million birds annually. These islands had a history of environmental degradation because of invasive alien species, human disturbance, and contaminants that caused the extirpation of 27 seabird populations.

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