Top threats to seabirds identified
Scientists reviewed more than 900 studies and found that seabirds face big threats both on land and at sea. This helps explain why they are one of the most threatened group of vertebrates.
Seabirds are in danger. Taken as a whole, they are one of the most threatened groups of vertebrates in the world. Steep declines in seabird populations have been noticed almost everywhere, from albatrosses in the southern ocean to puffins in the North Atlantic. Even once abundant species, including some penguins, are now facing extinction. What is causing these declines? A new study is providing some answers.
For a long time we have known the general threats to seabirds – fisheries, invasive species, pollution – but we haven’t known which threats are the most dire, or had a big-picture understanding of how all seabird species are affected. A new study led by BirdLife scientists in collaboration with researchers from the British Antarctic Survey, the Centre for the Environment, Fishery and Aquaculture Science (CEFAS), the University of Washington and the Global Penguin Society, has changed that, by analyzing the problem at a global scale. For the study, scientists reviewed publications on threats to all 359 seabird species worldwide, identified the main drivers of seabird declines and quantified the magnitude of the impact of each threat.
“This study builds on work done in 2012, when we published a global analysis of threats to globally threatened seabird species – those listed as Critically Endangered, Endangered or Vulnerable on the Red List” says Cleo Small, Coordinator of the BirdLife International Marine Programme. “Not only have we updated these results, but we have also assessed threats to the other 249 seabird species that are not currently globally threatened, as these are potentially the threatened species of the future unless we act now”.
The results confirm that some of the usual suspects – invasive species, bycatch and climate change – are the top three threats, affecting 46%, 28% and 27% of all seabird species respectively. Hunting, egg collection and disturbance at breeding colonies are also driving declines in many species. Overfishing is affecting fewer species, but with high impacts on the species it affects.
The study also contradicts popular opinion, by concluding that plastic pollution is not yet a major cause of population declines of seabirds globally. It found only one report so far of plastics causing a significant impact at this level.
“Plastic ingestion is predicted to have a higher impact on small species that spend most of their time on the open ocean,” says Lizzie Pearmain, Marine Technical Officer at BirdLife International. “Many of these species’ population sizes and trends are poorly known, which makes it difficult to understand the real impact of plastics at population level.”
The analyses reveal other worrying news: many common seabirds are exposed to the same dangers as threatened species. In other words, if we don’t act to curb these threats now, we will soon see many other seabird species facing extinction.
The authors translated this conclusion into alarming numbers. The study estimates that more than 170 million individual birds (over 20% of all seabirds) are currently exposed to the individual impacts of bycatch, invasive alien species and climate change/severe weather, and that together over 380 million (around 45% of all seabirds) are exposed to at least one of these three threats.
It sounds desperate, but it’s not all bad news. The problem is big, but the solutions are (almost all) well known. We know how to mitigate the impact of bycatch on seabirds and other animals, how to eradicate invasive species from infested islands, and how to use the ocean’s resources sustainably. Climate change is arguably the most difficult challenge to address – but the impacts of climate change are usually exacerbated by the other top threats. Therefore, by solving problems posed by bycatch, invasive species and overfishing, we are also giving seabirds greater resilience, helping them to face the challenges of a changing ocean.