Marine environments cover more than 70% of the Earth’s surface and are vital to sustaining life. The oceans govern global climate and weather patterns and, through the activities of microscopic photosynthesising organisms, help create and maintain the planet’s atmosphere. Despite the pivotal significance of marine ecosystems, our knowledge of them remains poor. Seabirds are a conspicuous part of the marine realm and compared to other major groups of marine organism are exceptionally well-studied. Consequently, seabirds provide a crucial window onto the condition of the oceans and are excellent indicators of its health.

Figure 1. Proportion of seabird species in each IUCN Red List category

Figure 2. Current direction of trend for all seabird species

Figure 3. Percentage of species in each IUCN Red List category for the major seabird families. Number of species per family in brackets

The IUCN Red List Index (RLI) for birds tracks the movement of species through categories of extinction risk (). It reveals that although there has been a steady deterioration in the status of birds in all regions of the world, species associated with the marine environment—especially the open ocean—have fared particularly badly (, ). Of the 346 seabird species, 97 (28%) are globally threatened, 17 (5%) in the highest category of Critically Endangered, and a further 10% are Near Threatened (Figure 1). Nearly half (47%; 52% of those with known trends) of seabird species are known or suspected to be experiencing population declines (Figure 2). Seabirds are thus more threatened than all other groups of birds with similar numbers of species: 26% of parrots (Psittacidae; 374 species), 19% of pigeons/doves (Columbidae; 318 species), and 18% of raptors (Accipitridae; 238 species) are threatened (, ). The most threatened seabirds groups are the Sphenisciformes (penguins) and Procellariiformes (albatrosses and petrels). The albatross family (Diomedeidae) is especially imperilled—for long-lived, slow-breeding species, even quite small increases in mortality can lead to significant population declines (figure 3) ().

Certain countries—often those with large Economic Exclusion Zones (EEZs)—are particularly important for seabirds. These include the USA, Canada, Russia, Australia, New Zealand, Chile, South Africa and—when Overseas Territories are included—the UK and France. The highest densities of threatened seabirds are found in international waters in the southern oceans, with a particular concentration around New Zealand ().

Commercial fisheries are the most serious threat facing the world’s seabirds. Accidental bycatch affects 41% of threatened species (40 species) and each year longline (), trawl () and gillnet () fisheries are responsible for the incidental deaths of hundreds of thousands of seabirds. For several species of albatross, this level of mortality is unsustainable and they are now perilously close to extinction. In addition, the negative impact of overfishing on seabirds continues to increase as fisheries target ever smaller fish ().

The most pervasive threat to seabirds is invasive species, which adversely affect 75% of all threatened species (73 species)—nearly twice as many as any other single threat. For example, the introduced House Mouse Mus musculus is devastating seabird populations on Gough Island in the Southern Atlantic. Among the affected species are the Critically Endangered Tristan Albatross Diomedea dabbenena and the Endangered Atlantic Petrel Pterodroma incerta (). Other significant threats include pollution (, ), hunting and trapping and energy production and mining (). Climate change is already having a notable impact on the world’s oceans—disrupting the complex oceanographic phenomena and cycles that govern marine ecosystems. Declines in seabird populations off southern California suggest that these changes may be having a profound effect on marine life (). Many seabirds nest on low-lying islands that could be badly impacted by rising sea levels ().

Unfortunately, the behavioural and life-history traits of seabirds render them particularly vulnerable (, ). For long-lived, slow-breeding species, even quite small increases in mortality can lead to significant population declines. In addition, many seabirds have highly specialised diets, being reliant on just a few prey species, the abundance and distribution of which can alter dramatically in response to abrupt environmental changes.

Despite the enormity of the threats facing the world’s seabirds and the difficulties inherent in achieving conservation consensus within regions of the ocean beyond national jurisdiction, there are still numerous success stories that demonstrate that species can be saved. In Bermuda, an intensive recovery programme involving the provision of artificial nest burrows and the translocation of chicks has revived the fortunes of Bermuda Petrel Pterodroma cahow (). Similarly, conservation interventions for Zino's Petrel Pterodroma madeira and Magenta Petrel Pterodroma magenta have almost certainly prevented these species from becoming extinct ().

One of the main priorities for halting the declines of threatened seabirds is the control and eradication of invasive alien species. Given sufficient resources, spectacular recoveries can be achieved (, ). Perhaps the most ambitious eradication project to date is currently underway in the Antarctic—at 3,755 km² South Georgia is more than seven times larger than any island where rat eradication has previously been attempted (). BirdLife is currently working with Island Conservation, the University of California, Santa Cruz and a number of other organisations to compile a list of priority sites for future eradications and the provisional list for seabirds is now available (see Croxall et al. 2012).

Effective conservation depends on targeting those species and habitats of greatest importance and most immediate risk. To this end, the identification of Important Bird Areas (IBAs) on land has been a huge success—helping focus conservation energies and inform the designation of protected areas (). Now efforts are underway to develop the first comprehensive assessment of IBAs on the high seas ().

Ensuring effective seabird conservation requires improving and enforcing legislation, regulation and best practice standards. Over the past few decades, the world’s governments have endorsed many international agreements relevant to the conservation of marine biodiversity (). The challenge now is to harness this commitment and ensure that concrete actions are taken where they are most needed. For example, under the UN Fish Stocks Agreement, States have a duty to reduce the bycatch of albatrosses in their fisheries. Since 2004, BirdLife (especially through the ‘Save the Albatross Campaign’) has been working to help turn these commitments into action (). The good news—for albatrosses, fishermen and conservationists alike—is that simple measures can reduce the bycatch of seabirds without any negative effects on fish catches. Indeed, fish catches actually increase in some cases (). However, while the practical solutions exist, seabird bycatch in many fisheries remains at unsustainably high levels. Recognising the gap between knowledge, policy and actual action on the deck of fishing vessels, BirdLife’s Global Seabird Programme created the Albatross Task Force (ATF) to work directly with fishermen and raise awareness of seabird bycatch issues and the practical solutions to combat it. Since their formation in 2005, the Albatross Task Force teams have overseen dramatic reductions in the numbers of albatrosses and other seabirds killed in the bycatch 'hotspots' of southern Africa and South America (). 

To access more case studies on seabirds and the marine environment, please click on the following links.

• Congregation at particular sites is a common behaviour in many bird species
• Feathers have always been used by humans as decoration and status symbols
• Seabird guano, especially from Peru, transformed western agriculture in the nineteenth century
• The southern oceans are important for threatened seabirds
• Seabird communities are declining in the Southern Californian Current System
• Many albatross species are in alarming slow decline
• Birds in some families, notably seabirds, have deteriorated in status faster than others
• Oil spills significantly reduce populations of seabirds and are costly to clean up 
• Pesticides continue to poison birds on a large scale
• Seabirds suffer from eating our junk
• Longline fishing effort overlaps with foraging hotspots for seabirds
• Trawl fisheries cause significant mortality to albatrosses along the west coast of southern Africa
• Fisheries are targeting smaller fish with serious implications for seabirds
• Climate change is impacting the distribution, abundance and migration of Australian birds
• Native birds on Gough Island are being devastated by house mice
• Gillnets pose a significant threat to some seabird populations
• Seabirds are key indicators of the impact of climate change on the world’s oceans
• Offshore wind farms are impacting seabirds and migrating passerines
• Sea level rise poses a major threat to coastal ecosystems and the biota they support
• The biological traits of some bird species render them particularly vulnerable to climate change
• Most countries have ratified key international treaties although significant gaps remain
• Working with Regional Fisheries Management Organisations reduces albatross declines
• Bermuda Petrel is being conserved through translocation and provision of artificial nest-sites
• Eradicating introduced mammals from Clipperton Island led to dramatic recovery of seabirds
• The Albatross Task Force is bridging the gap between conservationists and fishermen
• Simple changes to fishing methods can get seabirds off the hook
• A 27,000km voyage of conservation has helped safeguard some of the world’s most imperiled seabirds
• Restoring island ecosystems by eradicating invasive alien species
• Rat eradication and captive breeding have helped save the Campbell Islands Teal from extinction 

   

Links
Global Seabird Programme

Compiled 2012

Recommended citation
BirdLife International (2012) Spotlight on seabirds. Presented as part of the BirdLife State of the World's Birds website. Available from: https://datazone.birdlife.org/sowb/spotseabirds