Dave Mehlman, the director of The Nature Conservancy’s migratory bird program, is blogging all week about the new “State of the Birds 2010” report, of which he is a co-author. Read all his posts on the report — then go to my.nature.org to learn more about the report and the Conservancy’s work to protect birds.
The 2010 State of the Birds report focuses on birds and climate change. Of all the habitat types examined for the vulnerability of their birds to climate change, oceans stand out: all of the 67 oceanic birds we considered had medium or high vulnerability to climate change. Two other habitat types also defined by their connection to marine environments showed high vulnerability to climate change: coasts and islands (including Pacific and Caribbean islands).
Birds of the nation’s oceans — which include species such as Laysan and Black-footed Albatrosses, Black-capped Petrel, shearwaters, puffins, Common and Thick-billed Murres, and auklets — have numerous traits which make them slow or unable to adapt to climate change:
- Most of these species have what scientists call “low reproductive potential” (they do not breed until several years old, produce one egg every year or every two years, and/or have very high mortality of young birds).
- Many nest in highly concentrated colonies on islands and forage long distances for food, which is in itself very vulnerability to climate change.
This combination of factors makes all ocean birds vulnerable — and argues for increased conservation attention for this group.
Birds of coastal habitats are almost equally at risk, primarily from rising sea level, but also from increased flooding and erosion. These species occur across the country in an array of habitats, including Black and American Oystercatchers, whose low-lying beach nesting habitat may disappear; Seaside and Saltmarsh Sparrows, which are exclusively dependent on low lying salt marshes that may be the first to go; and seabirds such as Ivory Gull, Aleutian Tern, and Kittlitz’s Murrelet, which depend on coastal marine food webs that are at risk of disruption.
Island birds, particularly those from Hawaii, showed marked vulnerability to climate change, paralleling a finding from the 2009 report. A variety of factors combine to produce this effect, including:
- Rising sea levels and temperatures, which reduce both coastal and terrestrial habitats;
- The small size of islands generally; changes in precipitation amounts and patterns; and
- Potential increases in frequency of natural disasters.
High elevation forest birds, such as the Puaiohi and ‘Akiapola’au of Hawaii, Elfin-woods Warbler of Puerto Rico, and Rota Bridled White-eye of the Northern Marianas face numerous challenges due to constriction or outright loss of their habitat and (in Hawaii) loss of previously malaria-free refuges. Coastal nesting island birds, as in the rest of the country, are at great risk; examples include the Laysan Finch of Hawaii, American Flamingo in the Caribbean, and Micronesian Megapode in the Northern Marianas.
(Image: American Flamingoes. Credit: cliff1066™/Flickr through a Creative Commons license.)