Climate change has birds out on a limb
14 Nov 2006
Nairobi, Kenya – A new report released today by WWF finds a clear and escalating pattern of climate change impacts on bird species around the world, suggesting a trend towards a major bird extinction from global warming.
The report, Bird Species and Climate Change, reviews more than 200 scientific articles on birds in every continent to build up a global picture of climate change impacts.
“Robust scientific evidence shows that climate change is now affecting birds’ behaviour,” said Dr Karl Mallon, Scientific Director at Climate Risk Pty Ltd and one of the authors of the report. “We are seeing migratory birds failing to migrate, and climate change pushing increasing numbers of birds out of synchrony with key elements of their ecosystems.”
The report, prepared by international climate change specialists, identifies groups of birds at high risk from climate change: migratory, mountain, island, wetland, Arctic, Antarctic and seabirds. While bird species that can move and adapt easily to different habitat are expected to continue to do well, bird species that thrive only in a narrow environmental range are expected to decline, and to be outnumbered by invasive species.
The report also shows that birds suffer from climate change effects in every part of the globe. Scientists have found declines of up to 90 per cent in some bird populations, as well as total and unprecedented reproductive failure in others.
Scientists also analyzed available projections of future impacts, including bird species extinction. They found that bird extinction rates could be as high as 38 per cent in Europe, and 72 per cent in northeastern Australia, if global warming exceeds 2ºC above pre-industrial levels (currently it is 0.8ºC above).
“Birds have long been used as indicators of environmental change, and with this report we see they are the quintessential ‘canaries in the coal mine’ when it comes to climate change,” said Hans Verolme, Director of WWF’s Global Climate Change Programme.
“This report finds certain bird groups, such as seabirds and migratory birds, to be early, very sensitive, responders to current levels of climate change. Large-scale bird extinctions may occur sooner than we thought.”
If high rates of extinction are to be avoided, rapid and significant greenhouse gas emission cuts must be made, WWF says.
The global conservation organization also believes that the current approach to bird conservation, focused on protecting specific areas with a high bird diversity, will fail because climate change will force birds to shift into unprotected zones. A major change in approach to bird conservation is required, according to WWF.
Examples of how climate change is affecting some bird species around the world:
Africa: The tawny eagle is an arid savanna raptor found in Asia and Africa. Small changes in precipitation predicted with climate change would likely result in the bird’s extinction in its African habitat in the southern Kalahari. If the mean annual precipitation stays the same but the inter-annual (year to year) variation increases by less than 10 per cent, the bird’s population will decrease considerably.
UK: The particular vulnerability of seabirds to climate change is illustrated by the unprecedented breeding crash of UK North Sea seabirds in 2004. The direct cause for the breeding failure of common guillemots, Arctic skuas, great skuas, kittiwakes, Arctic terns and other seabirds at Shetland and Orkney colonies was a shortage of small fish called sandeels, a crucial prey species for the seabirds. As a result, the nearly 7,000 pairs of great skuas in the Shetlands, for example, produced only a handful of chicks and starving adult birds ate their own young. Warming ocean waters and major shifts in species that underpin the ocean food web are thought to be behind the major sandeel decline.
USA: An unprecedented 2002 drought in southern California caused a 97 per cent breeding decline in four species: the rufous crowned sparrow, wrentit, spotted towhee and California towhee. Breeding success dropped from 2.37 fledglings per pair in 2001 (a normal year) to 0.07 fledglings per pair during 2002, the driest year in the region’s 150-year climate record. Precipitation in this region is expected to decrease and become more variable with global warming. Even slight increases in arid conditions would make these species vulnerable to extinction in a dry year.
Europe/Africa: Pied flycatcher birds and other species are shifting the timing of seasonal behaviors in response to climate change. Shifts like these can cause problems for birds if the plants and animals they interact with do not shift at the same rate. In Europe, earlier spring peaks in insect numbers mean that some pied flycatchers (long-distance migratory birds) no longer arrive from Africa in time to match food peaks with peak demands of their nestlings. This climate-change induced mismatch is strongly linked to 90 per cent declines in some European pied flycatcher populations over the past two decades.
Australia: Illustrating the vulnerability of mountain birds to climate change, the habitat of the golden bowerbird is predicted to shrink by 97.5 per cent with a future warming of 3°C and a 10 per cent decline in rainfall. The bird occupies cool habitat in Australia’s wet tropics on conical mountains surrounded by warmer lowlands. As temperatures rise, its suitable habitat will contract, and beyond 3˚C of warming is expected to completely disappear.
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