Global warming could doom many bird species
November 13, 2006
The report, "Bird Species and Climate Change: The Global Status Report", reviews more than 200 scientific articles on birds and identifies groups of birds at high risk from climate change: migratory, mountain, island, wetland, Arctic, Antarctic and seabirds. It says that species that can easily migrate to new habitats will likely thrive, while birds that live in niche environments may decline.
"Robust scientific evidence shows that climate change is now affecting birds' behaviour," said Dr Karl Mallon, Scientific Director at Climate Risk, an Australian climate change consultancy, 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."
"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 Program.
Emperor penguin numbers declined 50 per cent at Terre Adélie in Antarctica during a period of prolonged, abnormally warm and unusually variable winter temperatures.
© WWF-Canon / Fritz PÖLKING
"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," added Verolme.
The global status report: Climate change and bird species [pdf, 3.24 MB] | Summary - The global status report: Climate change and bird species [pdf, 1022 KB]
The WWF report cites specific examples from around the world. An excerpt:
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.
Asia: The Siberian crane is a critically endangered migratory wetland bird numbering 3,000 individuals worldwide. Siberian cranes breed in Arctic Russia and Siberia, and most winter in China in the middle to lower reaches of the Yangtze River. This bird's Arctic tundra habitat is forecast to decline by 70 per cent. Decreased precipitation, coupled with more intense rainfall events, also negatively affects the crane in its habitat in China. Increasing drought due to higher temperatures is thought to be one factor that caused a subpopulation of Siberian cranes, which once wintered in India's Keoladeo National Park, to shift out of the park and become locally extinct.
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.
This article uses quotes and an extended except from a WWF release.