Impacts on Birds & Wildlife
Global warming affects birds and other wildlife in countless ways, and can even cause extinctions. Audubon is closely monitoring how it is changing wintering and breeding ranges for birds. Audubon's groundbreaking 2009 report found dozens of bird species have been shifting northward over the last 40 years.By participating in citizen science projects like the Christmas Bird Count and Great Backyard Bird Count individuals can help support these research efforts. Getting involved with Audubon's Important Bird Areas program is another way to protect birds and their habitat from the impacts of global warming and other threats.
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How does global warming affect birds, other wildlife, and their habitats?
All organisms depend on their habitats for food, water, shelter, and opportunities to breed and raise young. Climate changes can affect organisms and their habitats in a myriad of ways. In fact, global warming impacts all life on earth, from individual organisms to populations, species, communities, and ecosystems. It can alter behaviors, population sizes, species distributions, plant and animal communities, and ecosystem functions and stability. How strongly different species will be affected varies, depending on differences in their ecology and life history. Species with small population sizes, restricted ranges, and limited ability to move to different habitat will be most at risk. Similarly, different habitats and ecosystems will be impacted differently, with those in coastal, high-latitude, and high-altitude regions most vulnerable.
When it comes to global warming, birds are like canaries in the coal mine, showing us that temperature increases are reshaping our ecology in potentially dangerous ways. According to a 2009 Audubon report, nearly 60% of 305 species found in North America in winter have been on the move over the last 40 years, shifting their ranges northward by an average of 35 miles, and in some cases by hundreds of miles.
Is wildlife already being affected by global warming?
There is mounting scientific evidence that global warming is already having profound effects on birds, broader biodiversity, wildlife habitat, and ecosystems. Here are some of the ways that global warming is affecting wildlife:
Geographic range
The ranges of many plants and animals are moving toward the poles and toward higher elevations. For example, the ranges of many British breeding birds were, on average, more than 11 miles farther north in the period from 1988-91 than they were in the period from 1968-72, according to comparisons derived from breeding bird atlases. (British butterflies are also being found farther north.)
Reproduction timing
Egg-laying, flowering, and spawning are occurring earlier for many species, in some cases disrupting delicate cycles that ensure that insects and other food are available for young animals. For example, Tree Swallows across North America have advanced egg-laying by as many as nine days from 1959 to 1991.
Migration timing and patterns
Spring migration is occurring earlier and fall migration later in many species. For example, 25 migratory bird species are arriving in Manitoba, Canada, earlier than they did 63 years ago; only two are arriving later.
Frequency and intensity of pest outbreaks
Global warming increases droughts in some areas; and spruce budworm outbreaks frequently follow droughts, perhaps because dry weather increases the stress on host trees or allows more spruce budworm eggs to be laid. Spruce budworms can be lethal to spruce trees, and spruce-fir forests are a very important habitat type in the northern hemisphere for a wide variety of plants and animals.
Can global warming cause extinctions?
Global warming is already causing extinctions in vulnerable species. Approximately 70 species of harlequin frogs in Central and South America have been driven to extinction by a disease that is linked with global warming. Warmer temperatures cause increased cloud cover that creates ideal conditions for a fungus that kills the frogs. This is only one cautionary example of how global warming disrupts the stability of ecosystems. As it continues, it will cause more extinctions.
Scientists predict 9-52% of all terrestrial species (1 million plants and animals) will be on an irreversible path to extinction by 2050. (These predictions are based on modeling of the effects of minimum to maximum climate warming impacts on a broad range of species in regions around the world.)
The planet's 25 biodiversity "hotspots" are especially vulnerable to climate impacts. These special places provide homes to 44% of the world's plants and 35% of its vertebrates, in less than 1.4% of its land area. A doubling of atmospheric carbon dioxide, which estimates suggest could occur in about 100 years, could lead to extinction of as many as 43% of these areas' endemic species.
What are some specific impacts on birds?
Under two scenarios of global climate change, there will be major shifts in the ranges and abundances of many of the 150 common bird species in the Eastern United States over the next 100 years or so; 50-52% of species will decrease in abundance by 25% or more, while 37-40% of species will exhibit range reductions of 25% or more.
Long-distance migrants may be more vulnerable to global warming than other species. As winter temperatures increased between 1980 and 1992 at Lake Constance in Central Europe, the proportion of long-distance migrant bird species decreased while the number and proportion of residents and short-distance migrants increased. In North America, many of our favorite songbirds are long-distance migrants. Species such as Baltimore Oriole, Barn Swallow, Wood Thrush, and Scarlet Tanager could well be driven from the places where we expect to find them, more ominously, from the habitats to which they are best suited.
A 90% decline in Sooty Shearwaters (Puffinus griseus) off the California coast in just seven years (1987 -1994) has been associated with warming of the California Current, which flows from southern British Columbia to Baja California.
All of the remaining marshland in the Blackwater National Wildlife Refuge (an Important Bird Area in Maryland that provides important habitat for many birds, including Black Rail and Saltmarsh Sharp-tailed Sparrow, two of Audubon's Red WatchList species) is expected to disappear within 25 years as a result of both climate change and aquifer extraction.
Global warming and associated drought in the Prairie Potholes region (southeastern Alberta and northeastern Montana to southern Manitoba and western Minnesota) will lead to significant reductions in the populations of 14 species of migratory waterfowl; 30-50% fewer prairie ponds will hold water in spring by 2060, with an associated 40-50% decline in the numbers of ducks settling to breed in the area.
The ranges of many European and African birds are likely to shift by at least 600 miles, with a decline in species richness and reduction in average range sizes (based on simulations made for the impacts of a variety of late 21st century climate models on European and African birds).
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