Migratory Songbirds
Polar bears seem to have gotten all the buzz when it comes to global warming affecting animal species, but climate change seems to have had a significant effect on birds as well. In its February 2009 report "Birds and Climate Change: Ecological Disruption in Motion," the Audubon Society analyzed four decades of research that tracked migratory patterns of 305 species of birds. Although many factors can cause birds to change their migratory patterns, climate change may be the one of the greatest factors in the birds' shift.
The society learned that as the overall climate has gotten warmer, birds also wintered farther north?over half of the species studied now spend winters about 35 miles further north from their traditional migratory location. Other species moved as far as 100 miles north, and the purple finch showing the greatest shift, clocking in at a 400-mile shift. Some coastal birds also moved further inland. These changes can have many ecological consequences, including loss of species. Although birds are highly adaptable animals, this study shows that they may be looking for new food sources. Certain species of birds live in wetlands, and as the climate continues to increase, wetlands will dry up and either displace the birds further, or cause the species to die out.
The journal Climate Research devoted its December 31st, 2007 issue to the topic of climate change and bird migratory patters. Oscar Gordo of the Departamento de Ecologia Evolutiva at the Museo Nacional de Ciencias Naturales in Madrid, Spain, published an article in this issue discussing bird migration dates and how climate change seems to also be having an effect on when birds travel. Gordo explains that as temperatures stay warmer longer, the birds do not start their migration as early as they once did.
Gordo contests that climate change also has an effect on the molting process, during which birds shed their feathers. If the climate changes and affects the available resources for the birds, they may not be able to molt properly. In fact, food availability may directly affect the quality of the feathers replaced in the molting process. If the bird finds itself in a harsher ecosystem than normal, it may not be able to produce high-quality feathers that are desirable in attracting a mate. This in turn affects reproduction and replacement rates in the species, and in worst case scenarios, could cause a species to die out.
How climate change will continue to affect birds is yet to be seen, but the data that?s been collected so far is an argument for curbing global warming.