Higher temperatures can directly alter their life cycles.
The loss of wetlands, beaches, and other habitat could have an equally important indirect effect, by making some regions less hospitable to birds than those regions are today. Data collected by the National Audubon Society s Christmas Bird Count show that during years with warmer temperatures, the majority of bird species do not have to fly as far south for the winter. Warmer temperatures also allow birds to spend their summers farther north. During summer, this bird is currently found throughout New England, the states that border the Great Lakes, and north of a line stretching from Missouri to Idaho. With a doubling of carbon dioxide, the Bobolink would not be found south of the Great Lakes.