Bird
habitat changing quickly as climate change proceeds
From University
of Wisconsin-Madison
The climatic conditions needed by 285 species of land birds in the United States have moved rapidly between 1950 and 2011 as a result of climate change, according to a recent paper published in Global Change Biology.
“Our goal was to look at the climate where these birds were
observed breeding over this period and determine where that ‘sweet spot’ was
moving as the climate changed in this period,” says first author Brooke
Bateman, a post-doctoral researcher at the University of Wisconsin–Madison.
Warming temperatures are the fundamental alteration of climate
change, and the researchers saw the expected northward expansion of suitable
conditions, Bateman says, but also a considerable expansion to the west.
Unexpectedly, the southern borders of suitable conditions did not, in general, move north, perhaps because a remnant population had not yet left that area.
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| Ptarmagan who landed in my backyard in Charlestown (photo by Will Collette) |
In general, the southern plains and lower Midwest faced the
greatest decline in ideal climate conditions, while the Dakotas, mid-Atlantic
and Pacific Coast showed the greatest increase.
The study, the largest examination of the velocity of climate
change for birds in the United States in the recent past, began by combining
detailed weather records for the lower 48 states with data on the location of
bird occurrences from the Global Biodiversity Information Facility.
The
researchers cross-referenced those data, creating a computer model of where the
birds nest, in terms of climate factors like average and extreme temperature
and precipitation.
In the face of climate change, a suitable climate for birds has
been moving, on average, eight tenths of a mile per year—about twice the pace
predicted by earlier studies.
The researchers then used the model to predict where the same
climate conditions for those birds would be located in 2011, reflecting the
ensuing changes in climate. Finally, using data from the 2011 North American
Breeding Bird Survey, they checked their work.
The results show that in the face of climate change, a suitable
climate for birds has been moving, on average, eight tenths of a mile per
year—about twice the pace predicted by earlier studies.
To make sense of their data, the researchers lumped bird species
into guilds—groups based on shared factors like diet, foraging location and
migration habits.
Hospitable climate moved relatively fast for short- or
long-distance migrants, carnivores, insect eaters, and birds that foraged in
the air or the canopy of trees.
Slow-moving guilds included permanent
residents, herbivores, omnivores, hummingbirds and birds that forage on tree
bark, such as woodpeckers.