Northern Birds Pushed South by Climate Fluctuations

[Cara J]

Northern bird populations that periodically wind up into southern climes in North America are driven by climate fluctuations that affect the availability of food, according to new research. Essentially, it’s a “chain reaction from climate to seeds to birds,” said Court Strong, an assistant professor at the University of Utah and lead author of the study released in the Proceedings of the National Academy of Sciences. “This is an explanation we’ve been seeking for a long time as to what causes the irruptions,” he continued. Irruptions are when populations of a species increase rapidly in number beyond their normal range. “It’s been difficult until this paper to find those relations.” A multidisciplinary team involving climatologists like Strong and bird researchers from the Cornell Lab of Ornithology examined more than two decades of citizen science information about pine siskens (Spinus pinus) from FeederWatch — a program that draws on bird enthusiast counts around feeders to track population numbers. They compared this information with international climate data sets from the European Centre for Medium-Range Weather Forecasts and the Global Precipitation Climatology Centre. Pine siskens are small birds usually associated with Canada’s boreal forest. They are facultative migrants, a term meaning they move [...]

 

Read more: http://wildlife.org/northern-birds-pushed-south-by-climate-fluctuations/