Birds Fly in the Face of Climate Change Expectations

 Researchers in California were surprised to find that West Coast birds have been growing larger in recent decades. “The finding that birds are getting bigger draws into question what’s driving the change in size.” Ms. Goodman and her colleagues analyzed data dating back 40 years from two different California bird observatories. Body mass and wing-span measurements of nearly 33,000 birds representing dozens of species collected from 1971 to 2010 were analyzed for variations over time.The researchers found that wing length had been steadily increasing and body mass had expanded. Some of the species migrate between Alaska and Latin America, while others breed locally or are short-distance migrants, but the rate of change in size did not depend on where the birds spent the majority of their longitudinal time. Ms. Goodman laid out a number of hypotheses. "More severe West Coast weather events may favor larger birds that are better able to cope with prolonged stresses since they have greater stores of energy" she said.