PRBO finds birds getting bigger

11/03/2011

Within the last 40 years, birds along the central coast of California have been expanding in size, most likely in response to climate change—which is counterintuitive, researchers say. A team of scientists from San Francisco State University and PRBO Conservation Science began tracking the trend years ago, after graduate student Rae Goodman noticed small but significant mass and wingspan increases across several species over several years. Experts have long thought that aggregate temperature increases would lead to decreases in animal size, if anything. Nat Seavy, a research director at PRBO, said the change makes sense if thought of not in context of aggregate temperature rises, but of increasing weather variability. “The point may be that temperature is just one of the pieces of climate change,” Seavy said. This trend, he added, can be the result of things like “extreme weather events happening with greater frequency.”