Behavior brief

Scared mama birds hatch long-winged chicks

Image: Flickr, linkurl:Kev Chapman;http://www.flickr.com/photos/25553993@N02/5346613557/

What mom doesn't get stressed out every now and then? Stress is usually considered a bad thing, but new research suggests that mom's stress can actually give her future offspring certain physical advantages, at least in the case of one bird species. A few years ago, experiments on barn swallows demonstrated that when ovulating females were exposed to models of predators, their eggs had higher levels of the stress hormone corticosterone, which resulted in reduced hatchability and smaller fledglings. A study published this month in linkurl:Functional Ecology;http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2435.2011.01834.x/abstract shows that nesting great tits exposed to stuffed models and audio calls of their predators also have smaller offspring, but the chicks' wings actually grow faster and longer, resulting in wings about 1.8 millimetres longer than the offspring of less stressed mothers -- a difference that might make the birds better...