Male spotted bowerbirds are like grad students, they learn under stress.
Males of the species, Ptilonorhynchus maculatus, were originally thought to mimic the sounds of predatory birds as a defense mechanism, but recent research suggests that are actually learning sounds heard while under stress.
Laura Kelly of the University of St. Andrews led the research team in a continuing investigation of bowerbirds imitative abilities. An earlier study by the team found that each bird learned to imitate sounds on their own. They weren't learning from other males, the researchers concluded, because each bird was imitating the sounds in distinctively different ways.
The new study found that although the birds mimicked calls from predatory birds, they accounted for only about 20 percent of their vocalizations. The rest were imitation of the calls of aggressive “bully” species, or less aggressive birds in distress. The bowerbirds mimicked alarm calls, predator calls, and mobbing calls, the cries birds make when ganging up on a predator.
The researchers speculate that when bowerbirds are distressed their learning capacity increases, and therefore pick up vocalizations they hear while under distress, either from attackers, bullies, or freaked out neighbors.
The study is published in Naturwissenschaften.
IMAGE: A spotted bowerbird in Australia (Wikipedia Commons).