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NERVOUS ZEBRA finches--those with a high, inborn level of the stress hormone corticosterone--are more willing to take risks than their more laid-back counterparts, according to a new study. Researchers from the United Kingdom's University of Exeter placed zebra finches with different levels of stress hormone in an unfamiliar environment. The birds with the most corticosterone were the first to explore the area and venture to new feeders. When the researchers scared the birds away from the feeders, they found that the more stressed birds were also the first to return.
The findings seem surprising at first, since bold behavior is generally associated with confidence, not nervousness. But the study's author, behavioral ecologist Thais Martins, explains that "corticosterone is released to help tackle stress by encouraging the animal to adopt key survival behaviors"--such as seeking out new sources of food.