Researchers at the University of Washington have found a species of crow that distinctly alters its behavior when attempting to steal food from another crow, depending on whether or not the other bird is a relative.

The Northwestern crow (Corvus caurinus) uses a passive strategy when it attempts to take food from kin but becomes aggressive when it tries to steal a morsel from a non-related crow. This is believed to be the first time that such a behavior pattern has been observed in any bird species.

The findings are published in the current issue of the journal Bird Behavior by Renee Robinette Ha, a UW lecturer in psychology, and James Ha, a research associate professor of psychology. In a companion paper to be published in the next issue of the journal Animal Behavior, the Has, a husband-wife team, quantified scrounging or thievery attempts among Northwest crows. When birds found valuable items such as small fish or clams, other birds tried to steal the food 46 percent of the time and 41 percent of those attempts were successful.

"This research shows these birds discriminate kin from non-kin," said Renee Ha. "They can tell who they are related to and treat birds differently. We know it is more complex and sophisticated than being based on just the birds they know. Crows and other corvids (ravens, jays and magpies) are highly complex cognitively and socially, and are very adaptive."

Earlier work by the Has showed that thievery is common among these birds, which are constantly looking for an opportunity to filch a snack from another crow.

To understand crow behavior, the UW researchers captured and banded 55 birds that foraged in a suburban Snohomish County park along Puget Sound north of Seattle. They also drew a small blood sample from each bird. The bands enabled the researchers to identify individual crows. DNA analysis of the blood allowed the Has to determine which o
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Contact: Joel Schwarz
joels@u.washington.edu
206-543-2580
University of Washington
11-Mar-2003