Featured Research

from universities, journals, and other organizations

Crows Alter Their Thieving Behavior When Dealing With Kin Or Other Birds

Date:
March 12, 2003
Source:
University Of Washington
Summary:
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.

Animal behaviorists have something new to crow about.

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 of the banded birds were related.

The researchers observed the crows for 223 hours over the course of 2 years, looking for instances of thievery involving two banded birds. The crows' behavior was remarkably different, depending on the target of a theft.

When the birds are related a crow will use a passive strategy and "walk up to or kind of sidle next to the bird with the food. Often the second bird will give up the food to the scrounger," said Renee Ha. "With aggressive scrounging, there is usually a flying approach by the thief who nearly lands on the other bird. This can be followed by vocalization, physical contact and attempts to take the food. Usually it also involves chasing and avoidance by the bird with the food."

She added that there does not appear to be any other pattern associated with scrounging. The sex or age of the birds do not seem to be factors and the birds will steal from relatives as well as non-relatives.

The researchers noted that the majority of the crows they observed engaged in hunting for food, as well as thievery. A few crows only hunted and none exclusively relied on stealing.

"Crows can not steal for a living because there are not enough opportunities to steal enough big food items. Scrounging fills a gap and crows will do it if the bird next to them has high value food that takes time to swallow," Renee Ha said.

James Ha added that the Northwest crows have complex social groups. "They tend to associate in stable groups that contain some of the same birds all of the time. But these groups are not kinship groups and the members are not all necessarily related to each other. They will try to steal food from familiar birds, kin or strangers," he said.

"This behavior seems to be specific to Northwest crows which are shoreline feeders of large prey, said Renee Ha. "Most people, regardless of where they live, are familiar with the more common American crow (Corvus brachyrhynchos), which feeds on worms and grain. That kind of food does not offer targets for thievery."

Co-authors of the study were Paul Bentzen, a former UW associate professor of aquatic and fishery sciences who is now with the biology department at Dalhousie University in Canada, and Jennifer Marsh, a UW psychology doctoral student. The research was funded by the Animal Behavior Society; Sigma Xi, a scientific honor society; and the UW.


Story Source:

The above story is based on materials provided by University Of Washington. Note: Materials may be edited for content and length.


Cite This Page:

University Of Washington. "Crows Alter Their Thieving Behavior When Dealing With Kin Or Other Birds." ScienceDaily. ScienceDaily, 12 March 2003. <www.sciencedaily.com/releases/2003/03/030312071637.htm>.
University Of Washington. (2003, March 12). Crows Alter Their Thieving Behavior When Dealing With Kin Or Other Birds. ScienceDaily. Retrieved July 30, 2014 from www.sciencedaily.com/releases/2003/03/030312071637.htm
University Of Washington. "Crows Alter Their Thieving Behavior When Dealing With Kin Or Other Birds." ScienceDaily. www.sciencedaily.com/releases/2003/03/030312071637.htm (accessed July 30, 2014).

Share This




More Plants & Animals News

Wednesday, July 30, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Raw: Otters Enjoy Water Slides at Japan Zoo

Raw: Otters Enjoy Water Slides at Japan Zoo

AP (July 30, 2014) River otters were hitting the water slides to beat the summer heatwave on Wednesday at Ichikawa City's Zoological and Botanical Garden. (July 30) Video provided by AP
Powered by NewsLook.com
In Virginia, the Rise of a New Space Coast

In Virginia, the Rise of a New Space Coast

AP (July 30, 2014) Every summer, tourists make the pilgrimage to Chincoteague Island, Va. to see wild ponies cross the Assateague Channel. But, it's the rockets sending to supplies to the International Space Station that are making this a year-round destination. (July 30) Video provided by AP
Powered by NewsLook.com
Rodents Rampant in Gardens Around Louvre

Rodents Rampant in Gardens Around Louvre

AP (July 29, 2014) Food scraps and other items left on the grounds by picnickers brings unwelcome visitors to the grounds of the world famous and popular Louvre Museum in Paris. (July 29) Video provided by AP
Powered by NewsLook.com
Jane Goodall Warns Great Apes Face Extinction

Jane Goodall Warns Great Apes Face Extinction

AFP (July 29, 2014) The world's great apes face extinction within decades, renowned chimpanzee expert Jane Goodall warned Tuesday in a call to arms to ensure man's closest relatives are not wiped out. Duration: 00:58 Video provided by AFP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins