10 January 2014

Crow Brainpower

Welcome back. Looking down from a window of our garage apartment, I often see birds feasting on the seeds and suet that cost my father-in-law a fortune to keep replenished. There is a wide variety of birds, which isn’t to say that I know one from another, only that they’re different.
American Crow (photo from
 www.planetofbirds.com)

I do know crows, and though they’re not lacking in Wisconsin, I haven’t seen any since we moved here a year ago. Crows weren’t that common where we lived in Virginia either. We usually knew when they were visiting because the house would reverberate. They would perch on the roof and peck at the metal chimney cover. I suppose they had a purpose, but they might have just been playing or teasing us. They’re crows.

Crows Response to Faces and Gazes

Parrots and corvids--crows, ravens and jays among others--are considered the most intelligent birds. They even compare well with primates. A University of Washington study of crows showed what had been long suspected: crows can recognize human faces.

The investigators wore a mask of a caveman when trapping and banding crows on campus. In the following months, they wore the mask but didn’t bother the crows; yet the crows scolded them much more than before they were trapped, even if the mask was worn upside down or under a hat. Two years later, when the principal investigator walked across campus wearing the mask, almost seven times more crows than had been tagged scolded him, suggesting the crows learned from parents or others in the flock.

In follow-up experiments, six students wore six different, more realistic masks while trapping crows at sites around the City of Seattle. Volunteers then wore those masks at the trapping sites and found the crows unfailingly scolded the individual who wore the “trapping” mask.

In spin-off experiments, collaborators from Humboldt State University and the University of Washington walked toward crows and looked either directly at the birds or at some other point. The crows fled sooner and more urgently when the humans were gazing directly at them. (The birds did not respond differently to a smile or a scowl.)

Crows’ Response to Change

A recent study from Germany’s University of Tübingen went further. One measure of an animal’s cognitive ability is how well it responds to change, its behavioral flexibility.

Using a computer touch screen, the researchers showed crows an image that the birds had to remember. (Yes, crows can be trained.) The crows were then shown two images, the one to be remembered and a different image. The crows had to select one of the two images, and the “correct” image varied in accordance with a switching behavioral rule.

The crows were able to respond to the switching rule and select the correct image, a task which can be difficult for most animals including humans.

As the tests proceeded, the researchers observed nerve cell activity in the region of the crows’ brains that is associated with the highest levels of cognition. From these measures, the researchers were often able to predict which rule the crow was following even before the crow made its choice.

The study provided insights into the evolution of intelligent behavior, being especially useful because the nerve cells regulating decision-making in birds and primates are similar though the anatomy differs.


New Caledonian crow using a short stick
 to get a longer stick to get food. (photo from
 www.newscientist.com/article/dn12495)
Wrap Up

The overview of the book Gifts of the Crow describes crows as having brains that allow them to think, plan and reconsider their actions, as well as design and use tools. But there are so many anecdotes to support the conclusion that crows are playful, social and passionate that I still wonder about those crows that kept pecking our chimney cover. Thanks for stopping by.
 

P.S.

- New York Times article (2008) on Univ. of Washington crow studies:
www.nytimes.com/2008/08/26/science/26crow.html
- 2010 paper in Animal Behaviour:
www.sciencedirect.com/science/article/pii/S0003347209005806
- Excerpt of 2012 book, Gifts of the Crow on Popular Science:
www.popsci.com/science/article/2012-06/how-crows-recognize-individual-humans-warn-others-and-are-basically-smarter-you
- Paper on crow response to human gaze in Ethology and article on Scientific American: 

onlinelibrary.wiley.com/doi/10.1111/eth.12064/abstract
www.scientificamerican.com/article.cfm?id=crows-show-off-social-skills
- University of Tübingen study in Nature Communications and article on Science Daily:
www.nature.com/ncomms/2013/131128/ncomms3878/full/ncomms3878.html
www.sciencedaily.com/releases/2013/11/131128103835.htm

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