Friday, October 9, 2015

Wild American Crows Use Funerals to Learn About Danger

Wild American crows use funerals to learn about danger

According to University of Washington Kaeli Swift and Dr. John Marzluff School of Environmental and Forest Sciences, a growing number of animals demonstrate seemingly ritualistic behaviors around the death or body of a conspecific, the evolutionary basis for this behavior remains unclear. 


The two researchers demonstrated that wild American crows (Corvus brachyrhynchos) are using funeral gatherings as an opportunity to engage in social learning, inform future resource use, infer novel predators, and that this behavior is not shared by another urban bird: the rock pigeon (Columba livia).

Credit: Walter Siegmund

Novel humans paired with a dead crow, a red-tailed hawk (Buteo jamaicensis), and a hawk with a dead crow all evoked mobbing and decreased foraging by crows, while pairing with a dead pigeon did not. These findings suggest that dead conspecifics, but not heterospecifics, represent a salient danger akin to observation of a predator. Mobbing and decreased foraging immediately after stimulus removal were strongest when crows were presented a hawk with a dead crow. 

Over the next 3 days they found that crows avoided food in areas associated with these dangerous events. However, site avoidance was uniform across stimuli suggesting that crow sensitivity to the identity of the threat dissipates after 24 hours. 

In addition, they demonstrated that crows use proximity to predators, dead conspecifics and predators with conspecific remains as a cue to learn and subsequently scold the associated human after only 1 training event, and that this association could last 6 weeks. Together, these data provide important insights into the nature of crow funeral gatherings and how crows navigate the threatening landscape.

Citation: Swift, Kaeli N. : Thesis (Master's)--University of Washington, 2015 http://hdl.handle.net/1773/33178

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