Dec 01, 2014
Friends or Foes: Facing the Facts About American Crows
David P. CraigWillamette University - Department of Biology
Who knows
what this
is ?
The Rook (Corvus frugilegus)i.e. the food-gathering crow of Eurasia
Everybody has a crow story
Everybody has a crow story
Everybody has a crow story
Everybody has a crow story
‘Welcome to Science Whitewing” “I got him, John!” “How was your climb?”
Predator Recognition by Crows
Crow Call TypesCaw
Scold
Sociality and Relatively Large Brains May Enable Discrimination
Can You Tell the Difference Between Dick Cheney and a Caveman?
CheneyCaveman
CheneyCaveman
Can Crows Tell the Difference Between Dick Cheney and a Caveman?
Two Main Questions
1) Can wild American Crows learn to recognize individual people?
2) Does social learning take place?
What About Ordinary Faces?
Study Treatments
• Ten trials per site
• Nine treatments per trial– Negative mask– Five neutral masks– Negative mask + armband– Two neutral masks + armband
The dangerous face is always
recognized, and especially likely to attract a mob,but not perfectly.
Two Mask Trials
• One mask at a time
• Choice among masks
When forced to select the Dangerous from a Neutral Mask, when both were presented simultaneously, Crows accurately
discriminated among all the ordinary masks.
Two Main Questions
1) Can American Crows learn to recognize individual people?
2) Does social learning take place?
Acquisition of Information
• Individual “trial and error” Learning– Allows Flexibility,– But Dangerous
• Social Learning– Flexible– Reduced Cost
Three Opportunities for Observational Learning
1) At time of capture2) Associating with
crows who were captured when they encounter the trapping mask at a later date
3) Young of crows who had been captured
Spread in the Geographical
Extent of Scolding the Extraordinary
Face over 2.8 Years
Urban Site (B.) shows a result
similar to the pilot study but not
elsewhere (A.)
Downtown urban site has similar density and unpredictable identity of humans as does the pilot campus site
Dangerous mask downtown was bald man, most similar to extraordinary face from campus
Individuals with the Direct Experience of Being Captured Learned to Discriminate Faces More Accurately Than Those
Only Observing Capture or Subsequent Scolding of Captors
Vertical Learning• We put a radio tag on young
crows (without ourselves wearing a mask) whose parents scold the dangerous mask
• While under parental care, the young observe their parents scold the dangerous mask
• Independent of parental care, the young crow scolds the dangerous mask
Crow Paradox
Face Recognition
Halloween Mask Sales on AmazonPredicted Election
San Onofre aka
St Onuphrius by the Spanish painter,
Francisco Collantes
(1599-1656)
Museo del Prado
CULT of CORAX