Social learning spreads knowledge about dangerous humans among American crows.

Bibliographic Collection: 
Publication Type: Journal Article
Authors: Cornell, Heather N; Marzluff, John M; Pecoraro, Shannon
Year of Publication: 2012
Journal: Proc Biol Sci
Volume: 279
Issue: 1728
Pagination: 499-508
Date Published: 2012 Feb 7
Publication Language: eng
ISSN: 1471-2954
Keywords: Animals, Crows, Face, Humans, Learning, Seasons, Social Behavior, Visual perception, Washington

Individuals face evolutionary trade-offs between the acquisition of costly but accurate information gained firsthand and the use of inexpensive but possibly less reliable social information. American crows (Corvus brachyrhynchos) use both sources of information to learn the facial features of a dangerous person. We exposed wild crows to a novel 'dangerous face' by wearing a unique mask as we trapped, banded and released 7-15 birds at five study sites near Seattle, WA, USA. An immediate scolding response to the dangerous mask after trapping by previously captured crows demonstrates individual learning, while an immediate response by crows that were not captured probably represents conditioning to the trapping scene by the mob of birds that assembled during the capture. Later recognition of dangerous masks by lone crows that were never captured is consistent with horizontal social learning. Independent scolding by young crows, whose parents had conditioned them to scold the dangerous mask, demonstrates vertical social learning. Crows that directly experienced trapping later discriminated among dangerous and neutral masks more precisely than did crows that learned through social means. Learning enabled scolding to double in frequency and spread at least 1.2 km from the place of origin over a 5 year period at one site.

DOI: 10.1098/rspb.2011.0957
Alternate Journal: Proc. Biol. Sci.