Social learning spreads knowledge about dangerous humans among American crows

Abstract

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.

Shared space, individually used: spatial behaviour of non-breeding ravens (Corvus corax) close to a permanent anthropogenic food source

“…Traps were checked at least twice a day (usually in the morning and before sunset) to enable birds to return to their night roost after marking. Caught ravens were handled and released as quickly as possible (after approximately 15 min), and care was taken to ensure that the head and eyes of each raven were covered during the whole procedure by a soft piece of cloth to prevent them from learning about human facial features (compare Marzluff et al 2010;Cornell et al 2012). While marking, we collected blood samples for sexing (following the procedure of Griffiths et al 1998).…”

Catch the wave: prairie dogs assess neighbours’ awareness using contagious displays

“…The acquisition of information from conspecifics proves adaptive in contexts including foraging [25], habitat choice [26], mate choice [27], parenting [28], tool use [29], and both anti-brood parasite [30] and anti-predator responses [31]. Although social learning and public information use are often considered tacitly different concepts [32 -34], the effective utilization of socially available information requires that individuals assess the veracity of the information they receive [35][36][37], and sample available information on an ongoing basis to ensure that information is up-to-date [38].…”

Distinct neural circuits underlie assessment of a diversity of natural dangers by American crows

“…The intensity varies, but not the fundamental aspects of the behaviour [6,8]. A person who has wronged a crow in the past is instantly recognized, scolded and mobbed [8,9]. Even a dead crow attracts a scolding mob [10,11].…”