Crows remembered one 'dangerous' human face for years — and warned their friends
Researchers at the University of Washington trapped wild crows while wearing a distinctive mask, then walked around campus in that same mask without bothering the birds at all. Crows scolded the 'dangerous' mask on sight — even years later, and even when other crows who'd never been trapped joined in, suggesting the warning had spread socially from crow to crow rather than through personal experience alone.