flock of rooks sits on fruit (nut) trees to look for walnuts

rooks winter temperate zone flock of sits fruit trees nut tree walnuts doldrum depression stressanxiety blues heavy fog gray crow sitting animal behaviour bird prey birdwatching branch city birds park clever corbie corvus rook crowd dumb animals feather gatherer waste horde huddle intelligence migration concept migratory ornithology raven scavenger smart swarm synanthropic wildlife wings