rooks gathered at top of tree

animal animals bare behaviour bernd bird birds birdwatching blues branch branches city clever concept corbie corvus crow crowd depression european feather flock gathered gatherer gray heinrich horde huddle inactive intelligence juglans migration migratory nature night ornithology persian prey raven regia rook rooks royal scavenger sits sitting smart spend stressanxiety sunset swarm temperate top tragic tree walnut walnuts waste wildlife winter wood zone