Jackdaw
Lorenz found that the birds have a hierarchy, with higher-ranked birds dominating lower-ranked birds. Pair-bonded birds share the same rank. Young males establish their individual status before pairing with females. Unmated females are the lowest members in the pecking order, and are the last to have access to food and shelter. Lorenz noted one case in which a male, absent during the dominance struggles and pair bondings, returned to the flock, became the dominant male, and chose one of two unpaired females for a mate. This female immediately assumed a dominant position in the social hierarchy and demonstrated this by pecking others. According to Lorenz, the most significant factor in social behaviour was the immediate and intuitive grasp of the new hierarchy by each bird in the flock.