Western Jackdaw - Behaviour

Behaviour

Generally wary of people in the forest or countryside, Western Jackdaws are much tamer in urban areas. Like Magpies, they are known to pick up shiny objects such as jewellery to hoard in nests. John Gay, in his Beggar's Opera, notes that "A covetous fellow, like a jackdaw, steals what he was never made to enjoy, for the sake of hiding it". In Tobias Smollett's The Expedition of Humphry Clinker, a scathing character assassination runs, "He is ungracious as a hog, greedy as a vulture, and thievish as a jackdaw."

Highly gregarious, Western Jackdaws are generally seen in flocks of varying sizes, though males and females pair-bond for life and pairs stay together within flocks. Flocks increase in size in autumn and birds congregate at dusk for communal roosting, with up to several thousand individuals gathering at one site. At Uppsala, Sweden, 40,000 birds have been recorded at a single winter roost with mated pairs often settling together for the night. Western Jackdaws frequently congregate with Hooded Crows or Rooks, the latter particularly when migrating or roosting. They have been recorded foraging with the Common Starling (Sturnus vulgaris), Northern Lapwing (Vanellus vanellus), and Common Gull (Larus canus) in northwestern England. Flocks are targets of coordinated hunting by pairs of Lanner Falcons (Falco biarmicus), although larger groups are more able to elude the predators. Western Jackdaws sometimes mob and drive off larger birds such as European Magpies, Common Ravens, or Egyptian Vultures (Neophron percnopterus); one gives an alarm call which alerts its conspecifics to gather and attack as a group. Occasionally, a sick or injured Western Jackdaw is mobbed until it is killed.

In his book King Solomon's Ring, Konrad Lorenz described and analysed the complex social interactions in a Western Jackdaw flock that lived around his house in Altenberg, Austria. He ringed them for identification and caged them in the winter to prevent their annual migration. He found that the birds have a linear hierarchical group structure, with higher-ranked individuals dominating lower-ranked birds, and pair-bonded birds sharing the same rank. Young males establish their individual status before pairing with females. Upon pairing, the female assumes the same social position as her partner. 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 of the Western Jackdaws in the flock.