FURTHER OBSERVATIONS ON THE BEHAVIOUR OF THE JAY GARRULUS GLANDARIUS

Abstract

Summary. The paper deals with the behaviour of captive and wild Garrulus glandarius. The Jay erects its plumage when cold or in conflict situations and depresses it when hot or when activated solely by the escape drive. Juvenile Jays often rest or sleep in contact. Adults never do and always show appeasing or aggressive behaviour when they closely approach one another. The flight‐intention movements are described and discussed. When mobbing a predator the Jay shows intention‐movements of both fleeing and attacking. Threat behaviour is variable. The more the plumage is erected the stronger are the conflicting drives of escape and aggression. The defensive‐threat display seems primarily concerned with defence of nest or young. The lateral display is self‐assertive and may be either threatening or sexual in context. It is considered to be derived mainly from sexual movements. The submissive display may be sexual or appeasing. It perhaps derived from such “simple” trembling as Homo and Columba show in situations where their escape drives are thwarted. Food‐begging is normal in juveniles and breeding females. Apparently correlated with a mood of dependence, it may be shown by non‐breeding females and adult males. It is not primarily sexual and may inhibit sexual behaviour in the partner. Nesting behaviour is described. Only sticks, roots, fibres and wires are used as material. Both sexes build. The incubating female leaves the nest if its supports are jarred. At approach of man wild Jays cower in the nest, tame ones show the defensive‐threat display. The reasons for this difference are discussed. The male feeds the sitting female. He shows great caution when coming to the nest. When both parents feed the young together (as they usually do) each tries to snatch any visible food from the nestling's mouth when the other withdraws its bill. Eggshells are eaten when the young hatch. Females sometimes eat their own eggs or young, probably from hypertrophy or perversion of the nest‐cleaning behaviour. Addled eggs are left in the nest for some time after the young hatch. There is no egg‐retrieving instinct. Some Jays removed white and bright blue dummy eggs from their nests, others accepted them. A female that had never seen young before at once accepted a half‐grown young Jay placed in her nest. Her mate showed fear of it at first but soon adopted it. Vocal mimicry is often linked with the subjective mood. Jays mobbing a man at their nest imitate alarm notes of other species and the calls of predators. Jays may utter the call of another species at sight of it. Tameness and reaction to handling are discussed. Jays reared by one or two people often show much fear of strangers when adult. Those which have been in contact with many different people when young do not.