Behaviour and life-history responses to chick provisioning under risk of nest predation.

This thesis examines risk management in breeding Siberian jays (Perisoreusinfaustus), which is indigenous to the northern taiga. Parent behaviour and the nestare cryptic. A new nest is built each year. It is placed on spruce or pine branches closeto the trunk and well insulated with lichens, feathers and reindeer hair.Nest failure rate was the main factor driving annual variations in jay numbers.The probability for nesting attempts to be successful ranged annually between 0.08and 0.70. Nest predation was rampant and a main cause of nest failure. Nest predatorswere mainly other corvids (primarily the Eurasian jay Garrulus glandarius). Habitatquality was the main factor determining the risk of predation. The risk for nest failuredue to predation was higher in thinned forests with an open structure and with a highabundance of man-associated corvid species (jays, crows, raven).[