Activity budgets and microhabitat use in the Siberian Jay Perisoreus infaustus in managed and unmanaged forest

Abstract

In this paper, we compare activity budgets and microhabitat use of Siberian Jays Perisoreus infaustus in spruce-dominated (pristine) forest and pine-dominated (managed) forest in northern Sweden. Besides tree species composition, the forest types differed in the abundance of dead standing trees, lichen and moss cover, and visibility. Three broods in each forest type were monitored for behavioural activity, use of tree species and vertical dimension (ground vs. tree) after fledging (from late May to late July 1998). We found significant difference in behavioural activity among the forest types. For adult jays the two dominating behavioural categories were food search and sitting, whereas for juveniles sitting and resting were the most common activities. Adult Siberian Jays allocated relatively more time for food search in the spruce-dominated forests juveniles spent relatively more time sitting and less time resting in spruce-dominated forest. Adult jays used tree species proportional to availability for food search in both forest types. Birch was used more than expected by abundance for sitting by adult jays in spruce-dominated forest, whereas spruce was used disproportionately for sitting in pine-dominated forest. Spruce-dominated forest may provide more diverse feeding opportunities than pine-dominated forest, and reduced visibility in spruce-dominated forest may offer better concealment from avian predators. The strong preference for spruce in pine-dominated forest suggest that spruce is an important cover component in Siberian Jay territories.