Nesting habitat requirements and nestling diet in the Mediterranean populations of Crested Tits Lophophanes cristatus

摘要

Most bird species show specific habitat requirements for breeding and feeding. We studied the pattern of habitat occupation, nestling diet and breeding performance of Crested Tits Lophophanes cristatus in a "typical" (conifer-ous) and an "atypical" (Holm Oak Quercus ilex) forest in eastern Spain during 2005-2007. We aimed to determine which microhabitat characteristics in the Holm Oak forest could account for the presence of Crested Tits, and checked whether the nestling diet in the Holm Oak forest resembled that obtained in the pine forest. Vegetation maps were produced using GIS from observations made in the field (tree species, tree and shrub cover). Nestling diet was recorded through video surveillance. Crested Tits bred in mature, low-density areas in the pine forest. Those breeding in the Holm Oak forest built their nests in areas including pine trees and avoided densely forested areas. Birds breeding in the pine for-est started laying by mid-April and the average dutch size was 5 eggs. In the Holm Oak forest, birds started laying by the end of April and average clutch size was also 5 eggs. Fledglings weighed around 12 g in both forests. Nestling diet, prey size and feeding frequency by the parents did not vary between the forests. The main prey types consumed were Lepidoptera larvae and Diptera.