The effect of percentage of tree cover on breeding performance of Great tit (Parus major)

Abstract

We studied ecology of P. major with focusing on the effect of percentage of tree cover on their breeding performance in urban area. We selected two study sites, Expo 70 memorial park (A) and University in Osaka Prefecture (B). The percentage of tree cover of site A (76.6%) was higer than site B (31.5%). Percentage of nest box used for breeding and number of pairs per 1ha of A (41.4%, 1.82/ha) were higher than those of B (33.3%, 0.23/ha). Mean brood size was similar between two sites (A : 7.8, B : 8.0).The percentage of fledglings leave the nest of A (56.1%) was lower than B (95.8%). In site A, fledglings in one nest box was predated by a snake. Mean home range size of site B (4.70ha) was larger than A (0.76ha). P major breeding in the site B where the percentage tree cover was lower than A, probably needed larger home range to feed their fledglings. Mean feeding frequency per hour was similar between sites (A was 13.5, B was 10.4). P. major of site A showed similar feeding frequency with B with small home range, so feeding efficiency of A may higher than B. Feeding frequency increased as chicks grow and also by larger blood size. Both of two sites, P major foraged almost from broadleaved trees. As other foraging sites than trees, parents of A foraged from ground or forest floor, and those of B foraged from windows or walls of buildings.