Locomotion patterns in wintering bark-foraging birds

Abstract

Locomotion patterns in the bark-foraging guild, three woodpeckers (Dendrocopos major, D. medius, D. minor) and three passerines (Sitta europaea, Certhia brachydactyla and C. familiaris), were studied during five winters (1990-1995) in mixed forests in Western Poland. The main aim of the study was to find the differences in locomotion between the studied species, as they might be important as a factor reducing competition for limited and unrenewable winter food resources. Locomotion and microhabitat utilization variables were used to obtain, on the basis of PCA, a smaller number of compound components describing mobility in foraging behaviour. PCA was also used to obtain a species body-size measurement from several external measurements . Interspecific differentiation of locomotion variables was very high and significant. Mobility of species was inversely correlated to body-size which was expressed specially in length of movement, speed of creeping, and ratio of foraging with stationary and dynamic patterns . Mean time of foraging on a tree was significantly longer in larger species, which was connected with the use of deep-foraging techniques by these species. Considering locomotion patterns, woodpeckers and passerines did not form strongly separate groups. Only both treecreepers showed very similar moving strategies, however, in this case also some significant differences were found.