NICHE SHIFTS OF COAL TITS PARUS-ATER IN DENMARK

Foraging behaviour of Parus guilds in Denmark was studied at two study sites on the mainland and on two islands on which Crested Parus crist atus and Marsh Tits P. palustris is were absent. In the absence of Cre sted Tits, island Coal Tits P. ater foraged among twigs and branches, which, on the mainland, were the domain of the Crested Tit. Comparing observations with and without Crested and Great Tits P. major present, I found significant differences in choice of foraging substrate and f oraging height of Coal Tits. Generally, Coal Tits foraged higher in th e presence of Great and Crested Tits. Consistently, there were no diff erences between mainland sites, nor between islands with respect to th e foraging niches of the Coal Tit. These results are consistent with t he hypothesis that interspecific competition has shaped the foraging n iches of the Parus guild.