Description:
<p>The habitat and spatial relations of 762 territories of willow warblers Phylloscopus trochilus, chiffchaffs Ph. collybita, wood warblers Ph. sibilatrix, and goldcrests Regulus regulus, as well as the intraspecific and interspecific effects on the habitat selection, were studied in two large forest areas in southern Finland. The occurrence of the species in 12 subareas depended on the forest fragmentedness, and the amount of spruce forests and forest edges. The habitat distribution of all four species differed significantly from the availability of different habitat types. When the habitats were classified according to the characteristics of vegetation, the preferences of different species were different, although chiffchaff and goldcrest resembled each other. However, all the species preferred habitats which were characterised by a high density of birds. The habitat amplitude of the abundant willow warbler did not vary much between subareas, but in the other species, an increase in the population density seemed to lead to acceptance of less preferred habitats. There was a possible effect of the goldcrest on the habitat amplitude of the chiffchaff. Association indices, which take the availability of different habitat types into account, revealed that the greatest differences in habitat utilisation patterns were between the willow warbler and both the chiffchaff and goldcrest, as well as between the goldcrest and wood warbler. However, a nearest neighbour analysis showed a slight association between the willow warbler and chiffchaff, which was due to differences in their territory size.</p>