Breeding forest birds in the Valdai Uplands, north-west Russia: assemblage composition, interspecific associations and habitat amplitudes

Seven study plots (16.9—21.0 ha) were established in representative forest habitats in the northern part of the Valdai Uplands. The breeding birds were censuses by the mapping method during four to five years, from 1985 to 1989. Forty-six pigeon, woodpecker and passerine species were found to have at least half a territory in the total plots during the study period. Anthus trivialis was the only species that nested in sphagnum bog pine forest. In other plots, Fringilla coelebs was the most numerous species. The average total densities ranged from 33 territories/km2 (bog pine forest) to 1027 territories/km2 (mesic grey alder forest). The average species richness and average total density were strongly positively correlated. Grey alder forest specialists were most closely associated. Spruce forest species formed a very distinct group, but the association among them was fairly low. There was a positive correlation between habitat amplitude and total sample size across 23 common species for the period 1986—1989. Turdus pilaris, T. iliacus, Hippolais icterina, Sylvia borin, S. atricapilla and Anthus trivialis had much narrower habitat amplitudes than could be expected on the basis of their sample sizes, whereas Turdus philomelos, Parus cristatus and P. montanus had much broader amplitudes. The expected number of habitats in a standard sample of 14 territorial pairs was highest in Turdus philomelos, Erithacus rubecula and Fringilla coelebs. Species which could be expected to be found in many habitats tended to occupy them more evenly.