The birds of Pasvik / E. I. Khlebosolov, O. A. Makarova, O. A. Khlebosolova [et al. ; English transl. Nikita Chernetsov]. - Ryazan : Golosgubernii, 2007. - 175 с. : ил., портр.

Figure 3.9. Succession and frequency o f foraging manoeuvres o f Eurasian Redstarts in pine for­ est. P —pick; S —searching for prey; F - flight; H* —hop on the ground; H F —hovering flight; FP —flight —pick —landing; LP —flight to the ground. N (S) is the num ber o f successions, in parenthesis the overall observation time (s). Numbers show the frequency o f foraging m anoeu­ vres afterth e preceding ones, arrows show the direction o f hops and flights (Shemyakina 2002). the crown, under the crowns and on the ground. Therefore they breed in sparse high pine forests with weakly developed herbaceous vegetation. When the m ic ro ­ habitats preferred by each species are located in different habitats, the birds are spa­ tially separated. In transitional habitats that contain microhabitats suitable for all tree species spatial separation is less pronounced and may be non-existent. 3 .1 .2 . W illow W a rb le r, Chiffchaff, and Arctic W a rb le r The Willow Warbler breeds in Pasvik in high numbers and dominates in forest habitats. The two other Phylloscopus species, the Chiffchaff and the Arctic Warbler, are rare and occur locally. The reason for this is that the structure o f forest vegeta­ tion in Pasvik is optimal exactly for the Willow Warbler. Here relatively sparse stands prevail, where uniform illumination by the sun provides the conditions for formation o f tree crowns that correspond to the specific features o f Willow Warbler’s foraging behaviour (Fig. 3.10). Chiffchaff, unlike the Willow Warbler, mainly occurs in denser forests with small clearings with well developed underbrush and shrub. This species forages in