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.

Black G rouse is smaller th an Capercaillie and can forage on catkins, buds and shoots in the m iddle and outer parts o f crowns o f large deciduous trees: b irch, alder, and willow (Fig. 2.7). The Hazel G rouse, like the Black G rouse, feeds on catkins, buds and shoots o f various deciduous trees. Due to its smaller size and th e ability to sit on th in twigs, it forages in the outer part o f he crown. It prefers trees th a t resemble bushes in th eir life form. T heir crowns consist m ainly o f dense th in twigs th a t can carry a bird and allow it to bite relatively m uch food around it in spite o f its small size (Fig. 2.7, Andreev 1979, 1980, S.V. Drovetski, pers. comm .). Willow and Rock Ptarm igans in w inter mainly feed on th e g round and take d if­ ferent parts o f herbs, subshrubs, and bushes (Fig. 2.7). They differ in th e ir body size and in the size and power o f th e ir bills. The Willow P tarm igan is th e larger species o f the two; it mainly eats twigs and has a larger and m ore powerful bill. The Rock Ptarm igan takes a smaller p ropo rtion o f twigs and therefo re does no t need such a powerful bill as the former species (S em enov-T ian-Shansky 1960, Sem enov-T ian- Shansky & Gilyazov 1991). 2 .4 .4 . Shorebirds and gulls Shorebirds and gulls are represented in Pasvik by a large n um b er o f species, form high population densities and play an im po rtan t role for th e local ecosystems. The reason for this is a large area and variety o f wetland hab itats, w hich are m ainly used by these birds, in the Pasvik valley. Ecological groups of shorebirds Waders (L im icolae) feed w hen running on the g round o f wading in shallow water. Their ecology is governed by feeding specialisation th a t determ ines many other im portant ecological characteristics. Food type and foraging m ethod s d e te r­ mine the use o f certain habitats. The m ain food o f nearly all shorebirds is inverte­ brates found in littoral, sediments, wet sand, shallow water, o r o n th e surface o r in the upper layers o f wet soil (Yudin 1965). In our study area several ecological groups o f shorebirds may be distinguished that differ in their specific m ethods o f searching for prey and foraging and exist together or separately in different habitats. Waders that inhabit shores of rivers, lakes, and seas In Pasvik several coastal waders live: the G re a te r R inged Plover, Ruddy Turnstone, Temm inck's Stint, C omm on Sandpiper, Oystercatcher. The foraging 96