Bird class (Aves) in Arctic fauna

摘要

The arctic avian fauna, in a wide sense, includes 241 species (2.8% of the world class richness). It is represented by its own arctic species, in a wide sense (74 species); penetrating far to the Arctic, mainly polyzonal and boreal species (25); visiting the southern Arctic belt (66); penetrating in some places to the southernmost portions of the Arctic (76 species). Some general features of the arctic avian fauna chorology, such as the role of borealand-montanous elements, a tendency of circumpolarity, regional and subzonal differentiation. The level of bird species richness (concrete faunas) of temperate and arctic zones is closely related to summer (mean July) temperatures. Within the Arctic this relation becomes more tight and is described by a logistic curve. The most important specific feature of the arctic avian fauna is a unique proportion of hydrophilous and dendrophilous evolutionary and ecological lines. Its composition is dominated by taxa of more ancient hydrophilous phyletic complexes, primarily of Charadriiformes and Anseriformes, representing more than a half of the avian fauna; Passcriformes stop dominating. In the context of ecological vicariation, proportions between Charadriiformes and Passeriformes are considered. Using birds as an example, a tendency of increasing the specific weight of carnivorous forms in the fauna from lower to upper latitudes is confirmed. In the class of birds, as in other taxa. demonstrating maximal indices of biological progress in the Arctic. the adaptive radiation as well as channel evolution are well pronounced in development of the given type of environment. In the context of global biotogenesis, considerations on the role of adaptive strategies of "tolerant-passive" type in formation of the arctic avian fauna are given.