Suchergebnisse

Ecologo-geographical differentiation and dynamics of spring migration of water and semiaquatic birds of the Putorana Plateau are analyzed. Eight points were surveyed in the northern, southern, western and eastern parts of the region on the total area of 250 000 km², applying the method of route census. The water and semiaquatic avifauna of the Putorana Plateau during the spring migration period includes 68 species. The birds fly in north, east and west directions. They make stops at the river deltas that thaw out early. Bird population density at stops is from 15 to 227, on average (n = 8) 94 ind./1 km of coastline. The population of birds on lakes is always much smaller than on the adjacent river sections. The entire spring migration of water and semiaquatic birds on the Putorana Plateau takes place from May 19 to June 27 and lasts on average (n = 10) 23 days. The main passage runs from May 25 to June 17 and lasts on average (n = 8) 7 days. Spring migration is most intense in the west of the Putorana Plateau, where at least 20 000-30 000 individuals of water and semiaquatic birds fly through the surveyed points. There are 19 species among the dominants of water and semiaquatic habitats, including Eurasian Wigeon, Common Teal, Greytaild Tattler, Northern Pintail and Little Stint.

The ecological patterns of structure formation and spatial differentiation of the winter fauna of mammals in the seas of the northeastern Palearctic are analyzed. The method of aviation route surveys in a 1 km wide zone was applied. Aerial surveys in the end of 1987-1988 winter period covered the Bering, Chukchi, East Siberian Seas, and the eastern part of the Laptev Sea. The recorded species of mammals (n = 7) are ecologically associated with open sea areas, sea ice, continental and island coasts, and continental tundra. The winter fauna of mammals in the seas of the northeastern Palearctic accounts for 23% of the total mammalian fauna of the region; pinnipeds and cetaceans predominate in terms of the number of species. The similality of the winter fauna of mammals in the Arctic Ocean and the Northern Pacific is 36%. Most of the mammals were observed on the leads in the contact zones between different types of ice or in iceholes among the ice of autumn formation. Polar bears were most often observed near the Wrangel Island, beluga whales - to the east and northeast of the Navarin Cape, walruses - to the south of the Providence Bay. The average density of the winter population of mammals in the surveyed seas of the Northeastern Palearctic is 6.2 individuals/100 km². Walruses, beluga whales, and ringed seals predominate in the population, totaling 94% of the animal numbers.

The ecological and geographical differentiation of the bird population at 18 sites of the Urup and Iturup islands was analyzed. The method of route accounting was applied. A total of 109 species were recorded, 62 of them on both islands. The coefficient of faunal commonality between the terrestrial habitats of the islands is 72%, and between the coastal-marine - 71%. The coefficient of similarity of the bird population between the land habitats of the islands is 36%, and between the coastal-marine - 29%. The values of bird population density on the islands are close both between terrestrial (610-757 ind./km2) and coastal-marine (536-607 ind./km2) habitats. The high population density is everywhere due to the abundance of numerically predominant species of the Far Eastern island and the Chinese fauna types. The total population of species of these faunas accounts for more than 50% of the population in terrestrial (282-469 ind./km2) and coastal marine (172-333 ind./km2) habitats. The spatio-temporal dynamics of the bird population is characteristic.