MODERN CONCEPTS ABOUT ORNITHOLOGICAL GEOGRAPHY OF THE COMMANDER ISLANDS

Abstract

The validity of the allocation of the Commander ornithogeographic district on the zoogeographic map of Kam-chatka has been confirmed. This diagnosis is relevant, despite some doubts among taxonomists about the inde-pendence of individual endemic Commander subspecies of birds. The similarity of the nesting and probably nest-ing bird fauna of Kamchatka, the Commander and Aleutian Islands was estimated using the Jacquard formula [Pesenko, 1982] based on the revision results of the avifaunistic lists of these regions. The opinion that the avifau-na of the Commander Islands is related to the Aleutian one was confirmed. The similarity index between the avi-fauna of the Commander and Aleutian Islands is greater (38.1%) than between the Commander Islands and Kam-chatka (24.7%), despite the fact that Kamchatka is much closer to the Commander Islands. The Commander avifauna meets the most important criteria of island faunas, such as impoverishment and subspecific endemism. In addition, the representatives of archaic forms lived on the Commander Islands not so long ago, which disap-peared primarily due to human extermination. The current state of most Commander endemic bird subspecies is quite stable. American mountain finch may show some tendency to decline.