Причины снижения численности западных подвидов гуменника ( Anser fabalis fabalis и Anser fabalis rossicus ): о чем говорят данные кольцевания?

Abstract

A total of 702 recoveries of Bean Geese ringed on the wintering sites in the Netherlands since the 1960’s have been analysed. For most of the ringed birds in this analysis the subspecies Anser fabalis fabalis or A. f. rossicus was identified at the time of ringing. The majority of recoveries are from the territory of the ex-USSR, primarily the Russian Federation. We have tested the hypothesis that hunting pressure is higher on Taiga Bean Geese, the subspecies A. f. fabalis, compared to Tundra Bean Geese, the subspecies A. f. rossicus. This has been checked by comparing the lifespan of the two subspecies and analysing the seasonal distribution of ring recoveries. On average, the lifespans of A. f. fabalis are shorter compared to A. f. rossicus, and there is a shift in the hunting periods towards spring. The reported drastic decrease in the numbers of A. f. fabalis wintering in the Netherlands could be caused by a possible change in Bean Goose wintering regions (the Eastern-European wintering sites becoming more important), but also by an overall decline in the numbers of this subspecies. According to the current analysis of ring recoveries from harvested birds, Taiga Bean Geese live on average shorter than Tundra Bean Geese do, apparently because the former are exposed to a higher hunting pressure. The Taiga Bean Goose subspecies is most vulnerable in western Siberia during the spring hunting season and, during the autumn hunting season, in the central parts of European Russia, starting from the Urals. This points to the need for additional protection measures in key seasonal staging areas and in all breeding areas, as well as for the need for a regional approach including both subspecies into the Red Data Books. Moreover, it is important to change the time of opening the spring hunting on waterfowl. Additional studies are required to more accurately determine the flyways, as well as the winter distributions of Anseriformes. This is primarily important to test the hypothesis whether there is a change in the wintering grounds of Bean Geese nesting in the Russian Federation.