The Status and Distribution of the Whooper Swan Cygnus cygnus in Russia I: Western Russia and Western Siberia.

Abstract

Most of the range of the Whooper Swan Cygnus cygnus falls within the borders of Russia and the associated republics. Although most research on this species has been conducted in Europe and Japan, a growing body of work has been developed since 1980 in Russia. As this work has mostly appeared only in Russian, and often in local journals, the accessibility and availability of that literature to non-Russian scientists has been extremely limited. We have compiled and reviewed the Russian literature, as it pertains to this species, from four regions. We have also attempted to give an overview of the populations, their breeding biology, wintering range, migration, and moulting behaviour in: 1) Western Russia (west of the Ural Mountains), 2) Western Siberia (east of the Urals and west of the Yenisei River, 3) Central and Eastern Siberia (from the Yenisei to the Lena), and 4) The Russian Far East (from the Lena to the Bering Sea). Each of these four regions is as large, or considerably larger than the area occupied by the European population, which is currently the only region for which accurate information on population size is available. The Whooper Swan population in Russia is large, generally secure, and seemingly expanding its range northwards. It suffers from a wide range of anthropogenic influences, including disturbance, habitat degradation, habitat loss, and hunting, but in some areas is also re-occupying breeding haunts where such negative influences have declined. The Whooper Swan ranges in Russia from the Kola Peninsula in the northwest east to the Anadyr Valley of Chukotka and to Kamchatka. The northern limit to its range lies close to 67degree-68degreeN. There is circumstantial evidence for a continued general expansion of its breeding range northwards. The breeding range extends south to 62degreeN in western parts of European Russia, but as far south as 55degreeN to 50degreeN in Sakhalin and Kamchatka. It winters south to 47degree-50degreeN in the west, however its southernmost wintering grounds are in Japan where for climatic reasons it can be found in large numbers at latitudes as low as between 35degreeN and 40degreeN. In Russia, the Whooper Swan is a breeding bird of the northern taiga, of forest-tundra, and in some places of the tundra too. Human influences during the mid 20th century have, in some areas, particularly in the west, greatly reduced the Whooper Swan's population and range below 19th century and early 20th century levels. Over the latter part of the 20th century, however, it has begun to re-occupy its former range. Population estimates vary enormously even for the same regions making overall estimation of the population virtually impossible. For example estimates for Western Russia and Western Siberia range from as few as 10,000 to more than 100,000 (Ravkin 1991, Rees et al. 1997). There is considerable room for further research in this the largest portion of the Whooper Swan's range. The population of the Russian Far East is thought likely to be in the region of 60,000 birds based on numbers wintering in Kamchatka, Japan, the Korean Peninsula and China. Although the majority of the Whooper Swan's world population breeds in Russia, most of these birds migrate to areas beyond Russian borders to winter in adjacent countries, around the Baltic Sea, the Caspian Sea, and the Sea of Japan. The timing of migration varies from region to region, but in autumn at least does seem largely driven by sharp falls in temperature, particularly of daytime temperatures from 5degreeC to 0degreeC. Evidence from widely different areas in Russia point to spring and autumn migration taking place in different waves. In spring, pairs and families predominate among early migrants, non-breeders among later migrants. In autumn, non-breeders migrate earlier than breeders, as evidenced by the very low proportion of young in migratory flocks early in the season, and the high presence of pairs, families and flocks containing broods during the latter part of the season. In the western part of its range it may be found on migration in company with both Mute Cygnus olor and Tundra (Bewick's) Cygnus columbianus bewickii swans, while in the eastern part of its range it commonly uses the same staging areas as Tundra Swans. Given the enormity of the Whooper Swan's breeding range within the political boundary of modern Russia, combined with the small number of resident swan biologists, and the difficulty of access to most areas, it is not surprising that even the most basic information is not available for some areas. It is nevertheless impressive that many papers have been published on this species in its Russian range in recent decades. Given the immense scale of the four regions of Russia, we have addressed Western Russia and Western Siberia in this paper and address Central and Eastern Siberia, and the Russian Far East in a subsequent paper (Brazil & Shergalin in press). Given the enormous extent of suitable habitat for the Whooper Swan in Russia, it is clear that it is to Russia that we must look in the future to clarify the true status of the species.