山 階 鳥 研 報(J. Yamashina Inst. Ornithol.),34:279-308,2003

The Status and Distribution of the Whooper Swan Cygnus cygnus in Russia II: Central and Eastern Siberia, and the Russian Far East

Mark A. Brazil* and Jevgeni Shergalin**

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, although Brazil & Shergalin (2002) have reviewed much of the literature that pertains to Western Russia and Western Siberia. Here we continue that review, providing an overview of the status and distribution of the species in two further regions: 1) Central and Eastern Siberia (from the Yenisei to the Lena), and 2) The Russian Far East (from the Lena to the Bering Sea). Each of these 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 two regions addressed in this paper are characterised by large areas of potential Whooper Swan breeding habitat though the majority of the population winters beyond the borders of Russia. The breeding range extends east almost as far as the easternmost limits of Russia, in the Anadyr Valley of Chukotka and on Kamchatka. The northern limit to its breeding range lies between 67-68°N, and exceptionally north to 72°N, but whereas the breeding range extends south to 62°N in western parts of European Russia, it reaches as

far south as 55°N to 50°N on Sakhalin and in Kamchatka. Whereas many birds from the western range winter south to 47-50°N in Europe, a large proportion of the birds breeding in Central and Eastern Siberia, and the Russian Far East migrate to wintering grounds in central Asia and eastern Asia, where the southernmost wintering Whooper Swans are in Japan. There, for climatic reasons, they can be found in large numbers at latitudes as low

as between 35°N to 40°N. Published population estimates vary enormously for Central and Eastern Siberia, however, the population of the Russian Far East is thought to be more reliably in the region of 60,000 birds based on numbers wintering in Kamchatka, Japan, the Korean Peninsula and China. Key words: Distribution, Russia, Russian Far East, Siberia, Status, Whooper Swan Cygnus cygnus. キ ー ワ ー ド:分 布,ロ シ ア,ロ シ ア 極 東 部,シ ベ リ ア,生 息 状 況,オ オ ハ ク チ ョ ウCygnus cygnus.

Received 15 May 2002, Revised 2 July 2002, Accepted 20 July 2002. * Biodiversity and Conservation , Rakuno Gakuen University, 582-1 Midorimachi, Bunkyodai, Ebetsu-shi, Hokkaido 069-8501, Japan. E-mail: [email protected] ** "Zoolit" , Sopruse pst. 175-58, Tallinn 13413, Estonia. E-mail: [email protected]

279 280 Mark A. Brazil and Jevgeni Shergalin

Introduction The Whooper Swan Cygnus cygnus is a wide-ranging Palaearctic species that has been extensively studied only in the westernmost part of its range in Iceland, the British Isles, Scandinavia, and Continental Europe. It has been studied to a rather lesser extent in Japan, China, and Russia. The great expanse of Russia not only provides the single largest continuum of northern swan habitat in the world, but it also contains almost all of the Whooper Swan's breeding range (see Fig. 1). The status and distribution of the Whooper Swan in the western part (Western Russia and Western Siberia) of this enormous region have been reviewed by Brazil & Shergalin (2002). In Russia, the Whooper Swan ranges from the Kola Peninsula in the northwest close to Finland, all the way eastwards to the Anadyr River (R) valley of Chukotka, and Kamchatka in the extreme northeast facing the Pacific Ocean. At its northern extent it can be found beyond 67°N on the northern part of the Kola Peninsula and in the lower

(northern) parts of the Pechora R. In western Siberia, it reaches 66°N in the Ob R region, and further east it reaches 67°N in the Taz R valley. A little further east, in the Yenisei

R valley it can be found at 68°N and continuing eastwards through Central and Eastern

Siberia and the Russian Far East, the northern limit of its range lies close to 67-68°N.

The Whooper Swan breeds regularly further south in the Russian Far East (55°N to 50°N on Sakhalin and in Kamchatka) than it does in western parts of Russia (as far south as 62°N) (Brazil & Shergalin 2002). Birds breeding in the central and eastern parts of its range winter south to between 47°N and 50°N at Lake Balkhash, Mongolia, across northeastern China, into southern Primor'ye in the region of Lake Khanka, though some may also migrate south-westwards away from the breeding grounds thus reaching areas around the Caspian Sea or further west; much remains to be learned about migration routes throughout Russia. The southernmost regular wintering grounds of this species are in Japan, where for climatic regions it can be found in large numbers at latitudes as low as between 35°N and 40°N each winter (Brazil 1991). Population estimates for the Whooper Swan remain speculative for various reasons (see Brazil & Shergalin 2002), however, the central Siberian and Eastern Asian population has been perhaps more reliably estimated to be in the region of 60,000 birds, giving a 1% threshold for Ramsar Convention criteria of 600 birds in that region, and making it very similar in size to the northwest European population (Laubek et al. 1999, Miyabayashi & Mundkur 1999). Our aim in writing this paper was to continue the review of the distribution and status of the Whooper Swan in Russia begun by Brazil & Shergalin (2002) and extend it to Central and Eastern Siberia and the Russian Far East.

Distribution and Status For the purposes of our review we have considered four large regions. The two western regions, 1) Western Russia, i. e. the region west of the Ural Mountains, and 2) The Whooper Swan in Central and Eastern Siberia, and the Russian Far East 281 282 Mark A. Brazil and Jevgeni Shergalin

Western Siberia, from the Ural Mountains east to the Yenisei R have been reviewed previously by Brazil & Shergalin (2002). Here we continue with regions 3) Central and Eastern Siberia, from the Yenisei R east to the Lena R, and 4) The Russian Far East from the Lena R east to the Bering Sea. Each of these four regions is as large, or larger, than the whole of the Whooper Swan's European Range (Fig. 1).

3. Central and Eastern Siberia. From the Yenisei River to the Lena River For the purposes of this review we have chosen to define Central and Eastern Siberia

as the region from the Yenisei R in the west (approximately 85°E) to the Lena R in the

East (125°E) and from the Taymyr Peninsula in the north (77°N) to the border with Mongolia in the south at about 50°N (see Fig. 2). This region, itself almost the same area as the whole of Europe from northern Scandinavia to the Mediterranean countries and from Ireland to Greece, spans a similar range of habitats as already seen in Western Siberia, from the northern tundra to the southern steppe, but it also incorporates not just two of Russia's greatest rivers (the Yenisei and Lena) but also the single largest, deepest and oldest freshwater body on Earth-Lake Baikal. The distribution of the Whooper Swan across this enormous region is disjunctive and

Fig. 2. Central and Eastern Siberia showing main locations mentioned in the text and approximate breeding area of Cygnus cygnus. The Whooper Swan in Central and Eastern Siberia, and the Russian Far East 283 highly variable, thus for example Emel'yanov & Savchenko (2001) considered that in the Yenisei R region of Siberia the number of Whooper Swans is extremely low and does not exceed 400-500 birds. To the east of the Yenisei R, in the Lower Tunguska R basin (which eventually flows west into the Yenisei), the Whooper Swan is a passage migrant that also nests at wetlands in the flood-plains of tributaries of the Lower Tunguska, and also occurs on larger lakes in the inter-stream areas. Nevertheless numbers in the Lower Tunguska R basin were small, at about 20 pairs in the 1980s. As a result of a sharp decline in motorised water transport and other anthropogenous influences, however, numbers are increasing even in the southern, more developed part of the Lower Tunguska valley, such that now about 150 pairs occur in the region (Mel'nikov 2000). South of the Tunguska R, we reach the Angara R, the only outflow of the Lake Baikal drainage system, which flows northwest eventually joining the Yenisei R. There, in the early 1980s, Mel'nikov et al. (1990a) studied the waterfowl of the middle part of the Upper Angara R) in the region of Verkhne-Angarskiy Razlom (Upper-Angara water- shed). A peculiarity of this region is the large number of small lakes, formed mainly as a result of changes in the riverbed. These wetlands with abundant old floating vegetation, aquatic vegetation and well-vegetated shorelines with Typha latifolia, Iris spp. and swampy meadows of Phragmites australis, or grassy bogs and especially those with rich submerged vegetation, provide suitable habitat for the Whooper Swan where sites are only seldom visited by people. As in much of their range, here separate pairs of swans each occur on separate large water bodies. Mel'nikov et al. (1990a) found comparatively high densities of breeding Whooper Swans in the central parts of the hollow, between the Upper Angara R and the Kotera R (Verkhneangarskiy razboi), where there was one pair/20km2. Elsewhere in the region, the nesting density is considerably lower at one to three pairs/100km2. The greatest density recorded was of three pairs in an area of 25km2. The total number of Whooper Swans nesting in the main part of the Verkhne-Angara depression was 80-100 pairs. Here brood size before fledging ranges from 1 to 6 cygnets, and averages three young. About 20-25% of pairs did not produce young, many of them were probably non-breeding pairs although some pairs may have lost nests or broods to predators and poachers. Mel'nikov et al. (1990a) noted that during the breeding season a single pair usually occupies several neighbouring lakes that might be separated by as much as 500-800m depending on the availability of food resources. They move from one to another water body in search of food, making locating nests and broods very difficult. In this region, they seem to prefer interconnected clusters of small open water bodies amidst marshes rather than larger water bodies such as lakes (from which they are commonly absent), largely because of the influence of man (teams of fishermen commonly net the larger lakes and so scare off birds that might otherwise breed there). The Upper Angara depression is, according to Mel'nikov et al. (1990a), the only area in the south of central Siberia, where the Whooper Swan is common, or even numerous. After the completion of the Baikal-Amur Railway, the rate of development in the region has increased and in order to avoid a decline in the species Mel'nikov et al. (1990a) deemed it important that a game reserve be established in the region of the Upper Angara 284 Mark A. Brazil and Jevgeni Shergalin where Whooper Swans occur in their largest numbers. In the enormous Irkutsk Region, the availability of suitable nesting habitat for the Whooper Swan is limited by the topography. Since the 1950s and 1960s, when industrial development of this region began, Whooper Swan numbers have declined. It used to occur quite commonly during summer as a breeding bird mainly in the basins of the Lower Tunguska and Kirenga rivers, and at isolated lakes of the Prisayanie [the area around Sayany], the Lena-Angara Plateau, and the Vitim-Patom upland. More recently, numbers in those regions were very small (just a few pairs) not exceeding 50 pairs in the whole Irkutsk Region (Mel'nikov et al. 1990b). Although Whooper Swans migrate on a broad front through this region their numbers are small everywhere. Migration, often at night, commonly precedes prolonged bad weather accompanied by snowfall in autumn. Intensive development of the Irkutsk Region, a surge in mass usage of water-motor transport and intensive forest-exploitation since the beginning of the 1970s combined with the building of the Baikal-Amur railway, has led to a sharp increase in the extent of disturbance to what were once remote wetland habitats. There has been an associated sharp decline in the number of breeding Whooper Swans, particularly in the river flood plains of the region. Increased access has led not only to added disturbance, but also to increased poaching (Mel'nikov et al. 1990b). The region of Northern Lake Baikal and the Upper Angara depression (3,800km2 in area), mostly consisting of the flood plain of the Upper Angara R and its tributaries, was also studied by Sadkov & Safronov (1990). In the middle reaches of the Upper Angara the depression reaches 60km in width (Kumoro-Uoyan extent), and is covered with sedge/grass meadows and sedge/horsetail swamps, with a number of lakes of various sizes connected by a net of channels. Whooper Swans begin to arrive in spring into the Upper-Angara hollow during the first half of April with migration continuing during May and finishing in early June although total numbers are rather small. They arrive in pairs and small flocks of 6-30 birds, some arriving at night others early in the morning from the southeast (perhaps indicative of them arriving from wintering grounds in eastern China) having traversed the North-Mui mountain ridge and northern spurs of the Barguzinskiy mountain ridge, or flown through passes in the upper parts of tributaries of the Upper Angara R (Kotera, Svetlaya, Akuli rivers). On migration, flocks of 30-100 birds may rest in river valleys, and on lakes in Kumoro-Uoyan, dependent on the weather conditions. If visibility is good in the mountains, then they continue their migration during the daytime and follow passes through the Upper-Angara and North-Baikalian ridges. In the autumn small numbers appear on passage during the first half of September, but migration is concluded during October because all water in the region freezes over (Sadkov & Safronov 1990). The number of breeding pairs of Whooper Swans is extremely low because of the limited availability of suitable habitat and because of disturbance. Pairs nested in the lower part of the Upper Angara R and Kichera R until the 1960s, but have not been reliably recorded since (Sadkov & Safronov 1990). Unsuccessful breeding of pairs in the area resulted from human disturbance and to sharp fluctuations of water level. The Whooper Swan in Central and Eastern Siberia, and the Russian Far East 285

The Lake Baikal Region Until the 1950s and 1960s, the Whooper Swan bred widely in the Lake Baikal region. Its range included practically the whole shore of Lake Baikal, particularly the mouth of the Upper Angara R, Chivyrkui Bay, Bolshoi Arangatui L, the Barguzin R valley, and the Selenga R delta. From the 1960s onwards, however, its numbers and distribution have declined sharply in the region so that now it is considered to be a rare breeding species with as few as 45-50 pairs in the whole of the Lake Baikal basin (Dorjiev & Elaev 2001). Now, pairs breed regularly only on suitable water bodies of the isthmus of Svyatoi Nos Peninsula, in Chivyrkui Bay, in the Upper Angara R valley, and in the Barguzin R valley1, although Yumov (2001) considered it to be only a rare breeding species there. On migration, Whooper Swans appear along both the eastern and western shores of Lake Baikal, and in Western Trans-Baikalia along the Selenga R valleys and its tributaries, and on Gusinoe L, Taglei L, and on the lakes of the Borgoiskaya, Orongoiskaya and Ivolginskaya depressions. As with breeding numbers, current migrant numbers are considerably lower than 50 years ago. In the 1950s and 1960s, polynias in the Selenga R delta and in Chivyrkui Gulf (Bay) held up to several hundreds birds. And flocks of up to 500 birds were recorded annually during spring on the lakes of the Borgoiskaya and Barguzinskaya depressions (Dorjiev & Elaev 2001). In Southern Baikal and in southeast Trans-Baikalia, the Whooper Swan is an uncommon, even scarce, migrant passing through from mid April until the end of May, more rarely small groups are seen during June; it is also a rare breeding species here. In Middle Baikal spring migration starts about 10 days later and nomadic non-breeding birds have occasionally been sighted into June and July. The simultaneous arrival of swans at sites far removed from each other on the same or consecutive days has also been noted from this region (Shinkarenko et al. 1990, Popov et al. 1998, Elaev et al. 2000). In autumn, the first Whooper Swans reappear in Southern Baikal from 13 September onwards and the last have passed through by 23 October. Although they may occur widely in autumn, their numbers are low. They occur at this season in small flocks of no more than 15-30 birds, usually in much smaller groups of just 4-8 birds, presumably family parties. Whooper Swans particularly like the Selenga R delta for resting and feeding on migration as the many shallow sors and channels thaw early in spring and are rich in food especially the pondweed Potamogeton perfoliatus, yellow waterlily Ceratophyllum spp., and Nuphar pumila (Shinkarenko et al. 1990). During the 1960s, 1970s and 1980s, the Whooper Swan bred only once in the Selenga R delta, in June 1987, when a clutch of three eggs led to the raising of three young (Shinkarenko et al. 1990), since the mid 1980s however they have bred regularly, with one or two pairs in the western sector of the delta (Fefelov et al. 2001). The decline in numbers of Whooper Swans visiting Southern Baikal during the mid 20th century has been attributed to loss of habitat, particularly at stopover sites, caused by the raising of the water level in Lake Baikal following the construction of the Irkutsk Hydroelectric Power

1 The Barzugin River flows into the eastern side of Lake Baikal . 286 Mark A. Brazil and Jevgeni Shergalin dam. Now only small numbers (a few individuals or tens, up to 220 are recorded) (Shinkarenko et al. 1990). More generally in the central Siberian region, the Whooper Swan is considered to be a rare bird of the taiga and forest-tundra habitats (Rogacheva 1988, 1992). Along the Yenisei R, the Whooper Swan occurs as far as 70°N, although breeding has only been confirmed as far north as 68°15'N in southern forest-tundra around Ust-Khantaika (Rogacheva 1988, 1992). The southern limit of its modern breeding range in central Siberia is less clear. In the early 1960s, the Whooper Swan occasionally nested in swamps and lakes along the upper reaches of the Kamenka and Gorbilok rivers in the watershed of the Angara, Podkamennaya and Tunguska rivers (58°N, 105°E). They have also bred as far south as Sayany, and in Khakassia, although they were a rare breeding bird there at the beginning of the 20th century and remain so, while in the Minusinsk depression they are considered a rare nomadic species (Rogacheva 1988, 1992). Their natural breeding range may continue southwards beyond the border of Russia, as they also breed to the south of the Irkutsk/Lake Baikal regions in Mongolia (see Batbayar 2000, Brazil in press). Along the east bank of the Yenisei R, Whooper Swans probably breed on most suitable bodies of water in the Putorana Mountains and in the region of the Norilsk lakes. Near Pyasino L its breeding range abuts that of its smaller relative the tundra-breeding Bewick's Swan (Rogacheva 1988, 1992). The richest region or habitat for Whooper Swans in the whole of central Siberia is deemed to be the northern taiga and forest-tundra along the west bank of the Yenisei. In the middle taiga region, numbers used to be high also along the upper reaches of the Taz, and Elogui river basins, but although they still occur there, they are now rare there (Rogacheva 1988). Particularly during the 1950s and 1960s, the swans of central Siberia were often killed by hunters and fishermen, however, by the late 1970s and the 1980s such persecution was reduced, and the prognosis for the population seemed more favourable (Rogacheva 1988, 1992).

4. The Russian Far East. From the Lena River to the Bering Sea The fourth and final region of Russia consists of the Russian Far East. From the Lena R eastwards lies yet another enormous region encompassing Yakutia and Chukotka. For the purposes of this review, the Russian Far East includes the region from the Lena R in the west (approximately 125°E) to the Bering Straits in the east forming the international border with the USA, and to the Kamchatka Peninsula in the southeast and the Anadyr Region in the northeast facing the Bering Sea from 155°-180°E. It stretches from the shores of the East Siberian Sea at about 72°N as far south as the narrow finger of Russian territory bordered by China to the west and the Sea of Japan to the east, known as Ussuriland, to approximately 43°N, and including the Amur R, the Island of Sakhalin, the Kurile Islands and the region bordering the Sea of Okhotsk (see Fig. 3). Only one population of Whooper Swans is currently recognised in the whole of eastern Eurasia east of the Ural Mountains. Variously described previously as the Central Siberian and/or Eastern Asian population, it was estimated to be of 30,000 birds by Perennou et al. (1994) and also by Scott & Rose (1996). We feel, however, that this is an The Whooper Swan in Central and Eastern Siberia, and the Russian Far East 287

Fig. 3. The Russian Far East showing main locations in the text and approximate breeding and wintering areas of Cygnus cygnus.

over-simplification based on limited information, as migration data suggests that birds from this vast area winter in quite different regions. Some birds from east of the Urals may migrate west or southwest, while others migrate southwards or southeast. Further- more, those breeding in central Siberia may migrate to central Asia, Mongolia, and China by way of Lake Baikal, whereas those birds from further east breeding in Yakutia and Chukotka migrate via the eastern Russian coast and Sakhalin Island to Japan. More recent population estimates, have suggested that a revised population size of 60,000 is more appropriate for the Central Siberian/East Asian population, but in fact this figure may be appropriate for the Russian Far East alone. Approximately half of this total winters in Japan, with a further 10,000-15,000 wintering in China, 7,500-8,000 in 288 Mark A. Brazil and Jevgeni Shergalin

Kamchatka, Russia, 3,500 in the Republic of Korea, and 500 in DPR Korea according to Miyabayashi & Mundkur (1999), although their figures for China are very much higher than those indicated by Li (1996) and Ma (1996) for example. A small sub-population, of fewer than 50 birds, winters on the Aleutian and Pribilof Islands of Alaska and breeding has also occurred in the region (Sykes & Sonneborn 1998, Mitchell 1998). Though politically and geographically part of the New World, biogeographically the links to Asia are so great in the area of the ancient Bering land-bridge, that this cannot be regarded as a separate population. Starting in the west of this huge region, we must first consider the Lena R itself. In the Lower Lena R valley, the Whooper Swan occurs widely in the taiga zone and even penetrates into the tundra. Transformation of the landscape by people along both lower streams and upper parts of some tributaries has, however, greatly reduced the availability of nesting sites within the main river flood plains. For example, compared with the 1950s, breeding on the large islands of the lower parts of the Vilyui R has dropped by a factor of 7-10. A similar decrease has been noted from the main Lena R valley too. Nevertheless, Labutin et al. (1987, 1988) found pairs and small flocks (up to 10 birds) many times in summer on tributaries of the Lena R, though more commonly closer to the foothills. And on migration, during May and September the Whooper Swan is by no means rare (Labutin et al. 1987, 1988). Further north, towards the Lena R delta, the Whooper Swan is rare although even there it does occur during the migration season and it has even bred on occasions as far north as the southern part of the delta (Sofronov 2000). It also strays out on to the sub-arctic tundra where, for example, a single bird was recorded on 9 August one year near the lower part of the Kengdei R (a tributary of the Lena) (Sofronov 2000). At the opposite extreme, in the far south of the Russian Far East, in the narrow southeastern finger of Russian territory between the Sikhote Alin mountain range and the border with China, the Lake Khanka area is important. There, Glushchenko (1990) considered that the Khanka-Sungacha Lowland (45°N, 132°E) was the only reliably reported breeding site of the Whooper Swan in the Primorskiy Krai, although Vorob'yov (1954) had not been aware of it breeding there, so perhaps it is a recent colonist of this rather southerly region (one of the southernmost breeding sites in its entire range). In 1987, for example, conditions in the Lake Khanka basin were quite favourable during summer as water levels were not high and disturbance from fishermen was lower in some regions. Censuses carried out from 23-25 May and again from 11-12 September 1987 found five breeding pairs in swampy areas in the eastern part of the Khanka Lowland, between the Spasovka R mouth and the Sungacha R mouth, and one pair in the Sungacha R valley on Mamonovskoe bog. Besides breeding birds, on the eastern shore of Lake Khanka 25 summering Whooper Swans were found (6 pairs, a solitary individual and groups of 5 and 7 birds). During the September census only four solitary adults specimens and five pairs were relocated, only two of which had chicks (3 and 4 cygnets), thus the total of young reared in the area was just seven (Glushchenko 1990). The Lake Khanka area, at approximately 45°N, is one of the most southerly breeding sites known for the Whooper Swan, it lies on the same latitude for example as northern Italy. As the water The Whooper Swan in Central and Eastern Siberia, and the Russian Far East 289 levelin Lake Khanka risesin late summer swan numbers decline with deteriorating feedingconditions (Glushenko & Bocharnikov 1991). Although breeding is scarcehere, the Whooper Swan is a common migrant through the Ussurian Territorynortheast of Lake Khanka. In spring it appears very early in Southern Primorie,some years as early as 8 March, although more typicallythey arrive from mid-March onwards and the lasthave passed through by mid April. Large flocks were seen flyingnorthwards over Lake Khanka in early April 1945 (Vorob'yov 1954) presumably on theirway from Korean or perhaps Chinese winteringgrounds. In autumn, passageoccurs during October and in the firsthalf of November, and although,according to Przewalskiand Jankowskii,some used to winter along the shore of Southern Primorie, no recentdata are availableon winteringin the Gulf of Peter the Great (Vorob'yov 1954). In southern Ussuriland,the Whooper Swan is not an especiallycommon species, though it appears on migration in both spring and autumn in flocksof up to 80 birds. During springit appears during the last10 days of March and in the earlypart of April with flocksappearing as lateas 22 April (Panov 1973). In autumn, migrationtakes place during October-November and involvesfar more concentratednumbers with several thousand birds noted both on the sea, at rivermouths and on freshwaterlakes such as Khasan L. The firstbirds appear as early as the firstdays of October, with numbers peaking in lateOctober and earlyNovember. For example on 22 October 1962, a flockof about 1,220 birdswas reportedon Khasan L (Panov 1973). In southeasternRussia, only the Whooper Swan breeds in the Prichankayskaya Lowland (43°50'N, 132°30'E), although both Whooper and Bewick's swans migrate through in spring and autumn (Glushenko & Bocharnikov 1991). The numbers breeding here are small as they are near or even at the southeasternmost limit of the species' breeding range. There were just one to six pairs nesting in 1980-1988, with relatively low nesting success, and with an additional 20-25 non-breeding birds summering in the area. For example in 1987, five breeding pairs had raised just seven young between them by the second half of September. At the mouth of the Razdolnaya R in South Primorye (43°N, 31°50'E), the Whooper Swan is the commonest of the swans during spring migration, appearing as early as 5 March (1989) although the main migration occurs during late March and the first third of April, with migration usually ceasing after 20 April, although occasionally flocks have been seen as late as 28 April (1986). Swans stop regularly and for a long time in open water areas of the Razdolnaya R delta, with the largest concentrations (200-300) on Utinoe L. They also regularly stop at Tikhaya Lagoon, and occasionally near the edge of the fast shore ice on shallow water (Gorchakov 1996). During the early part of the spring migration, they pass through in small flocks of 10- 15 birds, but as the intensity of the migration increases, so flock size also increases. The majority (57% of the total number), passed through in flocks of 30-70 birds, and the largest flock recorded was of 122 on 29 March 1989 (Gorchakov 1996). Although some swans were noted at night, the majority (51%) passed through during the evening between 18:00 and 20:00. Although weather conditions seemed not to affect passage intensity, the height of passage (normally about 150-300 meters) was lower in bad windy 290 Mark A. Brazil and Jevgeni Shergalin weather and higher (500 meters and higher) in clear weather with light or no wind (Gorchakov 1996). In the Khabarovsk Krai, which includes the valleys of the Ussuri and Amur rivers, the Tatar Strait separating the island of Sakhalin from the mainland, the mouth of the Amur and the Shantar Islands in the westernmost arm of the Okhotsk Sea (see Fig. 3), the Whooper Swan is a common migrant during spring and autumn, and a scarce breeding species. The Whooper Swan also bred (in the 19th century) and may still breed at lakes in the region of the lower reaches of the Amur R (Vorob'yov 1954). In the Khabarovsk Region, the Whooper Swan continues to breed in the northern and central parts, but it is in decline and must now be considered a rare breeding bird, and as such it was added to the region's Red Data list in 1999. Until the mid-1980s it still nested on lakes within 90 km to the northeast of Khabarovsk City, however the southern border of its range retreated northwards to Bolon L as a result of forest fires, poaching and other forms of disturbance. Since the mid-1980s it has declined from 20-25 pairs to just three pairs in 1999 (Roslyakov & Voronov 2001). The most important site for breeding is currently Mukhtel' L, and for resting and feeding during migration-the Amur estuary. Neither of these, unfortunately, have nature protection status, and disturbance at Mukhtel' L has increased considerably since a site for recreation was developed, and in the Amur estuary poaching occurs in the autumn when several tens of birds are shot each year. In the Khabarovsk Region, the first migrants appear along the Lower Amur R area in the last third of April, with mass migration occurring into early May. In 1986 and 1987, in the region of the Malyshevo-na-Amure settlement, Roslyakov (1990) observed flocks of 75-180 birds migrating at very low altitudes (50 to 150m), crossing the Amur R from south to north in the direction of Bolon' L. In spring 1986 and 1987 in this area about 2,000 Whooper Swans were seen between 28 April and 12 May. In the Bolon' L basin (Lebyazh'ie and Kiltaksin lakes) between 1-14 April 1986 and 1987 at least 2,000-2,500 Whooper Swans were seen at one time. That figure is, however, a considerable reduction from numbers recorded there in the past. In 1976-1980, for example, 5,000-6,000 swans were counted, and 3,000 in 1986-1987. Roslyakov (1990) considered that in earlier counts/estimates migrating Bewick's Swans might have also been included, counted as Whooper Swans by mistake. Spring passage over the Amur R valley occurs during mid and late April and lasts until late May. The estuary of the Amur is a very important stopover area for both Whooper Swans and Bewick's Swans that form great concentrations there during May as the ice of the shallow coastal waters is breaking up (Babenko 2000). During spring migration flocks ranging in size from a few hundred to about 1,500 Whooper Swans have been found resting on Orlik L, on the My, Chomi, and Amur rivers, and on the Gulf of Schast'ia, with 5,000 or more Whooper Swans passing through the Lower Amur R area. Babenko (2000) reports as many as 2,000-3,000 on the Shantar Islands in spring, and on 17 May 1991 in the Amur estuary between the Berkha and Uarke capes, a total of about 4,150 Whooper Swans was found in flocks of 5-50 birds (Babenko 2000). The autumn migration of the Whooper Swan is best seen along the seashore and along the Tatar Strait where, during autumn, at least 8,000-10,000 birds pass through, whereas The Whooper Swan in Central and Eastern Siberia, and the Russian Far East 291 inland fewer birds, in the region of 2,000-2,500, can be seen. Autumn migration through this region begins as early as the beginning of September. Low altitude migration is typical, with birds moving through at heights no greater than 200-300m asl in small flocks of 3-53 birds. Departure from the Shantar Islands in the western arm of the Sea of Okhotsk, occurs from the middle of October onwards and great flocks of swans, number- ing in the thousands, are recorded at the Amur estuary during the same period, then along the seacoast and through the Tatar strait (Babenko 2000). In autumn, it occurs on migration at Evoron L, on the Shantar Islands, and large flocks of 5,000-6,000 occur in the Zaliv Schast'ya (Gulf of Happiness), at the Amgun' R mouth, and on Bolon' L; and also jointly with Bewick's Swans up to 3,000-5,000 gather on the western shore of Sakhalin Island and in the Amur Estuary. Large flocks of up to 100 early migrants (presumably non-breeders) have been seen during August (1986) on Mukhtel' L (Bab- enko 2000). In addition to being a very important migrant through this region, the Whooper Swan is also a breeding bird. The first breeding birds arrive in the northern Khabarovsk Krai from the middle of April onwards, though they may be delayed in cold springs, as in 1987 for example, when first arrival did not occur until 27 April. Before 1970, the Whooper Swan was a rather scarce breeder in the Lower Amur R area and the Shantar Islands, with no more than 50 pairs nesting there mainly in inaccessible northern sites. During the late 1970s, the number of breeding pairs increased considerably, first to 150-200 pairs in 1980 then to at least 350-400 pairs in 1987 in the whole of the Khabarovsk Territory, furthermore they began nesting closer to human dwellings, and even in the vicinity of Khabarovsk, with 2-5 pairs breeding each year in the region of lakes Kabar-Katar-Dabanda, 28-30 pairs in the Bolon' L basin, 20-40 pairs in the basin of Evoron-Chukchagirskoe lakes, up to 20 pairs in Amgul' R basin, 8-10 pairs on Udyl' L, 25-30 pairs in the region of the Orel'-Chlya lakes, and 30-60 pairs elsewhere (Roslyakov 1987, 1990). Breeding has occurred or still occurs in the Bolon' L basin, Chukchagir L (75-80 pairs), and Udyl L, also on the Shantar archipelago (where about 20 pairs nested in 1986), in the region of Mukhtel L (15-17 pairs), in the basin of Katar Kabar-Dabanda L, in the region of Evoron L, and in the basins of the Amgun', Salgin, Tugur, Uda, and Kava rivers, with increases in numbers noted in some areas, decreases in others (Roslyakov 1990, Babenko 2000). Over the period 1997-2000, however, Poyarkov (2001) reported a sharp decrease in the number of waterfowl species passing through this region and in breeding, particularly of Common Teal Anas crecca, Northern Shoveler A. clypeata, Garganey A. querquedula, Tufted Duck Aythya fuligula, and also of the Whooper Swan. Babenko (2000) also considered that the breeding population of this area was in decline from the mid 1980s onwards. Although the causes are not known they are most likely to be related to increasing disturbance and poaching. The only information on Whooper Swans wintering in the Khabarovsk Krai region is old (L. M. Shul'pin 1936, in Babenko 2000), reported that they wintered on the Ul'ya R, which flows into the Sea of Okhotsk, however no more recent information is available. A little to the east across the Tatar Strait, on Sakhalin Island, as many as 5,000 Whooper Swans were considered to migrate through until the 1950s, with a considerable 292 Mark A. Brazil and Jevgeni Shergalin reduction (to about one third) over the following 25 years, according to Ben'kovskiy & Ben'kovskaya (1990). Small numbers have also been reported there in winter, however, as all inland waters freeze over for from 4-6 months each winter, the few wintering birds are restricted to polynias, and springs. Numbers are small, perhaps no more than 50 or so, but these may be encountered at the Piltun hot springs, and at various lakes including Dagi, Nevskoe, Dobretskoe, Tunaicha, and Airup where they feed on sedges and duck- weed. Wintering birds are, however, not infrequently shot by hunters or caught by predators (Ben'kovskiy & Ben'kovskaya 1990). Further to the east, on the volcanic island of Iturup, in the southern Kuril Islands, about 30-40 Whooper Swans also winter on polynias in lakes and rivers of Kurilskoe village, and near various hot springs, although they are unfortunately the target for local hunters. In addition to wintering in small numbers on Iturup, Ben'kovskiy and Ben'kovskaya (1990) considered that small numbers might also breed there as there are many remote, and suitable sites for them. Now continuing northwards through the Russian Far East, in the Kava R drainage of the Magadan Region, small numbers of Whooper Swan summer and breed, and 40-50 individuals moult on the Kava R itself (Krechmar & Krechmar 1997). Spring migrants, heading north or northeast, arrive from the direction of the Ushki Gulf. They fly mostly in pairs or in small flocks of up to 60-70 birds, though most commonly in groups of 15 to 30 (Krechmar & Krechmar 1997). They fly low, at heights of 70-150m and commonly follow river valleys, such as those of the Burgali, the Chukcha, and Kava R. The arrival of the first birds in spring is during late April and early May, usually coinciding with the formation of breaks in the ice. In some early and extensive polynias, spring migrants may arrive earlier such as on the upper Kava R or on the Chelomdzha R. Although mass migration may occur during May, migration is mostly over before the beginning of June, recommencing again in late September and taking place mainly during October (Krech- mar & Krechmar 1997). In northern Yakutia, east of the huge Lena R, the Whooper Swan is distributed in the taiga forest zone being replaced on the tundra by the Bewick's Swan. Further east, however, to the east of the Kolyma R basin in Chukotka, the range of the Whooper Swan extends well beyond the border of the taiga zone and it inhabits the whole Beringian forest-tundra, including the basins of the Gijiga, and Penjina rivers, the Koryak Upland and the Anadyr Krai, however it is Bewick's Swan that breeds further north on the Chukotka Peninsula. Over wintering of Whooper Swans has even been recorded in this region, on polynias in the Apuka and Anadyr rivers, by far the northernmost wintering observations on record in Asia at about 65°N (Kishchinskiy 1988).

In northern Yakutia, along the Lena R it breeds as far north as 72°N, whereas in the Vilyui R basin it breeds only to about 66°N (Degtyarev 1987). In the drainage basins of the Indigirka and Kolyma rivers, the Whooper Swan occurs widely in the northern taiga and, in certain places in the forest-tundra too up to about 69-70°N. Syroechkovski (in press) considers that Whooper Swans have expanded their range northwards on the Taymyr (Central Siberia) and in Yakutia in recent decades and this may be a pattern that can be expected to continue as global warming influences spring thaw and autumn The Whooper Swan in Central and Eastern Siberia, and the Russian Far East 293 freeze-up across the northern regions of Russia. Numbers seem to be lower in Western Yakutia than further east, with small numbers in the Middle and Lower Lena R basin, but considerably higher numbers in the Indigirka and Kolyma Lowlands, with as many as 2,000-8,000 there during autumn. Densities have declined considerably in the Middle-Kolyma region, however, according to V. I. Perfil'yev (in Degtyarev 1987) from 21 birds/100km2 in 1966, to 8 in 1970, and just 2 in 1975. Aerial surveys conducted in 1983, indicated that in the Indigirka R basin their density was 12.7/100km2, 10.2 in the Upper Kolyma, and 6.5 in the Middle Kolyma. Satellite tracking has shown that among birds wintering in Japan are some that summer along the Indigirka and Kolyma rivers (Kanai et al. 1997). Declines in densities of Whooper Swans, particularly in central Yakutia, have been attributed to the fact that their nesting and moulting habitat is experiencing degradation as a result of agricultural development, and intensification of disturbance by sport hunters and fishermen (Degtyarev 1987). In the northeast, in the lowlands between the Indigirka and the Kolyma rivers, the considerable number of lakes provide ideal summer habitat for the Whooper Swan and, not surprisingly, it is in this region that it occurs most commonly in Yakutia. In this region, within the limits of the taiga zone, the Whooper Swan can be found everywhere, and along river valleys it even penetrates into the mountain massifs (Degtyarev 1990), as it does in certain parts of Sweden (Nilsson et al. 1998).

Along the Indigirka R, it can be found as far north as 70°N, 30km from Olenegorsk. The northern border of its range deviates southwards to 69°30'N through the foothills of the Ulakhan-Sis, and Suor-Uit mountain ranges, then along a line from Andryushkino settlement, Kolymskoe settlement, and to Anyuisk settlement at 69°N. To the east, in the

Kolyma R valley, single birds have been observed almost up to the river mouth at 68°- 69°N (Degtyarev 1990). Research from 1978 to 1987 in the region between the Indigirka and the Kolyma rivers provided information on migration, population, and ecology (Degtyarev 1990). The highest density of Whooper Swans was of 25.3/100km2 to the east of the Indigirka R in two isolated foci-in Ozhoginskiy dol and Shangina R basin, where there are many lakes, extensive bogs and little human activity. Northern regions (the Indigirka-Allaikhovskoe interstream area, the lower parts of the Rassokha, Kolyma and Omolon rivers), and also the southeastern regions of the lowland basins of the Ozhogin and Yasachnaya rivers are also quite densely inhabited with 9-16 recorded/100km2. These regions also have many suitable lakes, however, they are also used for agriculture and for water transport, so disturbance is greater (Degtyarev 1990). In regions with a raised relief, lakes are considerably fewer and the number of Whooper Swans is lower. In the Sedema R basin, for example, where altitudes reach 230 m asl, the density was 6.8/100km2, while on the Alazeia and Yukagir plateaux, which reach heights of 500-900m, Whooper Swans occur only in river valleys with flood plains and at densities of just 0.01-0.5/100km2 (Degtyarev 1990). Lower swan densities are typical of regions used for agricultural purposes such as cattle pasturing and hay-mowing. Therefore, in spite of a complex network of lakes, including large lakes up to 100km2 in 294 Mark A. Brazil and Jevgeni Shergalin area, the swan density in the basins of the Uyandin, Druzhina, and Selennya rivers was just 2.6; while in the less disturbed upper and middle stream of the Alazeya R it was 6.3/ 100km2 (Degtyarev 1990). Unfortunately, Degtyarev's (1990) paper is unclear on the extrapolation to the Indigirka area (some 127,200km2) and he may have found them at densities of 6.2/100sq km throughout, or perhaps numbering some 6,200 birds in the region. It is clear, however, that he estimated the population in the basins of the Alazeya and Kolyma rivers to be 5,800 birds. The population was considered to have increased until 1966 to as many as 21 birds/ 100km2 in the middle reaches of the Kolyma R (see V. I. Perfil'yev, in Degtyarev 1990), but thereafter, as a result of the loss of both breeding and moulting habitat due to lake drainage, it decreased dramatically to as few as two birds/100km2 by 1975. In 1983 and 1984, densities of 6.3 and 8.5/100km2 were found in the same region indicating that the population had stabilised and might be increasing once more (Degtyarev 1990). This increase seems to be further supported by observations made during migration from a fixed observation point at Srednyaya in the middle Kolyma, that indicate that numbers were growing over a period of 10 years (during the 1980s). In the area of the Indigirka northern taiga Whooper Swan density remained practically stable at 14.4 birds/100km2 in 1980 and 14.8/100km2 in 1985 (Degtyarev 1990). Whooper Swans breeding in the Yakutia region have a distinct preference for small wetlands, with 68.6-77.4% of pairs recorded from lakes with an area of from 0.01-1km2. Lakes of 1.1-6.0km2 were considerably less attractive (only 17-20.1% of pairs used these), and larger wetlands were only seldom used (4.7-11.4% of pairs) (n=172). A closer examination of those wetlands inhabited by Whoopers revealed that they preferred round grassy-shored lakes with sloping and indented banks (43.8%) with developed coastal-water vegetation, they were less often found on slightly-overgrown lakes with boggy banks (16.1%) and lake-like extensions of grassy-sided rivers (1.8%). Moulting Whooper Swans were sighted on large (6-10km2) lakes with indented shorelines. In 8- 9% of cases, birds were observed on open ground near wetlands, some of them resting on the bank, others out on open ground; such exposed birds fled into the forest at the approach of a low flying aircraft (Degtyarev 1990). In Yakutia, Whooper Swans are typically found in small numbers, in pairs (53.2- 74%), alone (14-34.4%), or rarely in small groups of 3-15 individuals (1-9.3%) (n= 368). By the last third of August pre-departure concentrations begin to develop and then birds may gather into small flocks of up to 35 birds. In Zapolyar'ye (Traps-Polaria), where the brackish wetlands have rather poor vegetation, aerial surveys in search of the large cygnets were quite effective, allowing an assessment of breeding success. The reproductive capacity of Whooper Swans in the study area appeared rather low. Although as many as 49-65% in peripheral areas and as many as 78% of birds in the central and southern areas formed territorial pairs, few actually bred (Degtyarev 1990). In the sparse forests of the tundra area of the Alazeya and Kolyma rivers, the proportion of young was only 4.3% (in 1984). In the lower parts of the Indigirka R, situated further to the west, the figure was 7.8% (in 1980), and 7.1% (1985), while in the The Whooper Swan in Central and Eastern Siberia, and the Russian Far East 295 middle reaches of the Indigirka and Kolyma rivers it was 7.7% (in 1983). Very similar indices of reproductive success were also obtained during autumn counts of migrating birds by Degtyarev (1990) who confirmed the low output achieved by birds breeding in this region. Not only did few pairs breed, but also their output of young was low, with the average brood size varying from 2.6 to 3.3 (n=25). In marginal areas around the main breeding range, their output was even lower at just 1.7 (n=6) (Degtyarev 1990). In northeast Yakutia, however, the Whooper Swan seems to have a healthy popula- tion that is at a higher density than in adjoining regions of the breeding range, and it has probably reached its maximum density, as indicated by its stable numbers and low rates of reproduction (Degtyarev 1990). In northern Yakutia, Perfil'yev's (1972, 1976, 1979, 1987), studies from 1957 onwards have shown that the Whooper Swan nests widely in the Vilyui R basin, but that it also occupies habitat and regularly nests in the Kolyma and the Lower Lena rivers. Information from the Middle Kolyma suggests that Whooper Swan numbers there have not been stable; it was considered as rare there in summer 1960 (Krivosheev 1963), but during the mid 1960s moulting concentrations of Whooper Swans numbered many tens and may have exceeded a hundred (they mixed with Bewick's Swans for moulting). Since the mid 1960s, however, densities have declined steadily from 2.1/10km2 (of surveyed areas) in 1966, to 0.2/10km2 by 1975, a decline that Perfil'yev considered related to loss of both nesting and moulting habitat. The northern limit of the Whooper Swan's breeding range seems to have shifted most considerably on the Lena R where it was not recorded in the lower reaches from 1955 to 1957 (Kapitonov 1962 in Perfil'yev 1987), however, by 1974 it was a common breeding bird in the region where nests have been found at 72°N. The extreme northeastern part of Russia known as Chukotka2, is also within the breeding range of the Whooper Swan. Although little is known of the population further east, wherever comparable taiga and forest tundra habitat exists in a relatively undisturbed state, then it probably remains a common bird. It is widely distributed in the taiga zone, with the northern limit of its breeding range coincident with the distribution of coniferous forests over most of the region (Kondratiev 1991). Only in the eastern part, apparently, does it extend beyond the northern limits of the taiga zone tree-line (Kondratiev 1991). It is a common breeding bird of the Anadyr forest-tundra, absent only from the lower stream of this river. Population data and information on its breeding status in this large region, are, however, very limited. Preliminary estimates suggest that a modest c 2,200 individual Whoopers inhabit the region in summer. The populations of the Penzhin-Parapol valley and Anadyr were considered to be quite stable with about 1,100 birds in the former making this the largest centre of breeding in the extreme northeast (Kondratiev 1990). Birds banded in Japan have not been found in this northeasternmost portion of Russia prompting Kondratiev (1990) to speculate that the birds breeding there migrate instead to Kamchatka for the winter, while those reaching Japan do so presumably from Yakutia and possibly areas further west.

2 A region spanning the Arctic circle and stretching eastwards from the Kolyma River and lying north of the Kamchatka Peninsula. 296 Mark A, Brazil and Jevgeni Shergalin

Portenko (1981, in Krechmar 1990) obtained 12 specimens from the Anadyr R Basin and considered that it undoubtedly bred there. That was subsequently confirmed by the detailed field studies of the ecology of the Whooper Swan in the middle reaches of the Anadyr R made by Krechmar (1990) from 1975 to 1987 using automatic photographic and recording equipment. These studies revealed a great deal about this bird where it breeds at the northernmost limit in East Asia. Here, the period between lake-ice thawing in spring until freezing over again in autumn usually fluctuates within 110-120 days and this coincides almost exactly with the minimum time necessary for the large-bodied Whooper Swan successfully to complete its reproductive cycle. According to Krechmar (1982a) and Krechmar & Gusakov (in Kondratiev 1991), there is a small but very stable population of 100-200 birds breeding in small- and medium-sized lakes in "alas" depressions along the middle reaches of the Anadyr R, and about 1,100 birds in the Penzhina-Parapol Valley further to the south. During the breeding season, birds were found at densities of 4-8 birds/100km2, and during autumn at an average of nine birds/100km2. Of about 184 Whooper Swans counted in a 500km2 area of the Magadan State Reserve by S. V. Tarkhov (Kondratiev 1991), only about 30% were breeding pairs, and the remainder were non-breeders, a figure remarkably coincident with estimates from northwest Europe too, and presumably also true of the northern regions of Yakutia and Chukotka. Just as the Icelandic Whooper Swan population at the extreme northwest of the species' range is atypical for breeding in essentially treeless boreal and tundra-like habitat, rather than typical forested taiga, so the population breeding in the extreme northeast, in the Anadyr region of Russia is atypical in breeding in the forest-tundra and shrubby tundra landscapes of the Anadyr R valley. Here it ranges almost to the shore of the Bering Sea, the extreme eastern Asian outpost for this species. In this region its range does not meet that of Bewick's Swan, which is completely absent from the middle reaches of the Anadyr R even on migration. In spring, Whooper Swans begin to arrive in Anadyr during the middle or even at the beginning of April. At that season, wintry conditions may still continue and temperatures at night quite often fall to minus 30℃ and, occasionally, even to minus 40℃. The only habitat available to these early arrivals are the polynias, open patches of unfrozen water, in the midst of the still icebound Anadyr R and its tributaries. Both on the polynias and at the breeding sites in the area of the flood-plain landscapes of the Anadyr R, Whooper Swans usually appear in pairs or in small groups of 3-5 individuals, presumed to be pairs with their previous year's offspring (Krechmar 1990). There they remain until intensive snow melt begins to expose their nesting habitat, which may be situated as much as several tens of kilometres from the polynias. Waiting at the polynias allows that portion of the population that will attempt to breed the possibility of reaching the breeding sites almost immediately after conditions become favourable for nesting. This movement, from the polynias out to the breeding territories, happens during mid May or at the beginning of the last third of May, making these among the latest of all Whooper Swans to commence breeding. Just after their appearance within the nesting range, Whooper Swans very willingly visit and remain at "oases of spring" -that is sites where the snow melts early, The Whooper Swan in Central and Eastern Siberia, and the Russian Far East 297 where wind-blown silt and sand promote rapid melting of the snow. At such sites, Whooper Swans gather in small parties of up to 10 birds with other waterfowl and Sandhill Cranes Grus canadensis and, as soon as small shallow-water grassy lakes are released from ice, Whooper Swans very willingly visit them to feed. During this same period (mid to late May), considerable numbers of Whooper Swans continue to arrive from the wintering grounds, but most of these later arriving birds probably do not participate in breeding (Krechmar 1990). In the Anadyr region, Whooper Swans prefer medium-sized or even very small lakes for breeding. Where they do select larger wetlands, they select shallow bodies of water with many islands so that the topography serves to protect their nests from late ice movements (Krechmar 1990). Of the 41 nests that Krechmar (1990) examined, 22 had been built on islands in small lakes, 16 were built in shallow water amidst thickets of sedges, a range of arctic species and swampy areas with horsetails, and two were on upland coastal spits near the northern banks of larger lakes. Although the number of lakes in the willow flood land of the Anadyr Lowland is much higher than in the surrounding hilly areas with dwarf (or prostrate) forest-tundra, it seems that few of the lowland lakes are actually suitable for breeding and the main nesting sites are found in the forest-tundra where they favour lakes in "alas" depressions, which provide oases of vegetation amid the surrounding barren landscape (Krechmar 1990). The most favoured region for breeding is actually in the interstream area between the Anadyr and the Mayn rivers, to the west of Anadyr. There, Whooper Swan pairs sometimes occupy territories that are as close together as 5-6km whereas, even in suitable habitat, breeding pairs are usually separated by 10km or more (Krechmar 1990). In contrast to Whooper Swans nesting elsewhere, those of the Anadyr region don't, as a rule, use their previous year's nest as the foundation for the new nest. In this region, at the extreme climatic limit of their range, where winter snow cover is considerable and spring melt unpredictable, and the breeding season critically short, the nesting pairs cannot even wait for the snow to melt on their old nest. Instead, they build a new nest in the vicinity of the old one, but in a more favourable site for the weather in that particular year (Krechmar 1990). Northeast of the Anadyr R, towards the Bering Straits, the Whooper Swan becomes scarce. Portenko (1981; in Krechmar 1990) considered that the rarity of Whooper Swans in the central and eastern parts of the Chukchi Peninsula made it more likely that they only visited there to moult. To the south of Chukotka lies the enormous Kamchatkan Peninsula, separating the Okhotsk Sea from the Pacific Ocean. At its base (in the north) lies the Penzhina-Parapol Region3, a forest-tundra region of lake-alas lowlands, with weakened permafrost, summer thawing, and many-lakes. There, Gusakov (1987) studied the Whooper Swan population by means of aerial and ground surveys between 1977 and 1983 covering as much as 17,000 sq km in some years. The habitat here consists of a complex patchwork of shallow water

3 Within the borders of the Penzhinsk administrative district of the Kamchatka Region . 298 Mark A. Brazil and Jevgeni Shergalin bodies with rich submerged and emergent vegetation (with much Menyanthes trifolium and Sphagnum moss) and surrounded by dwarf Siberian pine Pinus spp., alder Alnus spp., Middendorff's birch Betula middendorffii, and willow Salix spp. The flooded hollows, shallow lakes, and their islands provide ideal habitat for the Whooper Swan, which is common in the area, and a wide range of other waterfowl species including Sandhill Crane. Bewick's Swan is only a rare migrant through this region, the majority passing further west. During the first aerial survey (20-23 September 1979), when some lakes were already freezing over, the population in the area consisted of: non-breeding pairs (lacking broods 50%), cygnets (27%), breeding pairs (18%), and single individuals (5%). The average size of fledged broods was 2.9 (somewhat higher than Krechmar (1982b) found just to the north along the Anadyr R) (Gusakov 1987). The average density of the Whooper Swan population in the Penzhina-Parapol was of 7-9 individuals/100km2 over the years 1979, 1980, 1981, during which time up to 60% of the population was considered to consist of non-breeding pairs (Gusakov 1987). The Kamchatkan Peninsula is both an important breeding ground and a surprisingly important wintering area for the Whooper Swan. Given the generally extremely severe winter climate of northeast Russia, a surprisingly large number of Whooper Swans remain to winter on the Kamchatka Peninsula. This is because of the peninsula's comparatively mild maritime climate, its considerable number of ice-free rivers, its numerous springs (many of them hot), and the extensive aquatic vegetation that remains available all year round (Gerasimov & Alekseev 1990). In addition, the extensive plains, the density of wetland habitats amounting so some 10,000km2 of swamps, and more than 10,000 lakes, provide favourable resting areas for migrants and a considerable extent of suitable habitat for breeding (Gerasimov & Alekseev 1990). The chain of the volcanic Kuril Islands is like an arcing series of stepping stones linking Kamchatka to the northern Japanese island of Hokkaido, where many more Whooper Swans spend the winter. In the north, the limit of breeding in Kamchatka is reached at the narrow base of the Kamchatkan Peninsula between the Penzhinskaya Gulf and the Parapol dol depression, which lies between the mountains of the base of the peninsula (Gerasimov & Alekseev 1990). With the exception of the small population breeding in Anadyr, and the exceptional record of breeding on Attu in the Aleutian Islands, Kamchatka represents the northeastern edge of the species' breeding range. The importance of migration along the Kamchatkan Peninsula has been confirmed by Gerasimov (2000), who found that in addition to considerable numbers of shorebirds, waterfowl, and gulls, 2,200 Whooper Swans passed through the Ozero Kharchinskoe GR in Central Kamchatka (56°32'N; 160°52'E) between 27 April and 27 May 1999. Breeding occurs as far south as the Pravaya Khodutka R in southeastern Kamchatka, where at the beginning of July 1980, 4-5 pairs of adults and two broods each of two cygnets, were sighted along the upper part of the river (Gerasimov & Alekseev 1990). Aerial surveys of the upper and middle parts of the Kamchatka R valley, in the central part of the peninsula, on 25-26 May 1986, found 21 pairs with clutches and cygnets and two pairs without nests in the upper third of the Kamchatka R. Another survey on 22- The Whooper Swan in Central and Eastern Siberia, and the Russian Far East 299

25 May 1987 found seven pairs on nests, 11 pairs without nests and a further 30 birds alone and in flocks mainly in the middle part of the river basin (Gerasimov & Alekseev 1990). Extrapolation of observed data to the area of habitat suitable for breeding in the entire Kamchatka R valley suggests that at least 90-100 pairs may breed in the centre of the peninsula. In Kamchatka, an example of their preference for well-developed valleys of large rivers as breeding habitat is well seen in the Kamchatka R basin. Of 25 nests observed, 16 were located on former riverbeds, seven on bogs within 10m of lakes, one was on a small lake, and one was on an island in an extensive lake (Gerasimov & Alekseev 1990). Some Whooper Swan pairs in Kamchatka begin breeding quite early. In the Kamchatka R valley in late May 1986 two pairs were incubating clutches (two eggs each) and in one nest there were already three downy cygnets (at a time when birds to the north in Anadyr are only just commencing their breeding season). Egg-laying in these nests must have begun by about the 20th of April. Elsewhere, for example at the Kharchinskoe L GR, two Whooper Swan broods, one with four, the other with three downy cygnets the size of Eurasian Wigeon A, penelope, were seen at a more typical date of 27 June 1982 (Gerasimov & Alekseev 1990). Clutches in Kamchatka ranged from 2-7 eggs (n=7) averaging 3.1, while the number of cygnets observed in broods (n=16) also ranged from 2-7, but averaged 3.3 cygnets. Further northeast, in the Anadyr R area, full clutches of Whooper Swans were larger on average (5.3 eggs; range 4-6), while in winter 1984 of fifteen families the average was four cygnets per pair (Krechmar & Kondratiev 1986). An initial survey of the whole of Kamchatka in 1966-1968 by questionnaire indicated that a considerable number of Whooper Swans, some 5,000-5,500, winter in this region (Gerasimov & Alekseev 1990). Then during late February and early March 1980, the first aerial survey of wintering Whooper Swans in Kamchatka was conducted. The region being far too extensive to cover adequately with the single aircraft available, a question- naire survey was made before the flights in order to help locate wintering concentrations so that flight lines could be planned to cover them (Gerasimov & Alekseev 1990). To put the area in context, to give some indication of the scope of the undertaking, and to help envisage the scale of both the landscape and the distribution of the swans, the highly volcanic Kamchatkan Peninsula covers an area of approximately 472,300km2, whereas for example the whole of the UK (considered an important and well-known wintering area for the western population) amounts to only 244,020km2, and Iceland (a well-studied and important breeding area) just 102,820km2. From the aerial survey made of 1,977km of non-frozen rivers, and from the visual counts of 1,287 Whooper Swans, combined with additional survey information from hunters and responses to questionnaires, it was estimated that the minimum wintering population in Kamchatka in 1980 was a considerable 7,500 birds. That is more than the wintering population of Scotland, England, and Wales combined at the latest census in January 2000 (Cranswick et al. in press), a wintering population that has received considerable annual research attention for many years. The Kamchatkan wintering 300 Mark A. Brazil and Jevgeni Shergalin population was distributed as follows: in the south of the peninsula there was a minimum of 1,300; along the southeastern shore there were 1,200; in the southwestern region-800; in the middle region of the western shore-1,000; along the northwestern shore-500, and in the southern part of the centre of the peninsula there were another 1,200 birds. Regions in the northeast of Kamchatka, including the Ozernaya, Uka, Khailyulya, and Ivashka river basins, could not be investigated from the air. Questionnaires, however, indicated that only about another 20 Whooper Swans would have been missed from this region (Gerasimov & Alekseev 1990). During a repeat survey in 1984 of the richest parts of the southern and southeastern regions of Kamchatka, 1,553 Whooper Swans were found along 1,750km of ice-free rivers (that is more birds in a shorter distance than in the previous survey) confirming that the lower limit of the previous survey had probably been correct. The repeat survey also revealed the impracticality of complete coverage by aerial survey of all non-frozen water channels. Even small channels and springs may hold a considerable number of swans, and these numbers are variable. For example, on 11 December 1984, at a spot on the Pinacheva R used by Whooper Swans for resting and roosting, 60 were counted, but two days later, on the 13 December, 100 were found at the same site from the air, and 216 were found there in the early morning of 15 December 1984 during a count from the ground. Given this extent of variability of numbers observed at one small location, Gerasimov & Alekseev (1990) concluded that in the many branching water channels, amounting to many thousands of kilometres, the likelihood of missing flocks of birds was very high. Thus, numbers wintering in Kamchatka are likely to be even higher than indicated, making this one of the most important regions for wintering Whooper Swans in the Far East, outside Japan. To the east of Kamchatka lie the Commander Islands, the westernmost islands in the chain that stretches east all the way to Alaska. As Whooper Swans both breed and winter in Kamchatka, it is not surprising that they are also regular migrants, more frequent in the autumn, on the Commander Islands, and also winter there from early October to mid-April (Johansen 1961). Where the immense blade-shaped Kamchatkan Peninsula forms the northeastern border to the Okhotsk Sea, across that sea in the southwest lies the somewhat smaller, but equally elongated, island of Sakhalin. Sakhalin lies so close to the eastern coast of the Amur region and to the northern tip of Hokkaido that it is visible from both. It is a major stepping stone between the far eastern parts of Russia and northern Japan. On this eastern Russian island, which lies immediately north of Hokkaido, the Whooper Swan used to breed on lakes and rivers in both the southern and northern regions until the 1930s. Now, however, it appears to be a rare bird breeding only in the northern half of the island on lakes near Tungusskiy Cape (north of Pogibi Cape), in the northern part of Chaivo Gulf, in the surroundings of Baikal Gulf and on lakes of the Shmidta Peninsula (Nechaev 1991). Nechaev (1991) has also seen birds during summer at sites in the south such as at Svobodnoe L, where they bred as recently as 1983 (Nechaev 1991), and in the latter half of the 19th century, small numbers were also reported wintering in the south of the island. Sakhalin is an important and traditional flyway for both Whooper and Bewick's The Whooper Swan in Central and Eastern Siberia, and the Russian Far East 301 swans migrating between their wintering grounds in Japan and their breeding grounds in eastern Russia. The Whooper Swan is abundant on migration, with many sites on Sakhalin Island used as transit stops by birds as they head north to breed or south to winter in Japan. In spring, the first northbound flocks appear in the south of the island on shallow bays and lakes, especially in Aniva Gulf, in southern Sakhalin, as early as the last third of March with the earliest records of all on 20 March in 1938 and 1980 (Gizenko 1955, Nechaev 1991). Despite such early arrivals, the main mass of birds actually appear in southern Sakhalin a month later during the second half of April, when they concentrate mainly in the Aniva Gulf. Both fresh and saltwater are still largely frozen at this time of year and swans rest at patches of unfrozen water in otherwise iced-over rivers, lakes or gulfs, and at ice-free river mouths (Zykov & Revyakina 1996). Numbers of migrants are much greater during April and the migration ceases in the south during the first third of May, as by then all birds have left Japan, but migration continues in the north of the island until the middle of May (Nechaev 1991). Flocks vary considerably in size from a few tens of birds to several hundreds, but individual flock sizes give little indication of the importance of migration sites, which may see a steady or even rapid turnover of individuals. So, for example, between 09:00 and 11:00 on 8 May 1984, Nechaev (1991) observed 1,200 swans migrating north although none of the flocks consisted of more than 100 individuals. Further south, in the Japanese islands of Honshu and Hokkaido, Bewick's and Whooper Swans mainly follow different migration routes, however, these converge on Sakhalin. Direct observation and satellite telemetry of banded birds has shown that both species rest at the same sites (e. g. Nechaev 1991, Kanai et al. 1997). The largest reported concentration of Whooper Swans on Sakhalin appears to have been that of Nechaev (1991) who observed 12,500 birds on Svobodnoe L from 12thto 14th May 1984. So large was their concentration that their voices could be heard at a range of up to three kilometres. That number was larger than the then known Japanese wintering population of Whooper Swans (9,476 in January 1984; WBSJ 1992) indicating that perhaps Sakhalin is also an important transit route for Whoopers wintering elsewhere in east Asia, or that the flock also contained many Bewick's Swans. Zykov & Revyakina (1996) have counted as many as 16,000 swans in southern Sakhalin (e. g. on 2 May 1993) with the majority of them Whoopers (c 1,000 Bewick's amongst them). They also observed intensive passage, for example over the Susuya R valley, where 646 swans passed in just two hours on 5 May 1993. Flock sizes ranged from 11 to 200 (average 58). Flocks of swans also rest in southern Sakhalin on the channel connecting Tunaicha L to the sea (500 there on 26 April 1993 for example) where as many as 1,000-2,000 can occur, and on Tunaicha L where up to 5,000 swans gather (Zykov & Revyakina 1996). While the majority of birds pass through Sakhalin during April, occasionally individuals are reported as late as early June (e. g. near Aniva Cape on 1 and 6 June 1980 (Nechaev 1991). In northeast Sakhalin, the distribution of swans in spring is entirely dependent on annually variable ice conditions. Migration through this area is taking place when there are still few widely scattered polynias at the mouths of large rivers, in certain bays, and along some sections of the coastline. Consequently, the swans may be widely dispersed in small groups or greatly concentrated, depending on the availability of open water. For 302 Mark A. Brazil and Jevgeni Shergalin example, hunters recorded a concentration of several thousand swans in the southern part of Nabilskiy Gulf in spring 1992 (Zykov & Revyakina 1996). After the spring migration has passed through Sakhalin a small number of birds remain, usually immature birds. Several pairs, however, also breed on Sakhalin, at sites such as Svobodnoe, Sladkoe, and Ainskoe lakes (Zykov & Revyakina 1996). In autumn, swans concentrate in the northeastern part of Pil'tun Gulf, where as many as 15,000-16,000 swans are known to rest (Zykov & Revyakina 1996), however, both Bewick's and Whooper Swans may occur together here and their proportions at this season are not reported. On the whole, however, birds pass through quickly in autumn, resting only for short periods, whereas in the spring they may stay for prolonged periods.

Conclusions Despite the considerable research effort on the Whooper Swan in Europe, especially in the northwest, the vast majority of the Whooper Swan's breeding range falls within the political boundary of modern Russia. The enormity of the Central and Eastern Siberian and Russian Far East region, combined with the small number of resident swan biologists, and the difficulty of access to most areas, has meant that for many areas even the most basic information is not available. Given the difficulties involved, it is impressive that so many papers have been published on this species in its Russian range in recent decades, yet so much remains to be learned from this enormous region.

The northern limit to the species' normal breeding range in Russia is between 66°N and 68°N, although it has also bred north to 70°N and even 72°N. Whereas it breeds south to approximately 62°N in the west, in the Russian Far East it can be found breeding as far south as 50°-55°N. Its wintering range is also latitudinally variable, with birds in the west wintering as far south as 47°N to 50°N in the Caspian Sea area, Kazakstan, Mongolia and China, although in Japan, for climatic reasons, it can be found wintering regularly as far south as from 35°N to 40°N. The breeding range in Russia includes a range of different habitats that include various types of wetlands (rivers, marshes, lakes), in northern taiga forest, northern forest tundra, tundra (occasionally), southern taiga, forest-steppe, and steppe. Whooper Swans breeding in western Russia, west of the Ural Mountains, and those breeding to the north of that mountain range, are presumed to migrate to winter in the east Mediterranean, and the Black Sea area. Those breeding in Western Siberia are presumed to winter to the south in and possibly also including the region around the Caspian Sea. Birds from the Central and Eastern Siberian regions may winter in Mongolia, China, and East Asia, while those breeding in the Russian Far East migrate to winter primarily in Kamchatka and Japan. Population estimates remain highly speculative and there is a clear need for further investigation to clarify both the migratory movements from different regions and the sizes of populations breeding in particular regions. On the basis of estimates of wintering populations outside Russia, the numbers breeding in western Russia and Western Siberia may be as few as 10,000 or as many as 70,000 (Rees et al. 1997), although research in the The Whooper Swan in Central and Eastern Siberia, and the Russian Far East 303 area by Krivenko (1989, in Ravkin 1991) suggested a late summer population for the West Siberian Plain alone of 52,000 and Ravkin (1991) based on his surveys supposed there to be a very much larger population in that area, exceeding 100,000 birds. Figures from Central and Eastern Siberia are also difficult to assess, but it seems likely that the population of the Russian Far East is in the region of 60,000 birds. The breeding population within Russia is large, and may be expanding its range northwards. In some parts of its western Russian range it was reoccupying areas during the latter half of the 20th century from which it had been eliminated earlier as a result of persecution, while in other areas it is losing habitat and its range is contracting as a result of habitat loss and disturbance during the breeding season. 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. As a migratory species, the Whooper Swan is therefore the responsibility of a large number of countries, nevertheless as the host of the majority of breeding Whooper Swans it is Russia that shoulders the greatest responsibility for maintaining the non-endangered status of this species. That said, current research on the species is strongly biased towards activities in the extreme western and eastern parts of the range, in Europe and Japan. The extensive range of the Whooper Swan and the considerable area of suitable habitat available for it in Russia make clear that substantial further research efforts should focus on that country. In particular future research should focus on elucidating the main migration routes between breeding and wintering areas so as to be able to protect important stopover sites along their various flyways.

Acknowledgements

For their help in providing additional information facilitating the completion of this paper we are grateful to: Mr. Alexander Abuladze, Dr. Sergei Bukreev, Mr. Vladimir Dinets, Dr. Eugene Syroechkovskiy Jr., Dr. Lev Vartapetov, and Mr. Oleg Zhuk. We also thank several anonymous referees who provided important input to an earlier draft, and Eng-Li Green of Alcedo Publishing for preparing the maps.

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Mel'nikov, Yu. I., Vodop'yanov, B. G., Naumov, P. P. & Mel'nikova, N. I. 1990b. The Whooper Swan number change in Irkutsk Region in connection with intensive development of region. In Ekologiya i okhrana lebedei v SSSR [Ecology and Conservation of Swans in the USSR]. pp. 82-85. Vtoroe vsesoyuznoe soveshchanie po lebedyam [The Second Meeting on Swans]. Odessa, 20-24 September 1988. Melitopol State Pedagogical Institute, Melitopol. Mitchell, C. D. 1998. Whooper Swans (Cygnus cygnus) in North America. Swan Specialist Group Newsletter 7: 7-8. Miyabayashi, Y. & Mundkur, T. 1999. Atlas of Key Sites for Anatidae in the East Asian Flyway. Wetlands International-Japan, Tokyo, and Wetlands International-Asia Pacific, Kuala Lumpur. Nechaev, V. A. 1991. Ptitsy ostrova Sakhalin [Birds of Sakhalin Islands]. Inst. of Biology and Pedology, Vladivostok. Nilsson, I., Andersson, O., Gustafsson, R. & Svensson, M. 1998. Increase and changes in distribution of Breeding Whooper Swans Cygnus cygnus in Northern Sweden from 1972-75 to 1997. Wildfowl 49: 6-17. Panov, Ye. N. 1973. Ptitsy yuzhnogo Primor'ya. Fauna, biologiya, povedenie [Birds of southern Ussuriland. Fauna, biology, behaviour]. Nauka, Novosibirsk. Perennou, C., Mundkur, T. & Scott, D. A. 1994. The Asian Waterfowl Census 1987-91: Distribution and Status of Asian Waterfowl. AWNB Publication No. 86/IWRB Publication No. 24. Perfil'yev, V. I. 1972. Zapasy promyslovykh vodoplavayushchikh ptits Severo-Vostoka i ikh ratsionalnoe ispolzovanie [Resources of huntable waterfowl of the North-East and their wise management]. In Priroda Yakutii i eyo okhrana [Nature of Yakutia and its Conservation]. pp. 19-25. Yakutsk. Perfil'yev, V. I. 1976. Novye dannye po rasprostraneniyu ptits v nizov'ye Leny [New data on bird distribution in Lower Lena]. In Byul. NTI. Biol. Problemy Severa [Bull. of Scient.-Techn. Inform. Biol. Problems of the North]. pp. 22-24. Academy of Sciences, Yakutian Branch, Yakutsk. Perfil'yev, V. I. 1979. Vliyanie antropogennykh factorov na chislennost'vodoplavayushchikh ptits severa Yakutii [Influence of anthropogenous factors on number of waterfowl of the north of Yakutia] . In Okhrana i ratsionalnoe ispol'zovanie zhivotnogo mira v prirodnoi srede Yakutii [Conservation and Wise Management of Wildlife in the Natural Environment of Yakutia]. pp. 112-119. Yakutsk. Perfil'yev, V. I. 1987. Lebed-klikun i malyi lebed' na severe Yakutii [The Whooper Swan and Bewick's Swan in the north of Yakutia]. In Ekologiya I migratsii lebedei v SSSR [Ecology and Migrations in the USSR]. pp. 134-136. Nauka, Moscow. Popov, V. V., Murashov, Yu. P., Olovyannikova, N. M., Stepanenko, V. N. & Ustinov, S. K. 1998. Redkie vidy ptits Baikalo-Lemskogo zapovednika [Rare bird species of Baikal-Lens Nature Reserve]. In Trudy Baikalo-Lenskogo gosudarstvennogo prirodnogo zapovednika [Proceedings of the Baikal-Lena State Nature Reserve, Issue 1]. pp. 95-98. Moscow. Poyarkov, N. D. 2001. Tendentsii izmeneniya chislennosti guseobraznykh Nizhnego Priamur'ya za poslednie 20 let [Trends of Anseriformes number changes n Lower Cis-Amur River area]. In Aktual'nye problemy izucheniya i okhrany ptits Vostochnoi Evropy i Severnoi Azii [Actual Problems of Study and Conservation of Birds of Eastern Europe and Northern Asia]. pp. 504-506. Matbugat Jorty Press, Kazan. Ravkin, Yu. S. 1991. Number and distribution of Mute Swans Cygnus olor, Bewick's Swans C. bewickii, and Whooper Swans C. cygnus in the West Siberian plain. Wildfowl Supplement 1: 68-72. Rees, E. C., Einarsson, O. & Laubek, B. 1997. Cygnus cygnus Whooper Swan. BWP Update Vol. 1(1): 27-35. Rogacheva, E. V. 1988. Ptitsy Srednei Sibiri [Birds of Middle Siberia]. Nauka, Moscow. Rogacheva, E. V. 1992. The Birds of Central Siberia. Husum, Husum. Roslyakov, G. E. 1987. Lebedi Nizhnego Priamur'ya i Shantarskikh ostrovov [Swans of the Lower Cis-Amur River area and the Shantar Islands]. In Ekologiya I migratsii lebedei v SSSR [Ecology and Migrations in the USSR]. pp. 136-138. Nauka, Moscow. Roslyakov, G. E. 1990. Swans in Khabarovsk Territory. In Ekologiya i okhrana lebedei v SSSR [Ecology and Conservation of Swans in the USSR]. pp. 89-91. Vtoroe vsesoyuznoe soveshchanie po lebedyam [The Second Meeting on Swans]. Odessa, 20-24 September 1988. Melitopol State Pedagogical Institute, Melitopol. Roslyakov, A. G. & Voronov, B. A. 2001. Gnezdovanie gusei i lebedei v Khabarovskom krae [The Breeding of The Whooper Swan in Central and Eastern Siberia, and the Russian Far East 307

geese and swans in Khabarovsk Territory]. In Popovkina, A. B. (Ed.) Problemy izucheniya i okhrany guseobraznykh ptits Vostochnoi Evropy i Severnoi Azii [Problems of Study and Conservation of Anseriformes of Eastern Europe and Northern Asia]. pp. 106-107. Tez, dokl. [Abstracts of 1st Meeting of Working Group on Geese and Swans of Eastern Europe and Northern Asia, Moscow, 25-27 January 2001]. Moscow. Sadkov, V. S. & Safronov, N. N. 1990. Migrations and dynamics of the Whooper Swan number in Northern Baikal and in the Upper Angara hollow (depression). In Ekologiya i okhrana lebedei v SSSR [Ecology and Conservation of Swans in the USSR]. pp. 91-95. Vtoroe vsesoyuznoe soveshchanie po lebedyam [The Second Meeting on Swans]. Odessa, 20-24 September 1988. Melitopol State Pedagogical Institute, Melitopol. Schadilov, Yu. M.-1991. Current conservation status and problems of management for swan populations in the USSR. Wildfowl Supplement 1: 376-377. Scott, D. A, & Rose, P. M. 1996. Atlas of Anatidae in Africa and Western Eurasia. Wetlands International Publication No. 41; Wetlands International, Wageningeh, The Netherlands. Shinkarenko, A. V., Mel'nikov, Yu. I., Podkovyrov, V. A., Zhuravlev, V. E. & Pyzh'yanov, S. V. 1990. Charac- ter of the presence and number of swans in southern and middle Baikal. In Ekologiya i okhrana lebedei v SSSR [Ecology and Conservation of Swans in the USSR]. Vtoroe vsesoyuznoe soveshchanie po lebedyam [The Second Meeting on Swans]. Pp. 97-98. Odessa, 20-24 September 1988. Melitopol State Pedagogical Institute, Melitopol. Sofronov, Yu. N. 2000. K ornitofaune delty Leny [On ornithofauna of Lena River delta]. Ornitologicheskie issledovaniya v Rossii [Ornithological studies in Russia] 2: 73-88. Sykes, P. & Sonneborn, D. W. 1998. First breeding records of Whooper swan and Brambling in North America at Attu Island, Alaska. Condor 100: 162-164. Syroechkovski, Jr., E. in press. Status and distribution of swans in the Siberian Arctic in the 1990s. Proceedings of the 4th International Swan Symposium, Airlie, Virginia. Vorob'yov, K. A. 1954. Ptitsy Ussurijskoi taigi [Birds of the Ussurian taiga]. Academy of Sciences, Moscow. WBSJ (Wild Bird Society of Japan) 1992. Results of the Annual Nationwide Waterfowl Census 1982-1992. Strix 11: 361-366 (In Japanese with English Summary). Yumov, B. O. 2001. K gnezdovoi ekologii nekotorykh vodoplavayushchikh ptits verkhoviy r. Barguzina (Severo-vostochnoe Pribaikal'ye) [On nesting ecology of some waterfowl in upper parts of Barguzin River (North-Eastern Cis-Baikalia)]. In Poppvkina, A. B. (Ed.) Problemy izucheniya i okhrany guseobraznykh ptits Vostochnoi Evropy i Severnoi Azii [Problems of Study and Conservation of Anseriformes of Eastern Europe and Northern Asia]. pp. 135-136. Tez. dokl. [Abstracts of 1st Meeting of Working Group on Geese and Swans of Eastern Europe and Northern Asia, Moscow, 25-27 January 2001]. Moscow. Zykov, V. B. & Revyakina, Z. V. 1996. Prolet lebedei na Sakhaline. [Migration of swans on Sakhalin Island]. In Ptitsy presnykh vod I morskikh poberezhiy yuga Dal'nego Vostoka Rossi i ikh okhrana [Birds of the Wetlands of the Southern Russian Far East and their Protection]. pp. 226-227. Dalnauka, Vladivostok.

ロシアにおけるオオハクチ ョウの生息状況 と分布II:ロ シア中部 と東部,極 東部

オオハ クチ ョウ(Cygnus cygnus)の 生息域 の大半 は,ロ シアお よびその周辺 の旧ソ連邦共和 国の境界内 に含 まれて いる。従来,本 種 に関 す る研究 の多 くは,ヨ ーロッパ と日本で行 なわれ て きたが,1980年 以 降,ロ シアで もか な りの量 の研究 が行 なわれるよ うにな った。 これ らの研 究の大半 はロ シア国内 の論文誌,そ れ も地方 の論文誌 で発表 され ることが多 いため,ロ シア以 外の研究者 が これ らの文献 に接 した り,入 手 した りす る機会 も非常 に限 られて いたが,こ れ ま でに ロシア西部 と シベ リア西部 に関す る文献 の多 くを整理検討 した(Brazil & Shergalin 2002)。 このたび私た ちは,引 き続 き文献 の整理検討 を行 な い,次 の2地 域:1)ロ シア中部お よび東部 (エ ニセイ川 か らレナ川 まで),2)ロ シア極東部(レ ナ川か らベー リング海 まで),に おける本種 308 Mark A. Brazil and Jevgeni Shergalin

の生息状況 と分布の全体像を明 らか に した。 現在,オ オハ クチ ョウの個体群 サイ ズに関す る正確 な情報が手 に入 るのは,ヨ ー ロッパ地域 のみであ るが,今 回扱 った ロシア2地 域の面積 は,ヨ ーロ ッパ のオオハ クチ ョウ個体群分布域 と同 じくらいか,あ るいはかな り上 回 ってい る。本論 文で扱 った2地 域 に は特 に,オ オハ ク チ ョウが繁殖可 能な広いハ ビタ ッ トがあ るが,個 体群 の大半 は,ロ シア国境 の外側 で越冬 して い る。東 に延び る繁殖域 は,チ ュコ ト半島の アナデ ィル渓谷 やカムチ ャツカな どの,極 東 ロシ ア東端 まで達 してい る。繁殖域の北限 は北緯67～68度 の間で あるが,例 外的 に北緯72度 に達 す るところ もあ る。ヨー ロッパ ロシア西部 にお ける繁殖域の南限 は北緯62度 であ るが,サ ハ リ ンとカムチ ャツカ にお ける南限 は北 緯55～50度 に達す る。西側生 息域 のオオハ クチ ョウの多 くは,北 緯47～50度 の ヨーロ ッパ まで南下 して越冬 す るが,シ ベ リア中部 および東部 とロシア 極東部 で繁殖 す る個体 の大半 は,中 央 ア ジアや東 ア ジアの越 冬地 まで渡 りをす る。 オオハ ク チ ョウ越冬地の南限 は,日 本で ある。日本で は,気 候的 な理 由によ り,北 緯35～40度 にか けて の低緯度地域 に多数のオ オハ クチ ョウが越冬 しているのが観察 され る。 シベ リア中部 お よび東 部の推定 個体数 は文献 によ ってば らつ きが大 きいが,ロ シア極東 部 の個 体数 はい くらか正 確 で,カ ムチ ャツカ,日 本,朝 鮮半島 および中国 における越冬数 か ら,約6万 羽が生息 してい る と考え られ る。 (摘要和訳 黒沢優子)

マー ク ・A・ ブラ ジル:酪 農学 園大学 環境 システム学科,〒069-8501北 海道 江別市文京台緑 町582.

イ ェ フ ゲ ニ ・シ ャ ー ガ リ ン: "Zoolit" , Sopruse pst. 175-58, Tallinn 13413, Estonia.