Soviet Studies in the Northward Movement of Birds
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Soviet Studies in the Northward show that thewarming trend hasbecome clearlypronounced since the 1920's in the Movement of Birds arctic belt from Iceland and Spitsbergen to Taymyr and Severnaya Zemlya. The average While actively engaged in the development difference intemperature between the be- of northern areas, the Russians andother ginning of thiscentury andthe 1950's is Soviet nations, quite naturally, have observed about 7 deg. C. for winter, 5 deg.C. for thatthe boundaries of animalhabitats are autumn, andonly about 1 deg. C. forthe gradually being extendednorthward. Since spring and summer. birds are the most mobile animals, they have Asa consequence, the vegetation period set an example in the opening of new fron- is extended, and more birds and other ani- tiers, and therefore most of the observations mals as well are lured north. In this connec- and studies of the shifting boundariesdeal tion, Uspenskiy cites lemmings as an with birds. The investigations cover not only illustration since they constitute an important the arctic belt, but the southern regions as food item for larger birds and mammals. well, because boundaryshifts inone area During the most intense warming period on involveshifts in adjacent areasto balance Yamal Peninsula in northwesternSiberia the changing situation. (1930 to 1949) the mass development of In search of data on the extent and rate lemmings was observed every year, not once of themovement, its variations with geo- in threeor four years, which is the usual graphicalareas andthe causes that induce cycle for the mammals in the area. the changes, I have examined most of the Because of suchfavourable conditions, Soviet papers discussing the phenomenon. some birds haveextended their ranges So far acomprehensive study covering all northward by2 degrees latitude (210 km. the aspects of the subject has not been writ- or 130 miles) during the last 50 years. The ten. But there are numerous reports discuss- record for this area is held by the willow ing observationsin specific areas,such as warbler (Phylloscopus trochilus), meadow Franz Josef Land, Yugorskiy andYamal pipit (Anthus pilaris) and possibly by the peninsulas, Taymyr, Baltic republics, etc. fieldfare (Turdus pratensis). The last-mention- Other papers discuss definite species and ed is extending its range not only northward groups of mammals and birds that have changed or are changing theboundaries of their habitats, the effect of climate and man's 58' 60' activity on bird life, and related topics. Changes of zoogeographicalboundaries innorthern Russia and Siberia have been studied in some detail by UspenskiyV3 and Syroechkovskiy?~. Uspenskiy participated in several expeditions which investigated thefauna and flora of thearctic belt in 1941, from 1948 to 1950, in 1957 andin 1958 fromthe estuary of thePechora in northeastern Europeto theestuary of the Yenisey in northern Siberia. The latitude of the belt extended from the Arctic Circle in thesouth to the northern tip of Novaya Zemlyaand Novosibirsltiye Ostrovain the PENINSULA north. Thusall of the arctic biomes from DO PGORSKIY the so-called arctic deserts through moss- lichen andshrub tundras tothe forest or taiga belt were investigated. In addition, Uspenskiy consulted studies written by earlierArctic explorers, namely, Jackson6 and Pearson.? It appears that, step by step, thetundra 6 is advancing into thearctic desert, and the taiga is moving into the tundra. In line with FIG. 1. Extension of northern boundary by plants, the mammals and birds are moving the Willow Ptarmigan from Karatayka river northward too. The prime cause of this race delta in 1899 (lat. 68"N.) to Cape Lyamchin is the warming of the Arctic. The tempera- parallel (lat. 69"5'N.) on VaygachIsland turedata compiled by Vizes and others9 in 1957. 202 NOTES AND INSTITUTE NEWS but also westward. A permanent colony has to Turukhansk (lat. 66"N.)in 1911, and to recently been established in Greenland. This Nikol'skoye (lat. 70"N.)in 1960. The chaf- event is described in detail by Salomonsen,lo finch (Fringilla coelebs), which prefers wood- a Danishornithologist, who has been ob- landmargins and partially cleared forests, serving fieldfares since theirappearance in has moved northward from Krasnoyarsk to Greenland in 1937. Now they have also been Komsa (700 km.) in 13 years. This unusual observed on Baffin Island and the Labrador speed is explained by two exceptional con- Peninsula. ditions: the warming of the climate set the Detailedinformation for atime span of record for the Yenisey valley in that period, 60 years is given by Uspenskiyl for Yugor- and at the same time the clearing of forests skiy-Vaygach-Novaya Zemlya sector where was very intense. theshrub tundra in the southtransits into The rook (Corvusfrugilegus), which the moss-lichen tundraand arcticdesert in prefers fields and clearings in forestsmade the north. By consulting the books written by man,has extended its habitat by about by earlierexplorers who had investigated 700 km. northward during the last 55 years, this area (Jackson;G Pearson;T Buturlinll), from Krasnoyarsk to Komsa. The birds that Uspenskiy obtained information on changes do not depend on changes in the environment of plant and animal life since the end of the broughtabout by man move northward at last century. a slower rate. They evidently are induced in To cite an example, between 1899 and this movement only by thewarming of 1957 the willow ptarmigan (Lagopus lagopus) climate. Syroechkovskiy4 assigns to this extended its northern boundary from Kara- group the black woodpecker (Dryocopus tayka river delta (68"N.) to Cape Lyamchin martius), coal tit (Parus ater), whooper swan (69"5'N.) on Vaygach Island(Fig. 1). Oc- (Cygnus Cygnus), merganser (Mergusmer- casionally the species has been observed on ganser) and some others.Their northward Novaya Zemlya as far as lat. 74"N., although movement has varied from 200 to 400 km. no breeding pairshave been noted on during the last 50 years. Novaya Zemlya. Thus the willow ptarmigan A valuablesupplement tothe investiga- extended its breeding range by about 1.5 tions conducted by Uspenskiy and Syroech- degrees or 160 km. in 58 years. kovskiy is provided by the Baltic and Syroechkovskiy4.5 has investigated changes Ukrainian ornithologists. For northern birds of faunal boundariesin the taiga and they record changes in southern boundaries, forest-tundra belts of Central Siberia, no- but for southern birds, changes in northern tably,along the Yenisey river from62"N. boundaries. Sometimes changes in boundaries to69"N. In 1956 heheaded the Zoogeo- are traced simultaneously by several orni- graphical section of the Biogeographical ex- thologists in various geographical areas and pedition organized by theInstitute of habitats. An interesting example of such Geography. For 5 months the group carried coordinated research is the tracingof out investigations in the Yenisey valley from boundary changes for the willow ptarmigan PodkamennayaTunguska in the south to in Estonia, Latvia and Lithuania. Dudinka in the north. In his paper on thevariations of bird Thisarea has also been investigated by fauna in Lithuania during the last 50 years, Middendorflz in the 1860's and by Tugarinov Ivanauskasl4 describcs the status of the and Buturlinl3 atthe beginning of the willow ptarmiganas follows. In 1903 the twentieth century. Thusfor some of the species was quitenumerous in Lithuania, species of birds thedata on habitatswere including its southernareas along the available for a period of almost one hundred Neman river. In 1959 onlysmall numbers years. The climatological data for this area of thebird could be found in the north- show that, in contrast to the European and eastern sector of the country. He adds that West Siberian north,the warmingtrend is thepreferred habitats forthe birds - the feltin all the seasons of theyear, not just upstream swamps and woodlands - have in the autumn and winter. changed littleduring the last 50 years,and In addition, the activity of man is very therefore man is hardly responsible for the pronounced in this area:forests have been disappearance of the species from Lithuania. cleared, virgin land has been tilled, buildings Investigating the status of the willow and roads have been constructed. As a result ptarmiganin Latvia and Estonia, Taurinsl5 of these combined developments, the house foundthat at the beginning of the 1930's sparrow (Passer domesticus), for example, about 3,000 pairs of the snecies inhabited has extended its boundary northward by the upstream swamp lands of Latvia. By the about 800 km. during the last hundred years late 1950's the numbershad decreased to or so, from Vorongovo (lat. 61"N.) in 1844 aboutatenth, andthe willow ptarmigan NOTES AND INSTITUTE NEWS 203 could be found onlyin the northernand Manitoba and southern Alaska (lat. 55"N.h eastern areas of the country. while in Europe the Gulf of Finland marks The number of willow ptarmigan is also the boundary (lat. 60"N.). This is the north- decreasing in Estonia. The main reason for ern thermal boundary for the Gadwall. The the decrease is considered to be the warming difference inlatitude is determined by the of climatecharacterized by milder winters oceancurrents: Europe is warmed by the with less snow. The white winter plumage Gulf Stream, while the east coast of America of the ptarmigan in snowless periods exposes is cooled by theLabrador and Greenland the bird to enemies. The field studies show currents which bring cold water masses that after a succession of several cold winters southward. Therefore on this continent the the numbers of the species increase. But since warming trend, as well as the northward milder winters begin to prevail, the north- movement of birds and other animals, is less ward movement of the willow ptarmigan is pronounced than in Europe and Asia. irrevocable. The leading pioneersin this hemisphere Thisdisplacement of the southern boun- arethe easternhermit thrush (Hylocirhla dary appears to be coordinated with the gutata) and robin (Turdus migratorius).