DENSITY AND SPATIAL DISTRIBUTION OF SEABIRD COLONIES OF THE BELLSUND REGION, SPITSBERGEN

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1 Irina Pokrovskaya Institute for Nature Preservation and Reserves Department of Ecology of Russian Federation Moscow Grigorij Terticky Institute of Geography Russian Academy of Sciences Moscow Wyprawy Geograficzne na Spitsbergen UMCS, Lublin 19П DENSITY AND SPATIAL DISTRIBUTION OF SEABIRD COLONIES OF THE BELLSUND REGION, SPITSBERGEN Investigations of seabird colonies were carried out mainly in July andfirst half of August, 1991; excluding the northern coast, where 4 colonies had been investigated in also in July. Some other researches, such as V. Kalyakin, M. Gavrilo, A. Golovkin and L. Bogoslovskaya also took part in the works on the northern coast. Bellsund Bay is situated in the middle of the western coast of the West Spitsbergen Island. This part of archipelago is the most attractive place for seabird nesting of all Svalbard (see Table 1). Calculations of the seabird in all colonies were made by a total counts method. In each colony, the whole square was divided into separate parts for the following mapping of every cliff, occupied with nests. Then the scheme had been corrected, when a researcher was climbing up along the slope. One can see for instance a scheme of the part of the colony on Ingeborgfjellet (Fig. 1). For the definite count of nesting birds we make an assumption that at a given moment half of the birds absent on the cliffs, and quantity of the count birds is multiplied by two. The whole number of marked colonies is 19, where individuals of 7 seabird species are nesting (Table 2). About half of all seabird individuals (47%) belong to species Little Auk (Alle alle), and 41% to Briinnch's Guillemot (Uria lomvia). Kittiwake (Rissa tridactyla) forms one tenth of all seabird population nesting in Bellsund Region. The common percentage of Black Guillemot (Ceppus grylle), Puffin (Fratercula arctica), Fulmar (Fulmarus glacialis), and Glaucous Gull (Larus hyperboreus) density is some more than one per cent, and total density of the first two species exceeds twice one of two last species. The nesting places of seabirds are distributed on the Bellsund square quite unevenly. An overwhelming majority (85%) is concentrated in two numerous colonies near narrow and long Aksel Island, in fact crossing Van Mijen Fiord 151

2 (see Fig. 2). Such a configuration of water and land creates a barrier for currents and, consequently, intensive mixing of water masses. These processes stipulate an increase of biological productivity in such parts of aquatories. The presence of high productive zones is a necessary condition for appearance of large colonies even at the background of hydrological front action. This phenomenon was noticed in 1982 by A. Golovkin (Golovkin 1982). In our case the macroscale processes of rise in biological productivity as a consequence of mixing the cold Arctic waters with the waters of Western Spitsbergen current take place in the Greenland Sea along the western coast. The necessity of ecological inveistigations, using two spatial levels, was emphasized by Swerpel and Zajączkowski (1990) for different ocean inhabitants. Different seabird species do not show equal preferrences for occupying large colonies near high productive aquatories. Based on this one can divide them into two groups: with high and low preferences. In thefirst group percentage of the individuals nesting in the Akselóya vicinity changes from 75 to 98%. They are mostly: Little Auk, Glaucous Gull, Kittiwake and Briinnich's Guillemot. But in other conditions spatial distribution of these species is not similar. Kittiwake and Briinnich's Guillemot are nesting only in two points except Akselóya vicinity: Dundrabeisen and Observatoriefjellet. In both places one can observe distinct stipulations which define high-productive zones near the colonies presence of an underwater geomorphological barrier or a large glacier. The densities of Kittiwake and Briinnich's Guillemot in Bellsund region constitute consequently 11 and 16% of all Svalbard population of these species. In our opinion these indices are quite high compared with the typical pattern of species distribution. The spatial distribution of Little Auk differs in principle. It reflects possibility of this species to colonize different biotopes with a broad spectrum of conditions. It nests in every investigated colony, predominating in density indices in fourteen of them. Akselóya vicinity attracts 75% of Little Auk population, but out of this location relation between Little Auk nesting distribution and presence of high-productive aquatories is not distinct. The percentage of Bellsund Little Auk density in all Svalbard population is not high about 3%. Distribution of Glaucous Gull as a predator of broad spectrum depends on its victim distribution, and thus determines presence of high-productive aquatories both directly and indirectly. The second group with low preference of large colonies near high-productive aquatories consists of Puffin, Black Guillemot and Fulmar. Some of their densities near the high-productive Akselóya location in all Bellsund population are consequently and 37%. But out of Akselóya location Puffin and Fulmar demonstrate quite close 152

3 relation between spatial closeness of nesting territories and high-productive aquatories. As in the case of Kittiwake and Briinnich's Guillemot these species occupy cliffs near distinct capes, prolonging under the water as a geomorphological barrier, and large glaciers, terminating in the sea. It is necessary to tell about probably not full detectability of these species out of some features their nesting ecology. Black Guillemot as Little Auk is a species-generalist and in its nesting distribution is quite independent of direct closeness of high-productive aquatories. Black Guillemot was marked in 18 of 19 investigated colonies, occupying them rather diffusionaly. Bellsund Puffin and Black Guillemot include consequently 26 and 28% of Svalbard populations and reflect a distribution pattern of these species at the archipelago representatively. Analoguous percentage of Fulmar is 4%. CONCLUSION Bellsund Bay, as the part of western coast of West Spitsbergen Island, is a favourable territory for seabird nesting because of presence of a large high-productive zone along the coast in the Greenland Sea. The local distribution of large seabird colonies on a microscale level depends on direct closeness especially high-productive patches of aquatories under them. Such localities usually form near geomorphological barriers. Aksel Island, playing the role of almost a full barrier in the mouth of Van Mijen Fiord, forms a unique high-productive locality inside Bellsund Bay, which concentrates large colonies with high density of seabirds. In Important Birds Areas in Europe" (1989) massif Ingeborgfjellet is suggested as the possible territory for a protected area. In our opinion a more logical decision is to suggest Aksel Island vicinity as the whole protected area management, including both coasts of fiord and aquatory between them. ACKNOWLEDGEMENTS The authors wish to thank the colleagues V. Kalyakin, M. Gavrilo, A. Golovkin and L. Bogoslovskaya, who took part in count at Ingeborgfjellet massif. We would like to express our warm gratitude to prof, dr Kazimierz Pękala, dr Slavomir Sverpel and their colleagues for valuable help during the field investigations. 153

4 REFERENCES Golovkin A. N : Rol ptitc v morskich ecosystemach. In Itogi nauki i techniki", VINITI, Zoologia pozvonochnich, 11, (in Russian), Important Birds Areas in Europe. (R.F.A. Grimnet, T. A. Jones, compil.). ICBP, Techn. publ., 9, Mehlum F., Fjeld P. E., 1987: Catalogue of seabird colonies in Svalbard Norsk Poiarinst. Rapp. 35. Swerpel S., Zajączkowski M., 1990: The physical environment of Southern Spitsbergen. In Atlas of the Marine Fauna of Southern Spitsbergen", Vol. 1, Polish Academy of Sciences,

5 <3 V* О Xl <D SB С а о. >, с о Х> cd 8 Jh Н tjo Е 155

6 О - leee than 1ooo Individuals? - 1ooo-1oooo individuals. Q individuals ф- 5oooo-1 ooooa individuals' - more than individuals Fig. 2. The distribution of seabird colonies in Bellsund region. 156

7 Table 1. Percentage of the seabirds, nesting on the western coast of Western Spitsbergen Island compared with their total density at Svalbard Archipelago (after Mehlum, Fjeld 1987). Spe elite Percentage of colony Percentage of popul*- nuaber tion density ' BrUnnlob*-» guillemot 7k 82 Klttlwak* 48 5o Łltil* шяк. 99 6o Puffin Toln*r Black guilleaot Ъ

8 Table 2. Density and distribution of seabird species in the nesting colonies of Bellsund region (total number of individuals) Number and name Fulmar Glaucous Kittiwake little Brttnnlch Black Puffin Totail number of colony gull auk guillemot guillemot of all birds 1 Be-llsundhesten Aldergondaberget Observatoriefjellet MldterhukenNW Ingeborgfjellet * * 177 T58 6 Kolfjellet Dundrabeleen Mldterhuken SW 3oo DundrafJellet Hamaren Bravaisberget Sundhogda Koilfjelleet Kolven + Klokkefjel Wi j kanderberge t Bohlinryggen HalvarsenfJellet Actlvekammen SE Actlvekammen HW Total number