Distribution and abundance of aquatic and marine bird in some areas of the southwestern part of the Kara Sea in the summer-autumn period 2015-2020

Abstract

The southwestern part of the Kara Sea is a little-studied area of summer-autumn migrations and feeding nomadism of water and sea birds. The shelf of this part of the sea includes promising areas for the extraction of hydrocarbon raw materials and the intensification of navigation along the northern sea route, which makes it necessary to constantly monitor birds in the zone of possible negative impact of mining complexes and ship traffic. In 2015-2020 in the summer-autumn period, bird counts were carried out in a section of the water area with an area of 56 thousand km2 during August–September (2015–2016 and 2018–2020), as well as the end of September–the first and second ten days of October (2017) Method of ship transect census with obtaining the abundance indicator – individuals per 1 km² (ind.∙km^-2). In the summer-autumn period 2015–2020 28 species of birds from 7 families (loons, gannets, petrels, ducks, gulls, skua, auks) were identified in this water area. Including - 6 species that have one or another conservation status. Of the so-called water birds (loons, ducks), the studied area in August–September is the most important for the black-throated diver, long-tailed duck, and king eider. The number of these species on the eve of the autumn departure of birds (August) increases in the shallow part of the water area adjacent to the coast, with their subsequent dispersal to deeper water areas west of the Yamal Peninsula. The population density (ind.∙km^-2) in coastal shallow waters during the period of the most active development of this biotope is 0.17 ± 0.036 for the black-throated diver; long-tailed ducks - 4.8 ± 1.2; king eider - 2.1 ± 1.25 and, presumably, significantly more for all three species, at closer distances from the coast, not examined from the vessel. Other species of this group (red-throated diver, steller's eider, white-fronted goose and bean goose, black goose) are rare in open waters and, apparently, during the entire summer-autumn period, they are mainly confined to a narrower coastal zone. Similar indicators of the abundance of nomadic seabirds (petrels, gulls, skuas and auks) ubiquitous in the water area of the survey area are, on average, for 5 years for August-September, ind.•km^-2: for the fulmar - 0.08 ± 0.026, glaucous gull – 0.067 ± 0.014; kittiwake – 0.057 ± 0.016; arctic tern – 0.025 ± 0.015; heuglin's gull– 0.066 ± 0.0049; pomarine, arctic skua and long-tailed skua 0.05 ± 0.013, 0.013 ± .004, 0.0038 ± .0017, respectively, brunnich's gullemot 0.16 ± 0.094, аtlantic guillemot – 0.0026 ± 0.0012. In late September–October, the abundance of kittiwakes, fulmars, and brunnich's gullemot slightly decreases or remains at the level of September, while the abundance of аtlantic guillemot increases (7 times). Arctic tern, heuglin's gull, long-tailed skua are disappearing from the water area, while glaucous gull, pomarine and arctic skuas are much rarer or almost disappear (5, 40 and 30-fold decrease in numbers, respectively). Generally, in the long-term aspect, the fulmar, three species of skuas, glaucous gull, kittiwake, arctic tern, black guillemot the entire area of the polygon area. At the same time, for the northern fulmar, kittiwake, andglaucous gull, in some years, uneven distribution is noted, which is expressed in significant (from 3 to 17 times) differences in abundance between large (about 25 thousand km²) areas of the studied water area. The heuglin's gulland arctic tern during their entire stay in the water area are mainly confined to coastal shallow waters, making up there, on the dates of the seasonal maximum, up to 80-90% of the total number at the range. On the contrary, the thick-billed murre avoids the zone of shallow water up to 50 m. Rare in the surveyed area are vagrant species (northern gannet, gray gull, black-headed gull, herring gull, little auk), species found in the peripheral part of their common range (great skua and, gray petrel), species rare at the present stage of the existence of their populations (white-billed diver), as well as species, the main habitat of which was not well examined (scoter, steller's eider, bean goose and white-fronted goose, black goose) or seasonally rare (little auk). The collection of material was carried out as part of environmental studies in the waters of the Kara Sea commissioned by OOO Gazprom Nedra for PJSC Gazprom.

Keywords: Kara Sea, sea and water birds, nomadism, migrations, annual and seasonal population dynamics