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RESPONDENT
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Irina Menyushina
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SITE NAME
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Neizvestnaya River upper reaches, Wrangel Island, Russia
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| Contact details
(phone/fax//e-mail//address): |
| (495)687-06-57 // v.n.ira@mail.ru // Prospect Mira, 103-109, Moscow, 129085, Russia
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PROJECT DETAILS |
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Start of survey:
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End
of survey: |
Team
size: |
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WEATHER
CONDITIONS
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Weather conditions: |
| The summer was unusually warm and freezing air temperatures started only in early October. Mosquitoes were unusually abundant for the island. In the end of the summer and even in September many plants started flowering again.
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| Date of ice-break on
rivers: |
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| Date of final loss of
snow: |
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BIOTIC
CONDITIONS
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| Rodents abundance evaluation: |
average
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Breeding conditions:
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Predators were represented by the Arctic Fox, Snowy Owl and Long-tailed Skua. The Pomarine Skua did not breed on the island this year.
The abundance of Arctic Foxes was low, but reached medium level in some areas. The majority of foxes were breeding. 46% of 68 monitored dens were inhabited. The density of fox litters in the monitoring area of 60 km2 equalled 0.1 per 1 km2. Distances between the litters varied from 2-7 km (mean 4.6 km). The first pups were recorded from the fist days of June to 23 June. Litters were of 5-9 pups (mean 5.5, n=10). Fox mortality in winter was low, as only two carcasses of Arctic Foxes in winter fur were found. Summer mortality was probably of about the same level. Wolves had a significant influence on Arctic Foxes: one fox was probably killed by wolves in the end of May - early June (it was found dead on a den), another one, a lactating female, was killed by Wolves on her den in early July and her litter of 14 pups died. Footprints of a Wolf were recorded near one more den in July simultaneously with disappearance of the female Arctic Fox; her brood of 7 pups was moved away by male. Death of juvenile foxes after attacks of wolves was recorded in early September. A further population increase of Arctic Foxes is expected next year.
The number of Snowy Owls was low and most of them were breeding. There were 49 breeding records. Nest density in the main area of monitoring was 0.18 nests/km2. Each female laid 5-10 eggs (mean 6.9 eggs, which is high; n=19). Most of the nests (89%, n=47) were successful. Brood size after fledging was 2-6 young (mean 3.57; n=23). The sex ratio was equal in chicks, while males slightly prevailed over females in adults. All age classes including young birds (23%, n=22) were represented in the population. Lemmings (63%, n=65) were the main diet of breeding Snowy Owls in July and August according to count of prey items found on owl nests; the rest of the prey items (35%) were remains of eider females, chicks of Snow Bunting, Long-tailed Skuas and waders. Warm weather allowed Snowy Owls to feed on lemmings through September and October, but most birds left the island in the middle of October.
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Rodent dynamics:
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| Populations of both lemming species increased. Abundance of the Vinogradov's Lemming was evidently higher than that of the Siberian Lemming Lemmus sibiricus portenkoi, in a ratio of approximately 3:1. Overall lemming abundance was estimated to be low to medium. In the best habitats the number of both species was locally medium, sometimes even high, but in habitats preferred by the Siberian Lemming numbers were rather low. At a transect of 59.3 km 87 winter nests and 307 inhabited lemming holes were counted. The mean of 1.48 nests/km reflects a low density and does not represent the real situation during the summer. According to other parameters such as frequency of lemming carcasses in nests of Snowy Owls (1.24 lemmings per observation, n=51 observations) and frequency of encountering of inhabited lemming holes (5.2 holes/km) the population of lemmings was at medium or locally even high level. This upper evaluation was also supported by size of Arctic Fox litters and Snowy Owl broods.
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Rodent species recorded:
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Summary
of fauna studies: |
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