|
|
RESPONDENT
|
|
Irina Menyushina
|
|
|
SITE NAME
|
|
Neizvestnaya River upper reaches, Wrangel Island, Russia
|
|
| Contact details
(phone/fax//e-mail//address): |
| (495)687-06-57 // v.n.ira@mail.ru // Prospect Mira, 103-109, Moscow, 129085, Russia
|
|
PROJECT DETAILS |
|
|
|
Start of survey:
|
End
of survey: |
Team
size: |
|
7.07
|
1.09
|
|
|
WEATHER
CONDITIONS
|
|
|
|
Weather conditions: |
| Rivers broke in the middle of May in the central part of the island, which is 1-2 weeks earlier than normal (D. Utkin reported break-up on the Mamontovaya River on 15 May in the middle reaches). Almost all snow-patches melted by mid July in the Central Mountains which indicates fairly warm weather in June and beginning of July. The rest of the summer was windy, cold and relatively dry. Temperatures dropped below freezing on 24 days, and snow covered tundra twice during July. Storm and rain in mid August were followed by snowstorm which lasted for 6 days. Weather conditions were unfavourable from mid July, in particular for waders and Long-tailed Skuas.
|
|
|
|
|
|
|
|
| Date of ice-break on
rivers: |
mid May
|
|
| Date of final loss of
snow: |
|
|
BIOTIC
CONDITIONS
|
| Rodents abundance evaluation: |
low
|
|
|
Breeding conditions:
|
Numbers of Arctic Foxes on the island were low, in particular in the Gusinaya River valley, but most of observed animals bred. Among dens inspected in different parts fo the island 51% (n=20) contained broods. In the permanent study plot, Arctic Foxes bred at a density of 0.13 pairs/km2, and non-breeding animals were not recorded. Mean brood size was 5.78 (n=9) in the plot. Density of Snowy Owls on counting transects dropped to 0.28 birds/km compared with 0.7 birds/km in 2002. In the permanent plot (45 km2) owls occurred at a density 0.7 birds/km2 and their nests at a density 0.15 nest/km2. Mean size of broods at fledging was 2.45 (n=22, range 0-4), which is low value. We found 9 females of Common Eider, 15 Snow Geese, 7 fledglings of Snow Bunting, 3 chicks of Long-tailed Skua and 10 eggs of eiders in food remains of Snowy Owls. High fraction of birds in owl diet and active hunting on Snow Geese near nests indicates utmost shortage of basic foods (lemmings) already in June.
The distribution of Long-tailed Skua was extremely uneven, and they occurred at a low to average density in different parts of the island. Most of birds nested, but breeding success was extremely low due to heavy predation pressure and unfavourable weather. Only 3 broods survived to fledging in August. 16 pairs bred in the permanent plot, and density (0.36 nest/km2) did not differ from 2002. 10 pairs (5 with chicks) survived by the start of cooling on 13 August, but skuas were not recorded in the plot after 18 August and were almost never seen elsewhere on the island.
Pomarine Skuas were rarely seen and did not bred. Pairs of Arctic Skuas were recorded in different parts of the island at a low density, and one of them bred successfully in the Gusinaya River valley.
Numbers of waders were lower than usual in the permanent plot according to visual evaluation. Dunlins and Grey Plovers were less common that normal, while Pectoral Sandpiper were very rare. Broods of waders were rare in July and August, and waders were almost never seen after storm in mid August.
Numbers of breeding Common Eiders were considerably lower that usual. In total 61 nest and 1 brood were found in different parts of the island, and 73.8% of nests concentrated in 3 dense colonies near nests of Snowy Owls in the middle reaches of the Neizvestnaya River. Nesting success was 80.4% in colonies near owls, 30% of solitary nests near settlement and 0% of solitary nests in tundra. 26% of nests were destroyed by predators, including 14.8% by owls and 11.2% by Arctic Foxes.
Numbers of Snow Geese nesting near owls were lower than usual. Geese nested near 17 owl nests from 20 inspected, but colonies exceeding 10 pairs were found near 3 nests only in the Neizvestnaya River basin. Large geese colonies were not found on the Gusinaya and Mamontovaya rivers, where also moulting geese with broods were almost not recorded. Nest predation was 27% in small colonies (n=193). Mean size of broods during moult in the Tundrovaya River basin in August was 3.9 (n=10, range 2-6), while mean brood size at fledging in the Neizvestnaya River area was 2.42 (n=63, range 1-7). Snow Geese nested near 6 of 7 nests of Snowy Owls in the permanent plot, and the total estimated number of pairs was 220-270. 120 nests was found and 24% of these were destroyed by predators.
Remains of 24 geese were found in colonies near owls nests, among which 15 geese had been taken by owls near nests, and 9 by Arctic Foxes during movement of broods to moulting sites. Accordingly, rodent-specialist predators took approximately 3% of breeding geese on nesting sites outside of the main colony.
8-10 flocks of geese with chicks totalling approximately 400 broods were found along 25 km long stretch of the valley of the Tundrovaya River. Geese remains were found near one from 6 surveyed dens of Arctic Foxes in the area and included remains of 2 adult birds and 19 chicks.
Breeding conditions were unfavourable for most species of tundra birds due to heavy predation pressure and adverse weather conditions in the second half of summer.
|
|
|
Rodent dynamics:
|
| Lemming numbers dropped to low and very low values in Siberain and Vinogradov's lemmings respectively. Siberian Lemmings were more abundant locally in the middle and upper reaches of the Neizvestnaya River and middle and lower reaches of the Tundrovaya River. Rodents were rarely seen on excursions, and their fresh burrows were almost never found. Undersnow nests of lemmings occurred at a mean density of 3.97 per 1 km, which is typical for low lemming numbers (196 nests were counted at a transect 49.4 km long and 10 m wide).
|
|
Rodent species recorded:
|
| Latin | Abundance |
|---|
| Lemmus sibiricus | rare |
| Dicrostonyx torquatus | rare |
|
|
|
Summary
of fauna studies: |
|
|
|