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RESPONDENT
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Vladimir Pozdnyakov
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SITE NAME
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Lena Delta, southern and eastern parts, Yakutia, Russia
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| Contact details
(phone/fax//e-mail//address): |
| (411-2)33-68-15/(411-2)42-13-72(fax) // vpozd@mail.ru // Kulakovskogo St., 12-59, Yakutsk-7, 677077, Russia
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PROJECT DETAILS |
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Project name:
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Waterfowl monitoring in the Lena River delta
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Start of survey:
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End
of survey: |
Team
size: |
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4.06
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12.08
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3
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WEATHER
CONDITIONS
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Weather conditions: |
Spring was unusually early and warm in the Lena River delta. Mean monthly air temperature was -2.4°C in May, which was 4.4°C higher than the long-term average. An unusual warming occurred from 11-16 May, when mean daily air temperatures were above freezing and reached +5.3°C on 14 May. This resulted in the mean air temperature of +0.4°C for the second 10-day period of May. A so high temperature has never been observed since the start of observations in the Lena Delta in 1976. Positive mean air temperatures, reaching +3.4°C, were then recorded on 24-25 and 29-31 May. This resulted in complete snow melt on the tundra by the end of May. Early spring onset was tampered by return of cold weather in early June. Mean air temperature for the first 10-day period of June was 1.1°C below the long-term average, and snow completely blanketed the tundra on 8-9 June. Air temperatures were not consistently above freezing until 10 June, which was 4 days later than normal. The second half of June was considerably (4.9°C) warmer than usual, and mean daily air temperatures reached +17.6°C on 22 June. Accordingly, in spite of the cold weather in the beginning of June mean monthly air temperature was 2.4°C above the long-term average.
Ice broke 4-7 days earlier than average in the different parts of the delta, and the river cleared unusually quickly. The water table was average. Ice-break occurred from 5-9 June on the Bykovskaya channel at the extreme south-east of the delta, while the mouths of channels at the north-east of the delta cleared only on 14 June.
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| Date of ice-break on
rivers: |
5-14.06
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| Date of final loss of
snow: |
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BIOTIC
CONDITIONS
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| Rodents abundance evaluation: |
low
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Breeding conditions:
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Arctic Foxes were very rare and did not breed. Cases of death of Arctic Foxes from starvation were recorded during the winter. However, fox predation on clutches considerably affected the breeding success of birds on large islands.
Rodent-dependent birds of prey occurred in very low numbers. Pomarine Skuas were numerous only during spring migration, while a few non-breeding birds were recorded in the tundra after 10 June. Arctic Skuas occurred in lower numbers than previously and did not breed on control plots, but their sporadic breeding elsewhere in the delta was possible. The Long-tailed Skua bred only in the mainland tundra to the south and south-east of the delta. Observations of the Snowy Owl during the summer were restricted to a single wandering bird seen on 16 June in the mainland tundra to the south-east of the delta. Rough-legged Buzzards bred at a low density, reflecting the low lemming numbers. They only nested on the riverside rocky bluffs of the Prymorky Edge and Tuora-Sis Ridge in the southern part of the delta, as well as on high banks of islands in the ancient seaside plain.
The weather was favourable for birds, which arrived earlier than average. Most species of waterbirds had already arrived to the delta by late May. A vagrant Sandhill Crane was recorded in the north-eastern part of the delta on 21 June. Based on transect counts abundances of waterbirds were high in the beginning of the breeding season. Brent Geese, King Eiders, Sabine and Ross's gulls occurred in higher numbers than in the previous years, which was in part favoured by the low predation pressure by Pomarine Skuas, which had departed early from the delta. However, successful nesting was observed mostly in birds forming colonies on small islands, inaccessible to Arctic Foxes. Thus, nest success of Brent Geese was 84.1%. Only very few nests were not successful in other birds nesting in colonies of Brent Geese. In contrast, all nests of Steller's Eiders in the typical breeding habitat on large islands (polygonal tundra bogs) failed due to predation. Also most nests of King Eiders, Willow Grouse (although rare) and White-fronted Geese on islands with similar habitats were destroyed. Approximately half of wader clutches was destroyed, but this was compensated by successful reproduction on small islands, and overall nest success was 70.6%. There were indications of replacement clutches in some Steller's and King eiders, Little and Temminck's stints, and Grey Phalaropes.
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Rodent dynamics:
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| Very low lemming numbers were observed in the Lena Delta for the second year in a row. Lemmings were not recorded at all during field trips on islands when searching for bird nests. Winter nests of lemmings were very rarely recorded, and their total number observed, primarily at the sites of winter snow packs, did not exceed 10 for the whole period of studies. A single lemming was captured in the period 26 June - 16 July in snap-traps (the total catching effort of 420 trap-nights).
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Rodent species recorded:
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Summary
of fauna studies: |
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