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RESPONDENT
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Pavel Tomkovich
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SITE NAME
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Tutakoke River, outer Yukon Delta, Alaska, USA
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| Contact details
(phone/fax//e-mail//address): |
| (495)6294474/(495)629-48-25(fax, for P. Tomkovich) // pst@zmmu.msu.ru // Zoological Museum, Bolshaya Nikitskaya St., 6, Moscow, 125009, 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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2.05
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8.06
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WEATHER
CONDITIONS
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Weather conditions: |
According to observations between 2 May and 8 June, the season seamed to be late one after two extremely early preceding springs on the Yukon-Kuskokwim Delta. However, in a long-term scale the spring was not that late. First pools of water on the early snow-free patches appeared on 3 May, and mean daily air temperature crossed the freezing point for the first time on the same or next day, although night frosts were recorded until 23 May. Sunny weather predominated on 1-3 May and from 23 May-5 June. Strong winds occurred on 8 days, all in May with one stormy day, 20 May. Precipitation was recorded in 11 days during the study period, mostly with snow (8 days) till 20 May and rain/drizzle (3 days) in June.
Snow cover was only ca. 20-30 cm deep judging by observation of tops of dry grasses poking out of snow in many places. Nevertheless snow-free patches were developing originally mostly along the river, where 50% of the ground became snow free on 9 May (complete disappearance of snow there on 18 May), while large areas at a distance were still untouched white. The following percentages of snow cover on the Brent Geese extensive plot reflect progress of snow melt: 97% on 13 May, 93% on 16 May, 75% on 22 May, 50% on 24 May, and the rest of snow almost completely gone by 28 May. Ice on the river became broken on 15 May when it started to "breath" with tides, but ice floats started to move with currents along the river only on 30 May. This date is only slightly later than the almost 30-year long regression line shows to be for 2006. Mass emergence of small flies took place on 29 May; first bumblebee was seen on 4 June. Meadows on areas earliest released from under the snow got green tint from growing vegetation on 1 June, and first flowers were recorded on 2 June in sedge Carex sp., on 4 June in Nardosmia frigida, on 5 June in dwarf willow Salix ovalifolia and Empetrum nigrum.
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| Date of 50%
snow-cover: |
24.05
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| Date of ice-break on
rivers: |
15.05
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| Date of final loss of
snow: |
28.05
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BIOTIC
CONDITIONS
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| Rodents abundance evaluation: |
low
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Breeding conditions:
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In spite of efforts to trap Arctic Foxes in the area during April through early May (USGS project), they were common judging from fresh tracks on snow (they could be regularly recorded until mid May), barking heard (on 4 dais in May) and animals seen (on 5 days in May and 3 days in early June). We observed no signs of fox after 4 June. A Mink was seen once. Surprisingly, not a single bird of prey was recorded during the whole season. The most common avian predators were Glaucous, Common (Mew) and Sabine's gulls that were seen or suspected to be egg predators, as well as Arctic (Parasitic) Skuas that were chasing waders, gulls and Arctic Turns. Long-tailed Skuas were uncommon only during migration, and occasionally a Common Raven was observed.
In early May, Tundra Swans, White-fronted Geese, Willow Grouse (Ptarmigans), Sandhill Cranes, Glaucous Gulls, and Snow Buntings were already in the area, hanging around mostly in flocks. However, the bulk of birds of various species arrived by mid-May only. The earliest wader was a Grey (Black-bellied) Plover on 4 May. First arrival dates for common and numerous local breeders were 5 May for Bar-tailed Godwit, 6 May for Pintail, Common Gull, and Lapland Bunting (Longspoor), 7 May for Emperor Goose, 9 May for Cackling Goose and Semipalmated Sandpiper, 10 May for Brent Goose, Black Turnstone and Dunlin, 13 May for Sabine's Gull and Arctic Tern, and 18 May for Spectacled Eider. First eggs were laid on 24 May by Emperor Geese, 25 May by Brent Geese, 26 May by Bar-tailed Godwits and Common Gulls, 27 May by Spectacled Eiders, Semipalmated Sandpipers and Glaucous Gulls, 29 May by Dunlin, 30 May by Black Turnstones and Sabine's Gulls, and 1 June by Arctic Tern. Dates of nest initiation in geese were 10 days later than in 2005 and 5 days later than in 2004, but at about the date indicated by the long-term regression line for the event (Patrick Lemons, pers. comm.).
Coastal meadows of the study area were considerably changed by tidal flooding in September 2005, causing difficulty for some birds to find appropriate cover for their nests. Thus, of 14 nests found in Black Turnstone, 12 were completely open and only two had some grass cover. Probably this was a reason of low survival rate of incomplete clutches in this species - only 23% of egg-clutches under observation (n=13) were completed before depredation, and these three clutches were subsequently successfully incubated. In three other wader species (Dunlin, Semipalmated Sandpiper and Bar-tailed Godwit), 53% of nests under control (n=15) survived between repeated checks in early incubation. We do not have precise figures, but it seems like gulls and Arctic Terns were nesting with higher success than waders probably due to their aggressive behaviour. Our general impression was that birds were nesting with moderate success, and at least in geese nest survival was higher than in 2004 and 2005.
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Rodent dynamics:
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| The only sign of presence of small rodents in the area was a winter nest found close to mudflats on 6 May that was undoubtedly excavated by an Arctic Fox.
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Rodent species recorded:
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Summary
of fauna studies: |
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