NEWS AND ANNOUNCEMENTS SUMMER 2008

see also SPRING 2008 / SUMMER 2007

Wrangel 2008		Nenetski 2008		Lena delta 2008

Mosquito, rough-legged buzzard and Co By Gunnhild & Anna

The field season in Nenetskij lasted from the 18th of June until the 18th of August. Anna Kosorukova and Gunhild Skogstad from the Arctic Predators project and Alexander Gatilov, a field assistant form Moscow, stayed for the whole period, whereas Rolf Ims and Eva Fuglei joined us for three weeks in July. The main effort was laid to Korovinskaya Bay, to the 36 grids from last year and the area around, which was searched for fox dens and raptor nests. Two trips were made to Lovetsky Island, one in mid July and one in August. Due to late snowmelt the work on the grids had to wait until the end of June, so the mustelid tunnel- and artificial egg experiments could go on for about six weeks. During the whole season, we actively collected samples for stable isotope analysis, with a special effort on predators. Overall, we had a good field season, much due to Alexander’s expertise on building a comfortable camp site out of practically nothing, on fish conservation and on general tundra life. Also the workers from Nenetsky Zapovednik were very important for both practical and social reasons. They provided us with a Nenets chym at the camp site, and several times with boat transport to Kos Nos and Lovetsky Island, where they welcomed us with delicious food, a hot sauna and great company.

Lemming winter nest counts showed low lemming abundance during winter, although we recorded many winter rodent tracks on our willow grids. Hares and willow ptarmigan were abundant, and both seemed to succeed in reproduction this year. Reindeer were observed regularly in our core area, but the large herd only migrated through the area a few times in August.

In Korovinskaya, there were several arctic fox dens with recent signs of activity, but only one den with documented reproduction. At this den, five cups were observed and two cameras worked for a long time. No signs of red foxes were registered; even Rolf did not see them ;-)

Ten nests of rough legged buzzard were found and visited regularly. On four of these, we placed cameras. Three nests failed or were abandoned during the season, and the chick number varied between one and four. We observed peregrine falcon sporadically, and two nests with chicks were found. During the first weeks of the summer, we observed several arctic and long-tailed skuas every day, but, by the end, only a few breeding pairs remained. Two nest of long-tailed skua were found, of which one succeeded. Also two nests, both successful, of arctic skua were documented in the core area. In August, a snowy owl was observed near the camp site three times.

The relatively low breeding intensity in predators this year reflected the low number of lemmings. The predation pressure on ptarmigan seemed to be high, as we regularly observed predated adult birds or eggs, and the eggs from artificial nests on the open tundra disappeared almost immediately. The prey remains from buzzard nests was dominated by root voles, young hares and ptarmigans, but occasionally we found collared lemmings and other birds of prey.

Lena Delta 2008, a report from Vladimir Pozdnyakov

In 2008, in the Lena Delta, the onset of spring was warm and early, although it was somewhat colder than in 2007. Average temperature in May was -3.4°C, 3.3° above the long-term average for this month. The first days with a positive average temperature were 10-12 of May, when temperature increased to +2.2°. Subsequently the average daily temperature was positive on the 22, 24, 25 (+5.4°) and 28-30 of May. In the lowlands of the Delta snow melted away in the third decade of May, and the tundra in the southern part of the Delta was free of snow already on 23 of May. Snow fell again on the 28 of May, but melted one day later.     

Average temperature in June was close to the long-term average: 4.1°C compared to 4.0°C. The first decade of June was, however, cold with an average temperature 3.2°C below the long-term average. In the evening of the 2 of June, rain together with a rapid temperature fall caused freezing of the tundra. Every grass-blade was covered with a layer of ice. In the southern part of the Delta there was a layer of up to 3 cm of ice on cables. According to the meteorological service in Tiksi, icing was observed in all meteorological stations in the tundra and the forest tundra zone of Yakutia, and persisted until 6 of June. The Lena Delta was again completely covered by snow. On 2 and 3 of June, there was 10.0-14.5 mm of precipitations. Until 9 of June, there was moderate snow fall every day. On 10 of June, snow cover was again 100% even in the southern part of the Delta. The average daily temperatures became positive only on 12 June, 6 days later than average. Average daily temperatures increased rapidly from -1.2°C on 11 June to 5.9°C on 12 of June. Due to such an abrupt warming, snow melted rapidly. The second half of June was rather warm. However, on 30 of June and 1 of July, there was a new cold spell with wind up to 30m/s and snow fall. In the northern part of the Delta, all higher objects such as buildings, barrels, drift wood or hummocks were covered with wet snow. The small ponds in the polygon tundra were full of wet snow and froze during the night. July was relatively cold, rainy and windy. On 28-29 of July there was a new snow fall.

Because of the early warm period and snow melt, the ice broke up in the Lena Delta 9-10 days earlier than usual. In the southern part of the Delta the ice broke up 31 of May. The water rose to very high levels, higher than the historical maximum of 41cm. All low laying parts of the islands were inundated, and when the temperature dropped, an ice layer of 5-7cm formed. This ice remained on the ground after the water level had dropped. On 10 of June all channels of the Delta were free of ice.

Lemming numbers were low for the third consecutive year. This year, however, we noticed a tendency for an increase in lemming abundance. Lemmings were trapped from the 13 of June to the 26 of July (603 trap-nights) and 18 animals were caught. In the beginning of June, when ice covered the inundated low laying tundra parts, we observed drowned lemmings under the ice layer. On the mainland tundra and in the mountains bordering the southern part of the Delta, the density of narrow skulled voles (Microtus gregalis) was very high, much higher that in the previous year. On 13-14 of June and 17-26 of July we caught 69 voles during 427 trap-nights.

Arctic fox breeding was not recorded this year. At the same time, arctic foxes were more numerous than last year. Adult animals wandering around were observed regularly in all parts of the Delta in June and July. Apparently the foxes were attracted to the Delta by the early snow melt and the high vole density on the adjacent territories. In the beginning of June we observed a fox which came from the sea-ice onto the mainland tundra in the south-east of the Delta. Similarly as in the previous year, foxes had a strong impact on nesting birds. They destroyed most nests on the larger islands.

Pomarine skuas (Stercorarius pomarinus) were numerous during spring migration and remained numerous until the beginning of July, but did not breed. They were more abundant in the southern part of the Delta, which is adjacent to the mainland tundra, than in the central and the northern parts. Arctic skua (Stercorarius parasiticus) numbers were similar to the previous year. The only nesting skuas were long-tailed skuas (Stercorarius longicaudus) in the mainland tundra to the south and south-east of the Delta. They did not nest on the islands of the Delta. In the beginning of July we observed rather large groups of nomadic long-tailed skuas (up to 40 individuals) in the inner parts of the Delta. There were no snowy owls (Bubo scandiaca) in the Delta this summer. As in the previous year, rough-legged buzzards (Buteo lagopus) were nesting only in the southern part of the Delta on the stony escarpments of the Primorski Kryazh and Tuora-Sis ridges, which are close to the river, as well as on the high river banks of islands which are remains from the old coastal plain.

The climatic conditions during the breeding season 2008 were unfavourable for birds, despite the fact that arrival was early due to the early onset of spring. All typical birds of the region were present in the Delta in the end of May, even Ross’s gulls. The subsequent drop in temperature and icing, as well as the inundation of feeding places, caused high mortality for waders and small passerines. We found dead grey plovers (Pluvialis squatarola), golden plovers (Pluvialis fulva) and lapland buntings (Calcarius lapponicus). Mortality of birds was high in all of northern Yakutia. Colleagues working in the valley of the River Yana at 69°N sent us dead ruffs (Philomachus pugnax), a golden plover, a curlew sandpiper (Calidris ferruginea) and a read-breasted pipit (Antus cervinus). As a result of the weather conditions, in the Lena Delta most birds began to nest only in the second decade of June, after the ice and snow cover disappeared. All wader species and the small passerines were breeding in low numbers. We found only 8 nests of little stint (Calidris minuta), 6 nests of turn-stones (Arenaria interpes), 3 nests of temminck stints (Calidris temminckii), 3 nests of red phalaropes (Phalaropus fulicarius) and 1 nest of curlew sandpiper (Calidris ferruginea). Ross’s gulls (Rodostethia rosea), Sabine’s gulls (Xema sabini) and arctic terns (Stera paradisaea) were not nesting on the small sandy islands in the channels of the Delta, which were inundated for quite a long time. Breeding numbers of brent geese (Branta bernicla) and king eiders (Somateria spectabilis) were lower than in the previous year. Only a few Steller’s Eiders were nesting. Predation rate from foxes and pomarine skuas was high. As in the previous year, breeding success was highest for eiders nesting close to colonies of brent geese on small islands, which were inaccessible for arctic foxes. On the larger islands breeding success of Steller’s eiders in their typical habitat (polygonal tundra-bogs) was close to zero. Also most nests of king eiders, willow ptarmigans (Lagopus lagopus) and white-fronted geese (Anser albifrons) found in these habitats were predated. Among the waders nests we found (see above) 3 nests of little stint and one nest of red phalarope were predated.

A cold and wet 2008 summer in Wrangel Island By Irina Menyushina

Field work was carried out from April 28 through September 15, 2008.

Our main base camp was at Verkhnaya Neizvestnaya (Upper reaches of Neizvestnaya River), at the model Plot “Verkhnaya Neizvestnaya” in the very center of Wrangel island (71˚ 12, 94’ N / 179˚ 19,24 W).           

 
During the field season, data were collected on numbers and spatial distribution of myophagous tundra predators, their breeding intensity, size of home ranges, breeding success, mortality of adults and young, factors of mortality. We also focused on interrelations between tundra predators in relation to increased pressure from larger predators such as wolves and wolverines. Monitoring of snow geese and eider numbers and breeding success while nesting under protection of snowy owls was continued. Special attention was paid to the impact of increased number and activity of wolves upon local arctic fox population.   Weather conditions were extremely unfavorable for wintering and breeding of myophagous tundra predators. The summer was very cold and wet, with frequent returns of cold with snow and rain, temperatures below zero and strong winds. In the beginning of June, due to 5 days snow storm, 37% of snowy owl families had abandoned their nests. Tundra birds (waders and passerines) were leaving in masses for southern areas and many of those who remained died from cold and lack of food. On Neizvestnaya River and in the Central Mountains a part of the snow fields did not melt until the end of the first decade of September - the time when a new snow cover started forming in the mountains.    

Food resource condition
Although the population cycle was in the growth phase, the numbers of both lemming species decreased compared to 2007. Probably, the actual cause for this change in the population cycle was strong icing during the autumn-winter season of 2007-2008, which in turn was caused by strong prolonged rains during September of 2007, followed by freezing.
Numbers of Siberian lemmings were very low, breeding very late, and apparently the major part of the population did not participate in breeding. Even in anthropogenic habitats, such as the settlement Somnitelnaya - the main base of the reserve on the island - young lemmings from the summer generation were observed only in August, one month later than normally. High numbers and intensive breeding of Siberian lemmings were recorded only in Ushakovskoe village - from visual observations of lemmings 27-28 of August 2008.
Numbers of collared lemmings were low in different areas of the island. However, in some local populations breeding and growth of lemming numbers was continuing. For instance, on one snowy owl nest at Verkhnaya Neizvestnaya I simultaneously recorded 20 collared lemming carcasses, among which non-breeding males were prevailing (testicles were inside abdomen).

In 2008, collared lemmings were obviously prevailing in the island’s tundra. Among lemmings caught by snowy owls there were 49 collared lemmings and only 6 Siberian lemmings.
In general numbers of lemmings in 2008 were low on the island and obviously insufficient for successful breeding of myophagous predators.

The number of waders in inner parts of the island was lower than usual due to birds leaving in mass in the beginning of June in response to a strong snow storm, and due to death of part of the adult population that remained within breeding habitats. The same situation was observed in passerines.
Numbers of snow geese nesting outside of the main colony were very low - the majority of geese stopped breeding due to very hard weather conditions and low density of nesting snowy owls.

Condition of food resources for myophagous predators did now support their successful breeding. In the diet of breeding snowy owls 85% of samples were lemmings. Among alternative food we found snow geese, common eider, eider eggs, chicks of long-tailed skuas, snow buntings and waders.

Snowy owl

Numbers of snowy owls on the island were very low with fewer birds than usuall at the beginning of the breeding season. Their distribution among different areas was typical: optimal breeding habitats in Northern Mountains and in the valley of Gusinaya River (Geese River) were occupied in the first place. Owl densities within the model plot at Verkhnaya Neizvestnaya were below average with 0.35 owl/km2. Non-breeding owls arrived later and spread relatively evenly over the island, the majority of them did not occupy permanent territories. In the Central Mountains and in Nasha River valley owl breeding was not recorded. Single pairs were found breeding in the Northern plain of the island - Tundra ofAcademy. Here, owls were absent or occurred rarely.

All sex and age classes were represented in the owl population on the island in 2008. Males were prevalent in the model plot where the proportion of sexes was 1 F:1.7 M (n=16). In other areas males prevailed also, except in the Tundra of Academy during the period of snow geese molting, where females prevailed. Data on the sex-age composition of the owl population in different areas of the island and proportion of sexes within owl litters were collected.

The majority of owls on the island attempted breeding, but many of them failed at the very beginning of the season. Therefore, the proportion of breeding owls was determined only within the model plot, were permanent observations throughout the season were carried out.

Owl nesting densities at the model plot were below average with 0.16 nest/km2. In other parts of the island densities were even lower. Altogether, data for 33 breeding pairs were collected on the island in 2008. Mean clutch size was 6.20 (range: 3-9; n=15).

Hard weather conditions and low lemming numbers were the reason for very low breeding success in owls. Many nests were abandoned during the snow storm in the first days of June. Litter size on wing was from 1 to 2 chicks. Mortality of adult owls was not observed in 2008.

Arctic fox

Numbers of arctic foxes on the island in 2008 were low in all areas of the island. A track survey during snow time in spring showed that the majority of foxes were leaving the island and returned to the breeding territories only in the second part of May. Probably, this was due to very low lemming numbers and their inaccessibility because of icing. At the model plot the maximal fox density was 0.13 pairs/km2.

At the model plot only half of the fox pairs were breeding. The majority of these foxes gave birth outside dens (perhaps due to predation from wolves and wolverines that were visiting arctic fox dens). This shift created new complications in identifying fox breeding status and litter size.

A total of 51 arctic fox dens were examined, tracks of wolf and wolverine visiting fox dens were recorded at 18 dens. On 17-20 breeding territories foxes were breeding.
Litter sizes at dens were: 4,4,4,4,4,8,5,3
Mortality of arctic foxes was high during all seasons. A total of 12 fox carcasses were found: 5 from the winter, 4 from the spring and 2 from the summer. One fox died of arctic rabies, 3 foxes were killed by wolves and wolverines and probably 3 more foxes died from wolf and wolverine predation. Four fox carcasses were found near dens and 3 near shelters of wolves and wolverines.  

Pomarine skua
First observation on 28.05.08; last observation 20.06.08.
On the model plot maximal number of pomarines war recorded during the end of last decade of June. Density was low - 0.36 birds/кm2.
Dark forms represented 12.5% of total number.
Pomarine skuas were not breeding in 2008 due to low lemming numbers.
Mortality of adult pomarine skuas was not recorded.

Long-tailed skuas
First meeting: 28.05.08.
Mass arrival: 30.05.08.
Beginning of nesting: 16.06.08.
Nest density at the model plot: 0.27nest/km2.
Medium numbers were recorded in all areas were surveys were conducted, except in the Northern Plain. Breeding success was very low; the majority of nests were destroyed by predators or perished due the weather conditions. Chicks on wing were observed in the valley of Geese River (2 juv, 1 juv - in litter), in the valley of Viyuchnyi Creek - 1 juv, and 3 litters of 1 juv in each at Balkovyi Creek (Tundrovaya mountain) in the second part of August.
In the snowy owl diet long-tailed skua chicks were recorded only once.
At the end of July long-tailed skuas started leaving their breeding territories, only single birds with chicks remained longer. By mid August the majority of adult skuas left the island.
Mortality of adult birds was not recorded

Female wolverine on the move