There were about three‐year cycles in the populations of arctic foxes, and the breeding productivities of brent geese and curlew sandpipers on the Taimyr Peninsula, Russia, The populations of arctic foxes and lemmings changed in synchrony. The breeding productivities of the birds tended to be good when the arctic foxes were increasing in numbers and poor when the arctic foxes were decreasing. There was a negative relationship between arctic fox numbers (or occupied lairs) and the breeding productivity of brent geese in the following year. Although there was evidence of wide‐spread synchrony In the lemming cycle across the Taimyr Peninsula, some localities showed differences, However, such sites would still have been influenced by the general pattern of fox abundance in the typical tundra zone of the Taimyr Peninsula, where most of the arctic foxes breed and from which extensive movements of foxes occur after a decline in lemming numbers. The results support a prey‐switching hypothesis (also known as the alternative prey hypothesis) whereby arctic foxes, and other predators, feed largely on lemmings when these are abundant or increasing, but switch to birds when the lemming population is small or declining. The relationships between arctic foxes, lemmings and brent geese may be further influenced by snowny owls which create fox‐exclusion zones around their nests, thus providing safe nesting areas for the geese.

During summer 1991, lemmings occurred at high densities in Arctic tundra at Pronchishcheva Lake in the northeastern Taimyr Peninsula, whereas, in 1992, lemming densities were substantially lower and decreased further during the summer. In 1991, avian predators such as Snowy Owls Nyctea scandiaca, gulls and skuas bred well; Arctic foxes Alopex lagopus were rarely observed in the study area but bred in the immediate vicinity. In both years there was a late thaw, but this did not deter breeding by birds. The insect food supply for waders showed similar patterns of abundance in both years. In 1991, 73 nests of nine species of wader were found within a 14‐km2 study area, and Dark‐bellied Brent Geese Branta bernicla bernicla nested in association with Snowy Owls. The overall density of wader nests was estimated to be 7 per km2. Clutches disappeared at only two wader nests and no Brent Goose nests, and the Mayfield estimate of the daily probability of predation for waders was 0.0022. In contrast, the daily probability of predation was 0.20 in 1992, when there was a similar breeding density of waders. Arctic foxes were seen searching for food daily within the study area, and fox droppings were found associated with nests taken by predators. The predicted scenarios for peak and decreasing lemming years (the Roselaar‐Summers hypothesis), i.e. low predation and high nest success in the peak year and high predation and low nest success in the decreasing year, therefore occurred.

SummarySpoon-billed Sandpiper Eurynorhynchus pygmeus is classed as globally Vulnerable, based on the only available population estimate, made in 1977, of 2,000-2,800 pairs. Surveys for breeding Spoon-billed Sandpipers were carried out in summer 2000 on the Anadyr estuary coast, the Chukotka autonomous region, Russia. Although six new breeding sites were found, only 16-17 breeding males/pairs were recorded on the northern coast of the Anadyr estuary and five males/pairs on the southern coast and more southerly lagoons. These numbers were much lower than expected, and the species was not recorded in several apparently suitable areas. Four formerly known breeding sites held only one displaying male between them. At no site was there evidence of an increasing or stable local population. Together with other indicative data these suggest a sharp decline in the population of Spoon-billed Sandpiper. The previous population size estimate obviously requires updating, both because there were some incorrect assumptions in the calculations made for the first population estimate, and also due to a recent population decline. It is likely that the current population numbers under 1,000 breeding pairs. Given that the population of this species may be substantially lower than the only previous estimate, and the evidence for a possible rapid decline in its population described in this paper, it is recommended that its IUCN status is changed from Vulnerable to Endangered. No reasons for the apparent rapid rate of decline are evident within the breeding range. ''Bottle-necks'' should be looked for at migration sites or wintering grounds, but currently, monitoring of the population is only possible on the breeding grounds.

No abstract

The Lena Delta is the largest arctic delta covered entirely by tundra. Protected since 1986, it is one of the richest areas in the Arctic north of 71˚ N for both species diversity and breeding densities. Between 6 June and 17 August 1997, 16 mammal species and 76 bird species were recorded in the Lena Delta Nature Reserve and the surrounding buffer zone. Several species are new to the region: far-eastern curlew, fieldfare, redwing, arctic warbler, red-breasted flycatcher, and common rat. New breeders are merlin and arctic warbler. These 1997 records, combined with those from earlier studies, give a total of 122 bird species for the region. Of these, 67 have been found breeding at least once. Densities ranging from 245 to 641 birds per km 2 were recorded in two restricted study areas. Such densities are unusually high north of 70˚ N for non-colonial breeding birds. Lapland longspur (100-300 individuals/km 2), red phalarope (up to 200 ind./km 2), and several Calidris species were the most common. Ruddy turnstone and dunlin had densities higher than those previously reported from the Lena Delta and other Siberian sites. Among the shorebirds, spotted redshank, pintail snipe, grey plover, dunlin, and curlew sandpiper may have extended their breeding range or increased in population during the last 15 years. But further evidence is still needed to confirm the westward extension of spectacled eider, long-billed dowitcher, and sharp-tailed sandpiper.