Summary

The fauna and ecology of birds of Ayon island in the East Siberian Sea was studied for 1.5 months in the summer of 2015. The number of birds was estimated by the number of sightings per season according to the daily list. Breeding densities were estimated by model plots method. Species status and abundance was compared with numbers obtained by similar single-season studies in 1958 and 1987.
Of all 62 species of birds recorded at Ayon island we sighted 51 species in our studies in 2015 and recorded nests of 19 species. Breeding was verified for 13 more species by observing non-flying broods, parents with food or typical behavior of a pair close to a nest or a brood. Density of territorial pairs was estimated for 4 species of loons and 7 nesting (or presumably nesting) species of ducks. We evaluated the nesting density for only those species whose nests were located within the model site: Pacific loon, Yellow-billed loon, Bewick’s Swan, Bean goose, King eider, Spectacled eider, Sandhill crane, Red phalarope, Temminck’s stint, Glaucous gull, and Vega gull.
The fauna of the nesting waders has drastically changed. Several species (Curlew sandpiper, Eurasian dotterel, Buff-breasted sandpiper) can be called not just declining in population but actually extinct on breeding grounds.
With a generally low densities of birds on Ayon Island, large colonies of Glaucous and Vega gulls were the ‘‘centers of bird life’’ there. However, all known colonies were destroyed by brown bears. The strategy of waterfowl and loons to seek refuge under the protection of the gull colonies, even though this is effective in reducing predation by fox, does not work for large predators, mainly the brown bear. Data on breeding success of certain species, and measurements of their nests and clutches, are presented.