the Yamal Peninsula that the snowy owls became the primary predator of willow ptarmigan and that the predation was so frequent, it may have been the cause of the change of their habitat usage to willow thickets by the local ptarmigan. The reliance on ptarmigan has caused some conservation trickle-down concern for the owls because ptarmigan are hunted in large numbers, with the hunters of Norway permitted to cull up to 30% of the regional population. In North America, avian prey on the breeding ground regularly varies from small passerines like snow buntings (Plectrophenax nivalis) and Lapland longspurs (Calcarius lapponicus) to large waterfowl like king (Somateria spectabilis) and common eider (Somateria mollissima) and usually the goslings but also occasionally adults of geese such as brants (Branta bernicla), snow geese (Anser caerulescens) and cackling geese (Branta hutchinsii). Drake eiders of often similar size to the owls themselves are not infrequently the largest prey amongst remains around the nest mound. One nest had the bodies of all eiders that attempting to nest in the vicinity around it. The threatened and declining Steller's eider (Polysticta stelleri) when nesting in the Utqiaġvik area would appear to avoid the vicinity of snowy owl nests when selecting their own nesting sites due to the predation risk. Intermediately sized seabirds are often focused on in lieu of available lemmings. Foods were studied intensively in Iceland. Among 257 prey items found with a total prey mass of , birds made up 95% of the diet. The leading prey were adult rock ptarmigan, at 29.6% by number and 55.4% by biomass and adult European golden plover (Pluvialis apricaria), at 10.5% by number and 7.2% biomass. The rest of the balance was largely other shorebirds, which were taken slightly more often as chicks than adults. Pink-footed geese (Anser fabalis) were taken in equal number as goslings and adults, with respectively estimated average weights at these ages of . On the isle of Agattu, the diet consisted entirely of birds, as there are no mammals found there. The much favored food in Agattu was the ancient murrelet (Synthliboramphus antiquus), at 68.4% of the biomass and 46% by number, while the secondary prey were followed numerically by smaller Leach's storm-petrels (Oceanodroma leucorhoa) (20.8%) and Lapland longspurs (10%) and in biomass by smallish ducks, the green-winged teal (Anas carolinensis) and harlequin duck (Histrionicus histrionicus) (13.4% biomass collectively). In the Murman Coast of Russia,