of passerines, shorebirds and waterfowl can provide a key resource when lemmings are not found regularly and may be the only means by which the young can survive at such lean times. In the Nome, Alaska area, the locally nesting snowy owls reportedly switched from lemmings to ptarmigans when the latter's chicks hatched. A somewhat varying diet was also reported in Prince of Wales Island, Nunavut where 78.3% of the biomass was lemmings, with 17.8% from waterfowl, 3.3% from weasel and about 1% from other birds. In Fennoscandia, among 2,700 prey items only a third were Norway lemmings (Lemmus lemmus) and a majority were voles at 50.6%, probably largely the tundra vole (Microtus oeconomus). A more detailed glance at Finnish Lapland showed that amongst 2,062 prey items, 32.5% of the foods were Norway lemmings (though in some years the balance could range up to 58.1%), 28% were grey red-backed voles (Myodes rufocanus) and 12.6% were tundra voles, with birds constituting a very small amount of the prey balance (1.1%). In northern Sweden, a more homogenous diet was found with the Norway lemming constituting about 90% of the foods. In the Yamal Peninsula, 40% of the diet was collared lemmings, 34% were Siberian brown lemming (Lemmus sibiricus), 13% were Microtus voles and ptarmigan and ducks both constituting 8% and with other birds making up much of the remaining balance. In some parts of the tundra, snowy owls may opportunistically prey upon Arctic ground squirrels (Spermophilus parryii). In the Hooper Bay area (much farther south than they usually nest), various rodents, in highland areas, and waterfowl, in marshland, were taken while breeding. When historically breeding on Fetlar in Shetland, the main prey for snowy owls was European rabbits (Oryctolagus cuniculus), Eurasian oystercatcher (Haematopus ostralegus), parasitic jaegers (Stercorarius parasiticus) and Eurasian whimbrel (Numenius phaeopus), in roughly that order, followed by other bird species with most (rabbits and secondary birds) prey taken as adults but for the oystercatchers and jaegers which were taken largely as fully grown but only recently fledged juveniles. 22–26% of oystercatcher and jaeger young in the island were estimated to be taken by snowy owls. Bird predation by nesting snowy owls is highly opportunistic. Willow (Lagopus lagopus) and rock ptarmigan (Lagopus muta) of any age are often fairly regular in the diet of breeding snowy owls but they cannot be said to particularly specialize on these. Evidence was found in