On the wintering grounds, mammals often predominate in the snowy owl's food inland doing so less in coastal areas.
Overall wintering snowy owls eat more diverse foods they do whilst breeding, furthermore coastal wintering snowy owls had more diverse diets than inland ones.
As in summer, moderately sized water birds such as teal, northern pintail (Anas acuta) and numerous alcids and the like are often focused on when hunting birds.
The diet in 62 pellets, amongst at least 75 prey items, from coastal Oregon showed the main foods as black rat (Rattus rattus) (at an estimated 40%), red phalarope (Phalaropus fulicarius) (31%) and bufflehead (Bucephala albeola) (19%).
Witnessed attacks were mostly upon buffleheads in Oregon.
In coastal southwestern British Columbia, the diet among 139 prey items was 100% avian.
The predominant prey were water birds, mostly snatched directly from surface of the water and largely weighing 400 to 800 g (0.88 to 1.76 lb), i.e. buffleheads (at 24% by number and 17.4% by biomass of foods) and horned grebes (Podiceps auritus) (at 34.9% by number and 24.6% by biomass), followed by variously other water birds, often the slightly larger species of glaucous-winged gull (Larus glaucescens) and the American wigeon (Mareca americana).
A different study of this area also showed the predominance of ducks and other water birds to wintering snowy owls here, although Townsend's vole (Microtus townsendii ) (10.65%) and snowshoe hare (Lepus americanus) (5.7%) were also notably in a sample of 122 prey items.

During winter, snowy owls consume more strongly nocturnal prey than lemmings such as Peromyscus mice and northern pocket gophers (Thomomys talpoides).
In southern Alberta, 248 prey items were found with North American deermouse (Peromyscus maniculatus), at 54.8% by number, and meadow voles (Microtus pennsylvanica), at 27% by number, as the main foods of snowy owls over 2 years.
Other prey in Alberta were grey partridge (Perdix perdix) (at 5.79% of total), jackrabbits, weasels and owls.
Richardson's ground squirrels (Urocitellus richardsonii) were consumed heavily in the Alberta study in a brief converged times of hibernation emergence and overwintering snowy owls.
The sexual dimorphism in prey selection was also studied here, with male owls mainly focusing exclusively on the small rodents, females also took the same rodents but supplemented the diet with all alternate and larger prey.
Overall, the meadow and montane voles (Microtus montanus) constituted 99% of over 4500 prey items in Montana.
In Horicon Marsh in winter, 78% of the diet was meadow vole, with 14% being muskrats (Ondatra zibethicus), 6% ducks and smaller balances of rats and other birds.
Snowy owls found in Michigan took meadow voles for 86% of the diet, white-footed mouse (Peromyscus leucopus) for 10.3% and northern short-tailed shrew (Blarina brevicauda) for 3.2%.
Of 127 stomachs in New England in four irruptive winters from 1927 to 1942, of 155 prey items, 24.5% were brown rats, 11.6% were meadow voles and 10.3% were dovekie (Alle alle), with a smaller balance of snowshoe hare and birds from snow buntings to American black ducks (Anas rubripes).
During the same years, stomach contents in Ontario included 40 identified prey items, led by brown rats (20%), white-footed mice (17.5%) and meadow voles (15%); of 81 prey items from Pennsylvania in 60 stomachs that were not empty, eastern cottontail (Sylvilagus floridanus) (32%), meadow vole (11.1%), domestic chicken (Gallus gallus domesticus) (11.1%) and northern bobwhite (Colinus virginianus) (5%) were the most often identified prey species.
Introduced common pheasants were found to be somewhat more vulnerable than native American gamebirds like ruffed grouse due to their tendency to crouch rather than flush when approached by a flighted predator like the snowy owl in a glade or field.
Some snowy owls wintering on rocky coasts and jetties were known in New England to live almost entirely off of purple sandpipers (Calidris maritima).
The availability of brown rats may draw snowy owls to seemingly unat
On the wintering grounds, mammals often predominate in the snowy owl's food inland doing so less in coastal areas. Overall wintering snowy owls eat more diverse foods they do whilst breeding, furthermore coastal wintering snowy owls had more diverse diets than inland ones. As in summer, moderately sized water birds such as teal, northern pintail (Anas acuta) and numerous alcids and the like are often focused on when hunting birds. The diet in 62 pellets, amongst at least 75 prey items, from coastal Oregon showed the main foods as black rat (Rattus rattus) (at an estimated 40%), red phalarope (Phalaropus fulicarius) (31%) and bufflehead (Bucephala albeola) (19%). Witnessed attacks were mostly upon buffleheads in Oregon. In coastal southwestern British Columbia, the diet among 139 prey items was 100% avian. The predominant prey were water birds, mostly snatched directly from surface of the water and largely weighing 400 to 800 g (0.88 to 1.76 lb), i.e. buffleheads (at 24% by number and 17.4% by biomass of foods) and horned grebes (Podiceps auritus) (at 34.9% by number and 24.6% by biomass), followed by variously other water birds, often the slightly larger species of glaucous-winged gull (Larus glaucescens) and the American wigeon (Mareca americana). A different study of this area also showed the predominance of ducks and other water birds to wintering snowy owls here, although Townsend's vole (Microtus townsendii ) (10.65%) and snowshoe hare (Lepus americanus) (5.7%) were also notably in a sample of 122 prey items.
During winter, snowy owls consume more strongly nocturnal prey than lemmings such as Peromyscus mice and northern pocket gophers (Thomomys talpoides). In southern Alberta, 248 prey items were found with North American deermouse (Peromyscus maniculatus), at 54.8% by number, and meadow voles (Microtus pennsylvanica), at 27% by number, as the main foods of snowy owls over 2 years. Other prey in Alberta were grey partridge (Perdix perdix) (at 5.79% of total), jackrabbits, weasels and owls. Richardson's ground squirrels (Urocitellus richardsonii) were consumed heavily in the Alberta study in a brief converged times of hibernation emergence and overwintering snowy owls. The sexual dimorphism in prey selection was also studied here, with male owls mainly focusing exclusively on the small rodents, females also took the same rodents but supplemented the diet with all alternate and larger prey. Overall, the meadow and montane voles (Microtus montanus) constituted 99% of over 4500 prey items in Montana. In Horicon Marsh in winter, 78% of the diet was meadow vole, with 14% being muskrats (Ondatra zibethicus), 6% ducks and smaller balances of rats and other birds. Snowy owls found in Michigan took meadow voles for 86% of the diet, white-footed mouse (Peromyscus leucopus) for 10.3% and northern short-tailed shrew (Blarina brevicauda) for 3.2%. Of 127 stomachs in New England in four irruptive winters from 1927 to 1942, of 155 prey items, 24.5% were brown rats, 11.6% were meadow voles and 10.3% were dovekie (Alle alle), with a smaller balance of snowshoe hare and birds from snow buntings to American black ducks (Anas rubripes). During the same years, stomach contents in Ontario included 40 identified prey items, led by brown rats (20%), white-footed mice (17.5%) and meadow voles (15%); of 81 prey items from Pennsylvania in 60 stomachs that were not empty, eastern cottontail (Sylvilagus floridanus) (32%), meadow vole (11.1%), domestic chicken (Gallus gallus domesticus) (11.1%) and northern bobwhite (Colinus virginianus) (5%) were the most often identified prey species. Introduced common pheasants were found to be somewhat more vulnerable than native American gamebirds like ruffed grouse due to their tendency to crouch rather than flush when approached by a flighted predator like the snowy owl in a glade or field. Some snowy owls wintering on rocky coasts and jetties were known in New England to live almost entirely off of purple sandpipers (Calidris maritima). The availability of brown rats may draw snowy owls to seemingly unat
Snowy owl