Snow Goose BTO - British Trust for Ornithology

Snow Goose Identification, All About Birds, Cornell Lab of Ornithology

BTO British Trust for Ornithology

Snow Goose - American Bird Conservancy

Snow Goose Facts, Distribution, Habitat, Lifespan and Pictures

COMMON SHELDUCK (Tadorna tadorna). Male or 'Sheldrake'. Note B.T.O. = British Trust for Ornithology metal alloy ring or 'band' on right leg Stock Photo - Alamy

Canada goose - Wikipedia

Snow Bunting BTO - British Trust for Ornithology

Geese, Squirrels and Bare Branches Muir of Dinnet National Nature Reserve

Understanding birds BTO - British Trust for Ornithology

Anser indicus (bar-headed goose)

Brent goose - Norfolk Wildlife Trust

Opposite View Wildlife Photography

BirdTrack migration blog (November–December)

Understanding birds BTO - British Trust for Ornithology

Full article: Use of GPS tags to describe the home ranges, migration routes, stop-over locations and breeding area of Taiga Bean Geese Anser fabalis fabalis wintering in central Scotland