Ole Jorgen Liodden / White-tailed eagle (Haeliaeetus albicilla) perched on snowy snag with wings raised, Flatanger, Norway, January.

Markus Varesvuo / Black grouse (Lyrurus tetrix) mating in snow, Utajarvi, Finland, May.

Markus Varesvuo / Willow grouse (Lagopus lagopus), Kiilopaa, Inari, Finland, January.

Markus Varesvuo / Willow grouse (Lagopus lagopus) perched on branch, Kiilopaa, Inari, Finland, January.

Markus Varesvuo / Willow grouse (Lagopus lagopus), Kiilopaa, Inari, Finland, January.

Markus Varesvuo / Willow grouse (Lagopus lagopus) Kiilopaa, Inari, Finland, January.

George Sanker / Mourning Dove (Zenaida macroura) perched on branch in snow, Acadia National Park, Maine, USA, February.

David Pattyn / Black necked grebe (Podiceps nigricollis) pair performing their courtship dance in the mating season. This early in the breeding season, one of the birds is still in its winter plumage. The Netherland...

David Pattyn / Black necked grebe (Podiceps nigricollis) pair running over the water surface together as a part of their courtship ritual. This early in the breeding season, one of the birds is still in its winter p...

David Pattyn / Black necked grebe (Podiceps nigricollis) pair performing their courtship ritual. This early in the breeding season one of the grebes is still in its winter plumage. The Netherlands.April 2014

David Pattyn / Black necked grebe (Podiceps nigricollis) portrait of an adult bird in winter plumage. The Netherlands.April 2014

David Pattyn / Black necked grebe (Podiceps nigricollis) portrait of an adult in winter plumage. The Netherlands.April 2014