Ismaele Tortella / Three Rock ptarmigan (Lagopus muta) feeding in winter plumage, city of Tromso in the background, northern Norway, March 2019.

Markus Varesvuo / Willow grouse / Ptarmigan (Lagopus lagopus) pecking twig, Utsjoki, Finland, April.

Markus Varesvuo / Willow grouse / Ptarmigan (Lagopus lagopus) fluffed up perched in snow, Inari, Finland, February.

Markus Varesvuo / Willow grouse (lagopus lagopus) flock in flight in snow, Utsjoki, Finland, October.

Markus Varesvuo / Male Willow grouse / Ptarmigan (Lagopus lagopus) portrait, Inari Kiilopaa, Finland, February.

Markus Varesvuo / Willow grouse / Ptarmigan (Lagopus lagopus) flying, Inari Kiilopaa, Finland, February.

Donald M. Jones / Willow Ptarmigan (Lagopus lagopus) trio in fall, transitioning to winter plummage, central Alaska

Donald M. Jones / White-tailed Ptarmigan (Lagopus leucura) in winter feeding on buds, western Alberta, Canada

Donald M. Jones / White-tailed Ptarmigan (Lagopus leucura) in winter, western Alberta, Canada

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.