Marie Read / Snowy Owl (Nyctea scandiaca) female perched, Amherst Island, Ontario, Canada, January.

Marie Read / Loggerhead shrike (Lanius ludovicianus) on an ice-covered fence after an ice storm, Anahuac National Wildlife Refuge, Texas, USA. January.

Marie Read / Northern cardinal (Cardinalis cardinalis) male perched amid snow-covered branches, New York, USA, February.

Marie Read / Common redpoll (Carduelis flammea), male perched in alder (Alnus rugosa) during a snowstorm in winter, New York, USA, January.

Marie Read / Snowy Owl (Nyctea scandiaca) female preparing to take flight from its perch on a fence, Barrie, Ontario, Canada. February.

Marie Read / Northern Cardinal (Cardinalis cardinalis) female perched amid berries and seedheads with falling snow, New York, USA. November. Non-ex.

Marie Read / Eastern screech-owl (Megascops asio) grey morph, roosting in tree cavity in winter, Lansing, New York, USA, January.

Marie Read / American robin (Turdus migratorius) male on snow-covered ground, Ithaca, New York, USA, April.

Ashley Cooper / Climber i on Sgurr Alasdair on the Cuillin Ridge, Isle of Skye, Scotland. March 2006

Peter Cairns / Aspen grove (Populus tremuloides) in winter, Grand Teton National Park, Wyoming, USA, January.

Peter Cairns / American Bison (Bison bison) standing in front of winter geysers, Yellowstone National Park, Wyoming, USA, February 2013..

Peter Cairns / American Bison (Bison bison) walking through deep snow, Yellowstone National Park, Wyoming, USA, February 2013..