Staffan Widstrand / Grey-headed woodpecker (Picus canus) on tree trunk in falling snow. Kalvtrask, Vasterbotten, Lapland, Sweden. January.

Juan Carlos Munoz / Golden-headed lion tamarin (Leontopithecus chrysomelas) captive portrait, Apenheul Park, Netherlands.

Stefan Rieben / Grey-headed Woodpecker (Picus canus) parents feeding chicks at nest hole, Zurich, Switzerland

Inaki Relanzon / White collared / Grey-headed lemur (Eulemur cinereiceps) male, captive, Manombo forest, Madagascar, critically endangered

Mary McDonald / Flock of Gray-headed Gulls (Chroicocephalus cirrocephalus) flying over Lake Nakuru, Kenya, East Africa

Andy Rouse / Grey-Headed albatross (Thalassarche / Diomedea chrysostoma) portrait, South Georgia

Andy Rouse / Grey-headed albatross (Thalassarche / Diomedea chrysostoma) portrait, South Georgia

Andy Rouse / Grey-Headed albatross (Thalassarche / Diomedea chrysostoma) portrait, South Georgia

Hermann Brehm / Grey-headed Woodpecker(Picus canus) male on tree trunk, Germany. January

Hermann Brehm / Great spotted woodpecker (Dendrocopos major) and Grey headed woodpecker (Picus canus) on tree trunk, Germany. December

Doug Gimesy / Grey-headed flying-foxes (Pteropus poliocephalus) hang in a tree with one coming in to land. Yarra Bend Park. Fairfield, Victoria, Australia. November.

Doug Gimesy / Grey-headed flying-foxes (Pteropus poliocephalus) hang in a tree with one coming in to land. Yarra Bend Park. Kew, Victoria, Australia. November.