Alan Murphy/ BIA / Myrtle Warbler (Setophaga coronata coronata), Texas

Donald M. Jones / Yellow-rumped Warbler (Setophaga coronata) female, western Montana

Donald M. Jones / Yellow-rumped Warbler (Setophaga coronata) female in autumn, Montana

Karine Aigner / Portrait of a Myrtle warbler, (Dendroica coronata coronata) with white background, Block island, Rhode Island, USA. Bird caught during scientific research.

Sue Flood / Emperor penguin chick flapping its wings (3 of 3) at Snow Hill Island rookery, Weddell Sea, Antarctica. November.

Sue Flood / Aerial of icebreaker Kapitan Khlebnikov, Snow Hill Island, Weddell Sea, Antarctica, November 2009.

Alan Murphy/ BIA / Myrtle Warbler (Setophaga coronata coronata) male, Texas

Scott Leslie / Yellow-rumped Warbler (Setophaga coronata) male in spring, Maine

Donald M. Jones / Yellow-rumped Warbler (Setophaga coronata) male calling, Troy, Montana

Rolf Nussbaumer / Yellow-rumped Warbler (Dendroica coronata), adult perched on icy branch of Yaupon Holly (Ilex vomitoria) with berries, Hill Country, Texas, USA. February

Rolf Nussbaumer / Yellow-rumped Warbler (Dendroica coronata), adult perched on icy branch of Yaupon Holly (Ilex vomitoria) with berries, Hill Country, Texas, USA. February

Alan Murphy/ BIA / Myrtle Warbler (Setophaga coronata coronata) male, British Columbia, Canada