David Perpinan / Male Lapwing (Vanellus vanellus) arriving at nest to incubate eggs, female leaves, Scottish Borders, Scotland, UK, June.

Frederique Olivier / Adelie penguin (Pygoscelis adeliae) lying down to incubate an egg, Antarctica.

Fred Bavendam / Ring-tailed Cardinalfish (Apogon aureus) male protectively carrying a fertilized egg mass in his mouth while they incubate, Bali, Indonesia

John Chan / Female Killdeer (Charadrius vociferus) returning to nest to incubate eggs, Southern California, USA, June.

John Chan / Female Anna's hummingbird (Calypte anna) returning to nest to incubate eggs after feeding, Southern California, USA, March.

David Perpinan / Male Lapwing (Vanellus vanellus) arriving at nest to incubate eggs, female leaves, Scottish Borders, Scotland, UK, June.

Ashley Cooper / Tourists watching Black browed albatross (Thalassarche melanophris) and Rockhopper penguins (Eudyptes chrysocome) nesting colony on Westpoint island, Falkland Islands, South America,February 2014

Dave Bevan / Canada goose (Branta canadensis) turning eggs over and settling to incubate them, Ceredigion, Wales, UK, March.

Dave Bevan / Female Common crane (Grus grus) rearranging nest and turning eggs before settling down to incubate, Gloucestershire, England, UK, May.

Dave Bevan / Avocet (Recurvirostra avosetta) turning eggs before settling down to incubate, Gloucestershire, England, UK. April.

Dave Bevan / Moorhen (Gallinula chloropus) settling on nest to incubate eggs and preening, Carmarthenshire, Wales, UK, March.

Steve Downer / Female Mute swan (Cygnus olor) turning eggs and settling to incubate them, Birmingham, England, UK, May.