Melvin Grey / Senegal thicknee (Burhinus senegalensis), leucistic. Gambia, Africa.

Rick Price / Beach stone-curlew (Esacus magnirostris) standing on exposed reef. Montgomery Reef, Doubtful Bay, The Kimberley, Western Australia.

Loic Poidevin / Spotted thick-knee (Byrhinus capensis) in bush, Masai Mara, Kenya.

Staffan Widstrand / Water thick-knee (Burhinus vermiculatus) portrait, Zimanga Private Nature Reserve, KwaZulu Natal, South Africa

Robin Chittenden / Great stone-curlew (Burhinus recurvirostris / Esacus recurvirostris) Sri Lanka.

Robin Chittenden / Great stone-curlew (Burhinus recurvirostris / Esacus recurvirostris) Sri Lanka.

Nick Upton / Stone curlews (Burhinus oedicnemus) group of four standing among volcanic rocks in steppe scrubland at dawn, Teguise Plain, Lanzarote, Canary Islands, February.

Nick Upton / Stone curlew (Burhinus oedicnemus) standing among volcanic rocks in steppe scrubland at dawn, Teguise Plain, Lanzarote, Canary Islands, February.

Alain Dragesco-Joffe / Spotted dikkop (Burhinus capensis) adult, Sahara, Niger.

Bernard Castelein / Senegal thick-knee (Burhinus senegalensis), Gambia.

Bernard Castelein / Senegal thick-knee (Burhinus senegalensis), Gambia.

Tony Heald / Water thick-knee (Burhinus vermiculatus) Etosha National Park, Namibia, March.