Neil Aldridge / Dwarf bittern (Ixobrychus sturmii) stepping onto a rock, Mapungubwe National Park, Limpopo Province, South Africa.

Gary K. Smith / Tourists walking across the stepping stones, Dovedale, Peak District National Park, Derbyshire, England, UK, July 2015.

Staffan Widstrand / Mimmi Widstrand, walking over stepping stones in stream, Laponia Circuit, along the Padjelantaleden trail, Padjelanta National Park and Sarek National Park, Norrbotten, Lapland, Sweden. Model released

Loic Poidevin / Portrait of armed ranger, Kaziranga National Park, Assam, India, March 2014.

Roland Seitre / Fishing cat (Prionailurus viverrinus) at edge of water, Singapore Zoo, Singapore. Captive, occurs in Asia. Endangered species.

Ernie Janes / Oystercatcher (Haematopus ostralegus) feeding on mussels as tide recedes, Norfolk, East Anglia, England, UK, February.

Ernie Janes / Moorhen (Gallinula chloropus) wading, Norfolk, January.

Alex Mustard / Girl leaps between stepping stones across a mountain river. Akureyri, Iceland. May 2011.

Roger Powell / Cattle egret (Bubulcus ibis) in full breeding plumage balancing on a bamboo cane as it walks along it Guerreiro, Castro Verde, Alentejo, Portugal, May

LYNN M. STONE / Royal Terns (Thalasseus maximus) stepping toward and then around each other in courtship ritual. Gulf of Mexico beach, St. Petersburg, Florida, USA, April.

Pete Oxford / Stepping stones through Red Mangrove (Rhizophora mangle). Sian Ka'an Biosphere Reserve, Quintana Roo, Yucatan Peninsula, Mexico.

Charlie Summers / Greater Roadrunner (Geococcyx californianus) stepping over snow. Bosque del Apache, New Mexico, USA, February.