Jabruson / Hippopotamuses fighting (Hippopotamus amphibius) taken before major crash in numbers in the 1990s due to political instability and hunting. Rwindi sector of the Virunga National Park. Democratic Repub...

Denis-Huot,Denis-Huot / Hippopotamus (Hippopotamus amphibius) males in a muddy pond, aerial view, Rwindi national park, Democratic Republic of Congo. Vulnerable species.

Jack Dykinga / Life returning after seasonal rains to burnt forest, Apache-Sitgreaves National Forest devastation of the 'Wallow Fire', Arizona, USA August 2011

Anup Shah / African elephants (Loxodonta africana) digging out a mud wallow, with calf aged 3-6 months, Masai Mara National Reserve, Kenya. February

Nick Garbutt / Male Bearded Pig (Sus barbatus) at forest wallow. Bako NP, Sarawak, Borneo, Malaysia.

Anup Shah / Low angle Warthog {Phacochoerus aethiopicus} about to wallow in mud, Serengeti NP, Tanzania

Tui De Roy / Galapagos Giant Tortoise (Chelonoidis nigra) group wallowing in seasonal pool on caldera rim, Alcedo Volcano, Isabella Island, Galapagos Islands, Ecuador

Tui De Roy / Volcan Alcedo Giant Tortoise (Chelonoidis nigra vandenburghi) wallowing in temporary rainy season pool, Alcedo Volcano, Isabella Island, Galapagos Islands, Ecuador

Lynn M. Stone / American bison (Bison bison), rolling in new dust wallow, Wind Cave National Park, South Dakota, USA. Non-ex.

Lynn M. Stone / American Bison (Bison bison) using horns and head to loosen up mound of Prairie Dog burrow to use as dust wallow. Note Prairie Dog in burrow lower right, Wind Cave National Park, South Dakota, USA, J...

Sandesh Kadur / Female Bengal tiger (Panthera tigris tigris) settling to wallow in a waterhole, with a cub joining her, Ranthambore National Park, Rajasthan, India. 2016.

Frederique Olivier / Close-up of a group of moulting Southern elephant seals (Mirounga leonina) in a wallow, Macquarie Island, Sub-Antarctic Australia.