Carol Walker / Two wild pinto Mustang stallions battle for dominance in Sand Wash Basin, Colorado, USA.

Carol Walker / Two wild Mustang stallions fighting in the White Mountain Herd Area, Wyoming, USA. August.

Fiona Rogers / Southern plains grey langur / Hanuman langur (Semnopithecus dussumieri) female grooming a domestic dog. Jodhpur, Rajasthan, India. March.

Mark Hamblin / 2020VISION / Two sub-adult Wild Domestic goats (Capra hircus) play fighting on hillside, Cairngorms National Park, Scotland, UK, February.

Michel Poinsignon,Michel Poinsignon / Merens horse (Equus caballus) mare with resting foal, Pyrenees mountains, France, August.

Fabrice Cahez / Wild cat (Felis silvestris) portrait, Vosges, France, June

Kristel Richard / A band of semi-feral Quarter mares and foals running across a creek, Estancia Don Amerigo, Chaco, Paraguay, January 2012

Laurie Campbell / Feral Goat (Capra hircus) male, Inverness-shire, Scotland, July

Kristel Richard / Wild / feral Dulmen ponies (Equus caballus) herd of mares and foals running on the Duke of Croy's estate, Meerfelder Bruch, North Rhine-Westphalia, Germany, May 2011

Kristel Richard / Wild / feral Dulmen ponies (Equus caballus) close up of herd of mares and foals running on the Duke of Croy's estate, Meerfelder Bruch, North Rhine-Westphalia, Germany, May 2011

Kristel Richard / Wild / feral Dulmen ponies (Equus caballus) close up of herd of mares and foals running on the Duke of Croy's estate, Meerfelder Bruch, North Rhine-Westphalia, Germany, May 2011

Kristel Richard / Wild / feral Dulmen ponies (Equus caballus) herd of mares and foals running on the Duke of Croy's estate, Meerfelder Bruch, North Rhine-Westphalia, Germany, May 2011