Carol Walker / Friesian horse, black stallion running in field, Livingston, Montana, USA

Carol Walker / Lusitano horse, grey stallion trotting, Portugal

Carol Walker / Herd of horses on ranch with mountains in background, Jackson Hole, Wyoming, USA, July 2011

Kristel Richard / Portrait of a grey Andalusian stallion, in Ciutadella, Menorca, Spain.

Carol Walker / Wild horse / mustang called Mica, rounded up from Adobe Town Herd Management Area in Wyoming and adopted by photographer Carol Walker. Running in pasture, Colorado, USA.

Kirkendall-Spring / Horses (Equues caballus) grazing in open landscape. Columbia County - Eastern Washington. Washington, USA, August.

Eric Baccega / Five day old purebred Andalusian foal (Equus caballus) playing in a field, Alsace, France, May.

Kristel Richard / A group of Pure Arab, Shagya Arab and East Bulgarian fillies running in snow, Kabiuk National Stud, Shumen, Bulgaria.

Nick Upton / Grey Irish Gypsy cob stallion (Equus caballus) grazing rough pastureland on Hackpen Hill with Oilseed rape (Brassica napus) and other arable crops in the background, The Ridgeway, Winterbourne Bassett...

Kristel Richard / Two Lipizzaner colts standing next to each other, Stubalpe, near Koflach, Styria, Austria, September. Editorial use only.

Jeff Vanuga / Guardian riding Camargue horse through water at sunrise, Camargue, Bouches du Rhone, France, May 2013.

Carol Walker / Wild Mustang horse mare and foal, Sand Wash Basin Herd Area, Wyoming, USA.

Carol Walker / Wild Mustang foal resting among wild flowers, Pryor Mountains, Montana, USA.

Carol Walker / Wild Mustang pinto mother and foal, Sand Wash Basin Herd Area, Colorado, USA.

Carol Walker / Pinto horses running on ranch, Martinsdale, Montana, USA.

Carol Walker / Wild Mustang, dun horse running near Adobe Town, Wyoming, USA.

Carol Walker / Horses in ranch, Martinsdale, Montana, USA.

Carol Walker / Chestnut Mustang running in snow, at ranch, Shell, Wyoming, USA. February.

Carol Walker / Wild Mustang, dun horse in dust. Sand Wash Basin Herd Area, Colorado, USA.

Carol Walker / Gray Andalusian mare by wooden doors, Phoenix, Arizona, USA.

Carol Walker / Skewbald Horse in ranch, Martinsdale, Montana, USA.

Carol Walker / Wild Mustang, palomino horse portrait, Sand Wash Basin Herd Area, Colorado, USA.

Carol Walker / Wild Mustang foals among wild flowers, Pryor Mountains, Montana, USA.

David Noton / Exmoor pony on Winsford Hill, Exmoor National Park, Somerset, England, UK. November 2013.

David Noton / Exmoor ponies on Winsford Hill, Exmoor National Park, Somerset, England, UK. November 2013.

David Noton / Exmoor pony on Winsford Hill, Exmoor National Park, Somerset, England, UK. November.

Carol Walker / Silhouette of cowboy trotting at sunset, Flitner Ranch, Shell, Wyoming, USA Model released

Kristel Richard / Close-up of a white Kathiawari mare, decorated for a wedding, Nageshri, Gujarat, India, January 2011

Carol Walker / Arabian horse, portrait, New Mexico, USA, March 2011

Carol Walker / Horses running in the snow, Flitner Ranch, Shell, Wyoming, USA

Carol Walker / Lusitano horse, grey stallion trotting, Portugal

Carol Walker / Purebred leopard appaloosa horse running in snow, Flitner Ranch, Shell, Wyoming, USA

Carol Walker / Wild Horse / Mustang shaking head and mane, Adobe Town Herd Area, southwestern Wyoming, USA, WINNER OF WILD HORSE SECTION, EQUINE IDEAL PHOTOGRAPHY CONTEST 2012

Carol Walker / Horse in snow storm with shed in background, USA

Carol Walker / Purebred grey Andalusian mare running in the snow, Longmont, Colorado, USA

Grzegorz Lesniewski / Herd of Carpathian Pony / Hucul (Equus caballus) in snow. Bieszczady National Park, the Carpathians, Poland, March.

Vladimir Medvedev / Yakut horses (Equus caballus) standing in snow, Berdigestyakh, Yakutia, East Siberia, Russia, March.

Edwin Giesbers / Silhouette of two backlit Konik Wild Horse (Equus ferus caballus). The Netherlands, July.

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

Kristel Richard / Wild Chincoteague (Equus caballus) two breeding stallions greeting one another, Chincoteague National Wildlife Refuge, Chincoteague Island, Virginia, USA, June

Kristel Richard / Two wild Namib stallions fighting, Namib Nakluft National Park, Namib Desert, Namibia, September 2008

Wild Wonders of Europe / Muñoz / Retuerta horses (Equus ferus caballus) once native, now re-introduced to graze in Campanarios de Azaba Biological Reserve, a rewilding Europe Area, Salamanca, Castilla y Leon, Spain

Kristel Richard / Konik horses (Equus caballus) - wild Konik newborn colt running around, testing his legs, Millingerwaard nature reserve, Netherlands, April

Wild Wonders of Europe / Hamblin / Konik horse and young foal interacting, Oostvaardersplassen, Netherland, June 2009

Will Watson / Welsh pony (Equus caballus), with dead bracken (Pteridium aquilinum) in long forelock / mane, Hergest Ridge, Herefordshire, England, UK, October

Kristel Richard / Close up of small curved ears of Kathiawari stallion, Inaj National Stud, Gujarat, India, January 2011

Carol Walker / Purebred black Friesian stallion trotting on hillside, Ojai, California, USA

Carol Walker / Wild horse / Mustang, close up of face, Pryor mountains, Montana, USA

Carol Walker / Buckskin Andalusian stallion running, Ojai, California, USA

Carol Walker / Silhouette at dawn of Cowboy, horse and dog, Wyoming, USA, February 2012, model released

Carol Walker / Wild horses / Mustangs, pinto mare and foal, McCullough Peaks, Wyoming, USA

Brent Stephenson / Iceland Pony (Equus caballus) low angle in profile. Faroe Islands, July.

Eric Baccega / White Camargue Horse (Equus caballus) head and neck portrait. Camargue, Rhone, France.

Carol Walker / Chestnut arabian stallion running, California, USA

Carol Walker / Close up of eye of Purebred Grey Andalusian mare, Longmont, Colorado, USA

Mark Bowler / Minature Shetland Pony {Equus caballus} in snow, UK

Mark Bowler / Miniature shetland pony (Equus caballus) mother and foal in field, UK

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 / Head portrait of a Classic pony stallion (Equus caballus) and one of his mares, in Auvergne, France.

Carol Walker / White horse of the Camargue, foal with its brown baby coat, Camargue, Southern France

Carol Walker / White horses of the Camargue, herd running through the sea, Camargue, Southern France

Carol Walker / White horse of the Camargue, amongst reeds on marsh, Camargue, Southern France

Jean E. Roche / Close up of nostrils of White horse of the Camargue on wetlands, Camargue, France, January 2009

Carol Walker / Two white horses of the Camargue, running through marshes, one kicking out at the other, Camargue, Southern France

Carol Walker / Mustang / Wild horse filly chewing on young stallion's tail, Montana, USA. Pryor

Carol Walker / Two white horses of the Camargue, head to head at water, Camargue, Southern France

John Cancalosi / Rhum pony, mouth wide open, Isle of Rhum, Scotland, UK.

Brent Stephenson / Iceland Pony (Equus caballus) portrait. Faroe Islands, July.

Wild Wonders of Europe / Widstrand / Exmoor pony at sunrise, one of the oldest and most primitive horse breeds in Europe, Keent Nature Reserve, The Netherlands, September.

Guy Edwardes / 2020VISION / New Forest pony grazing on Latchmore Bottom at dawn, view from Dorridge Hill, The New Forest National Park, Hampshire, England, UK, July. 2020VISION Book Plate.

David Tipling / 2020VISION / Exmoor Pony (Equus caballus) grazing, the ponies are used to manage grassland on the Sandlings heath, Suffolk, UK, February 2011. Photographer quote: 'These Exmoor ponies are used to replicate the gra...