Kristel Richard / A Shagya Arab stallion (Equus caballlus) is shown in hand in the courtyard of the Babolna Arabian Stud, Babolna, Komarom-Esztergom, Hungary.

Kristel Richard / A Shagya Arab stallion (Equus caballus) running in tall grass at the Babolna Arabian Stud, Babolna, Komarom-Esztergom, Hungary.

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

Kristel Richard / A wild Misaki-uma breeding stallion (right) brings back one of his mares to his band while another breeding stallion (left) charges him away, in the Cape Toi Reserve, Miyazaki Prefecture, Kyushu Islan...

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

Wild Wonders of Europe / Hamblin / Konik horse, portrait of stallion, Oostvaardersplassen, Netherlands, June 2009

Wild Wonders of Europe / Hamblin / Konik horses, mares and a stallion encouraging young foal to stand up, Oostvaardersplassen, Netherlands, June 2009

Wild Wonders of Europe / Allofs / White Camargue horse stallion with a Cattle egret (Bulbulcus ibis) on his back, Camargue, France, April 2009

Wild Wonders of Europe / Allofs / White Camargue horse, stallion in tall grass, Camargue, France, April 2009

Carol Walker / Wild Horses / Mustangs, sorrel stallion striking at another stallion, McCullough Peaks Herd Area, Cody, Wyoming, USA

Carol Walker / Purebred grey Andulasian stallion carriage horse, high trotting, Carriages Exhibition, Seville, Spain

Carol Walker / Purebred black Friesian stallion being trained to perform the 'spanish walk', Castle Rock, Colorado, USA Model released