Wild Mustangs of Nevada | Horse Breeding Season Wild Mustangs of Nevada, live in groups called herds. A herd consists of one stallion, and around eight females and their young, though separate herds have been known to mix when they are in danger. The mountain horses are very beautiful and Powerful. Domestics horses, which includes mustangs, usually live about 25 to 30 years in captivity, although some live into their 40's and beyond. Horses living in the wild, like the feral mustang populations