DIVIDE BASIN HERD MANAGEMENT AREA
The Divide Basin HMA encompasses a total of 778,915 acres; 562,702 of these acres are managed by BLM. The range can support between 415 and 600 head of wild horses. Currently there are an estimated 660 wild horses, and with the 2001 post-foaling population, the number is predicted to be approximately 763 wild horses.
The climate within the area is typical of a cold desert. Summers are generally hot and dry with long, cold winters. Temperatures can range from well below zero to the upper 90s. Annual precipitation ranges from a low of 7 inches up to 15 inches at higher elevations. Some wind is seemingly inevitable. Direction of prevailing winds is variable but is generally westerly.
Topography within the area is highly variable, ranging from mostly flat to slightly rolling foothills carved by drainages, and desert mountains featuring steep slopes, cliffs, and canyons. Preferred habitat for wild horses in the Divide Basin HMA is the rolling hills and flats found at lower elevations.
Wild horses in the Divide Basin HMA have many domestic bloodlines in their background including American Quarter Horse, Thoroughbred, Standardbred, Arabian, and smaller draft breeds such as Percheron. Nearly every coat color can be found within the herds. The animals tend to be of moderate to large size for wild horses. Habitat conditions are such that the horses are in very good condition. The combinations of size, conformation, coat colors and patterns, and excellent physical condition have become a draw for potential adopters.
The normal breeding period runs from March through September each year but peaks around mid to late June. The peak of foaling season for wild horses in the Divide Basin HMA has been documented to be on or around June 1. The horses social structure, combined with their size, strength, and adaptability allows them to compete favorably with wildlife and domestic livestock.
Horses traveling up to 10 miles to water have been noted, although 2 to 5 mile distances are more common. An adult horse normally consumes 10 to 12 gallons of water per day. Horses usually have adequate water from winter snows and spring runoff which fill reservoirs and intermittent streams.
During late summer and early fall, horses depend on the fewer perennial sources of water (i.e., reservoirs, streams, springs, and flowing wells), and on water wells pumped for domestic livestock and wildlife. No predation of wild horses has been documented in the Rock Springs Field Office area and is considered to have little or no effect on wild horse populations.
Wild Horses are managed on private lands within the HMA through an agreement with the Rock Springs Grazing Association. Most rangelands in the Rock Springs Field Office area provide seasonal and yearlong grazing for livestock (cattle, sheep, horses). Approximately 45 percent of the rangelands in the field office area are public lands which are used in conjunction with State and private lands for the grazing of domestic livestock.
Wildlife are an integral part of the environment. The Great Divide Basin HMA provides habitat for a variety of wildlife species, including big game species (elk, mule deer, and pronghorn antelope). There is potential for competition between wild horses and antelope, deer, and elk; however, this potential is generally minimal during all four seasons.