In 1971, wild horses and burros were found roaming across 53.8 million acres of Herd Areas (HAs), of which 42.4 million acres were under the BLM's jurisdiction. Today the BLM manages wild horses and burros in subsets of these HAs, known as Herd Management Areas (HMAs) that comprise 31.6 million acres, of which 26.9 million acres are under BLM management.
The BLM manages two special areas in southeastern Oregon for wild horses with Spanish Mustang characteristics. The two areas are located in the Burns District and are known as the Kiger and Riddle Mountain HMAs.
The Riddle Mountain HMA is located 50 air miles southeast from Burns, Oregon and is southeast, and adjacent, to Riddle Mountain. On the other side of Riddle Mountain is the Kiger HMA. Periodically, horses from the Kiger HMA and Riddle Mountain HMA are transferred to maintain genetic diversity. Quality animals with dun factor coloration and Spanish mustang characteristics are returned to the HMA following gathers to maintain the core of the breeding herd. There is a high demand for adoption of Kiger Mustangs for use as pleasure and breeding stock. They are noted for their intelligence and stamina.
No other horse in America is quite like the Kiger Mustang. Most wild horses are of mixed influence and characteristics while the Kiger Mustangs possess many characteristics of the original Spanish Mustang. The word mustang was derived from the word mesteno, which meant " unclaimed sheep" in the Spanish language and later came to mean "wild" or "unclaimed" horse. Mustang came about as an English language slang term for mesteno.
The Kiger Mustang exhibits physical color characteristics known as the "dun factor" which were also common to many of the horse the Spaniards reintroduced to North America in the 1600's. Color classifications of the dun factor are: dun, red dun, grulla (mouse gray), buckskin, and variations of these colors. Markings on animals with the dun factor include dorsal stripes; zebra stripes on the knees and hocks; chest, rib and arm bars; outlined ears; the top one-third of the ear on its backside darker than the body color; fawn coloring on the inside of the ears; bi-colored mane and tail; face masks and cob-webbing on the face. The less white these horses have, the stronger the dun factor. An individual horse having the dun factor may have many but not all of these markings.
Kiger Mustangs have the physical conformation of both the tarpan and oriental hotblood horses from which the original Spanish Mustangs came. They have small, round bones, small feet and very little feather on their legs and fetlocks. Their eyes are wide set and prominent. These animals also have distinctly hooked ear tips and fine muzzles. The Kiger Mustangs also look very much like the modern day Spanish Sorraias. They are indeed a unique breed of wild horse.
The Riddle Mountain HMA contains 28,000 acres. Topography varies from gently rolling hills to steep slopes and buttes with broad valleys. There were 66 horses in the herd at the last census in May of 2014.