The Namib Desert horse () is a feral horse found in the Namib Desert of Namibia. It is one of the two feral herd of horses ( the other being the Kundudo horses from Ethiopia) residing in Africa, with a population ranging between 90 and 150. The Namib Desert horse is athletic in appearance, resembling the European light riding horses from which it probably descends, and usually dark in color. Despite the harsh environment in which they live, the horses are generally in good condition, except during times of extreme drought. The horses have been the subject of several population studies, which have given significant insight into their population dynamics and ability to survive in desert conditions.
The origin of the Namib Desert horse is unclear, though several theories have been put forward. Genetic tests have been performed, although none to date have completely verified their origin. The most likely ancestors of the horses are a mix of riding horses and cavalry horses, many from German breeding programs, released from various farms and camps in the early 20th century, especially during World War I. Whatever their origin, the horses eventually congregated in the Garub Plains, near Aus, Namibia, the location of a man-made water source. They were generally ignored by humans, except for the periodic threat of eradication, due to the possibility that they were destroying native herbivore habitat, until the 1980s. In 1984, the first aerial survey of the population was made, and in 1986, their traditional grazing land was incorporated into the Namib-Naukluft Park. At several points, some horses have been removed from the herd, including the removal and sale of over one-third of the population in 1992. Since the early 1990s, close records of the population have been kept, and studies have been performed to determine the horses' effect on their environment. Despite being considered an exotic species within the park, they are allowed to remain due to their ties to the country's history and draw as a tourist attraction.
Characteristics
The most common color of the Namib Desert horse is bay, although there are a few chestnut and brown horses. There are even a smaller number of black horses but these are exceptional. The gene for gray does not occur in the breed. There are many individuals with dorsal striping but no zebra stripes. No other colors have been recorded. The Namib Desert horses are athletic, muscular, clean-limbed, and strong boned. They are short-backed with oblique shoulders and good withers. The horses have the appearance of well-bred riding horses in head, skin, and coat. Overall, they have good conformation, with few deformities. Club hooves are occasionally seen in foals, likely due to trauma to the hoof while traveling long distances.
Scientists studying the horses rate their body condition on a scale of one (excellent) to five (very poor), based mainly on estimated weight and muscle tone. The horses tend to remain in above average condition, despite the harsh environment in which they live, with stallions generally averaging better condition then mares. During severe droughts, the average body score decreases, but even then horses are found with moderate body scores and the entire population is never in very poor condition. The condition of the horses is directly correlated to rainfall, through a correlation to available forage, though temperature, distance between forage and water and individual energy expenditures also play a role.Greyling pp. 106–107 Studies during the 1990s found no evidence of equine disease among the population and few external parasites. Investigations of carcasses found four internal nematode parasites present (strongyles, small and large pinworms and ascarids), as well as the larvae of botflies.Greyling, p. 108
Behavior and ecology
The home range of the Namib Desert horse reaches north in the Namib Desert to the Koichab River, usually dry, and west to the Great Escarpment. Bands of horses range together, consisting of as few as two animals, although there are generally more. In observations between 1993 and 2003, between six and eleven bands were identified, including a mixture of bachelor herds, breeding groups and co-operating stallion groups (groups with more than one stallion that share breeding duties).Greyling, p. 103 The Namib Desert horse travels extensively, searching for food, water and shelter from the climate and insects. A 1994 study found that they have an average home range of , although not all of that is traversed each day. They must cover considerable distances, as much as between the few existing water sources and the best grazing sources. This creates severe selection pressure and removes weak animals from the population.
Due to scarcity of water, the Namib Desert horse sometimes goes without water for as long as thirty hours in summer and has been known to go close to 72 hours without water during the winter, significantly longer than most horses, even other feral herds. A 1991 study suggested that in 75 years of genetic isolation and water scarcity the population had developed physiological mechanisms which improved their ability to conserve water. In 1993, a second study showed that the physiological water-conservation ability did not differ between Namib Desert horses and other populations when dehydrated for periods of up to 60 hours, but suggested that the Namib Desert horse would show improved conservation ability when dehydration periods were extended to upwards of 72 hours, a common occurrence in their feral state.
The horses, especially young foals and juveniles, provide a major food source in the southern Namib Desert for the spotted hyena, along with gemsbok and springbok. However, the availability of other food appears to have a significant influence on predation rates among the horses. Leopards and black-backed jackals also predate young horses, although this is more rare. The harsh environmental conditions in which they live are the main driver of mortality among the Namib Desert horse, as they cause dehydration, malnutrition, exhaustion and lameness.Greyling, pp. 92–93 Other large plains animals, including the mountain zebra, may have once sporadically utilized the area for grazing during periods of excess rainfall, but human interference (including fencing off portions of land and hunting) have eliminated or significantly reduced the movement of these animals in the area.Greyling, p. 22 The endangered Hartmann's mountain zebra does exist in the Naukluft Mountain Zebra Park portion of the Namib-Naukluft Park, but their range does not intersect with that of the Namib Desert horse.Greyling, p. 26
Genetics Genetic testing results published in 2001 indicated that Namib Desert horses are one of the most isolated horse populations in the world, with the second-lowest genetic variation of all horse populations that have been studied to date. In part, this is due to their small founding population, and generally small modern population, made smaller during periods of drought. Despite the large domesticated breeding population from which the horses originally descended, at least one genetic bottleneck has occurred in the breed's history, resulting in a significant decline in genetic variation over a relatively short period of time. Although an ideal minimum population size for genetic variability would be around 200 horses, the current range cannot support this population given the average rainfall. Estimates for a necessary minimum population to maintain genetic effectiveness range between 100 and 150 animals.Greyling, p. 110
The 2001 testing showed the Namib Desert horse to be part of the Oriental horse grouping, genetically closest to the Arabian horse, although even this association was distant. They were closer to the Arabian than to the three South African breeds tested, the Nooitgedacht pony, the Boer pony and the Basuto pony. As the genetic similarity to Arabian-type horses is distant, they do not closely resemble them in outward appearance, although they are both of the "hot blooded" type, resulting in both being athletic, lean-muscled animals. Further, in blood typing studies done in the 1990s, a new variant was noted. Its absence from the blood samples of all other horse breeds indicates the presence of a mutation that probably occurred after the horses became established in the desert.
Breed history
Southern Africa has no native horse populations, so the origins of the Namib Desert horse trace to imported herds of horses. There are several theories on the ancestors of the Namib Desert horse, and the true story may never be known. One theory says that a cargo ship carrying Thoroughbreds to Australia wrecked near the Orange River, and the strongest horses swam ashore and traveled to the Garub Plains, the home of the Namib Desert horse, near Aus, Namibia. Another theory states that they descend from Cape horse/Basuto pony crosses ridden by Khoikhoi raiders traveling from southern Africa to north of the Orange River. The most likely theory has the Namib Desert horse descending from a combination of escaped South African military horses and Namibian-bred German horses. During World War I, horses were used in campaigns in Namibia between the German Schutztruppe and South African troops, and some escaped or were released into the desert. Prior to this time, a German Baron von Wolf built Duwisib Castle on the edge of the Namib Desert, where he held a herd of approximately 300 horses. Von Wolf was killed in action in Europe during World War I, and his farm was abandoned, leaving his horses on unfenced land relatively close to the area where the Namib Desert horses now roam. The Namib Desert horse phenotypically more closely resembles the horses bred by von Wolf and ridden by the World War I-era troops than the horses ridden by Khoikhoi tribesmen, making the former story the more likely. The genetic evidence of the 2001 study gave less credence to the descent from von Wolf's horses. He used Thoroughbreds, Hackneys and Trakehners in his breeding program, rather than the Arabian horse to which the Namib Desert horses are the most genetically similar.
Research in the archives of pre-1914 horse breeding operations found at Windhoek, combined with blood typing studies, suggests that the animals descended from a gene pool of high-quality riding animals, as opposed to work horses. A study released in 2005 reinforces the theory of the Namib Desert horse descending from a combination of European-descended breeding stock and escaped military horses. One possible source of breeding stock was a stud farm near Kubub, leased by Emil Kreplin (previously mayor of Lüderitz) from 1911 to 1919. Photo albums from the stud show animals with conformation and markings similar to those seen in the modern Namib Desert horse. In addition, in early 1915, during the fighting of World War I, bombs were dropped by a German aircraft onto the South African camp near Garub. Some ordnance seems to have been specifically targeted to land among a herd of 1,700 grazing horses, for the purposes of scattering them. These escaped army animals may have joined stock animals lost from Kreplin's stud farm during the turmoil of the war. horses in the area would likely have congregated at the few existing watering places in the Aus Mountains and Garub.Greyling, pp. 24–25
1970s to present