European wild horse
(Equus ferus ferus)
The wild horse is a large herbivore native to Europe’s grasslands, forests and mountains. Like other grazers, it plays an important role in maintaining semi-open landscapes made up of diverse ecosystems. Through activities such as grazing and trampling, it creates new habitats for various species of plant, fungi and insect, and is therefore considered a keystone species.
During the Pleistocene and early Holocene eras, many distinct species of wild horse roamed the steppes of Eurasia. But since the end of the last ice age, some 12,000 years ago, most of these species have been either domesticated or driven to extinction by human activity. Until recently, it was thought that no wild horses remained in Europe.
The Tarpan (Equus ferus ferus) is probably the ancestor of all modern horses, having ranged from Northern Spain to Central Russia for over 2 million years. After centuries of hunting and habitat destruction, it became extinct in the wild in the late 16th century, surviving only as a status symbol in the zoos of noblemen until 1909. It then appeared that Przewalski’s horse (Equus ferus przewalskii), a relative of the Tarpan and native to Asia, was the world’s sole remaining wild species.
Experiments aiming to resurrect the Tarpan commenced in the 1930s. The Heck brothers, in Germany, and Tadeusz Vetulani, in Poland, attempted to back-breed domestic horses which retained some Tarpan DNA, producing the Heck horse, which was considered a Tarpan lookalike, and the Konik Polski, which was mistakenly hailed as the true descendent of the extinct species, and subsequently introduced to several reserves within the Tarpan’s historical range. It is now evident that the Konik is a derivation of the Konik farm horse, and therefore not closely related to the Tarpan; thus, while it remains a part of many European ecosystems, recent projects have introduced more suitable breeds to the wild, such as the Hutsul horses in the Carpathian Mountains of Russia, the Karakachan in Bulgaria, and the Pottoka in Extremadura and in Northern Spain.
Many living horse breeds have retained a large proportion of their wild genes. This is partly because the domestication of horses, which occurred between 11,000 and 4,000 years ago, did not alter their genetic makeup as much as other domestic mammals, such as cows and sheep. In addition, a number of pony breeds seem to have escaped domestication altogether. Out of all the European ponies, the Pottoka (Equus caballus) is probably most genetically similar to the original European wild horse, as it has maintained the largest effective population size throughout its history, and been least affected by the losses in genetic diversity, or “bottlenecks”, experienced by most populations in recent millennia.
The Pottoka’s History, Behaviour and Ecology
The Pottoka has inhabited the Cantabrian Mountains and the Western Pyrenees for 40,000–100,000 years, appearing in prehistoric cave paintings throughout the region, and playing an important role in Basque mythology and tradition. By the late 20th century, it was listed as endangered, as its population had declined to fewer than 600 individuals. In 1995, the creation of the Pottoka studbook catalysed efforts to restore the population by founding herds exclusively with purebred individuals. Today, the number of Pottokas has risen to over 700, making it Europe’s largest population of wild horses.
The Pottoka stands at just 4ft tall, and has a black or dark-brown coat, a long black mane and a strong, thick neck. Its small size is likely to have made it a poor candidate for domestication. Historically, it inhabited semi-open landscapes with mild temperatures and high humidity, but today, its native range is largely limited to mountaintops due to habitat loss, agriculture and land privatisation at lower altitudes.
The Pottoka’s diet consists of a range of grasses, bushes and herbs. Preferred plants include genista, gorse, sagebrush, clover, and plantain, though it may also eat the bark and leaves of trees, and fruits like rose hips and blackberries. In winter, horses venture down into the valleys and forage for bark, twigs, weeds, and other plants under the snow. Unlike ruminants, such as the European Bison, the Pottoka has upper incisor teeth which allow it to graze vegetation close to the ground, thus opening up the soil for pioneer plant species to take root. It spends 13–20 hours a day eating, but drinks infrequently, as waterholes are sometimes situated far from grazing areas and in places where herds are vulnerable to predation. Up to 8 hours per day are devoted to resting, where it sleeps standing up or lying on its sternum, the latter being more conducive to deep sleep.
The Pottoka walks almost continually, as this improves digestion, circulation and mood. As a result, it regularly travels over 30 km per day. When it is not feeding or resting, it engages in a range of other activities which indirectly benefit the ecosystem, such as galloping, which disturbs mice and insects on the ground and exposes them to birds of prey; digging for roots, which leaves holes in dense clumps of grass where flowering plants can sprout; stripping dead trees of their bark and leaves, which adds more light and space to forests; and defecating, which attracts fungi and insects, like the psilocybe mushroom and the aphodius fimetarius dung beetle, and leads nettles and digested seeds to germinate in dungheaps. Horses also enjoy playing in streams or pools, churning up the water and thus increasing its oxygen content, and rolling about in groups on the ground, creating coats of dust or mud for protection against flies.
The Pottoka inhabits two types of group: natal bands and bachelor bands. The former consist of one or more stallions and 3–6 mares per stallion, along with any offspring who have not yet reached sexual maturity. Natal bands with one stallion, or “harems”, usually produce more numerous and healthier foals than those with multiple males. While multi-male groups tend to be less stable and less peaceful than harems, they are inevitably larger and more varied, and therefore less vulnerable to predators like wolves. Stallions in natal bands will mate with all the females during spring and summer, and are primarily concerned with the protection of their mares and foals from bachelors. Bachelor bands are made up of young males 2–8 years old who have reached sexual maturity but not yet succeeded in attracting a mate. Much of their time is spent play-fighting and developing other skills needed to acquire mares.
The survival of contemporary wild horse populations is threatened by a range of factors, including the diminution or isolation of small populations due to human activity, leading to a loss of genetic diversity or even extinction; the potential transmission of diseases, such as Babesia caballi, from domestic horses; the risk of hybridisation with domestic horses; and the extinction of small populations due to extreme weather or intense predation.
In order to mitigate these risks and facilitate the restoration of wild horses to their original ranges, populations should be managed by a single unified body, health and behaviour should be continually monitored, and contact with domestic horses should be minimised. Increasing knowledge of extinct species should also inform the selection and conservation of horse breeds in rewilding projects, and cooperation between all reintroduction centres should be encouraged.