The Przewalski horse: being wild in the wild (Part 10)

Reintroducing Takhis in East Asia is a long term process with a threefold objective: establish viable populations in parts of the horse’s historic range, restore degraded steppe ecosystems and foster socio-economic development, which in turn would guarantee the long term success of reintroduction.

When the first reintroduction program was launched in the late 1970’s, the Przewalski horses had been living in captivity for almost a century. To return to their native steppe, they first had to learn to be wild again. In addition to reducing genetic diversity, captivity had made the horses entirely dependent on men for their survival and inhibited their most basic instincts. In this context, reintroduction would be a marathon and a complex learning process for the horses.

All reintroduction projects consist of various stages that stretch over many years. They start with choosing the most suitable individuals and bringing them together as functional social groups. Preference is given to horses whose bloodlines best represent the founders’ genes and inbreeding coefficients are the lowest because they have more chances to successfully readapt to the harsh steppe environment. A veterinarian also checks the horses for clinically apparent, non hereditary diseases such as ataxia, a central nervous system disorder that prevents coordination of voluntary muscular movements[1]. The selected horses are first placed in semi-wild reserves where they can regain their natural instincts with minimal human interference. They are then transferred to large acclimatisation enclosures situated near the reintroduction site, where food, water and shelter are naturally available. Takhis are kept there as long as is necessary for them to adjust to their future environment (from one to several years) and for project managers to minimize local hazards. Eventually, the horses are released into the wild, but remain closely monitored until it is considered that populations have reached sustainable thresholds.

For Takhis, becoming wild again meant to learn how to live together as a social and reproductive family group, also called a band. Wild horse bands typically comprise a dominant stallion, a few mares (the harem), foals and yearlings. Two year old colts are typically chased away by the dominant stallion but may be tolerated. The stallion is responsible for structuring the band, ensuring its stability and for mating. Under the guidance of the lead mare, the horses seek food, water and shelter on their own year round. Stallion and lead mare pair up for protection: the stallion protects the rear biting and kicking while the lead mare leads the horses to flee[2].

Przewalski horses did not instinctively fall back into these normal roles and patterns. In the beginnings, deviant, aggressive behaviors were observed in reintroduced adults. Stallions confronted each other in sterile fights, which diverted them from their duty as genitor and structural element of the band, while other members failed to develop collective instincts[3]. Groups lacked cohesion, were regularly disorganized and reproduction was not ensured[4]. Natural instincts were slow to kick in even in wild born foals[5].

Przewalski horses from Le Villaret, Causse Méjean, Lozère, France

Przewalski horses from Le Villaret on the Causse Méjean, Lozère, France / Credit: Ancalagon

To remedy this situation, some breeding places relied on positive inter-species interactions. At the French site Le Villaret, Takhis were put together with deer and bison herds to provoke instinctive reactions and positive synergies, a successful experiment[6].

However, time is the bottom line: Przewalski horses have proven capable to adapt to the demanding East Asian steppe environment over time. An example of this dynamic process is the foaling time at Hustai National Park (Mongolia). The first released mares were conditioned to give birth in April-May, which are the months with the highest natality rate in Europe. On the Mongolian steppe, winters extend until late May, so foal mortality was significant at first. Gradually, foaling dates shifted to late May, June and even July, which resulted in higher life expectancy for the newborns. Another illustration comes from the horses reintroduced at the Kalamaili Nature Reserve (China). Semi-desert vegetation predominates in this region and Takhis initially struggled to survive due to limited water sources and food[7]. Progressively, the horses adjusted to the conditions of their new, rough environment and recent studies indicate that they behave differently from those reintroduced in milder areas[8].

The growth of Przewalski horse populations in their respective reintroduction sitesis a measure of their ability to adapt. There are nowover 450free ranging individuals for a rough total of 2,000 worldwide. As a result, the International Union for Conservation of Nature (IUCN)  reclassified the species from “Extinct in the Wild (EW)” to “Critically Endangered (CR)” in 2008, and then to “Endangered (EN)” in 2011, which acknowledges the undeniable success of the reintroduction programs.

Continue reading about the Przewalski horse: Part 1 I Part 2 I Part 3Part 4 I Part 5 I Part 6 I Part 7 I Part 8 I Part 9 I Part 11 I Part 12

REFERENCES – [1] Definition from the Merriam-Webster online dictionary. Foundation for the Preservation and Protection of the Przewalski Horse[2] The Horse, the Wheel, and Language: How Bronze-Age Riders from the Eurasian Steppes Shaped the Modern World, David W. Anthony, Princeton University Press, 2010, p 197. Reduction of inbreeding in a natural herd of horses, P. Duncan et al., Animal Behavior (1984) 32, pp 520-527. [3] Le cheval de Przewalski, video-documentary by Guillaume Lévis. [4] Le cheval de Przewalski, video-documentary by Guillaume Lévis. [5] Le cheval de Przewalski, video-documentary by Guillaume Lévis. [6] Le cheval de Przewalski, video-documentary by Guillaume Lévis. [7] The Przewalski Horse Newsletter (2006) from the Foundation for the Preservation and Protection of the Przewalski Horse. [8] Resource use, time budgeting, and Social Behavior of Reintroduced Przewalski’s Horses in Kalamaili Nature Reserve, China, J. W. Chiu, in Ecology & Evolutionary Biology, Princeton University, 2012.

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