One of the greatest comeback stories in the equine world belongs to the Przewalski’s horse (Equus ferus przewalskii), which went extinct in the wild during the 1960s. The species was saved in captivity and returned to the wild starting in 1992. Now living primarily in steppe and desert steppe regions of Mongolia, Przewalski’s horses are considered the only remaining wild horses in the world.
However, concerns have been growing that, due to captive breeding, the behavioral traits of the modern Przewalski’s horse have changed to an extent that may compromise prospects for the long-term survival of the species in its original habitat.
To compare the diet of today’s Przewalski’s horses to that of their extinct ancestors, researchers from the Research Institute of Wildlife Ecology from the University of Veterinary Medicine, Vienna, conducted stable isotope analysis of tail hairs taken from historic (pre-extinction) museum specimens of Przewalski’s horses and modern (reintroduced) horses now living in the Dzungarian Gobi. Because equine tail hairs grow continuously but are metabolically and isotopically inert once formed, they provide a record of an individual’s nutritional intake over a period of time.
The isotope analysis yielded evidence that a significant shift occurred in the diet of Przewalski’s horses. Prior to extinction, the species fed on nutritious grasses in the summer but were forced to also browse bushes in the winter. In contrast, modern Przewalski’s horses are year-round grass grazers.
The researchers posit that this change reflects the cessation of hunting of Przewalski’s horses by people living in the Gobi. Where once the species fled to areas where food was scarce to avoid hunters, the Przewalski’s horses now remain on grass-dominated pastures of the Gobi alongside local people and their livestock.
Reference: “Stable isotopes reveal diet shift from pre-extinction to reintroduced Przewalski’s horses,” Scientific Reports, July 2017
This article first appeared in the October 2017 issue of EQUUS (Volume #481)