Dr Monica Vasile, PhD Candidate

Scholars warn we are currently facing a mass extinction event. To support this claim, they estimate catastrophic extinction rates. By comparison, the number of documented extinctions validated by the International Union for Conservation of Nature Red List is tiny. Documenting the fact that a species is no more, or that it draws near the brink, proves to be a difficult task, prone to contention. Even for conspicuous species living in wide-open spaces, such as the Przewalski’s horse in the Mongolian steppes, expeditions and sightings were shrouded in controversy. How does one prove that a species has disappeared from the wild? This blog gives a glimpse into what it means to survey the wilderness and document the elusive existence of endangered species. It offers a snapshot into how humans have encountered and argued over the last surviving free-living Przewalski’s horses in the 1960s.

Scholars warn we are currently facing a mass extinction event. Some experts calculate 24 species are lost a day, others 150. Recorded numbers of past extinctions are tiny by comparison: only about 900 extinctions having been documented in the past 400 years, according to the IUCN Red List. Another 688 animal species are listed as possibly extinct, yet the gap between estimative mathematical models and empirical research is still huge, suggesting that we are swimming in a sea of unknowns (and of conservative stringent criteria). Searches for animals suspected extinct but fancied extant were organized often during the 20th century and some have yielded the animals, while others have only yielded controversy. In sheer optimism, the official Red List assessment states that the Turquoise-throated Puffleg (Eriocnemis godini), a hummingbird from Ecuador, “has not been recorded since the 19th century (..) However, it cannot yet be presumed to be Extinct because there was an unconfirmed record in 1976…” Bachman’s warbler (Vermivora bachmanii), a tiny golden-winged passerine, “cannot yet be presumed to be Extinct until all remnant patches of possible breeding habitat have been searched”, the swampy blackberry brambles and cane thickets of the southeast United States. Even the survival of conspicuous animals inhabiting wide-open areas, like the Przewalski’s horse (Equus ferus przewalskii) in the Mongolian steppes, was for many years shrouded in disagreement. How does one become certain that a species is no more? How does one document extinction?

Herd of Przewalski’s horses reintroduced in Hustai National Park, Mongolia. Photo by Kelsey Rideout. Creative Commons license.

In the summer of 1966, the Hungarian entomologist Zoltán Kaszab led an expedition to Mongolia. Looking to collect beetles, the expedition drove through scenic mountain steppes following old caravan roads, dry riverbeds in a barren habitat of pastures, gravels and sandhills close to the Chinese-Mongolian border. One day, they reached a mountain plateau, two thousand meters high, Takhiin Shar nuruu (Yellow Wild Horse Mountain Range). They sighted a troop of animals galloping away in the distance, which they recognized as Przewalski’s horses – a stout sandy-bay horse with a jumpy character and a white muzzle, considered to be the last undomesticated species of horse on earth. By then, these free-living horses were presumed rare or even extinct in the wild. IUCN estimated about forty left in the wild in 1958. Only captive horses bred in zoos prevented complete extinction. In 1966, 133 Przewalski’s were in zoos worldwide, descendants of thirteen animals captured by traders at the beginning of the 20th century.

Kaszab’s account was confident, “[m]y Mongolian companion, Namkhajdorj Balgan, recognized them at once with the naked eye as Przewalski wild horses, and subsequent observation with a telescope confirmed beyond any possible doubt that this was what they were (…)”. But Jiří Volf, the keeper of the zoo-bred Przewalski’s horse studbook (breed registry) at Prague Zoo, questioned the accuracy of this sighting, “I find it pretty unlikely to tell apart wild horses from kulans [wild asses, Equus hemionus hemionus] with binoculars, even less with the naked eye, in the steppe – where the air vibrates strongly in summer – at a distance of a few kilometers(!)”. Kaszab had failed to produce accurate photographs. When the horses appeared, he only had two exposures left on film, and in the race to get nearer, it was impossible to load the cameras. He took two contrejour photos and one showed the horses only from behind. From these, Volf conjectured the animals were too light-coloured and too rectangular-shaped to be Przewalski’s. He claimed that in fact all reported sightings of the previous twenty years were doubtful. He was not alone in this; other scientists also believed the horses were already extinct in the wild.

Zoltán Kaszab in Eastern Mongolia, near the village of Cagan Nuur, June, 1968 (photo: Z. Kaszab)

Sightings were prone to contention – extremely chancy, abrupt, and often vague. These animals survived precisely because they eluded human contact in the most unforgiving of environments. And even when ‘accepted’ sightings occurred, it remained unclear what it meant that one or two animals were sighted over an interval of twenty years, despite systematic searches. Was this not a proof of certain imminent extinction?

Kaszab considered Volf’s objections unfair. He was sure of what he saw, and even surer of what his Mongolian colleague saw. His photographs were low quality indeed, but he had not intended them as evidence for identification. Moreover, a Mongolian expedition by reputed scientists confirmed another sighting at the same place one year later. He concluded it was a fact that Przewalski’s still survived. Volf’s distrust was based on a previous Czecholslovak expedition (his co-nationals) and four other scientific expeditions, which failed to find wild horses. Perhaps he was also jealous, and thought that the captive zoo Prezewalski horses, which he carefully registered and cared for, were unique.

Volf might have also too readily dismissed Mongolians’ knowledge. One year after this debate, Ivor Montagu – famous British filmmaker, table tennis player, supposed spy, communist activist, and a member of the Fauna Preservation Society – sided with the ‘sighters’, and disclosed Volf ‘s dismissive opinions expressed in a letter, “He argues that Mongolian herdsmen lack knowledge of the difference between the takh (the horse) and the kulan (…) He says that few Mongolian zoologists have competence in mammalogy”. Montagu thought herdsmen can ‘distinguish between horses and asses when they please’, and Mongolian scientists know best how to judge the herdsmen reports (who were conscientious enough to send telegrams to zoologists to request verification).

Painstaking surveys and copious debates took place to document Przewalski’s horse extinction in the wild. The last recorded sighting by a Mongolian scientific party was in 1969, a lone stallion by a water source. From then on, the Red List recorded the species as extinct in the wild. But divergences, and hopeful expeditions, continued into the 1970s, as some believed the horses were hanging on in small numbers in the wilderness of the Gobi-Altai. Hunted, driven away from freshwater sources by domestic herds, and decimated by the dzud – unforgiving winter frosts, the free-living Przewalski’s horses waned away.  Yet, while they were nearing the brink, the captive population was growing. Reintroduction programs since the 1990s have been achieving some success and their current Red List status has been updated to endangered.

Monica Vasile is a PhD Candidate at Maastricht University and works in the project Moving Animals: A history of Science, Media and Policy in the Twentieth Century. She studies the history of animal reintroductions: how reintroduced animals such as the Przewalski’s horse became managed and understood during the 20th century. Her previous research concerned the political ecology of forests, commons and pastoral practices in the Carpathian Mountains. She holds a doctorate from University of Bucharest (awarded 2008), and held research positions at the Rachel Carson Center for Environment and Society in Munich and the Max Planck Institute of Social Anthropology in Halle.


Boyd, L, and KA Houpt. 1994. ‘Przewalski Horse–the History and the Biology of the Endangered Species, State Univ’. New-York Press, Albany.

King, Sarah RB. 2005. ‘Extinct in the Wild to Endangered: The History of Przewalski’s Horse (Equus Ferus Przewalskii) and Its Future Conservation’. Mongolian Journal of Biological Sciences 3 (2): 37–41.

Tsevegmid, D., and A. Dashdorj. 1974. ‘Wild Horses and Other Endangered Wildlife in Mongolia’. Oryx 12 (3): 361–70.