Much to my shame, I spent ages thinking “onager” was some kind of sports brand.

It’s actually a sub-species of wild ass (yes, yes), but it would be an awesome name because unlike some other equids, it’s never been tamed. And to put an extra feather in its cap of “wild and free”, it’s one of the fastest horses in the world, clocking up to 70kmh (43mph). This makes sense when it has to outrun environmental disasters like droughts and heatwaves.

Nomadic and sporadic

I don’t mean in some kind of slow-motion blockbuster sequence, more like migration across vast tracts of desert and salt plains to find water, food and the best breeding partners. Despite being a hardy beast, getting most of its moisture from bare shrubs and grass, it still needs to stay within 20km (12 miles) of a water source, and if you’re a wily female or a strong and smart male, this is where you will head.

Brood barons

Like some other equids, females congregate in herds, while a single male will either boss about his own harem, control the territory with the best resources, or both. The females move between each depending on preference, because quality is better than quantity when you only breed every other year and your foal has a 50% chance of survival.

In Nowzari et al.’s 2013 study in Iran’s Qatrouiyeh National Park, they found that mares with foals bagged areas with the best vegetation and water, while the others seemed happy slumming it further out. Almost all of them, however, took shelter in valleys during cold winds and rain, and on the plains during temperatures up to 44°C(111°F). Of course, for those outside the park, space can be at a premium when there’s cattle about, and international barriers can put the kibosh on an epic journey. And love, for that matter.

Obstacle horse

There are just two wild onager populations left, both in Iran, but previously there was a group on the edge of Turkmenistan too, with any potentially star-crossed lovers separated by the border. Farmland slap bang in the middle of their route also complicates migration, and tasting crops usually only gets them a taste of metal. Add to this poaching, sometimes on motorbike, for their hide, meat, or liver for medicinal purposes, and it’s no surprise their numbers are down to around 600. But human intervention isn’t completely awful.

The art is so-so too.

Wild guard

Extra water and hay to cope with droughts has boosted its numbers, and upgrading part of Bahram-e-Goor protected area to the aforementioned National Park has given the onager more space to run free. Of course, a spirit of the wild hates being handled by humans – Vick et al. found traces of extreme stress in some females, even 24 hours afterwards – but it can adapt to new environments fairly quickly, so captive breeding isn’t off the table. In fact, the Smithsonian Conservation Biology Institute bred two foals in 2011, and we even have good specs for freezing its sperm.

Well, if technology took the onager from the wild in the first place, the least it can do is help it back out there again!


Latin: Equus hemionus onager, although it has occasionally been treated as its own species Equus onager.

What? Wild sub-species of horse-like donkey, or “ass”, never tamed by humans. Stop laughing, that’s what it’s called. Well, that and the Persian or Iranian onager.

Where? There are just two wild populations left in protected areas of Iran, namely Bahram-e-Goor and Touran.

How big? 1.5 metres / 4 feet at the shoulder, and 2 metres / 6.5 feet long.

Endangered? Yes, there are fewer than 600 wild onagers left, thanks to competition with cattle, poaching, and breakup of migration routes, making water and food hard to find in extreme weather.

Probable motto: You couldn’t put stuff on my back, so now you’re putting stuff in my way.

They look beautiful. Do they need my help at all?

Yes. Due to poaching, competition with cattle, and man-made obstacles between breeding and drinking areas, their numbers have plummeted.

Chester Zoo in the UK offers onager adoptions to help fund conservation efforts, and in the US, the Smithsonian’s National Zoo and its Conservation Biology Institute has a joint breeding programme with The Wilds in Ohio.

Just to prove I’m not fibbing:

Dinerstein, Eric. No date. “Onager“.

Equus hemionus spp. onager“. No date. IUCN Red List of Threatened Species.

Evans, Andrew. 2011. “Baby onager“. National Geographic.

Nowzari, Haniyeh et al. 2013. “Habitat use by the Persian onager, Equus hemionus onager (Perissodactyla: Equidae) in Qatrouyeh National Park, Fars, Iran“. Journal of Natural History 47(43-44):2795-2814.

Onagers“. No date. Chester Zoo.

Pablos, María Teresa Prieto et al., 2015. “Cryopreservation of onager (Equus hemionus onager) epididymal spermatozoa“. Journal of Zoo and Wildlife Medicine 46(3):517-526.

Persian onager“. No date. Smithsonian’s National Zoo and Conservation Biology Institute.

Tizrouyan, Hamed. 2016. “Onagers on the verge of extinction“. Tehran Times.

Vick, Mandi M. et al. 2011. “Glucocorticoid response to changes in enclosure size and human proximity in the Persian onager (Equus hemionus onager)“. Stress 15(1):52-61.

Featured image credit: “Persian onagers” by Ann Zalek, ©