While dozens of zoos worldwide have Przewalski's horses in small numbers, specialized reserves are also dedicated primarily to the species. The world's largest captive-breeding program for Przewalski's horses is at the Askania Nova preserve in Ukraine. From 1998, thirty one horses were also released in the unenclosed Chernobyl Exclusion Zone in Ukraine and Belarus, evacuated after the Chernobyl accident, which now serves as a deserted "de facto" nature reserve. Though poaching took a toll on numbers, as of 2019 the estimated population in the Chernobyl zone was over 100 individuals.