CHERNOBYL — Motion-sensitive cameras in the Chernobyl exclusion zone have documented free-ranging populations of Przewalski's horses and other wildlife across a radioactive landscape larger than Luxembourg. The footage shows the horses sheltering in crumbling barns and deserted homes to escape harsh weather and insects, and bedding down inside.

The zone spans parts of Ukraine and Belarus and was established after an explosion at the nuclear power plant on April 26, 1986, sent radiation across Europe and forced the evacuation of entire towns, displacing tens of thousands. Four decades later, the area remains too dangerous for humans, and personnel rotate in and out to limit radiation exposure.

Przewalski's horses were introduced to the zone in 1998 as an experiment. Many died after their arrival, but others adapted and now form small social groups, typically one stallion with several mares and their young, alongside separate bands of younger males.

"The fact that Ukraine now has a free-ranging population is something of a small miracle." said Denys Vyshnevskyi, the zone's lead nature scientist. He often drives alone for hours setting camera traps in camouflaged casings attached to trees to track the horses.

Wolves prowl the zone, brown bears have returned after more than a century, and populations of lynx, moose, red deer and free-roaming packs of dogs have rebounded. Scientists have not recorded widespread die-offs among wildlife despite persistent radiation, though some frogs have developed darker skin and birds in higher-radiation areas are more likely to develop cataracts. Fires can send radioactive particles back into the air.

Parts of the zone now resemble European landscapes from centuries past. Trees grow through abandoned buildings, roads are overgrown by forest, and weathered Soviet-era signs stand beside leaning wooden crosses in overgrown cemeteries.

"Nature recovers relatively quickly and effectively," Vyshnevskyi said. "For those of us in conservation and ecology, it's kind of a wonder. This land was once heavily used — agriculture, cities, infrastructure. But nature has effectively performed a factory reset." Chernobyl is likely to remain off-limits for generations due to radiation hazards, yet it remains full of wildlife.