They descend on towns and villages, plundering crops and rampaging through homes. They occasionally attack humans. But perhaps most dangerous of all, the marauders carry with them highly radioactive material.

Hundreds of toxic wild boars have been roaming across northern Japan, where the meltdown of the Fukushima nuclear plant six years ago forced thousands of residents to desert their homes, pets and livestock. Some animals, like cattle, were left to rot in their pens.

As Japan prepares to lift some evacuation orders on four towns within the more than 12-mile exclusion zone around the Fukushima plant later this month, officials are struggling to clear out the contaminated boars.

Wild boar meat is a delicacy in northern Japan, but animals slaughtered since the disaster are too contaminated to eat. According to tests conducted by the Japanese government, some of the boars have shown levels of radioactive element cesium-137 that are 300 times higher than safety standards.