In this Friday, February 6, 2015 photo, sandhill cranes begin to stir after resting for the night at a roosting location along their winter migration route in Cecilia, Ky. According to counts made by biologists with the Kentucky Fish and Wildlife Resources, about 12,000 of the birds have stopped in Cecilia this week during their winter northward migration on their way to their nesting grounds in the Great Lakes region. (Photo by David Stephenson/AP Photo)

The camera rolls as actors dressed as historical Chinese soldiers act as though they have been hit by artillery, during filming of “The Last Prince” television series on location near Hengdian World Studios near Hengdian July 24, 2015. Hundreds of well-trained actors and other professionals are available at the Hengdian World Studios. The well-organised team coordinate complicated battle scenes to satisfy the huge appetite for productions about the war against Japan. (Photo by Damir Sagolj/Reuters)

Sri Lankan flood victims flock around a bus to receive food parcels on a inundated road in Colombo, Sri Lanka, Tuesday, May 17, 2016. The Disaster Management Center said that 114 homes have been destroyed and more than 137,000 people have been evacuated to safe locations as heavy rains continue. (Photo by Eranga Jayawardena/AP Photo)

British underwater photographer of the year – winner. “Love Birds” by Grant Thomas (UK). Location: Luss Pier, Loch Lomond, Scotland. Thomas’s initial idea was to frame a split shot of one swan feeding below the surface of the water but when he noticed how comfortable they were around him he was confident, with some patience, he could get that magical shot of the two. (Photo by Grant Thomas/UPY 2018)

A man walks on a slackline during the 7th edition of the European “Marmotte Highline Project” (MHP) festival in Lans-en-Vercors, near Grenoble, eastern France, on July 4, 2019. The event, during which the participants will be able to evolve on the various highlines located in the Regional Natural Park of Vercors, takes place until July 7, 2019. (Photo by Philippe Desmazes/AFP Photo)

Only after World War II did the secret spill: Ōkunoshima, located in the Inland Sea of Japan between Hiroshima and Shikoku, was the top-secret site for manufacturing chemical warfare. When the factories were closed down, a number of exotic wild rabbits were seen freely roaming the island. They were assumed to have been the test subjects for the chemical weapons, which the military failed to eradicate when the factory was demolished.