Japanese zoo culls 57 snow monkeys with 'invasive alien' genes by lethal injection

A zoo in Japan has culled 57 snow monkeys by lethal injection after discovering that they carried “invasive alien” genes.

Officials at Takagoyama Nature Zoo in Futtsu city, Chiba Prefecture, conducted the cull after finding out that a third of its 164 resident monkeys were not pure Japanese macaques.

A total of 57 monkeys were found through DNA testing to have been crossbred with the rhesus macaque, which is designated an “invasive alien species” and banned from possession according to a Japanese law passed in 2013.

The monkeys were subsequently put to death by lethal injection over a period of one month before the zoo operator reportedly held a memorial service for them at a nearby Buddhist temple.

“They have to be killed to protect the indigenous environment,” an official from Chiba Prefectural Government told local media, referring to the legally required culling of snow monkey rhesus macaque crossbreeds.

Japanese snow monkeys have long been a popular attraction living in sub-zero temperatures in many snow-covered mountainous regions of the country during the winter months.

The monkeys, which have distinct red faces and light brown fur, can often be found taking a warming bath in volcanic hot spring “onsen” baths in the wild.

The zoo reportedly began feeding wild snow monkeys in 1957, with an adjacent mountainous area subsequently designated a wild habitat for the simians.

The rise of rhesus macaques in the area - whose indigenous habitat is China and Southeast Asia - began during the 1990s, with regular culls carried out in the wild by officials to curb numbers since then.