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Japan wrestles with Formosan muntjac invasion

Small deer with cute-scary faces and an even worse bark are taking over parts of Japan

A Formosan Reeves' muntjac in Taichung. (, Tom Visbeek photo)

A Formosan Reeves' muntjac in Taichung. (, Tom Visbeek photo)

TAIPEI (Taiwan News) — Taiwan's indigenous Formosan Reeves’ muntjac is causing terror in Japan where it is spreading quickly in the wild, eating crops, and scaring the natives.

In addition to a face with exposed scent glands, tusks, and mini-horns, the muntjac's bark is considered strange and can go on for hours, according to a NOWnews article earlier this week. It added that since the muntjac are quick and smart they are hard to hunt, while locals were quoted as saying the muntjac cannot be trapped like wild boars because they are more agile and have thinner legs.

They can also jump up to 3 meters in height. Furthermore, modified traps cannot be set for fear of trapping cats.

The report added that Formosan Reeves’ muntjac were introduced to Japanese zoos starting in the 1960s. They escaped from a zoo on Oshima Island in 1970 when a typhoon blew down the fence and started breeding in the wild.

There were estimated to be at least 60,000 of the animals in Boso Peninsula in 2017, per Alchetron, and an annual population growth rate of about 15%. The current figure is said to stand at around 71,500 muntjac, with one Chiba resident quoted as saying. “These muntjac will eat our cherries, tomatos, and other crops as food, which has harmed the livelihood of local farmers. The most terrifying thing is its cry of, "Ah! Ah! Ah!"

Japan wrestles with Formosan muntjac invasion
Baby muntjac. (Wild Wonders of China photo)

There have been attempted culls of the animals but were judged to have failed dismally.

The Formosan Reeves’ muntjac (Muntiacus reevesi micrurus) is a subspecies of the Reeves' or Chinese muntjac. It has been described as a medium-to-large-dog-sized type of deer with short small horns, tusks, and prominent face glands — which have gained some international fame, of sorts.

Japan is concerned that in addition to the problems it causes to humans, Formosan muntjac are harming the local flora and fauna. Muntjac have spread over much of the world in zoos and so on, but there are also significant wild populations in parts of Japan, the Netherlands, and the U.K.

The U.K.'s Daily Mail calls the muntjac "a wolf in deer's clothing" that is taking over the country. They are said to devour gardens and woodland and breed like rabbits.

In addition to the males of the species having small horns, they also have huge face glands that are said to swell alarmingly like balloons with air, by Science Focus. The two sets of scent glands are used for mating, fighting, and territorial display. When the glands are inflated they let off a personalized smell that reveals the deer's sex, age, health, and even rank.

Japan wrestles with Formosan muntjac invasion
(Getty screenshot)

More fun facts

  • The Formosan Reeves’ muntjac is one of three deer species native to Taiwan
  • A muntjac is not much different from its fossil ancestor 4 million years ago
  • It weighs between 5-12 kg, 40-70cm long, with a tail length of 4-10cm
  • It is clay with a dark brown color at the back
  • Youngsters have white spots on their bodies
  • It forages alone in low-high altitude mountain forests throughout Taiwan
  • It is a crepuscular animal, meaning it goes out at dawn and dusk
  • Traditionally, it was hunted by Indigenous tribes for food, fur, and other items
  • Sightings suggest Formosan Reeves’ muntjac populations in Taiwan are increasing.
  • The Formosan muntjac is said to have evolved independently from its Chinese ancestor after the land bridge connecting Eurasia and Taiwan became separated about 10,000 years ago.

Japan wrestles with Formosan muntjac invasion
(Taipei Zoo screenshot)