An invasive Reeves' muntjac deer, known as kyon, damaged crops at Suzuki Farm in Koga City, Ibaraki Prefecture, by eating grape clusters [1].
The incident signals a growing threat to Japanese agriculture as the species expands its territory. Experts warn that if the muntjac becomes established in Ibaraki, it could lead to a risk of the animal spreading across the entirety of Honshu [1].
At the vineyard, Hiroaki Suzuki said the animal consumed approximately one bunch of grapes [1]. Suzuki described the experience of encountering the animal for the first time, noting that while it appeared cute at first glance, the presence of tusks created a sense of fear.
"If you are just watching, they are cute," Suzuki said. "But it is unbearable when they eat the grapevines. They are eating so much. Stop it, stop it" [1].
The spread is driven by the animal's broad diet and high reproductive capacity [2]. The population growth has been rapid in neighboring regions; in Chiba Prefecture, the population approximately doubled over a nine-year period ending in the 2024 fiscal year [1].
Local authorities in Ibaraki have attempted to monitor the spread of the species. In some instances, a reward of 2,000 yen has been offered for the photography of the muntjac to help track its movement [3].
Suzuki said he was surprised at the animal's presence in his fields. "I was really surprised," Suzuki said. "I felt like it was the first time I had ever seen an animal called a kyon" [1].
“"If you are just watching, they are cute," Suzuki said. "But it is unbearable when they eat the grapevines."”
The movement of the Reeves' muntjac from Chiba into Ibaraki represents a critical geographical shift. Because these animals are highly adaptable and reproduce quickly, their establishment in new prefectures creates a stepping-stone effect that could facilitate a colony-wide expansion across Japan's main island, potentially leading to widespread agricultural losses and disruption of local ecosystems.
