Why Does Chiba Prefecture Have No Bears? Expert Explains Geography and History

By Yuto Okada / Yomiuri Shimbun Staff Writer

21:06 JST, January 24, 2026

CHIBA — As serious injuries caused by bears rise, particularly in northeastern Japan, Chiba Prefecture stands out as the only prefecture on Honshu where bears do not live. There is no historical evidence of bears in the prefecture either. A researcher points to several possible reasons, including the fact that a vast urban belt lies between Chiba and the wooded mountain areas of neighboring prefectures where bears are found, making it difficult for bears to reach Chiba.

“There are no bears in Chiba, and the chances of them coming here in the future are low,” said Sayaka Shimoinaba, a researcher at the Natural History Museum and Institute, Chiba. According to Shimoinaba, there are no records in the prefecture of bears being captured, nor have archaeologists unearthed substantial bear remains that would confirm their presence. She added that local histories of counties, towns and villages from the Meiji era (1868–1912) through the Showa era (1926–1989), as well as folk tales, also contain no indications that bears ever lived there.

Japan has two species of wild bears: the brown bear, which lives only in Hokkaido, and the Asian black bear, which inhabits Honshu and regions farther south. The Asian black bear once lived on Kyushu, but it is believed to have gone extinct there. On Shikoku, the population is small and feared to be at risk of extinction.

On Honshu, Chiba — along with neighboring Ibaraki Prefecture and Osaka Prefecture — was long considered bear-free. But in Ibaraki, a carcass believed to have been hit by a car was found in 2006, followed by additional sightings. In Osaka, the first bear was captured in 2014. That left Chiba as the only bear-free prefecture on Honshu.

Even looking back as far as the Jomon period (ca 10,000 B.C.–ca 300 B.C.), no trace of bears has been confirmed in Chiba.

At Jomon-era sites across the prefecture, including shell mounds, archaeologists have excavated bones of deer, wild boar and other animals. Complete sets of bones have been found, suggesting those animals lived near the settlements at the time. As for bears, however, while fragments of bone believed to have been used as ornaments have turned up, no substantial remains — such as a clustered set of bones — have been discovered.

One theory suggests that due to the Holocene glacial retreat, which caused sea levels to rise as temperatures increased, the Boso Peninsula was an isolated “island” separated from Honshu at that time. However, Shimoinaba said, “To be honest, we don’t really know.”

She also said it is unlikely that bears could make their way into Chiba from areas where they are known to live, such as western Tokyo, western Saitama and northern Ibaraki. The prefectural border consists largely of plains that are not suitable bear habitat, and the surrounding urban sprawl creates an additional barrier. Passing such hurdles and entering Chiba would be difficult, she said.

Even if a bear did reach Chiba, it is unclear whether it could survive there long term. The area of forest considered suitable habitat is limited, raising doubts about whether a stable population could be sustained. While some tree species in the prefecture’s forests could provide food, Shimoinaba said the forested area is not large enough for bears to establish themselves.

“Given what bears are capable of, the chance that one could wander into Chiba by accident may not be zero,” she said. “But even if one did, it wouldn’t take hold here.”