Endangered Siberian flying squirrel spotted for first time along Ulsan's Taehwa River

Two Siberian flying squirrels — a natural monument and Class II endangered species under the Ministry of Climate, Environment and Energy — have been confirmed living along a riverside walking trail in the middle reaches of Ulsan's Taehwa River.

Ulsan city said Tuesday that nature interpreter Lee Chan-suk first spotted one of the squirrels at around 2:20 p.m. on Sept. 9, photographing it as it peered from a woodpecker hole in an acacia tree along the Taehwa River trail. Citizen scientist and photographer Yun Gi-deuk then captured two individuals on video at the same location at dusk on Sept. 17 and Sept. 23.

Han Sang-hun, a researcher at the Korean Peninsula Wildlife Research Institute who reviewed the photos and footage, confirmed the animals were Siberian flying squirrels. "The two seen together in the video are likely a breeding pair — flying squirrels normally live solitary lives, with males and females apart," Han said.

The Siberian flying squirrel is a small rodent in the squirrel family, measuring roughly 15 to 20 centimeters in body length. It glides between trees by spreading a membrane of skin between its front and hind legs. Nocturnal, it is active from dusk to dawn and has large dark eyes and long whiskers adapted for nighttime activity. The species was designated a natural monument in 1982 and is also protected as a Class II endangered wild species.

Flying squirrels had previously been confirmed in forested areas of Ulsan, including around Seoknamsa temple in Deokbyeon-ri, Sangbuk-myeon, Ulju-gun; Baenae village in Icheon-ri; and a Japanese cypress forest on Cheonmasan in Buk-gu. This marks the first time a nest has been observed along the Taehwa River trail, a popular destination for residents.

A city official called the discovery "welcome news that demonstrates the ecological value of the Taehwa River," and asked visitors to walk quietly along the trail, noting that the squirrels sleep during the day as nocturnal animals.