NAHA, OKINAWA PREF. – A critically endangered flightless bird found only in northern Okinawa Island is under increasing threat from vehicles, which killed a record number this year, according to officials at the Environment Ministry’s Yambaru Wildlife Conservation Center.
With many paved roads running through the core of the forested habitat of the Okinawa rail, whose existence was confirmed just three decades ago, 34 of the birds were fatally struck by vehicles this year, up from 33 for all of last year and 20 in 2009.
By contrast, the number of bird kills between 1995 and 2004 totaled 26.
“The reason for this sharp increase remains unclear, but we believe the birds may be more frequently coming out onto the roads to find food, having gotten used to people and cars,” said Makoto Fukuda, an official at the conservation center.
“We’re asking people to drive slowly and remain especially vigilant when traversing areas where rails and other precious forest creatures like the Ryukyu long-haired rat are more likely to appear,” he said.
Fukuda said the rails are most likely to be struck by vehicles in early mornings and early evenings when the birds feed on earthworms, snails and other small creatures they find along the road or among leaves in roadside gutters.
Twenty-six of the run-ins with vehicles so far this year proved fatal, compared with 31 last year. Of this year’s eight surviving birds, five have been released back into the wild after recovering — another record.
The rail, which was designated by the central government as a natural monument in 1982, inhabits only the Yambaru region in the northern quarter of Okinawa Island. Okinawa is home to a number of rare species found nowhere else in the world.
Extensive road construction in heavily forested, sparsely populated Yambaru poses a major threat to the rail, though it has also suffered from a loss of habitat through logging and from predation by the introduced Javan mongoose, as well as by feral dogs and cats.
A 2001 survey estimated there were 1,200 rails remaining in the wild, but a survey four years later put the figure at only 717. The decline prompted the Environment Ministry in 2006 to move the rail into the critically endangered category of its Red Data List for birds.
The population has since recovered to around 1,000, but wildlife officials think the increase alone does not account for the higher number of road deaths, nor does better accident reporting by the public in recent years stemming from increased awareness of the rail and its importance.
Vehicle traffic also poses a serious threat to other wildlife in subtropical Yambaru, which hosts a whopping 48.1 percent of all bird species in Japan, 35.9 percent of its amphibian species, 19.5 percent of its reptile species and 7.4 percent of its mammal species.
Fukuda noted that this year has seen a record number of the large, nocturnal Ryukyu long-haired rat, which is also designated as a natural monument, killed by vehicles.
The center is working with more than two dozen other groups to implement the “Stop Roadkill” campaign to save not only the rail and the rat but also other vulnerable, rare species that fall victim to traffic along Yambaru’s forest roads, including the Anderson’s crocodile newt and the Ryukyu black-breasted leaf turtle.