YOMIURI SHIMBUN (Tokyo, Japan) 17 October 10 Cane toads threaten Ishigakijima ecosystem
Okinawa: Tens of thousands of cane toads have apparently spread throughout Ishigakijima island in Okinawa Prefecture, raising concerns about their impact on the ecosystem of the island's indigenous organisms.
Cane toads are 8 to 16 centimeters long, produce a strong toxin, are voracious eaters and have strong reproductive abilities. They lay up to 50,000 eggs at once.
According to the Environment Ministry's Ishigaki Ranger Office, about 30,000 to 50,000 cane toads are estimated to live across the island. The office is seeking islanders' cooperation in capturing cane toads, due to concerns they may invade neighboring islands, such as Iriomotejima, which is home to critically endangered Iriomote wildcats.
Several cane toads reportedly were brought to Ishigakijima island in 1978 to help exterminate the Anomala albopilosa scarab beetle, which is harmful to sugarcane.
According to the Ishigaki Ranger Office, a cane toad consumes about 600 kilograms to one ton of food a month. This has led to fears of a drop in the number of cicadas and stag beetles, species native to the island.
The increased number of cane toads also is likely to disturb the ecosystem of Utsunomiya's tip-nosed frog, designated an endangered species in the Environment Ministry's Red Data Book.
When a cane toad feels threatened, it releases a milky white poison from the salivary glands beside its eyes. Humans are not harmed by touching the toxin, but if snakes or birds eat the toads, the poison can kill them.
The ranger office began asking the island's residents to become "cane toad hunters" in 2008, and 88 residents registered this year. In the hunting season from Sept. 18 through Oct.11, they captured a record number of about 6,500 cane toads.
Cane toads threaten Ishigakijima ecosystem