The Law of Unintended Consequences

During my morning walk, I observed a mongoose for the second time as it crossed the path in front of me. The mongoose was introduced to Okinawa in 1910 to control the venemous Habu snake, however, that logic has backfired. The mongoose is a nocturnal predator, while their intended prey hunts during the day. Since their introduction to Okinawa, the mongoose (and feral cat) population has expanded resulting in negative effects on species of native birds, mammals, and reptiles. Mongoose readily eat eggs and young and have contributed to the decline of rare bird species such as the Okinawa Rail and Pryer's Woodpecker.

Mongoose

Controlling the mongoose and feral cat population is key to preserving these endangered species. When Joanne & I were hiking up north this past weekend in the Yanbaru forest, we observed many live traps set along the trail as part of an ongoing mongoose & feral cat eradication program. Although we didn't see any captured animals (or Habu), we did see a van along the road with a several men resetting traps. (BTW, I did see my first Pryer's Woodpecker, a bird endemic only to northern Okinawa.)

Mongoose in Trap

And in case you were wondering,Trimeresurus flavoviridis, or the Okinawan Habu, is a true pit viper averaging 4-5 feet in legth. They are not typically aggressive but will bite if provoked. Until recently over 300 people in a year used to be bitten by the snake while working in the field or in one’s garden. The snake often occurs in close proximity to country homes in search of rats and mice and it is not uncommon to encounter one inside houses, barns, etc. Though fatal cases are rare since the intoduction of anti-venom, Habu-biting incidents still number about 100 a year in Okinawa. Its potent venom combined with its nasty temperment is feared and revered in the islanders’ mind.

Habu