If you thought Snakes On A Plane was an improbable action film, you might be surprised to learn there is some historical truth to it, although these reptiles are coming to Hawaii, not leaving it. Snakes have been stowing away on planes for more than 70 years, with diabolical consequences for Pacific bird life. New research on the venom of the snakes involved has revealed the threat to island birds is greater than previously realized.
Guam used to have 14 native bird species and no snakes. In the 1950s brown tree snakes, native to Australia, were sighted on the island, and thereafter people noticed falling bird numbers. Eventually, it was realized the snakes had slithered up the landing gears of military planes during the Second World War and made their way to the island.
Brown tree snakes (Boiga irregularis) have a venom that although "not dangerous to humans, is 100 times more toxic to birds than to mammals,” Dr Bryan Fry of the University of Queensland said in a statement. Consequently, Guam now has three surviving species of native birds. Having not encountered a snake for millions of years, the other birds didn’t have time to evolve survival mechanisms.
US military planes fly frequently between major bases on Guam and Hawaii, where the rich native bird life is just as unfamiliar with snakes as Guam’s used to be. If a pregnant snake, or breeding pair, make the journey the consequences will be horrific. Fry told IFLScience planes putting down their landing gears for arrival in Hawaii have had brown tree snakes fall out.
Snake-sniffing dogs have been deployed to try to catch the stowaways, but Fry told IFLScience; “No method like that will ever be 100 percent effective.”
Fry reports more bad news in a study of the venom of brown tree snakes and their relatives published in the Journal of Molecular Evolution.
He explained to IFLScience it used to be thought there was something distinctive about the brown tree snake that made it a “super-pest”. However, he and his colleagues found the bird-killing molecule in its venom, formed from the joining of two smaller toxins, is very similar to those of other Boiga or cat-eyed snakes, the genus to which it belongs.
The brown tree snake just happened to be in the right place at the right time to catch a wartime ride. While the main threat comes from Guam, if a different cat-eyed snake were to make it to Hawaii from any of their habitats across Asia or Australia, the effects could be just as bad.
Fry hopes that the more known about cat-eyed snakes’ biology and behavior, the better the chances will be of preventing them from infesting vulnerable islands.