The brown tree snake, an invasive snake species in Guam, has caused devastation among the birds of this Pacific island. It has also caused power outages when it is burnt to a crisp having climbed powerlines. The experts wanted to find a way to protect birds feeding at bird boxes so they put a bird box on the top of a un-climbable, 3 foot, metal pole. Inside the box they placed tasty mice, a favourite prey animal of the brown tree snake.
One of the scientists, Thomas Seibert from Colorado State University, said: “We just sat there watching in shock”. As this clever snake shimmered its way up the slippery metal pole. It achieved this feat by wrapping itself around the pole and then tucking its body underneath the lasso that it had formed. It then rippled the body which allowed it to slowly climb the pole. It helped to explain why the birds of Guam couldn’t find safety.
Seibert said, “We suspect that its ability to move in so many different ways and do so proficiently has probably added to all of the woes that it has caused, because it can get almost anyplace.”
They believe that this extraordinary technique may have been developed in its home forests of Australia and Indonesia where there are smooth barkless trees. They decided that because the lasso only goes around the tree once they could climb trees with quite a wide circumference. However, there are limits. The longest recorded length of the species was one found in Guam measuring almost 10 feet in length.
The method of climbing is very slow and perhaps at the limits of the snake’s mechanical and psychological abilities. Although it’s a reminder of the intelligence and resourcefulness of wild animals.
The brown tree snake is also known as the brown catsnake. Perhaps the latter name is in recognition of its arboreal nature i.e. it climbs trees expertly as do cats which are also often arboreal being excellent climbers. It is native to eastern and northern coastal Australia, eastern Indonesia, Papua New Guinea and many islands in north-western Melanesia. It is famous for extirpating (destroying to extinction) the majority of the native bird population of Guam.
It feeds on birds, rats, bats, lizards and other small rodents in its native habitat and preys on birds and shrews in Guam. It is a rear-fanged snake. It is venomous but the venom is difficult to inject into a human because of the rear-fanged configuration. The venom is weak.