Brown tree snakes are native to Australia and a variety of Pacific islands, but in Guam, they are an invasive species. An invasive species is a type of animal or plant that is not native to a given ecosystem and can often harm native animals and plants by either hunting them too much or hogging the ecosystem’s food and resources. These predatory brown tree snakes have used their strong climbing skills to wipe out much of the native bird population and cause problems with electricity lines. Researchers from Colorado State University and the University of Cincinnati have now recently observed a new climbing behavior in these snakes that makes them pose an even greater danger.

 Normally, snakes climb by wrapping their body in multiple layers around a pole. They can inch up their top coil while holding on with their bottom coils and make progress up a pole in this manner. The difficulty with this method is that snakes are limited to climbing poles with a relatively narrow circumference. To find out how the snakes are able to get up wider trees or poles, the researchers set up a wide pole in the enclosure of a brown tree snake with a mouse on top as bait. They saw the snakes loop their tails around their bodies in a lasso-like shape and hoist themselves up. The method was very slow, with the snakes moving only 0.4 centimeters per second on average and slipping downwards frequently. Additionally, it seemed to be energy intensive, leaving the snakes breathing rapidly. Still, they were able to get up the pole, indicating it is a strategy for climbing thicker columns.

This tree climbing technique wouldn’t have been useful for hunting the bird prey favored by the brown tree snakes in Australia, as the trees preferred by those birds are too thick even for the snake to wrap its body in the lasso-climbing position. However, the snakes can use this lasso-climbing maneuver to reach the prey and electrical wires of Guam, adding to its danger as an invasive species.

Julie Savidge is a Professor in the Department of Fish, Wildlife and Conservation Biology at the Colorado State University with a B.S. in Zoology from Colorado State University, a M.S. in Wildland Resource Science, from the University of California, Berkeley, and a Ph.D. in Biology, University of Illinois, 1986

Managing Correspondent: Emily Kerrr

Press Release: Brown tree snakes use their tails as lassos to climb wide trees

Scientific Article: Lasso locomotion expands the climbing repertoire of snakes

Image Credit: U.S. Fish and Wildlife Service