Guam’s brown tree snakes master a new ‘lasso’ climbing technique

Movements and postures of snakes climbing smooth vertical cylinders. (Current Biology photo)

A team of researchers from Colorado State University and the University of Cincinnati has discovered a new mode of snake locomotion — ‘lasso locomotion’ — that allows Guam’s brown tree snake to ascend much larger smooth cylinders than any previously known behavior.

According to the study published in Current Biology, the ‘lasso locomotion’ used by brown tree snakes circumvents many functional challenges for gripping and climbing large vertical cylinders.

During this lasso locomotion observed by the study, the snakes climbed smooth, vertical cylinders (15–20 cm diameter) using a lasso-like body posture, in which the head and neck were oriented uphill of a posterior body loop that encircled and gripped the cylinder.

Within the loop, small bends to the left and right propagated posteriorly and these bends provided the propulsive mechanism by moving part of the body uphill while simultaneously shifting grip location.

The study concluded that the brown tree snakes’ versatility of locomotion may exacerbate its ecological impacts of invasive species. In addition to lasso locomotion, brown tree snakes are adept at bridging large gaps, swimming, using lateral undulation to climb steep surfaces with 1-mm projections, and crawling on branches and wires that are a small fraction of their body.

“Collectively, these abilities contribute to their detrimental ecological and economic impacts, such as decimating the native vertebrate fauna of Gua9 and short-circuiting electrical lines,” the study stated.