Quirks & Quarks

Snakes tie themselves in knots to climb up slippery poles after endangered prey

The invasive brown tree snake slithered like no-one had ever seen before, using a technique researchers called 'lasso locomotion'

The invasive brown tree snake slithered like no-one had ever seen before

Scientists observed the brown tree snake using a never-before-seen climbing technique they call 'lasso locomotion' (Bjorn Lardner, USGS)

Researchers trying to protect endangered birds from a predatory tree snake were stunned to discover it bypassing what they thought would be an unclimbable obstacle using a climbing technique they'd never seen before. 

The brown tree snake is an invasive species on the Pacific island of Guam, having likely made its way there in the late 1940's in shipments of goods from its native New Guinea or Australia. The snake is arboreal, and can grow up to 3 metres in length.

Since it's arrival the snake has devastated much of Guam's native forest bird population, leaving small populations of a few species in in small pockets. One of those is called the Micronesia starling, and scientists including Julie Savidge, Professor Emeritus from the  Department of Fish, Wildlife and Conservation Biology at Colorado State University, were trying to figure out the best way to save this rare bird.

The Micronesia starling population has been decimated on Guam by the invasive brown tree snake (Submitted by Julie Savidge)

The researchers built next boxes on metal poles, and surrounded the pole with a cylindrical metal stove-pipe baffle. They had thought that the width and smooth metal surface of the baffle would make it difficult for the snake to climb.

Lasso locomotion

Savidge and her colleagues were astounded when video revealed snakes using a never before seen new method to defeat this obstacle. They observed the snake looping its body around the baffle and literally knotting itself. It then squeezed the surface very tightly, with its belly against the metal baffle.

Lasso locomotion in slow motion in the field. Colorado State University

The snake then, slowly and laboriously wiggled its way upwards. The snakes in the experiment were clearly working hard — they took breaks and breathed heavily as they progressed toward the bird box.

The researchers dubbed this new behaviour "lasso locomotion" and are now developing new barriers to protect the birds in hope that the snakes have no more new climbing strategies to unveil.

Lasso locomotion in an enclosed area. Tom Siebert

 

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