brown-tree-snakes-utilize-their-tails-as-lassos-to-climb-broad-trees

Snakes do a lot more than slither. Some swim, while others sidewind across sand ( SN: 10/ 9/14). Some snakes even fly ( SN: 6/29/20). However nobody has ever seen a snake move the manner in which brown tree snakes do when they climb up certain trees. By wrapping its tail around a tree or pole in a lasso-like grip and wriggling to propel itself, a brown tree snake can shimmy up structures that would otherwise be too wide to climb.

Much better understanding how brown tree snakes ( Boiga irregularis) navigate might inform techniques to control their population in Guam, where the snakes are an invasive species. The reptiles are infamous for having actually eliminated nearly all of the native forest birds on Guam and often cause power blackouts by clambering up utility poles.

The discovery of brown tree snakes’ lasso climbing method, reported online January 11 in Current Biology, was somewhat serendipitous. Julie Savidge, an ecologist at Colorado State University in Ft. Collins, and associates were examining methods to keep these tree-climbing snakes far from Guam’s Micronesian starlings– one of only two native forest birds left on the island.

One of these methods involved tests to see whether a broad pipe, or baffle, around a pole could avoid predators from reaching a starling nest box at the top. In evaluating hours of footage of the baffle to monitor how well it prevented brown tree snakes, the group saw one snake do something entirely unanticipated: The snake lassoed itself around the baffle and started scooting upward.

” We were in overall shock,” states research study coauthor Thomas Seibert, also an ecologist at Colorado State. “This isn’t something that a snake is expected to do.”

Footage of a brown tree snake, captured with an infrared cam at night, exposes the special way that this species climbs up: The snake lassos itself around a pole and wriggles the loop of its tail to propel itself upward. The strategy allows the reptile to vibrate up structures that would otherwise be too wide to climb up.

Brown tree snakes and other snakes generally climb up trees that are too smooth to slither up by coiling around a trunk several times. Covering around a tree numerous times restricts the width of a tree that a snake can scale. Using a single, big, lasso-like grip enables the brown tree snake to climb wider trees– or baffles, describes study coauthor Bruce Jayne, a biologist at the University of Cincinnati in Ohio.

In later laboratory experiments, the scientists observed numerous brown tree snakes utilizing this lasso-like posture when placed inside an enclosure with a broad pole topped with a dead mouse for bait. The lasso climbing approach is not extremely efficient. Five brown tree snakes, varying from about 1.1 to 1.7 meters long, climbed up less than a millimeter per 2nd, typically.

” This was extremely difficult[for the snakes] As an outcome, the snakes probably use the lasso-like motion just on the unusual occasions that they come across trees or poles too large and smooth to be scaled any other method.

infrared image of brown tree snake climbing tree
Using infrared cameras to watch nighttime brown tree snakes at night, researchers observed the reptiles using a bizarre technique to climb broad poles: The snakes (one visualized) utilized their tails as lassos to grip a pole and wriggle their way up. J. Savidge et al/ Current Biology 2020

It’s “kind of whacky” to see a snake move like this, states Gregory Byrnes, a biologist at Siena College in Loudonville, N.Y., who was not involved in the work. Byrnes is not completely amazed that brown tree snakes have devised a way to deal with broad trees or baffles.

Evaluating the limitations of brown tree snake agility might help design new baffles or other tools to protect threatened birds on Guam, Savidge states. Currently, after the scientists placed a number of bird boxes on utility poles on the island that were too large for brown tree snakes to lasso their way up, “the birds adopted these birdhouses and have done very, very well,” she says.


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Much better understanding snakes’ repertoire of climbing up methods might likewise make for much better robots, states Henry Astley, a biologist at the University of Akron in Ohio who was not associated with the work.

He visualizes snake bots crawling through earthquake rubble to browse for survivors or twitching within large equipment to carry out examinations. Finding brand-new, creative methods in which real snakes exploit their unbelievable flexibility could help engineers make much better use of serpentine makers.

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