Tree snakes come in many colours and sizes, and most are highly nocturnal. In Costa Rica I come across many species, both venomous, like the beautiful Eyelash Viper, or non-venomous, such as the many active snakes that can be found living around aquatic breeding sites, where lizards sleep on their perches and night-time frogs are active.
At the moment I am teaching at La Selva Biological Research Station and during my time here have been supervising several student projects focusing on the morphological adaptations seen in different frogs and snakes. The cat-eyed snakes of the genus Leptodiera are species commonly known to eat lizards, frogs, and even the eggs of the many tree frogs in the main swamp here.
However, several other interesting species which fill a similar niche can also be found. Almost every night we have come across 1 or 2 species of Blunt-headed tree snake. Belonging to the genus Imantodes, these beautiful long snakes have huge eyes in comparison to their head size. Holding on with their long prehensile tails, these snakes silently manoeuvre their slender bodies between the slightest of twigs and branches.
Last night we found 2 other tree snakes belonging to separate but closely aligned genera that behave in exactly the same way – one was Sibon longifrenis. These snakes really are beautiful, and being various shades of green and brown they are extremely well-camouflaged amongst the moss. As other tree snakes, even their eyes perfectly match their cryptic colour.
We were lucky enough to find a pair in one tree, but rather than tree frogs, or frogs eggs, these snakes actually feed only on snails and slugs. Their mouthparts are specially adapted to extract snails from shells. To observe this behaviour in action is a very special moment for any herpetologist.
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