Hi Steno and Wulf,



The notion that snakes are capable of expanding their ranges over large bodies of water - particularly salt water - is taken for granted, but there is a paucity of direct observational data to support the idea. As one who has personally witnessed the massive displacement of rafts of vegetation during the flooding of tropical rivers, it would be easy for snakes to be thrust well out to sea on such material, but who has actually searched such detritus for its faunal passengers? Similarly, occasional observations of terrestrial snakes that are usually found in association with water - such as Pseudechis porphyriacus - have been observed at times in the open sea, kilometres from land. And I have no doubt that large snakes such as the pythons you mentioned, are not only capable of swimming out to sea, but probably readily do so between islands as population, environmental or ecological conditions dictate. I suspect that some snake distributional patterns may be based more on the founder effect of such a dispersal pattern, than as a direct consequence of sea level perturbations. Anyway, I feel it would be very enlightening to get hard data on such behaviour. Given the obvious difficulties with such investigations, I suppose the best we can hope for is the fragments of (opportunistic) sightings that are occasionally made - usually by non-herpetologists. Thanks for the references as well, Wulf.



Regards



Richard Wells

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