A Herpetological Roundup

Gray Tree Frog (Dryophytes versicolor), Mansfield-et-Pontefract, Quebec, July 11, 2010.

Five things make a post:

  1. New tree frog genus. North American (and a few Asian) tree frogs previously included in the genus Hyla — including Gray and Green Tree Frogs — have been moved to a new, sister genus, Dryophytes, thanks to a major revision of tree frog taxonomy (PDF). This follows other moves to split genera that spanned continents: Bufo (toads), Rana (true frogs) and Elaphe (rat snakes) have all been split up; North American toads are now Anaxyrus, North American true frogs are now Lithobates (except on the Pacific coast), and North American rat snakes are now Pantherophis. So this is not really a surprise move.
  2. Water snake outreach. The Lake Erie Water Snake (Nerodia sipedon insularum) remains on Canada’s endangered species list, but it was removed from the U.S. list in 2011, after a rebound in its U.S. population, which now numbers 10,000 adults. An invasive fish, the round goby, has something to do with it: the water snakes happily feed on them. But public outreach played a role as well. On Cool Green Science, the Nature Conservancy’s blog, Ted Williams looks at the outreach efforts of Dr. Kristin Sanford, whose research showed that habitat loss was less of a factor than human persecution. Her (now quite dated) website: Respect the Snake.
  3. Don’t shoot snakes. An Arizona bill that would lift a ban on firing a gun within city limits if it’s to shoot a rat or a snake is facing opposition — from people opposed to shooting snakes.
  4. Do snakes fart? Scientists are building an animal fart database, and yes, snakes are included. While passing gas might not be a good sign for an obligate carnivore, if by fart we mean making noise while defecating, I can attest that snakes certainly do. (With some of my larger and stinkier charges, I usually hear it before I smell it — at least if I’m in the same room.)
  5. Stressed snakes strike first. A snake’s background level of stress — rather than the stress of encounter, handling or confinement — may determine how likely it is to strike, according to a new study. [LiveScience]

Hand-Feeding Wild Water Snakes

Tim Jones, a retired zoo director, has been hand-feeding the Diamond-backed Water Snakes (Nerodia rhombifer) that live in his private pond. The snakes have become so habituate to his presence that they’re comfortable taking food off his tongs. It doesn’t hurt that water snakes are rather food-motivated (which is a polite way of saying they’re extreme gluttons). You’ll note in the above video, along with shorter videos here and here, that they’re strongly directed by scent: if your fingers or pants smell like fish, it is by snake reasoning fish. Nom.

Now, Jones points out that this is a pond on private property; feeding wild animals is usually a no-no for very good reasons. You’d think that there would be little harm in habituating water snakes to human contact, or having them associate humans with food, and in a perfect world there wouldn’t be. It’s just that very few people would see an approaching water snake as friendly. Thwack. The end.

Some people might be surprised at the idea of tame water snakes, but I’m not. At one point, as some of you may remember, I kept three of them: two Banded Water Snakes (Nerodia fasciata) and a Northern Water Snake (N. sipedon), the latter under a provincial licence. They had insanely voracious appetites, but they were no less tame than any of my other snakes, and I put them to use in educational displays, where they wigged out people who believed water snakes were aggressive.

Basically, they’re just big garter snakes.

But mine were all born in captivity. That matters. It’s not reasonable to expect a wild animal to be friendly or tame: most will assume that a creature a hundred times their size is a threat to them. A snake has no idea that people are scared of it, or that being friendly and non-threatening toward people is a reasonable survival strategy. That’s counterintuitive.

Wild water snakes are bitey because they’re large enough for it to be a worthwhile defence strategy; smaller snakes of the same family, like brown and red-bellied snakes (Storeria), never bite, because there’s no point in doing so. Garter snakes are somewhere in between: some do, some don’t — it depends on the species, the individual and the circumstances.