My first snake of 2012 was the previously-posted gray rat snake (Pantherophis spiloides or whatever) discovered at Grand Bay WMA just east of Valdosta on 08 January 2012. My second snake of the year, featured here, was a southern banded watersnake, Nerodia fasciata fasciata, found in the same area of Grand Bay on 28 February. This is probably also an intergrade with the Florida banded watersnake, Nerodia fasciata pictiventris. March may be when Spring officially launches in south Georgia, but that doesn’t mean snakes aren’t out and about on the warmest of southern-winter days.
Anybody who knows me really well can probably testify that I have a fairly obsessive love of watersnakes and anoles. I own and frequently return to two beloved books, one covering each group: North American Watersnakes (2004) by J. Whitfield Gibbons and Michael E. Dorcas and Lizard in an Evolutionary Tree (2009) by Jonathan Losos. The former covers the non-venomous watersnakes (including genus Nerodia) extensively and the latter extensively covers genus Anolis. I’ve joked in the past that you may have one bible, but I’ve got two: North American Watersnakes and Lizards in an Evolutionary Tree. (I know, lame joke — I don’t use it anymore.)
Bad jokes aside, I’ve never exhausted my curiosity and interest in these two very different genera of reptiles. They’re both at the heart of my natural history
In central and south Florida, I’ve caught, observed, and photographed innumerable Florida banded watersnakes, Nerodia fasciata pictiventris. Until February, on the other hand, I had not caught and photographed the other (more common) subspecies of the north, Nerodia fasciata fasciata, the southern banded watersnake.
By most accounts, Nerodia fasciata fasciata should be the dominant subspecies in around the Valdosta area. Having said that, it is entirely
possible likely that these two subspecies have intergraded throughout this region. Valdosta is in that wonderfully wiggly line of intergradation between many of the southeastern and Floridian subspecies derivations.
Unless I have a concrete and evident reason to believe otherwise, my working assumption will be that Nerodia fasciatas found in and around Valdosta will be Nerodia fasciata fasciata. I do, however, concede that there’s always going to be the possibility of either — and even intergradation of the two.
UPDATE: As of mid-April 2012, I now assume the Grand Bay population is an intergrade of the two Nerodia fasciata subspecies, pictiventris and fasciata. These posts will be tagged for both subspecies.
One of the problems with distinguishing between the two subspecies is that the entire species is extremely variable in colors and patterns. Check out my published Nerodia fasciata posts, for example, and you can get a sense of their variation (note: there are plenty more to come in the near future). Because of this, there are no easy-to-spot and reliable visual cues in pattern and color to distinguish between the two. The University of Florida’s profile page for Nerodia fasciata provides some key differences between the two subspecies, but I’ve found more than a few Florida banded watersnakes in far-south Florida that did not fit so snuggly in their visual-identification key. Bandeds are extremely variable in coloration and pattern.
Gibbons and Dorca (2004) state that N. f. pictiventris has less than 128 ventral scales, whereas N. f. fasciata has more than 128 ventral scales. If only I’d remembered to count this individual’s ventral scales on 28 February 2012! Heh.
[Update: Check out this post from 15 April for a successful ventral scale count of another individual.]
Indeed, I’m in an awkward stage of trying to slow myself down in the field — trying to be more precisely (and thoughtfully) analytical. In central and south Florida, identification of native species was easier because of range mapping. Here in south Georgia, it’s a different story. Hybridization is rampant. Similar species range and overlap one another. The biodiversity of native species isn’t nearly as dense as it seems in Florida, but it is more complicated because of these overlapping ranges.
I’m looking forward to tracking down many more Nerodias over the next few months, both to the north and to the south of Valdosta. I also plan on testing Gibbons and Dorca’s ventral scale methodology. I’ll track down a few Florida bandeds in central and/or south Florida and run the counts, and then contrast those with counts of south and central Georgia southern bandeds. Of course, this will only happen when I can actually get my hands on the snakes (which, with watersnakes, isn’t always that easy).
For the record and for those who don’t crave all-things-watersnake, this is a non-venomous watersnake. They are often confused as cottonmouths and thus killed out of fear and ignorance. Remember: just because you see a snake and there’s water nearby, that doesn’t mean the snake is a cottonmouth — and that doesn’t mean you need to kill it. These snakes are just like the rest of us, trying to scratch out a living in the world around them.