Clarkii By County: Miami-Dade

17 Sep

In anticipation of an upcoming article on the Salt Marsh Snake (Nerodia clarkii) in Herp Nation Magazine Issue #18, and the (hopefully) near completion of the data-gathering phase of my research on clarkii in southern Florida, I’m going to review some of my experiences with the species. Instead of a smattering of stream-of-conscious ideas and such, I’ve decided it would be interesting to systematically review what I know of the species in every Florida County I’ve come across them in. For my readership, I think the interest will be in the fact that a.) the foraging and movement ecology of clarkii seems to be different on a local level, in other words they simply act different in nearly every county; and also the pattern and coloration is extremely variable across their range (more elaboration in future postings, and of course the upcoming Herp Nation Magazine article.) So sit back, relax, enjoy.

8735951007_cef982fd7c_z 8737020874_7da550f14e_z


Let us begin from the familiar: Dade County – Everglades National Park. Yes, there are other sites in Dade from which to view clarkii, but ENP is rife with them and many herpers have seen the species there. For this reason, I’m sorry to inform you that if you’ve seen clarkii in ENP, you may not have seen clarkii. From our work so far, we’ve encountered 19 Nerodia clarkii-like animals there, of which sixteen have been hybrids between N. clarkii and the Florida Watersnake, N. fasciata, and only three have been pure clarkii. This is one of the interesting things about the species: they readily hybridize with Florida Watersnakes, especially in large-scale mixing zones such as the Everglades. Our work initially began in ENP where we were testing the use of traps for detecting clarkii. Without giving away the data, the interesting tidbit about clarkii at this population is that road cruising seems to be the best way to come across them, and it also seems to be one of the only productive ways to turn them up. Of course I’m not saying it’s impossible to hike them up in ENP, they certainly forage, eat and live outside of the roadways. However, perhaps because of the dense mangroves with extremely deep mud that makes the habitat difficult to search, or perhaps because they forage at different times or in different manners from other populations, we found only a single clarkii by hiking, despite much time spent looking. (And full disclosure: the clarkii we hiked was on a right-of-way, meaning it would’ve been road cruised in seconds had we not already been out of the car.)

Dr. Chesnes checking a trap for clarkii

Dr. Chesnes checking a trap for clarkii


Now on to the variation. Holding with their hybrid nature, most of the clarkii encountered in ENP are banded in some way:

Pure clarkii:

15263277375_149118d244_z clarkii x fasciata:

8737089472_6c2c5caeb1_zPure clarkii:


clarkii x fasciata:  8737101614_ea45180a5e_z

However, occasionally one will look a little more classic clarkii (not that I know what that is, and I can’t seem to find a great picture of one.) And it seems that the red trait is not a recessive one even when fasciata is in the mix, and hybrids will still often turn up with a clarkii bloodred coloration: this individual was a clarkii x fasciata:




That’s all for this segment, in the weeks ahead we’ll take a gander at Indian River, St. Lucie, northern and southern Monroe, Collier and Lee Counties – and maybe, just maybe a new county record or two. Don’t forget to check out issue 18 of Herp Nation Magazine, coming out in a few months for my article on Mangrove Saltmarsh Snakes (



NOTE: This research on Nerodia clarkii was partially funded by a Palm Beach Atlantic University Quality Initiative Grant, so many thanks to them. To help us continue our last few months of research, please consider making a small donation to Field Ventures



2 responses to “Clarkii By County: Miami-Dade

  1. Chris Montross

    17/09/2014 at 5:20 pm

    Josh what are you using to determine pure vs hybrid status of the found specimens? Your results of hybridization is interesting especially with solid colored hybrids in what I was always aware of as a very variable species. Maybe not just well mixed then?

  2. Josh

    17/09/2014 at 5:49 pm

    I was hoping someone would ask, Chris! Obviously the ideal would be to genetically test every individual, but obviously that’s not do-able for every individual, and from the conversations I’ve had with clarkii geneticists it seems like the differences genetically between the two are still being hammered out (I’d talk more about this, but as a friend is working on it for his Master’s Thesis, I wouldn’t want to scoop him.)

    Anyways, morphologically, the way to differentiate the two species is by counting the midbody scale rows – fasciata has 23 and clarkii has 19-21. Typically, hybrids will have 22 midbodies (and indeed the 16 I called “hybrids” had 22).

    I suppose it’s also possible for a hybrid to have 21 or 23, (in that case I’d look to pattern and coloration), but my friend who’s working on the genetics is pretty adamant that if it’s 21 it’s clarkii, and if it’s 23 it’s fasciata.


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