Unknown Snake Species, Northwest Austin, Texas

 Report courtesy of Marla

Edited by Jerry Cates

Marla Wrote:

"Dear Jerry---I live in Northwest Austin and this morning found a snake sunning himself on my back deck.  I could not identify what kind it was, even after searching through your website. 

I didn't think to take a picture, but if you could identify the species based on my description, I would really appreciate it.   The snake had a slender body with a slightly tapered tail and was about 3 feet long.  It had a narrower neck and and a distinct (wide?) head.  Its base color was black/dark grey with distinct whitish markings on its back - two longitudinal strips (NOT a spinal stripe) with circular/diamond blotches running down the center of its back between the stripes.  It looked very much like a ladder painted on the snake's back.  

This snake looked nothing like the pictures I viewed of garter/ribbon/lined snakes.  Do you have any idea as to what it might be? Thank you very much---Marla "

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My Reply: 

Marla---Lots of possibilities exist, but based on your location and the description you provided I think we can home in on the species, especially if you work with me a little.  

Nothing in your description suggests the snake is poisonous. The slender body and wide head suggest a rat snake, but the black/dark gray background color with whitish markings suggest a Nerodian water snake instead. 

Although the Nerodians tend to become rather stout bodied as they get older, the younger ones can be fairly slender.  In your area the blotched water snake (Nerodia erythrogaster transversa) is common, especially if you are near a creek or pond. It has dark gray blotches, and a lighter background color that in younger specimens is almost white.  The arrangement of the spinal blotches, and the side blotches below them, can produce a pattern that resembles a ladder.  Below are some web pages with blotched water snake photos:  

Blotched Water Snake, Temple, Texas, 22 March 2007 (Courtesy of Molly C.)

Blotched Water Snake, Austin, Texas, 28 April 2007 (Courtesy of Chris S.) 

Blotched Water Snake Swallowing Prey, Temple, Texas, 3 June 2004 (Courtesy of J.S.)

You also mentioned that the blotches were circular or diamond-shaped. Sometimes people describe the diamond-backed water snake (Nerodia rhombifer rhombifer) this way to me, and I suppose that pattern could be considered a type of ladder.  The web pages below have photos of that species:

Diamond-backed Water Snake,  Austin Texas, 24 March 2007 (Courtesy of Kathy B.)  

Diamond-backed Water Snake, 20 March 2007 (Courtesy of Jojania N.)  

Diamond-backed Water Snake, East Texas, 29 March 2007 (Courtesy of John R.)

Look all these photos over and see if they resemble what you saw.  If so, please do let me know (you'd be surprised how often I never hear back) but if not perhaps they will help you describe the way they differ from what you saw.  From those differences, we should be able to get to the bottom of what you saw---Jerry