Monday, March 10, 2014

coast garter snake ~ 03/10/14 ~ Midpen Preserve

coast garter snake
Thamnophis elegans terrestris
(ssp. of western terrestrial garter snake)

I don't know how to sex snakes, but I'm calling it a she.  She was quick and sought refuge in the pond, but a long-legged herp fellow was quicker on his feet.  We thought the two red dots on her head were a nice addition to a very pretty little snake.

edited 04/01/14 - Thanks to Cindy's comment, I revised the ID from Santa Cruz garter snake (Thamnophis atratus atratus) to best guess a ssp. of the western terrestrial garter snake, the coast.  All 3 ssp. of aquatic garter snakes (T. atratus) do not have any red on their sides like this one clearly shows.  Doh! 

The other possibility would be one of the common garter snakes (T. sirtalis).  While Cindy says CA red-sided (T. sirtalis infernalis), I lean towards valley (T. sirtalis fitchi).  Look at this picture and tell me it doesn't look the same with that large eye and black wedges?  Well, okay, the individual shown above has 8 labial palps (typ. of western terrestrial, elegans), rather than only 7 (typ. of common, sirtalis), but that's apparently not 100% diagnostic.  Plus, neither T. sirtalis ssp. is supposed to be found in this area of the Santa Cruz Mountains, and we're confident, somehow, that this is not the endangered San Francisco garter snake (T. sirtalis tetrataenia). Confused, yet?  Join the club!

For a handy-dandy key to CA garter snakes, check out CA Herps.  And, for a brief summary of the confusion around garter snakes (with links) check out my CA red-sided post from Fort Ord.


Cindy said...

oops, I think my initial mistake may be perpetuating itself. The first photo is what I first thought I saw on that snake in the field - a mostly dark gartersnake with one yellow racing stripe down the back - a Santa Cruz gartersnake (Thamnophis atratus atratus). But when the long-legged herper pulled it out of the water, red stripes suddenly appeared on its sides below the dark head. That would make it a coast gartersnake in my book (T. elegans terrestris) or a California red-sided gartersnake (T. sirtalis infernalis) if you are contrarian re ranges. See Nafis' Key to California Gartersnakes. Mine is heavily annotated. I made the same mistake this weekend at another peninsula location until the expert pulled the snake out of the brush and I could see the red on the side. Unless something has changed once again in the gartersnake world since I last checked which is highly possible.

Katie (Nature ID) said...

Booger. Those garter snakes are difficult. I ended up correcting a past ID from Pinnacles as I was looking into this post, also what I thought was an aquatic garter snake ssp. It looks like that's not correct either. I think you're right about it being T. elegans terrestris. I didn't think it was red-sided because it didn't have a red head, but then the juvies may not anyways. I'll fix tomorrow...

randomtruth said...

I thought it was sirtalis fitchi because of the dark back and head, pretty distinct side stripe, and limited red, but I could be talked into elegans terrestris. Especially since it was a juvenile.

Katie (Nature ID) said...

Sigh... I've been staring at too many snake pictures the past few days. Somehow it's reassuring to me that you two, people I consider very good with herp IDs, have difficulty sorting these out, too. I think Cindy is right in that the garter snakes will be reclassified again. As it is, it doesn't seem very intuitive or consistent.