Garter Snake Spotting

by Carl Strang

From time to time I encounter Chicago garter snakes (our local version of the eastern garter snake) at Mayslake Forest Preserve. When I do, I attempt to get good photos. I would like to see if individuals can be distinguished by details of their color pattern. I had good success with this at Fullersburg Woods with fawns, at least until their spots faded. Here is a photo from June 5.

The snake chose to leave before I could get a clearer look than this.

The snake chose to leave before I could get a clearer look than this.

In my files were photos of two other encounters in past years. One of these clearly had a different pattern.

This individual was photographed in 2010. Eight columns of pale scales separate the back of the head from the first dark spot that interrupts the side stripe. That number is only 5 or 6 in the first photo.

This individual was photographed in 2010. Eight columns of pale scales separate the back of the head from the first dark spot that interrupts the side stripe. That number is only 5 or 6 in the first photo.

The final snake, from last year, was more like this month’s individual.

The separation is five columns in this one.

The separation is five columns in this one.

Nevertheless, the two color patterns are different. Check out the small dark stripe, between the head and that first spot, at the boundary of the belly scutes and the side scales. That stripe is confined to the upper edges of the belly scutes in the 2012 snake, except for one little spot. In this year’s individual that stripe extends onto the lower halves of three adjacent side scales.

The color patterns are distinct in these three photos. They only are valid individual markers, though, if they do not change over time. I don’t know if such is the case.

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