EPOW - Ecology Picture of the Week

Count the Scales

Eastern Garter Snake (Thamnophis s. sirtalis), Family Colubridae
Edwin B. Forsythe National Wildlife Refuge, New Jersey, USA

Explanation:  While hiking through a wildlife refuge in central coastal New Jersey along the Atlantic coast, I happened upon this wriggling ribbon.  This is an eastern garter snake, a subspecies of the aptly-named common garter snake that ranges commonly through North America.  This eastern subspecies inhabits a wide range of habitats from southern Canada south into Mexico.  

But this is also a lesson in identifying snakes, particularly garter snakes.  You need to ... count the scales.

More specifically, you count the number of scales on one side of the head, particularly the lower labial scales (scales along the "lower lip") and the upper labial scales (along the "upper lip").  And also the number of dorsal scales at midbody (on the back), and the number of ventral scales (on the belly), and the number of subcaudal scales (on the underside of the tail). 

The main photo above suggests that the upper labial scales number 7, including one barely visible at the front of the mouth opening.  When I caught the snake, I counted 10 lower labial scales, and 19 mid-dorsal scales.  These counts alone, along with the general appearance of the stripes and markings, identify this tolerant individual indeed as a common garter snake ... here, on the eastern U.S. seaboard, an eastern garter snake.