Common Gartersnake

Thamnophis sirtalis

Distinguishing Characteristics

Photo: Trevor Persons

  • Medium-sized, approximately 18 to 36 inches in length
  • Brownish, olive, or grayish above with darker checkerboard pattern
  • Three light yellowish stripes prominent, faint, or absent
  • Plain yellowish below
  • Short tail, 1/4 or less of total body length
  • Dorsal scales keeled (longitudinal raised ridge along midline of each scale)
  • Commonly confused with eastern ribbonsnake and common watersnake

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Status and Distribution in Maine

  • Common and secure
  • Statewide

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  • Forested uplands, brushy fields, meadows, grassland, old buildings, and rock outcrops, as well as wetter areas such as streams, bogs, and marshes
  • Commonly found under rocks, logs, boards, and debris piles

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  • Earthworms account for 60–95% of this snake’s diet, although it also eats other invertebrates, amphibians, fish, and even small birds

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Seasonal Changes

  • Overwinters in upland settings, in ant mounds, rodent burrows, and root tunnels

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Natural History Notes

  • Most commonly encountered snake in Maine
  • Gives birth to live young in July to mid-September
  • Earthworms account for 60-95% of this snake’s diet, although it also eats other invertebrates, amphibians, fish, and even small birds
  • May release musky discharge when handled

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Share Your Sighting

There is much still to learn about the distribution and ecology of Maine’s herpetofauna, and we encourage members of the public to share their photo-documented observations as part of the Maine Amphibian & Reptile Atlas Project (MARAP).

To see if a township still needs documentation of a species, consult this distribution map (PDF). If a township lacks a photo or specimen record, we want your observation!

There are two ways to share your observations:

Submit your reptile or amphibian observation online

No service? No problem. Click here to download the survey to your device while connected, then take offline to collect observations from anywhere. Tip: The survey works best on Google Chrome and Safari.

Or upload sightings to the iNaturalist citizen science project through their website at or mobile app.

  1. When submitting an observation through iNaturalist add a description of the location (and other noteworthy information) to the “notes” field. This serves as a check on the locations automatically generated by smartphone cameras, which may be imprecise if cell service or GPS coverage is weak.

Thank you for doing your part to help conserve Maine’s reptiles and amphibians.