Reptilia · Squamata
Thamnophis sirtalisLinnaeus, 1758
Common Garter Snake
Photograph by Wilson44691, Public domain, via Wikimedia Commons
A day-active, meat-eating snake from the Nearctic region, reaching 140 cm nose to tail.
Reptilia › Squamata › Colubridae › Thamnophis
- Grows to
- 1400mm
- greatest recorded
- Eats
- Carnivorous
- Active
- Diurnal
- Lives up to
- 20years
Longer than 86% of all colubrid snakes anyone has measured.
The bar is the rank itself: its length is the share of the family this animal exceeds. The chart below is the family’s real spread, on a logarithmic scale because body length here runs from 98 to 3,800 mm. The solid rule is this animal. Every bar is a count of real species, and nothing on this figure is estimated.
What is known
47 sourced facts, each taken from a named scientific dataset. How to read these.
Cited from a dataset unless a row is marked otherwise.
Standing in the world
- Still living
- Extant
- Conservation status
- Least Concern
- Status assessed · the year the Red List last looked
- 2007
- Population trend
- Stable
The animal itself
- Limbs
- None
- Pupil
- Round
- Venomous
- Yes
- Fangs
- At the back of the mouth
- Longest recorded life
- 20years
- Preferred body temperature · chosen in a laboratory gradientmeasured
- 29.3°C
- Body temperature when active · measured in the wild
- 25.6°C78 °F
- Body temp in the wild · mean, when active
- 24–36°C75–97 °F
Stark et al. 2020
mean body temperature of active individuals in nature
body temperature of active animals in nature
Size
- Length snout to vent · greatest recorded
- 549.4mm21.5 in
- Length nose to tail · greatest recorded
- 1400mm4 ft 7 in
- Largest female · snout to vent
- 400mm15.5 in
- Largest male · snout to vent
- 500mm19.5 in
- Hatchling length · nose to tail
- 175mm7 in
- Body mass · greatestcomputed
- 667.1g1.5 lb
- Body mass · a typical adult
- 150g5.3 oz
- Body mass at hatchingmeasured
- 2.35g0.08 oz
snakes only in this source
snout-vent length; the source column mixes this with straight carapace length
computed from length by a family-level allometric equation, not weighed
AnAge rates this record "acceptable"
How it lives
- Diet
- Carnivorous
- How it hunts
- Active foraging
- Active
- Diurnal
- Where it lives
- Semi-aquatic
- Habitat
- Forest, Grassland, Shrubland, Wetlands
- Biome
- Temperate Broadleaf & Mixed Forests
- Region
- Nearctic
- Mainland or island
- Mainland
- Highest it lives · above sea level
- 2540m
- Range size
- 8,219,687km²
- Density
- 1.7–89per hectare
msotly amphibians and earthworms, also bird nestlings, burd eggs, fish, small mammals and invertebrates (Sheldon 2022)
Active (Murphy et al. 2003)
Camper 2019, Hu et al. 2020
Scharf et al. 2015, Hu et al. 2020, Deepak et al. 2022
most abundant on or near the summits of the highest peaks (Beane et al. 2010), 0-2540 (O'Shea 2018)
Breeding
- Reproduction
- Viviparous
- Gestation or incubation
- 100days
- Average clutch
- 27eggs
- Eggs or young per clutch
- 1–101eggs
- Mean clutch
- 7.6–32.5eggs
- Clutches in a year
- 1per year
- Clutches a year
- 0.23–0.88per year
- First breeds at
- 22.5–36months
- Age at first breeding · female
- 730days
Feldman et al. 2015, Meiri et al. 2019
mean 27 (Meiri et al. 2019), 7-80 (Guyer et al. 2019), 5-101 (Beane et al. 2010), 1-101 (Camper 2019), means: 10-15, mean=30 (Murphy et al. 2003), 7-36 (O'Shea 2018), 3-80 (Sheldon 2022), 15-80 (Phillips et al. 2022), means 7.6-32.5 (Rossman et al. 1996)
Naming and history
- Suborder
- Serpentes
- Infraorder
- Alethinophidia
- Subspecies
- Thamnophis sirtalis annectens BROWN 1950 Thamnophis sirtalis concinnus (HALLOWELL 1852) Thamnophis sirtalis dorsalis (BAIRD & GIRARD 1853) Thamnophis sirtalis fitchi FOX 1951 Thamnophis sirtalis infernalis (BLAINVILLE 1835) Thamnophis sirtalis pallidulus ALLEN 1899 Thamnophis sirtalis parietalis (SAY 1823) Thamnophis sirtalis pickeringii (BAIRD & GIRARD 1853) Thamnophis sirtalis semifasciatus COPE 1892 Thamnophis sirtalis similis ROSSMAN 1965 Thamnophis sirtalis sirtalis (LINNAEUS 1758) Thamnophis sirtalis tetrataenia (COPE in YARROW 1875)
- Described by
- Linnaeus
- Moved to another genus · since it was first described
- Yes
- Described in
- 1758
- Type locality
- Canada
Keeping one
4 ft 7 in × 2 ft 4 in × 3 ft 5 in(140 × 70 × 105 cm)
Minimum length × width × height, for one animal. Bigger is always better.
The standard sizes snakes as a fraction of total length: 1 × 0.5 × 0.75.
Mindestanforderungen an die Haltung von Reptilien (Sachverständigengutachten), German Federal Ministry for Nutrition, Agriculture and Forestry, Animal Welfare Division, 10 January 1997. The standard states these floor areas are recommendations rather than binding limits.
From this animal’s own total length of 4 ft 7 in (1400 mm), at 1 × 0.5 × 0.75 times it, following the German federal welfare standard — how this is worked out.
In a laboratory thermal gradient this species settled at 85 °F (29.3 °C).
Preferred body temperature, recorded in a laboratory gradient where the animal could choose freely. A measurement of the animal, not a setting for a thermostat.
Feeding
A prey item should be between the same width as the widest part of the snake's body and about 1.5 times that width.
Widely used across snake husbandry references. An alternative formulation gives prey at 10-15% of the snake's body mass. This is established practice, not a measurement.
64kJ per day
Worked out for an animal of 667 g, the heaviest recorded for Common Garter Snake — so it is the top of the range, not a figure for a particular animal. Weigh yours and the number will be lower.
An upper estimate, not a feeding target, and not veterinary advice. The equation covers only what an animal burns staying alive, so a growing, gravid or recovering animal needs more — and it was measured on wild animals, which move far more than one in an enclosure. Body condition and a vet who knows the species are what a feeding decision should rest on. Where this comes from.
Morphs
1 with peer-reviewed genetics behind them, 4 resting on breeder consensus. Most references present both with the same confidence.
What each pairing produces → · Two genes at once →
- Skin colourpeer reviewed
- Heritable Variation in Garter Snake Color Patterns in Postglacial Populations — PLoS ONE 2011
- Albinobreeder consensus
No black pigment, leaving yellow and pink over white, with red eyes.
- Anerythristicbreeder consensus
Red and orange absent, leaving a black, grey and white animal.
- Flamebreeder consensus
Red intensified along the flanks, built up over generations by selection rather than by one gene.
- Melanisticbreeder consensus
Heavily increased black, giving an animal that is nearly uniformly dark with the stripes lost.
Worth knowing. Melanistic garter snakes also occur naturally in some wild populations, particularly around the Great Lakes, where dark animals warm faster in a cool climate. The trait in the hobby comes from those populations rather than from a mutation that arose in captivity.
What nobody knows
These are not gaps in our research. No scientific dataset records them for this species — and saying so is information you cannot get from a reference that simply leaves a field out.
- — Length snout to vent · adult female mean
- — Length snout to vent · adult male mean
- — Length snout to vent · adult mean
- — Female length · mean, nose to tail
- — Length nose to tail · adult male mean
- — Length nose to tail · adult mean
- — Largest female · shell length
- — Largest male · shell length
- — Hatchling length · snout to vent
- — Largest juvenile · snout to vent
- — Largest juvenile · shell length
- — Egg length
- — Egg width
- — Body mass · adult female, mean
- — Eats arthropods
- — Eats vertebrates
- — Eats plant matter
- — How the young develop
- — Hatchling length · smallest recorded
- — Hatchling length · largest recorded
- — Mature from · youngest recorded
- — Mature by · oldest recorded
- — Size at maturity · smallest recorded
- — Size at maturity · largest recorded
- — Colour on the back
- — Pattern on the back
- — Sex decided by
- — Red List criteria
- — Active season · shortest recorded
- — Active season · longest recorded
- — Home range · largest recorded
- — Active in
- — Lowest it lives · above sea level
Others in Colubridae
Take this data
Everything on this page is available as data under CC BY 4.0 — use it freely, credit it, no permission needed.
This species as JSON · the whole dataset
Cite this page
The Reptile & Amphibian Encyclopedia (2026). Thamnophis sirtalis. Retrieved 2026-09-08, from https://www.allanglescreatures.com/species/thamnophis-sirtalis
@misc{thamnophis_sirtalis_2026,
title = {Thamnophis sirtalis},
author = {{The Reptile & Amphibian Encyclopedia}},
year = {2026},
url = {https://www.allanglescreatures.com/species/thamnophis-sirtalis}
}Sources
- Meiri, S. (2024). SquamBase — a database of squamate (Reptilia: Squamata) traits. Global Ecology and Biogeography. Public domain (CC0).
- AnAge, Human Ageing Genomic Resources (de Magalhães et al.), used under CC BY 3.0.
- Oskyrko, O. et al. (2024). ReptTraits: a comprehensive dataset of ecological traits in reptiles. Scientific Data. Used under CC BY 4.0.
- Catalogue of Life (dataset 3LR), used under CC BY.