The blackneck garter snake (Thamnophis cyrtopsis), named for the black blotches behind its jaws, has a large population that ranges from southern Colorado and Utah south into Mexico and Guatemala.

Nonvenomous, it grows to be 40.5–71 centimeters (16 to 28 inches) long. It likes to eat amphibians, especially frogs, toads, and tadpoles, as well as fish. Sometimes it also eats skinks, crustaceans, and earthworms.

If threatened or disturbed, this garter snake emits a strong, unpleasant smelling musk from its anal glands and may also expel feces. To make itself look larger, it might also flatten its head and body when it feels it’s in danger. These snakes generally do not bite, though, unless seriously provoked.

Blackneck garter snakes communicate with each other mainly through the release of chemical pheromones. They also have an inner ear through which they can detect sounds, and they can sense vibrations in the ground through their jawbone.

The blackneck garter snake occurs in a wide range of habitats, from dry deserts to forested mountains. It prefers being near a consistent water source, which could be anything from a stream to a lawn sprinkler.

Introduced species, such as bullfrogs and sunfish, feed on the blackneck garter snake and also compete with them for prey, which impacts the garter snake’s population. In some areas, its habitat has been lost or fragmented because of urbanization, deforestation, or the expansion of agriculture. Even so, the International Union for Conservation of Nature (IUCN) has listed their status as being of least concern and their population is considered relatively stable.

  1. What are the characteristics of the blackneck garter snake’s early life?

    • Answer

      The blacknecked garter snake is born live, after it grows in an egg within its mother’s body. With this type of birth, garter snakes are considered oviparous. Blackneck garter snakes are 8–10 inches (20–25 cm), with between 1 and 24 offspring at a time. The young go off on their own right away, having no more association with their mother.

  2. How are blackneck garter snakes part of a food web?

    • Answer

      Blacknecked garter snakes eat a variety of prey: frogs, toads, tadpoles, fish, skinks, crustaceans, and earthworms. They are also prey for a variety of other vertebrates, including bullfrogs, sunfish, and other snake species. Flatworm and roundworm species can also live in these snakes, some being parasitic, or causing harm, and others commensal, providing benefits to the snake.

  3. Why can it be hard to find snakes such as the blacknecked garter snakes in the wild?

    • Answer

      These snakes’ skin pattern helps to camouflage them in their natural habitat. They can also sense that a human is walking nearby, as they detect sounds and sense vibrations in the ground and move quickly to hide.


the art and science of cultivating land for growing crops (farming) or raising livestock (ranching).


an animal able to live both on land and in water.

anal gland

one of two sacs located on either side of the anus of some mammals, which secrete a liquid used to identify members of a species. Also called anal sacs or scent glands.


type of animal (an arthropod) with a hard shell and segmented body that usually lives in the water.


destruction or removal of forests and their undergrowth.

Plural Noun

waste material produced by the living body of an organism.


environment where an organism lives throughout the year or for shorter periods of time.

International Union for the Conservation of Nature (IUCN)

environmental organization concerned with preserving natural ecosystems and habitats.


substance released by an animal that influences the behavior of other animals of the same species.


total number of people or organisms in a particular area.


to annoy or make angry.


process in which there is an increase in the number of people living and working in a city or metropolitan area.


having to do with venom or organisms that secrete venom.