Narrow-headed Garter Snake

DESCRIPTION:
The Narrow-headed garter snake is medium-sized, typically reaching total lengths of 700–1,115 mm. The dorsal coloration varies from olive-gray to brown, often with paired, dark, irregular dorsal blotches that are most prominent anteriorly and fade posteriorly. The lateral stripes are generally absent, making it more distinguishable from most other related species. They possesses a distinctively elongate and narrow head with dorsally positioned eyes. The dorsal scales are strongly keeled, arranged in 21 scale rows at midbody.

DISTRIBUTION & STATUS:
Endemic to the Mogollon Rim region and the associated watersheds of Arizona and southwestern New Mexico. In Arizona, they primarily occupy upper reaches of the Salt, Verde, Black, and Gila river systems. Historically more widespread, the species is now restricted to fragmented populations due to habitat loss, hydrologic alteration, and nonnative species introductions. This species is federally listed as Threatened under the U.S. Endangered Species Act, and critical habitat has been designated in select perennial stream systems.

HABITAT:
Inhabits high altitude (701-2430m) perennial streams with clear, cool water and rocky substrates. They prefer complex stream segments with pools, riffles, and abundant in-stream cover (boulders, woody debris), as well as riparian zones with dense overhanging vegetation. Adjacent upland riparian habitats are used for thermoregulation and hibernation. The species exhibits high fidelity to aquatic environments and is considered an obligate riparian specialist.

FOOD HABITS:
The Narrow-headed garter snake is an aquatic predator. Its primary prey includes native and non-native fishes including dace, suckers, and juvenile trout. Secondary prey includes frogs, tadpoles, and other amphibians in habitats where fish are less abundant. Prey is typically captured via ambush or active pursuit within the water column.

REPRODUCTION:
Sexual maturity is reached at about 2-3 years. This species hibernates between October or November to March and after, mates during the late spring to early summer. The species is viviparous, rearing live young, and gives birth around mid to late summer to a a litter of 6-18 young. Reproductive frequency may vary annually depending on environmental conditions and prey availability.