Ridge-nosed Rattlesnake

Appearance

''C. willardi'' is a rather small rattlesnake with all subspecies measuring one to two feet in length. Color patterns are generally a dark brown base with pale or white horizontal striping, but vary slightly between subspecies. The distinctive ridges along each side of its nose, which are a series of upturned scales, are unique to its species and are the origin of its name.

Naming

Common names: Ridge-nosed rattlesnake, Willard's rattlesnake, Willard's rattler'

Status

This species is classified as Least Concern on the IUCN Red List of Threatened Species . Species are listed as such due to their wide distribution, presumed large population, or because they are unlikely to be declining fast enough to qualify for listing in a more threatened category. The population trend was stable when assessed in 2007.

Although four of the five subspecies are secure, the New Mexico ridge-nosed rattlesnake is an endangered species and listed as threatened by the US Fish and Wildlife Service. Remaining populations are scattered throughout New Mexico, Arizona and the northern part of Mexico. Habitat destruction is the cause of declining numbers, but critical habitat designations have been proposed.

Behavior

Rattlesnakes are primarily ambush hunters; they coil and lie waiting for prey to approach within striking distance. The diet of ''C. willardi'' includes small mammals, lizards, birds, and large centipedes. The young feed primarily on large centipedes and lizards, whereas adults feed primarily on mammals and birds.

Like other rattlesnakes, ''C. willardi'' is ovoviviparous, meaning it gives birth and does not lay eggs. Contrasting with viviparous animals, the young still develop within an egg inside the female snake until their time of birth. Copulation occurs from late summer to early fall, and gestation lasts about four to five months. Females give birth to two to 9 young in late July or August. Both sexes appear to reach reproductive maturity around 400 mm in body length. Although captive snakes have reproduced annually, wild females probably reproduce every second or third year.

Habitat

''C. willardi'' is rarely found outside habitats at high elevation. Wooded mountain ranges, primarily in the southwest, are where this reclusive species is found. Each subspecies’ range is limited to select mountain ranges, making human encounters rare events.

Defense

Due to the generally small size of the snake, venom discharge yields are low; thus, the largely hemotoxic venom is not as life-threatening as that of other rattlesnakes. No documented deaths have been caused by ridge-nosed rattlesnakes, but pain and discomfort can still result from a rare bite.