Coluber constrictor
(Racer)

Key Characteristics
Large eyes with round pupils
Solid color dorsally on adults
(blotched pattern on young)
Smooth scales
Fast moving

General Description:
Racers are, as their name implies, fast and sleek snakes.  Their speed contrasts with the slow moving Rubber Boa.  Besides their rate of movement, other Racer characteristics that contrast with Rubber Boas, are their large eyes and round pupils.  Racers are visual predators, relying on visual cues to help them identify prey.  In fact, Racers will sometimes raise their head and upper body while foraging.   Racers are generally a solid color both dorsally (green, tan or blue-gray) and ventrally (yellow to cream).  These snakes are unusual among Idaho snake species because juveniles are colored differently than adults.   Juveniles have a light gray ground, a series of brown saddles dorsally and blotches along their sides (Stebbins 1985).   As the young snakes age, these dark markings fade from the tail towards the head, and the ground color becomes green, gray or tan.  Juvenile Racers could be mistaken for young Gopher Snakes, but the smooth scales help distinguish Racers from Gopher Snakes, which have keeled scales. 

Racers are medium-sized snakes, which in the Pacific Northwest reach total lengths of around 120 cm (48 in.) (Storm and Leonard 1995).  However, in other parts of their range, Racers can get as large as 196 cm (77 in.) (Behler and King 1979).

Racers mate in May, and lay 3-6 eggs (but as many as 28 in parts of their range) in June or July (Behler and King 1979, Nussbaum et al. 1983).  An interesting note is that Racers will sometimes lay their eggs communally with other species (Nussbaum et al. 1983).  The eggs generally hatch in August (Storm and Leonard 1995), and the young resemble the adults in form but are colored differently (as described above).

Habitat:
Racers can be found in a variety of habitats ranging from open forests to rocky or brushy desert areas.  They are often encountered along desert/agricultural interfaces, where they can take advantage of the higher density of prey items such as rodents, insects and amphibians.  In arid habitats, Racers will include lizards in their diet as well.

Idaho Distribution:
Racers can be found across most of Idaho and are absent only from the northernmost portion of the state.   From southern British Columbia, east to Maine, and south across the U.S. to southern Florida, Guatemala, and southern California.

Diet:
Diet typically includes small mammals, birds, reptiles, amphibians, and large insects.

Ecology:
Inactive during cold weather; in central U.S., hibernatesClick word for definition from November to March. In Idaho, adults emerge from den in late April to early May, and return to distinct hibernaculaClick word for definition by October; hibernates with other snakes. In Michigan and other cold-winter areas, adults are active on bright overcast or sunny days in summer, and only on sunny, warm days in spring and fall. Adults hide underground, in crevices, or under surface cover when inactive. Home range size has been estimated at 1.4 ha for nongravid females in Utah, and about 10 ha in Kansas. In Utah study, population density was estimated at 0.65/ha. Separate studies estimated adult annual survivorship at 79% in Utah, 62% in Kansas, and 54% in Michigan. Individuals sometimes nest communally, and may climb shrubs and small trees.

Reproduction:
Egg-laying peaks in early to mid-June in southern Michigan, and late June or early July in Utah, Colorado, and Idaho. Female lays clutch of 3-28 eggs (3-6 in Idaho). Average clutch size is higher in eastern range than in west; mean clutch size is about 6 in Utah, 12 in Kansas, and 15 in Michigan. Eggs hatch in 6-9 wk. Females become sexually mature in 3 yr in Utah, 2-3 yr in Kansas, 2 yr in Michigan.

Conservation:

Status:

Unprotected nongame species

Global Rank:

G5

State Rank:

S5


Design optimization and revision by Ean Harker ©1999, 2000
Original images provided by Charles R. Peterson ©1998
Original work by John Cossel Jr. © 1998