Coluber constrictor Linnaeus, 1758
North American Racer
Click to enlarge
Basis for Listing
The North American racer has a large range that extends across the United States and into southern Canada and northeastern Mexico. Large gaps occur in its distribution in southwestern states and in the Dakotas and Minnesota (Ernst and Barbour 1989). The blue racer (Coluber constrictor foxii) is the subspecies found in Minnesota. It occurs in ten counties in southern Minnesota where localized populations inhabit the Mississippi, Minnesota, and St. Croix river valleys. Its limited distribution makes it vulnerable to local extirpation from overcollection for the pet trade, habitat degradation, and den site destruction. For these reasons, the North American racer was listed as a species of special concern in Minnesota in 1984.
The North American racer is a medium- to large-sized, slender snake. Adults range in size from 90-152 cm (36-60 in.), with the record size being 183 cm (72 in.) (Conant and Collins 1998). The dorsal ground color ranges from blue or gray to brown. The chin and throat may be yellow or white, with the rest of the ventral surface being white. The young have a gray dorsal ground color, with reddish-brown or black blotches, while their bellies have a white ground color covered with small reddish-brown spots. The young do not attain adult coloration until their third summer. The scales of this species are smooth and the anal plate is divided. There are few other snake species in Minnesota that adult North American racers may be confused with, but the young resemble those of several other species. However, the only other species with smooth scales and a blotched pattern is the milksnake (Lampropeltis triangulum), which has a single anal plate (Oldfield and Moriarty 1994).
The North American racer occupies a variety of habitats in the deciduous forest region including forested hillsides, bluff prairies, grasslands, and open woods. Woodland margins and field edges are the preferred summer habitat. During winter months, North American racers hibernate in mammal burrows, caves, rock crevices, gravel banks, stone foundations, and old wells (Ernst and Barbour 1989).
Biology / Life History
The North American racer emerges from hibernation during late April, remaining near its hibernacula for several days (Oldfield and Moriarty 1994). Breeding usually takes place in May and early June, and 8-21 eggs are laid under rotting logs, stumps, or inside mammal burrows in late June or early July (Fitch 1963; Oldfield and Moriarty 1994). Eggs hatch in 43-65 days, with hatchlings emerging from the nest in late August or early September. The young are about 20-35 cm (8-14 in.) at emergence (Oldfield and Moriarty 1994).
Conservation / Management
North American racer populations have been drastically reduced in many states due to habitat destruction, pesticide use, and human persecution (Ernst and Barbour 1989). Isolated populations are extremely vulnerable to habitat degradation and loss from intensive agricultural practices and urban sprawl. Young North American racers that feed on invertebrates may be particularly at risk from pesticide use. As this species often utilizes a large home range, it is are also subject to being killed on busy roads. In addition, over-harvest for the pet trade threatens isolated populations.
Conservation Efforts in Minnesota
While habitat loss is a significant threat to North American racer populations in Minnesota, protection and management of grasslands and savannas helps enhance remaining habitats. The Nongame Wildlife Program has conducted educational workshops in southeast Minnesota to inform local landowners about the natural history and identification of snakes.
References and Additional Information
Conant, R., and J. T. Collins. 1998. A field guide to reptiles and amphibians of eastern and central North America. Third edition. Houghton Mifflin Company, New York, New York. 616 pp.
Ernst, C. H., and R. W. Barbour. 1989. Snakes of eastern North America. George Mason University Press, Fairfax, Virginia. 282 pp.
Fitch, H. S. 1963. Natural history of the racer Coluber constrictor. University of Kansas Publications, Museum of Natural History. 15(8):351-468.
Oldfield, B., and J. J. Moriarty. 1994. Amphibians and reptiles native to Minnesota. University of Minnesota Press, Minneapolis, Minnesota. 237 pp.