The Cold Blooded News The Newsletter of the Colorado Herpetological Society Volume 28, Number 1;   January, 2001

Two Lined Snakes (Tropidoclonion lineatum lineatum)
from Jefferson County, Colorado

David Chiszar(1), Hobart M. Smith(2), and Laura A. Lembke(2)

We report two specimens from a distant location in Jefferson County, verifying the fact that one or more populations of T. l. lineatum exist in that county, and that they are not confined to Dry Gulch.

On October 16, 2000, DC found a specimen of T. l. lineatum LOR 25 m west of the intersection of 74th Place and Secrest Court, Arvada. (UCM 61079) The next day, DC and HMS walked through this area and found a shed skin from a T. l. lineatum in a rock wall bordering the south-east corner of Quaker Acres Park, about 150 m west of the site of the previous specimen. These two sites are about 18 km northwest of Livo's (1988) locality within Jefferson County.

The significance of the new localities resides not only in their documentation of an additional population of T. l. lineatum in Jefferson County, but also in their westerly position (approximately 105° 16' 7" W). Within Colorado, there is a more westerly location for T. l. lineatum in Boulder County (approximately 105° 17' 28" W), but it is unlikely that any sites will be found farther west in that county because the currently known localities for T. 1. lineatum in Boulder County are in edge habitats where the prairie abuts the mountains. Inasmuch as T. l. lineatum is a grasslands species (Hammerson, 1999), we suspect that it simply cannot survive in the mountain habitat of western Boulder County. Within Jefferson County, however, there is a more-or-less continuous prairie extending west of the present Arvada sites for at least 10 km into the Ralston Creek drainage. If T. l. lineatum inhabits this embayment of prairie, then we can expect westerly locations for the taxon as far as 105° 20' W. In other words, we may be dealing with the western-most population of T. lineatum in the entire state of Colorado. The westernmost localities known for the species elsewhere (Conant & Collins, 1991; Wright & Wright, 1957) are in central New Mexico (Degenhardt et al., 1996). Since species are generally more vulnerable to environmental insults at the periphery of their ranges than in more central areas, it can be hypothesized that T. l. lineatum in central Jefferson County exists precariously and will be rapidly extinguished by land developments now occurring there. In this context, the Jefferson County Open Space area associated with Tucker Lake may eventually harbor a relictual population of this snake.

References:

Conant, R., & J. T. Collins. 1991. A field guide to reptiles and amphibians, eastern and central North America. Boston: Houghton Mifflin Co.

Degenhardt, W. E., C. W. Painter, & A. H. Price. 1996. Amphibians and reptiles of New Mexico. Albuquerque, New Mexico: University of New Mexico Press.

Hammerson, G. A. 1999. Amphibians and reptiles in Colorado. Niwot, CO: University Press of Colorado & Colorado Division of Wildlife.

Livo, L. J. 1988. Tropidoclonion lineatum lineatum (Lined Snake). Geographical distribution. Herpetological Review 19(3), 61.

Wright, A. H., & A. A. Wright. 1957. Handbook of snakes of the United States and Canada. Vol. 2. Ithaca: Comstock Publishing Associates, a division of Cornell University Press.

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