|Scientific Name:||Pantherophis bairdi (Yarrow, 1880)|
Coluber bairdi Yarrow, 1880
|Taxonomic Notes:||This species formerly was included in E. obsoleta (Olson 1977). Electrophoretic data for specimens of bairdi and obsoleta from Texas are consistent with those expected for a single polytypic species, whereas morphological evidence suggests that hybridization between the two taxa is a rare event more characteristic of two species than of subspecies (Lawson and Leib 1990). Burbrink et al. (2000) and Burbrink (2001) examined genetic and morphological variation and concluded that E. bairdi and E. obsoleta are different species.
Utiger et al. (2002) examined mtDNA variation in New World and Old World "Elaphe" and determined that North American ratsnakes included in the genus Elaphe form a monophyletic limeage that is distinct from Old World snakes that also have been regarded as Elaphe. They resurrected the genus Pantherophis for the ratsnakes north of Mexico, including the following species: Pantherophis obsoletus (and P. alleghaniensis and P. spiloides, if one recognizes those taxa as species), P. guttatus, P. emoryi, P. vulpinus, P. gloydi, and P. bairdi. Crother et al. (2003) noted this proposal but did not adopt it, pending further review. Burbrink and Lawson (2007) agreed with Utiger et al. (2002) that these species do not belong in Elaphe, but suggested that the genus Pantherophis might belong in Pituophis. We retain this species in Pantherophis, following Utiger et al. (2002) pending further information of the relationships of these taxa.
|Red List Category & Criteria:||Least Concern ver 3.1|
|Assessor(s):||Hammerson, G.A., Lavin, P. & Mendoza Quijano, F.|
|Reviewer(s):||Cox, N., Chanson, J.S. & Stuart, S.N. (Global Reptile Assessment Coordinating Team)|
Listed as Least Concern in view of the probably relatively stable extent of occurrence, area of occupancy, number of subpopulations, and population size. This species has a limited distribution and area of occupancy, but it is not threatened across most of its range.
|Range Description:||The species' range includes only southwestern Texas (central Hill Country, Trans-Pecos) and adjacent areas in northeastern Mexico: southwestern Edwards Plateau of Texas west through the dissected canyons of the Stockton Plateau and the Big Bend Region to the Davis Mountains, thence south into Mexico along Coahuila Folded Belt to the front range of Sierra Madre Oriental of Coahuila, Nuevo Leon and Tamaulipas; also the Sierra San Carlos of south-central Tamaulipas, at elevations of around 305 to 3,050 m asl (1,000 to 10,000 feet) (Lawson and Lieb 1990, Werler and Dixon 2000). Within this range, the distribution appears to be spotty (Tennant 1998), but this may in part reflect the snake's secretive behavior (Ernst and Ernst 2003).|
Native:Mexico; United States
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||This species is represented by at least a few dozen distinct occurrences or subpopulations. Werler and Dixon (2000) mapped several dozen collection sites in Texas; these represent probably at least 20 distinct occurrences. For Mexico, Lawson and Lieb (1990) listed three locations for Coahuila, three for Nuevo Leon, and three for Tamaulipas, so probably there are at least several subpopulations south of Texas. The total adult population size is unknown but probably at least several thousand. The extent of occurrence, area of occupancy, number of subpopulations, and population size are probably relatively stable.|
|Current Population Trend:||Stable|
|Habitat and Ecology:||Habitats include a wide variety of vegetational associations, from Chihuahuan desert scrub in Texas to Sierra Madrean pine forest in Tamaulipas (Lawson and Lieb 1990). In Texas, this terrestrial and arboreal snake inhabits wooded rocky canyons of Edwards Plateau, pinyon pine-needle grass uplands in Chisos Mountains, barren road-cut bluffs with scattered seep willow, and mesic canyons in montane forest and low desert areas in the Trans-Pecos region (Tennant 1984, 1998). Rocky, igneous or limestone habitats apparently are favoured, especially those with caves, deep crevices, and/or sheer canyon walls; eaves and wooded crevices associated with ranch outbuildings are also occasionally used (Lawson and Lieb 1990).|
|Major Threat(s):||This species is not significantly threatened.|
|Conservation Actions:||The species occurs in Big Bend National Park. Occurs in several protected areas in Mexico.|
Burbrink, F.T. 2001. Systematics of the eastern ratsnake complex (Elaphe obsoleta). Herpetological Monographs 15: 1-53.
Burbrink, F.T. and Lawson, R. 2007. How and when did Old World rat snakes disperse into the New World? Molecular Phylogenetics and Evolution 43: 173-189.
Burbrink, F.T., Lawson, R. and Slowinski, J.B. 2000. Mitochondrial DNA phylogeography of the North American rat snake (Elaphe obsoleta): a critique of the subspecies concept. Evolution 54: 2107-2114.
Crother, B.I., Boundy, J., Campbell, J.A., de Quieroz, K., Frost, D., Green, D.M., Highton, R., Iverson, J.B., McDiarmid, R.W., Meylan, P.A., Reeder, T.W., Seidel, M.E., Sites Jr, J.W., Tilley, S.G. and Wake, D.B. 2003. Scientific and standard English names of amphibians and reptiles of North America north of Mexico: update. Herpetological Review 34: 196-203.
Ernst, C.H. and Ernst, E.M. 2003. Snakes of the United States and Canada. Smithsonian Books, Washington, D.C.
IUCN. 2007. 2007 IUCN Red List of Threatened Species. Available at: www.iucnredlist.org. (Accessed: 12th September 2007).
Lawson, R. and Lieb, C.S. 1990. Variation and hybridization in Elaphe bairdi (Serpentes: Colubridae). Journal of Herpetology 24: 280-292.
Olson, R.E. 1977. Evidence for the species status of Baird's ratsnake. Texas Journal of Science 29: 79-84.
Tennant, A. 1984. The Snakes of Texas. Texas Monthly Press, Austin, Texas. 561 pp.
Tennant, A. 1998. A Field Guide to Texas Snakes. Second edition. Gulf Publishing Company, Houston, Texas.
Utiger, U., Helfenberger, N., Schmidt, B., Ruf, M. and Ziswiler, V. 2002. Molecular systematics and phylogeny of Old and New World ratsnakes, Elaphe auct., and related genera (Reptilia, Squamata, Colubridae). Russian Journal of Herpetology 9(2): 105-124.
Werler, J.E. and Dixon, J.R. 2000. Texas Snakes: Identification, Distribution, and Natural History. University of Texas Press, Austin, Texas.
|Citation:||Hammerson, G.A., Lavin, P. & Mendoza Quijano, F. 2007. Pantherophis bairdi. The IUCN Red List of Threatened Species 2007: e.T63860A12722977.Downloaded on 26 May 2018.|
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