USGS Home
Contact USGS
Search USGS

A Survey of the Herpetofauna of the Comanche National Grasslands in Southeastern Colorado

Areas within the Comanche National Grasslands of High Herpetological Diversity

As a result of extensive field work in southeastern Colorado, several areas have been identified as regions of high diversity or of occurrence of rare/uncommon species, and many occur within the boundaries of the Grasslands. Some areas are highly localized, some span several counties and others are likely very extensive but have not been surveyed due to inability to get permission to enter private property. Below is an annotated list of such areas with species of note which occur there.

1. Baca County
   Although much of Baca County has been overfarmed and habitat quality is severely degraded, there remain several areas which have a high concentration of amphibian/reptile species. In addition, since the county is the southeastern-most in Colorado, several species which reach their northernmost or westernmost limits just within Colorado are also found here. The following regions are identified as important to the maintenance of amphibian and reptile diversity:
   1. The area immediately adjacent to Baca County Road C, between 5 miles and 7 miles east of the junction with Highway 287. Texas horned lizards (P. cornutum), western box turtles (Terrapene ornata ornata) and western hognose snakes (H. n. nasicus) are abundant in this region of shortgrass prairie.
   2. Carrizo Canyon and the adjacent canyonlands. Because of the varied topography, relatively permanent water along stream beds and southern location, these canyonlands have a rich herpetofauna. This area provides good habitat for a number of otherwise uncommon species of snakes, including the Texas blind snake (Leptotyphlops dulcis dissectus), ringnecked snake (Diadophis punctatus arnyi), night snake (Hypsiglena torquata janii), ground snake (Sonora semiannulata), wandering garter snake (Thamnophis elegans vagrans) and blacknecked garter snake (Thamnophis cyrtopsis cyrtopsis). Great Plains skinks (Eumeces obsoletus) are commonly encountered, and spiny softshell turtles (Trionyx spiniferus hartwegi) are abundant in the permanent ponds along the creeks of this area.

   In 1996, field work extended east and slightly south of Carrizo Canyon, into Las Animas County. Two county distributional records were obtained: two specimens of the plains narrowmouth frog (Gastrophryne olivacea) were found in a deep, shaded pool on an unnamed creek approximately 1 mile south of Carrizo Creek, and numerous western painted turtles (Chrysemys picta bellii) were observed in a cattle pond. I would expect these species to occur in appropriate adjacent habitat within the boundaries of the southern section Grasslands

2. Las Animas County
   1. The herpetofauna of the Black Mesa area, which just extends eastward into the southern section of the Grasslands, is largely unknown, but because of its variable topography and lack of extensive human modification, it is likely to contain some interesting distributional surprises. Our field work in this area has been hampered by an inability to obtain permission to trespass on private land (which includes most of this vast area). This region of the extreme southwest is most promising for future work if the cooperation of landowners can be obtained.

   One county distributional record of note was obtained in 1996. Based on the finding of a shed skin in a fissure in a creek bank, the presence of the common kingsnake (Lampropeltis getulus holbrooki/splendida) was confirmed. This snake represents an intrusion of the fauna found further south in New Mexico (where it is much more abundant), and its presence strongly indicates that other amphibians and reptiles typically found further south may be present in Colorado in this area. For example, if the western diamondback rattlesnake (Crotalus atrox) occurs in Colorado, as has persistently been reported but never documented, it seems likely that the Black Mesa region is where it will be discovered. This region seems most likely to yield new state distributional records.

3. Otero County
   1. Comanche National Grasslands, northern unit. Much of this area has good to excellent habitat for a wide variety of amphibians and reptiles. Like Carrizo Canyon, the varied topography provides numerous habitats in close juxtaposition, favoring a diverse herpetofauna. Rourke Road, approximately 1.0 mile north of David Canyon Road, cuts through bluffs which are continuous to the south with prairie habitat. Numerous stock ponds provide breeding ponds for amphibians, and the broken shale provides cover for numerous species. These areas are excellent habitat for green toads (Bufo debilis insidior), chorus frogs, eastern fence lizards, racers, ground snakes and prairie rattlesnakes. All grassland habitat in the general area is also excellent habitat for Texas horned lizards, which are moderately common in this region. Vogel Canyon is excellent habitat for red-spotted toads (Bufo punctatus), plains leopard frogs (Rana blairi), collared lizards, Texas horned lizards, eastern fence lizards, six-lined racerunners (Cnemidophorus sexlineatus), Colorado checkered whiptail lizards (Cnemidophorus tesselatus), plains garter snakes (Thamnophis radix) and lined snakes. Continued protection of this northern section of the Grasslands should be actively promoted, as it provides a protected area for many species of the southeastern Colorado herpetofauna. Cattle grazing is compatible if it is kept to a low level; fencing of some ponds to exclude cattle, particularly towards the bluffs north of and just south of David Canyon Road, should encourage the continued presence and successful breeding of green toads. Establishment of additional shallow basins may also aid these threatened amphibians.

   2. Much of the habitat along Highway 109, beginning approximately 3.0 miles south of La Junta. Parts of this region are on the Grasslands and parts are private, and as in Las Animas County, the highway provides a readily-sampled transect through intact habitat. Texas horned lizards, lined snakes and plains milk snakes (Lampropeltis triangulum gentilis) are commonly encountered 2.0 miles north and south of the junction of David Canyon Road with Highway 109. A live specimen of longnose snake (Rhinocheilus lecontei), a species only encountered a few times after tens of thousands of miles of road surveys (usually as a DOR), was found on Highway 109 south of the Grasslands northern section border.