Durango Mountain Kingsnake — Lampropeltis greeri Webb 1961

Other Common Names: Greer’s Kingsnake

Spanish Name:Culebra Real de Greer

Original Description: Webb, R. G. 1961. A new kingsnake from Mexico, with remarks on the mexicana group of the genus Lampropeltis. Copeia 1961(3):326–333. 

Holotype & Type Locality: Michigan State University 190, a young male, collected by J. Keever Greer and Robert G. Webb on 18 July 1958, from Rancho Santa Barbara (Weicher Ranch), 29 miles west-southwest of Ciudad Durango, Durango, México, at an elevation of ca. 7400 ft.

Etymology:The species name is a patronym honoring the late John Keever Greer (deceased 1980), mammalogist and field companion of R. G. Webb in Durango. Greer and Webb were students at the University of Kansas, and together took several trips to Mexico in the late 1950s and early 1960s. Greer went on to earn his Ph.D. at Michigan State University (under the mammalogist Rollin H. Baker), and later became Curator of Mammals and Director of the Stovall Museum of Natural History (now the Oklahoma Museum of Natural History).  Webb’s “Reptiles of Oklahoma” (1970) was published by the Stovall Museum of Natural History during Greer’s tenure as director. 

Scientific Describer:Robert Gravem Webb (1927–2018), long-time professor at the University of Texas at El Paso, was the foremost student of the herpetofauna of the Sierra Madre Occidental. During this period of fieldwork in western Mexico, Webb (then a graduate student at the University of Kansas) collected herpetological as well as mammal specimens, in association with the mammalogist Rollin H. Baker, at that time on the University of Kansas faculty and Webb’s mentor during the sojourns to Mexico.  

Distribution: Eastern versant of the Sierra Madre Occidental of west-central Durango, then south through various outlier ranges and upland areas in Zacatecas, Aguascalientes, Jalisco, and Nayarit at relatively high elevations (> 2000 m). 

Habitat: This species occurs in pine-oak forest and open oak savannas, nearly always associated with rocks that receive daily sun exposure. Individuals have been found in crevices and beneath rocks. Although most snakes have been found under rock cover, occasionally they are encountered crawling on the surface during the day. 

Growth and Size:  As adults, greeri are similar in size to other Mexicana kings, though perhaps a bit smaller than alterna or ruthveni. The largest snakes we have seen were just under 1 m total length; males attain larger size than females. As with the other species, there are no growth data available for wild specimens, but juvenile greeri seem to grow more slowly than the other species in captivity. Sexual maturity is attained at 3–4 years in captives. Field collectors have reported communal egg-laying at Rancho Santa Barbara. 

Pattern Variation:Although there is some variation evident among both wild-caught and captive-propagated Durango animals, it does not appear to encompass some of the variation seen in specimens at the southern range limits near the Jalisco-Aguascalientes border or in Nayarit. Among Durango specimens, ground color can be light gray, dark gray, greenish, or tan. Most snakes have red-orange saddles or crossbands, prominently bordered by black, that narrow laterally; these bands may terminate at the ventrals or sometimes extend onto the ventral surface. Some specimens from Durango have greatly reduced red-orange dorsal markings, with this color confined to a few bands or entirely lacking. A feature common to nearly all “standard” looking Durango specimens is the presence of an elongated nuchal blotch with a central opening (or “window”). Snakes observed in the field from near the Sierra Fria in Aguascalientes had a ground color of buff or tan with a “typical” greeri pattern of red-orange crossbands bordered by black that narrow laterally. Snakes from the southernmost known locality (Sierra de Laurel, Jalisco) were more variable, and displayed both ringed and crossband patterns, and either with abundant red markings or with red greatly reduced. One pattern element that is consistent among all known populations of greeri is that head color matches the light ground color of the body. 

Relationships:Based on mtDNA sequence data, L. greeri is clustered with L. ruthveni within a broader Mexicana assemblage. However, this preliminary dataset raises a number of questions that hopefully can be addressed by additional work underway. Recent discovery of a snake provisionally assigned to L. alterna from the eastern slopes of the Sierra Madre Occidental in northern Durango, in a setting where one would expect to see greeri, raises additional questions and suggests the potential for range contact.  

Conservation Status:Durango Mountain Kings are still known from only a handful of localities, with much of the presumed range largely inaccessible and minimally modified by human activities. Livestock grazing, ranching, farming, and logging occur at most sites, but the close association of this species with rock outcrops provides a buffer to most local disturbances. The popularity of Rancho Santa Barbara as a collecting site for greeri over many years is evident in the most accessible areas of the ranch, but effects on local kingsnake density are unknown. 

Captive Stock: To the best of our knowledge, all captive stock is descended from animals collected from Rancho Santa Barbara or the nearby Río Mimbres in western Durango, and thus the captive gene pool is quite restricted. L. greeri was heavily collected from this area for several years prior to the Mexican government’s decision to halt the exportation of native herpetofauna.  Individual specimens with greatly reduced black pigment (“hypomelanism”) are now being produced in limited numbers; these are the result of multiple generations of selective breeding.  We have not seen wild examples of this variant.  Our breeding group consists of Rancho Santa Barbara animals.