Throughout much of its contemporary North American range the Smooth Green Snake (Opheodrys vernalis) can be abundant at certain times and under certain conditions. However, it was probably never abundant in Texas - at least within the time that “modern” man has been there. During the most recent North American glaciations (none of which extended farther south than southern Illinois), when the climatic features of what was to become the State of Texas were certainly more boreal than they are today, it is possible that O. vernalis was a common element of the fauna, much as it remains in most of the northern United States and southern Canada.
The generally accepted post-Ice Age scenario involves the more cold-adapted biological associations south of the last glaciation retreating northward as the climate subsequently warmed, leaving some populations behind, much like peripheral puddles that form when a pond dries up. Such remnant populations, when, or if they are eventually discovered, are said to be “relictual.” There is little doubt that the remaining populations of the Smooth Green Snake in Texas are but relicts of a formerly much wider distribution.
Troubling, however, is the seeming reality that the Texas populations are apparently the only remaining “peripheral puddles” of Opheodrys vernalis to be found anywhere south of the latitude of the final Pleistocene glaciations (excepting, of course, the montane populations in the Southwest that persist in areas that are “elevationally” boreal). Portions of the intervening areas (especially eastern Oklahoma, Arkansas, and Missouri) would appear to constitute much more ideal habitat for the species than coastal Texas, but no unequivocal, documented specimens of O. vernalis exist from these areas.
The known history of the Smooth Green Snake in Texas is rather controversial, however, filled with erroneous identifications, undocumented sightings, and once extant but now tragically lost specimens. Currently represented from the state by only 6 indisputable museum specimens (two of which may have vanished), a couple of tentative fossil records from central and far west Texas, and 4-6 unvouchered sight records likely corresponding to actual specimens that somehow either never made it into collections of record or were so placed but are now irretrievably lost.
Additionally, the acknowledged expert on this species, the late Arnold B. Grobman (1918-2012), maintained throughout his lifetime that all legitimate Texas specimens of Opheodrys vernalis "were established via human agency" (Grobman 1941, Walley 2003), despite the fact that this species has never been popular with local herpetoculturists. Curiously, Grobman's rather dogmatic pronouncement was adopted by Bryce C. Brown (1950), who succeeded Strecker as The Authority on Texas Herpetology, even though Brown's thesis advisor at Texas A&M College, William B. Davis (1949) had personally collected (and published on) an O. vernalis found near Sealy, Austin County, a year before Brown's magnum opus was published.
All of the known, verified Opheodrys vernalis specimens collected in Texas have been found in coastal prairie, habitat hardly considered typical for the species. The most recent examples were road casualties discovered in the 1960s, which would make half a century since a specimen from the state has been brought to the attention of science. Admittedly, this is a small, cryptically-colored, and secretive snake, but still, some of the known specimens have come from relatively populous areas of the state; the locality of one of the later specimens, near Hobby Airport in Houston, has now been swallowed up by the state's largest city.
The alleged Helotes, Bexar County, Texas specimens
But perhaps the most controversial and yet tantalizing Texas “record” for the species rests almost entirely upon the authority of one individual, Albert J.B. Kirn (1885-1950), an avocational naturalist who resided in the community of Somerset, in southwestern BexarCounty, for the last twenty-seven years of his life. A self-taught, "broad spectrum" biologist who concentrated in ornithology, Kirn authored or co-authored numerous papers in various fields of natural history during his lifetime (Messerly 1998). Later in life, he occasionally published anecdotal herpetological notes in the journal Herpetologica and corresponded with Lawrence M. Klauber and Cornell herpetologists Albert and Anna Wright. Somewhat surprisingly, however, he never personally went to print with his discovery of preserved Smooth Green Snakes, allegedly from the village of Helotes, Bexar County, at the southern edge of the Edwards Plateau just northwest of San Antonio.
The presumed Helotes specimens were first mentioned in J. Walker Davenport’s booklet, Field book of the snakes of Bexar County, Texas, and vicinity. (Davenport 1943), which stated, “This snake is not considered a native of this part of the country but Mr. A. J. Kirn found three pickled specimens of O. vernalis in the collection of specimens by the late Gabriel Marnoch, labeled Helotes, Texas. Several collectors report having seen this snake in the Helotes region but none have been brought into the [reptile] garden.”
The ReptileGarden, which Mr. Davenport operated, was part of the WitteMemorialMuseum in San Antonio. At one time one of the largest fund raisers for the museum, the ReptileGarden exhibited many local snakes in a large concrete pit from which daily shows were performed for the benefit of paying spectators, including the opportunity to sample the culinary adventure of fried rattlesnake.
To fill their pit, the ReptileGarden paid local collectors to bring in snakes from the countryside. It is not surprising that commercial collectors would tend to concentrate on larger, heavier species given that their remuneration was based on the total weight of snakes they caught. Also, since such collectors probably were not especially concerned about the subtleties of identifying small, relatively “worthless” species, it is doubtful that many of them would have appreciated the differences between the very similar and locally abundant Rough Green Snake (Opheodrys aestivus) and the Smooth Green Snake.
Gabriel Wilson Marnoch (1838-1920) (the "Marnock" spelling seems to appear only in the herp literature), the hypothetical collector of the specimens in question, was the son of an immigrant Scottish physician who settled in the Helotes area during the 1870s. An ardent naturalist, Marnoch collected the type specimens for forms that E.D. Cope would describe as "Lithodytes latrans" (Barking Frog), "Syrrhophus marnockii" (Cliff Chirping Frog), "Eumeces brevilineatus" (Short-lined Skink), "Eutaenia cyrtopsis ocellata" (Eastern Black-necked Garter Snake) as well as the type of the Texas Banded Gecko (Coleonyx brevis), later described by Leonard Stejneger. Marnoch seems to have done most of his collecting in the immediate vicinity of his home at Helotes, but is known to have obtained some specimens from an area on the Guadalupe River, about 22 miles distant from Helotes (T. Vermersch, pers. com.).
The only other published reference to these specimens is contained in a portion of a letter from Kirn to Albert and Anna Wright, which they subsequently included in their Handbook of Snakes (Wright and Wright 1957): “Letter from Kirn, Somerset, Tex., May 6, 1946: ‘Did I ever tell you that there are two smooth-scaled snakes, Opheodrys v. blanchardi (?) in the collection at St. Mary’s Univ., San Antonio? They are from the Marnock collection, and the jar is labeled "Green snakes, Helotes." There is no label on the specimens.’” Interestingly, the number of snakes involved curiously changes from three to two. This is apparently the last published reference to even the possibility that these specimens might represent a genuinely relictual population of this species in the Texas Hill Country; herpetologists writing on the fauna of Texas since then have ignored these accounts of the seemingly lost specimens.
John K. Strecker, in his "An Annotated Catalogue of the Amphibians and Reptiles of Bexar County, Texas," published in the Bulletin of the Scientific Society of San Antonio in 1922, noted that "He [Marnoch] did some exchanging but at the time of his death , less than fifteen per cent of his collection was foreign material and most of this representing generic groups not found in Texas." This of course opens the possibility that Marnoch's specimens could have been obtained by trade from another collector residing within the traditional range of O. vernalis, and possibly presents a logical explanation for how they ended up in the natural history collection of Saint Mary's University.
According to Strecker (1922), "After her husband's death, Mrs. Marnock presented a portion of his collection to the Scientific Society of San Antonio and sold the balance to the Baylor University Museum," which Strecker curated. Upon its dissolution, the collections of the Scientific Society were presumably also donated to St. Mary's University, where Kirn discovered the Green Snakes in question. Since there were apparently no O. vernalis among the Marnoch specimens obtained by Strecker (although the superficially similar O. aestivus was represented [Strecker 1922]), it remains conceivable that some of the specimens donated to the Scientific Society might have originated from outside the area, possibly considered exotic natural history curiosities by the Marnochs.
Unfortunately, Saint Mary's University no longer maintains a natural history collection. According to Emma H. Messerly, who wrote an account of Kirn's ornithological work in Oklahoma, his extensive ornithological collections, including his field notes, etc., were also donated to Saint Mary's University upon his death in 1950. By the early 1960s, however, the St. Mary's natural history collection (presumably including Marnoch's donated specimens as well) was in disarray and was itself subsequently donated to the "Natural Science for Youth Foundation," which "distributed the specimens among their affiliate museums." (Messerly 1998)
Consequently, it would appear that Marnoch's three (or two) Smooth Green Snake specimens purportedly from Helotes are now thoroughly lost to science - a shame, for if they were extant a count of their ventral scutes could possibly determine whether they belonged to the appropriate subspecies (O. v. blanchardi), as do all unequivocal Texas specimens of O. vernalis (if they instead had counts characterizing the nominate subspecies [O. v. vernalis], this would constitute evidence that Marnoch had indeed obtained them elsewhere).
Gabriel Marnoch's homestead as seen from the bluff across Helotes Creek, near Helotes, Texas.
Photo by Tom Lott, April 1961
The admittedly sparse fossil evidence from the Edwards Plateau would appear to indicate that two different species of Opheodrys (O. aestivus and "O. sp. indet.") inhabited the area during the late Pleistocene (Wisconsin) (Holman 1969). Furthermore, with the exception of large tortoises, the herpetofauna of this period appears to have consisted of currently extant species that continue to occupy the Plateau or nearby areas (Holman op.cit.). Even though distinguishing between fossil vertebrae of the two species of Opheodrys is difficult and likely prone to subjective error (Holman and Richards 1981), the fact that there are only two currently existing species of Opheodrys increases the likelihood that O. vernalis may have persisted in relict populations on the Edwards Plateau into recent times. Habitats on the Edwards Plateau superficially resemble those currently occupied by O. vernalis in the montane western portion of its current range and the more mesic areas of the Plateau are well-known for harboring relictual Pleistocene flora and fauna. At any rate, the existence of a population of O. vernalis on the Plateau is no more improbable than that of those that have been found in the coastal prairies.
The Helotes area of northwestern BexarCounty has undergone extensive developmental pressure during the last fifty years and is now contiguous with the metropolis of San Antonio. Less than two miles from Marnoch’s old homestead is a large AAAAAA high school that serves the residents of the area. If O. vernalis had ever occurred in this region, it is likely long gone, considering the attention this iconic locality has historically received from herpetologists. If so, it would join the ranks of a considerable number of other snake species known to have once been found there but which apparently are no longer: e.g., Prairie Kingsnake (Lampropeltis calligaster), Common Kingsnake (Lampropeltis getula), Milk Snake (Lampropeltis triangulum), Western Hog-nosed Snake (Heterodon nasicus), and the Eastern Garter Snake (Thamnophis sirtalis), among others.
Brown, B. C. 1950. An annotated check list of the reptiles and amphibians of Texas. Waco: BaylorUniversity Studies.
Davenport, J. W. 1943. Field book of the snakes of Bexar County, Texas, and vicinity. San Antonio: Witte Me-
Davis, W. B. 1949. The smooth green snake in Texas. Copeia 1949(3): 233.
Grobman, A. B. 1941. A contribution to the knowledge of variation in Opheodrys vernalis (Harlan), with the description of a new subspecies. Misc. Publ. Mus. Zool. Univ. Mich. 50: 1-38.
Holman, J. A. 1969. The Pleistocene amphibians and reptiles of Texas. Michigan St. Univ. Mus. Publ. 4: 163-192.
______ and R.L. Richards. 1981. Late Pleistocene occurrence in southern Indiana of the Smooth Green Snake, Opheodrys vernalis. J. Herpetol. 15: 123-125.
Messerly, E.H. 1998. Albert J.B. Kirn and his work in Oklahoma. Bull. Okla. Ornith. Soc. 31(2): 9-20.
Strecker, J.K. 1922. An annotated catalogue of the amphibians and reptiles of Bexar County, Texas. Bull. Sci. Soc. San Antonio. 4: 1-31.
Walley, H. D. 2003. Liochlorophis, L. vernalis. Cat. Am. Amphib. Rept. 776.1-776.13.
Wright, A. H., and A. A. Wright. 1957. Handbook of snakes of the United States and Canada. Ithaca, N. Y.: Comstock Publishing Co.