University of Kansas Publications
Museum of Natural History
Volume 13, No. 5, pp. 289-308, 4 figs.
February 10, 1961
Occurrence of the Garter Snake,Thamnophis sirtalis,in the Great Plains and Rocky Mountains
BY
HENRY S. FITCH AND T. PAUL MASLIN
University of Kansas
Lawrence
1961
University of Kansas Publications, Museum of Natural History
Editors: E. Raymond Hall, Chairman, Henry S. Fitch,
Robert W. Wilson
Volume 13, No. 5, pp. 289-308, 4 figs.
Published February 10, 1961
University of Kansas
Lawrence, Kansas
PRINTED INTHE STATE PRINTING PLANT
TOPEKA, KANSAS
1961
Occurrence of the Garter Snake,Thamnophis sirtalis,in the Great Plains and Rocky Mountains
BY
HENRY S. FITCH AND T. PAUL MASLIN
Introduction
The common garter snake (Thamnophis sirtalis) has by far themost extensive geographic range of any North American reptile,covering most of the continental United States from the Atlantic tothe Pacific and from south of the Mexican boundary far north intoCanada and southeastern Alaska. Of the several recognized subspecies,the eastern T. s. sirtalis has the most extensive range, butthat of T. s. parietalis in the region between the Mississippi Riverand the Rocky Mountains is almost as large. The more westernT. s. fitchi occurring from the Oregon and California coasts eastthrough the northern Great Basin, has the third largest range, whilethe far western subspecies pickeringi, concinnus,infernalis and tetrataenia,and the Texan T. s. annectens all have relatively small ranges.
Since the publication of Ruthven's revision of the genus Thamnophismore than 50 years ago, little attention has been devoted tothe study of this widespread and variable species, except in thePacific Coast states (Van Denburgh, 1918; Fitch, 1941; Fox, 1951).However, Brown (1950) described the new subspecies annectensin eastern Texas, and many local studies have helped to clarify thedistribution of the species in the eastern part of the continent andto define the zone of intergradation between the subspecies sirtalisand parietalis. In our study attention has been focused uponparietalisin an attempt to determine its western limits and its relationshipsto the subspecies that replace it farther west.
Taxonomic History
Thamnophis sirtalis parietalis Say was described (as Coluberparietalis) in 1823 from a specimen obtained in what is now WashingtonCounty, Nebraska, on the west side of the Missouri Riverthree miles upstream from the mouth of Boyer's River [Iowa], orapproximately eight miles north of Omaha. Although the type localitywas unequivocally stated in the original description, Nebraskawas not mentioned since the state was not yet in existence. Because[pg 292]the mouth of Boyer's River, the landmark by means of which thetype locality is defined, is in Iowa, the impression has been impartedthat the type locality itself is in Iowa (Schmidt, 1953:175), and toour knowledge the type locality has never been associated with Nebraskain the literature.
Like all t