WESTERN RATSNAKE
Pantherophis obsoletus
(Say 1823)


păn-thĕr-ō-phĭs — ŏb-sō-lē-tŭs




An adult Western Ratsnake from Marshall County. © Lisa Wehrly.
An adult Western Ratsnake consuming a chicken egg in Atchison County. Image © Mark McDaniel.
An adult Western Ratsnake from Cherokee County, Kansas. Image © Lisa Wehrly.
An adult Western Ratsnake from Chautauqua County, Kansas. Image © Dan Fogell.
An adult Western Ratsnake from Linn County, Kansas. © Suzanne L. Collins, CNAH.
A juvenile from Geary County, Kansas. Image © by Sarah Burnett
An adult Western Ratsnake from Johnson County. © Jessica Lawrenz.

Description:
Harmless. Keeled scales; generally uniform black on the head, body, and tail. Some adults have an indistinct pattern of dark blotches; those from south-central Kansas may be more distinctly blotched. Belly cream or yellow-white, with large indistinct darker areas. Young are patterned and colored like Great Plains Ratsnakes, but lose this pattern as they grow older. The blotches on young Western Ratsnakes are darker brown and generally longitudinal (longer than wide) compared to young Great Plains Ratsnakes. Their background color is also gray while that of the Great Plains Ratsnake is light brown to tan.
Juveniles:  Have dark brown blotches (longer than wide) on a light gray background. The blotches are squarish and often have small projections toward the head and the tail from each corner. A dark brown back band crosses the top of the head in front of the eyes and extends back through the eyes to the rear upper labials on each side. Adults: At about 3 years of age (18 to 20 inches) an ontogenetic shift occurs as Western Ratsnakes change from blotched juveniles to darkened adults. The degree of dorsal darkening varies from completely black individuals throughout most of the state to faintly blotched specimens in south-central Kansas (Miller, 1986, Irwin et al., 1992). The chin (and ventral edges of the upper labials) is white to cream and the belly is cream to yellowish with many gray to dark-brown diffuse squarish blotches. In many adults, bright red and/or white pigments can be seen between the black scales.
Adults normally grow 1,067- 1,830 mm (42-72 inches) in TL; largest specimen from Kansas: male (KU 216168) from Jefferson County with TL of 1,912 mm (75 1/8 inches) and a weight of 1,729 grams (3 pounds, 13 ounces), collected by Roger Christie on 9 July 1990; maximum length throughout range: 101 inches (Boundy, 1995).

Distribution:
Widely distributed in the more forested eastern half of the state, On the western edge of its range, it is found along riparian corridors. They are commonly found in abandoned buildings and barns and are often the most common large snake in suburban areas.

(, Museum Voucher) (, Observation) (, Literature Record)
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  • Occurrence Summary:  
  • 553 Total Records 
  • 460 Museum Vouchers 
  • 93 Other Observations 
Some county occurrences indicated below may be too imprecise to map above.
County Breakdown: County Name (# occurrences):
Allen (9); Anderson (7); Atchison (4); Barber (14); Barton (1); Bourbon (23); Brown (6); Butler (5); Chase (2); Chautauqua (1); Cherokee (34); Clay (2); Cloud (4); Coffey (2); Cowley (8); Crawford (15); Dickinson (1); Doniphan (15); Douglas (116); Elk (6); Ellsworth (4); Franklin (44); Geary (8); Greenwood (9); Harper (11); Harvey (6); Jackson (1); Jefferson (14); Johnson (6); Kingman (1); Labette (9); Leavenworth (12); Lincoln (3); Linn (19); Lyon (3); Marion (1); Marshall (12); McPherson (2); Miami (10); Mitchell (1); Montgomery (4); Nemaha (1); Neosho (7); Osage (2); Pottawatomie (7); Pratt (1); Reno (1); Republic (1); Rice (1); Riley (10); Russell (1); Saline (9); Sedgwick (5); Shawnee (5); Sumner (11); Unknown (3); Wabaunsee (2); Washington (7); Wilson (9); Woodson (6); Wyandotte (6);

Natural History:
Inhabits forested areas, particularly the rocky hillsides of open woodlands and wooded areas along streams and rivers. Active from late March to November; become more nocturnal during summer. Six to 44 eggs per clutch laid in June or July; hatch in 1-2 months. Constrictor. Hawks are the main predator.
Adult Western Rat Snakes eat mice, rats, squirrels, and birds, as well as bird eggs. Linsdale (1925) reported predation of a Blue Jay nest on 11 July 1923. Cary et al. (1981) reported predation on a bat in Texas County, Missouri. Juveniles eat small frogs, lizards, and small rodents. They are adept climbers. When first threatened they often assume a “kinked” posture and remain motionless. If molested further, they will vibrate the tail and expel malodorous musk. William L. Hoyle discovered a moderate-sized specimen in the cupola of a barn near Grenola (Elk County), Kansas on 29 July 1933 that was consuming the eggs of an English Sparrow (Burt and Hoyle, 1935). Upon subsequent dissection, it was determined adult female English Sparrow was consumed at the same time.

Occurrence Activity:
Remarks:
This was the first species of amphibian or reptile to be documented in what we can be sure was Kansas. And, Thomas Say was the first person to document an amphibian or reptile in the geographic area that would eventually become Kansas. He described the type specimen of the Western Ratsnake from Isle au Vache (Cow Island), Kansas (an island on the Missouri River in present-day Atchison County). His type locality description stretches from NE Kansas to western Iowa.
Interestingly, Cow Island was the site of Cantonment Martin, a military camp established as a supply base for Major Stephen H. Long’s engineering expedition of 1819-20 of which Say served as the naturalist. This expedition set out to survey the Rocky Mountains and the major tributaries of the Missouri River.
This species exhibits an ontogenetic color shift as it matures. Newborn individuals are light gray with well-defined dark blotches. In their second year, the pattern begins to be obscured as the snake transitions to an overall dark animal.
Specimens from the southwestern portion of its range in the state show a propensity for maintaining more of their blotched pattern as adults.

Bibliography:
1822 Say, Thomas. In James, Edwin. Pages 1783 in Account of an expedition from Pittsburgh to the Rocky Mountains, performed in the years 1819, '20, by order of the Hon. J. C. Calhoun, Secretary of War, under the command of Major Stephen H. Long. Volume 1. H. C. Carey & I. Lea., Philadelphia. pp.
1856 Hallowell, Edward Notice of a collection of reptiles from Kansas and Nebraska, presented to the Academy of Natural Sciences, by Dr. Hammond, U.S.A. Proceedings of the Academy of Natural Sciences, Philadelphia 8():238-253
1857 Hallowell, Edward. Note on the collection of reptiles from the neighborhood of San Antonio, Texas, recently presented to the Academy of Natural Sciences by Dr. A. Heerman. Proceedings of the Academy of Natural Sciences, Philadelphia 8():306-310
1857 Hallowell, Edward. Notice of a collection of reptiles from Kansas and Nebraska presented to the Academy of Natural Sciences, by Doctor Hammond, U. S. A. Proceedings of the Academy of Natural Sciences, Philadelphia 8():238-253
1877 Mozley, Annie E List of Kansas snakes in the museum of the Kansas State Univeristy Transactions of the Kansas Academy of Science 6():34-35
1882 Yarrow, Henry C. Check list of North American Reptilia and Batrachia with catalogue of specimens in U. S. National Museum. Bulletin of the United States National Museum (24):1-249
1885 Cragin, Francis W. Recent additions to the list of Kansas reptiles and batrachians, with further notes on species previously reported. Bulletin of the Washburn College Laboratory of Natural History 1(3):100-103
1885 Cragin, Francis W. Second contribution to the herpetology of Kansas, with observations on the Kansas fauna. Transactions of the Kansas Academy of Science 9():136-140
1904 Branson, Edwin B. Snakes of Kansas. University of Kansas Science Bulletin 2(13):353-430
1907 Ditmars, Raymond L. The Reptile Book; A comprehensive, Popularised Work on the Structure and Habits of the Turtles, Tortoises, Crocodilians, Lizards and Snakes which Inhabit the United States and Northern Mexico. Doubleday, Pae, and Company, New York. 472pp.
1911 Hurter, Julius. Herpetology of Missouri. Transactions of the Academy of Science St. Louis 20(5):59-274
1925 Linsdale, Jean M. Land Vertebrates of a Limited Area in Eastern Kansas. Thesis. University of Kansas, Lawrence, Kansas. 312pp.
1925 Linsdale, Jean M. Land Vertebrates of a Limited Area in Eastern Kansas. Thesis. University of Kansas, Lawrence, Kansas. 312pp.
1928 Burt, Charles E. Some distributional and ecological records of Kansas reptiles. Transactions of the Academy of Science St. Louis 26():186-208
1929 Taylor, Edward H. A revised checklist of the snakes of Kansas. University of Kansas Science Bulletin 19(5):53-62
1935 Burt, Charles E. Further records of the ecology and distribution of amphibians and reptiles in the middle west. American Midland Naturalist 16(3):311-366
1935 Burt, Charles E. and William L. Hoyle. Additional records of the reptiles of the central prairie region of the United States Transactions of the Kansas Academy of Science 37():193-216
1951 Dowling, Herndon G A taxonomic study of the American representative of the Genus Elaphe Fitzinger, with particular attention to the forms occurring in Mexico and Central America ():1-195
1952 Dowling, Herndon G. A taxonomic study of the rat snakes, genus Elaphe Fitzinger. IV. A check list of the American forms. Occasional Papers of the Museum of Zoology, University of Michigan (541):1-12
1963 Fitch, Henry S. Natural history of the Black Rat Snake (Elaphe o. obsoleta) in Kansas. Copeia 1963(4):649-658
1973 McLeran, V. Friendly constrictors. Kansas Fish and Game (30(2)):8-11
1976 Caldwell, Janalee P. and Gregory. Glass. Vertebrates of the Woodson County State Fishing Lake and Game Management Area. Pages 62-76 in Preliminary inventory of the biota of Woodson County State Fishing Lake and Game Management Area. Report No. 5. State Biological Survey of Kansas, Lawrence. pp.
1977 Plummer, Michael V. Predation by Black Rat Snakes in bank swallow colonies. Southwestern Naturalist 22():147-148
1978 Fitch, Henry S. and E. Raymond Hall. A 20year record of succession on reseeded fields of tallgrass prairie on the Rockefeller Experimental Tract. University of Kansas Museum of Natural History Special Publication (4):1-15
1979 Rundquist, Eric M. Herps observed or collected during the first three months of 1979. Kansas Herpetological Society Newsletter (30):42893
1981 Cary, D. L., R. L. Clawson, and D. Grimes. An observation of snake predation on a bat. Transactions of the Kansas Academy of Science 84(4):223-224
1981 Guarisco, Hank The Black Rat Snake (Elaphe obsoleta obsoleta). Kansas Herpetological Society Newsletter 41():6-8
1982 Fitch, Henry S. Resources of a snake community in prairie-woodland habitat of northeastern Kansas. Pages 83-97 in Herpetological communities: A symposium of the Society for the Study of Amphibians and Reptiles and the Herpetologists League, August 1977.  Wildlife Research Reports 12. 239 pp. U. S. Fish and Wildlife Service, Washington, D. C. pp.
1983 Gress, Robert J. Black Rat Snake predation on nestling Pileated Woodpeckers Kansas Ornithological Society Bulletin 34(3):27-28
1986 Miller, Larry L. The status of the black rat snake in Sumner County, Kansas Kansas Herpetological Society Newsletter (64):12
1991 Fitch, Henry S. Reptiles and amphibians of the Kansas ecological reserves. Pages 71-74 in Multidisciplinary Guidebook 4. Kansas Academy of Science, Lawrence. pp.
1991 Gress, Robert J. Snake predation on nestling Eastern Phoebes followed by turtle predation on snake. Kansas Ornithological Society Bulletin 42(3):29
1992 Irwin, Kelly J., Larry Miller and Travis W. Taggart Geographic distribution: Elaphe obsoleta lindheimerii Herpetological Review 23(1):27
1993 Collins, Joseph T. and Suzanne L. Collins. Amphibians and Reptiles in Kansas. Third Edition. University Press of Kansas, Lawrence, Lawrence. 397pp.
1994 Fitzgerald, Eve and Charles Nilon Classification of habitats for endangered and threatened species in Wyandotte County, Kansas Kansas Department of Wildlife and Parks, Pratt, Kansas. 98pp.
2002 Miller, Larry L. Shawnee County herp count. Journal of Kansas Herpetology (4):15
2002 Riedle, J. Daren and A. Hynek. Amphibian and reptile inventory of the Kansas Army Ammunition Plant, Labette County, Kansas. Journal of Kansas Herpetology (2):18-20
2002 Taggart, Travis W. Results of the KHS 2002 fall field Trip. Journal of Kansas Herpetology (4):11-13
2002 Utiger, U., N. Helfenberger, B. Schatti, C. Schmidt, M. Ruf, and V. Ziswiler 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
2003 Freeman, Craig C. A natural areas inventory of the Ft. Leavenworth Military Reservation, Leavenworth County, Kansas. II. Open-file Report No. 117. Kansas Biological Survey, Lawrence, Kansas. 199pp.
2003 Pisani, George R. Elaphe o. obsoleta (Black Ratsnake) Escape behavior, habitat. Herpetological Review 34(1):66
2006 Taggart, Travis W. Distribution and status of Kansas herpetofauna in need of information. State Wildlife Grant T7. Kansas Department of Wildlife and Parks, Pratt. vii + 106pp.
2007 Mann, A. M. A Taxonomic Investigation of the Black Rat Snake, Elaphe o. obsoleta (Say) [Reptilia, Squamata, Colubridae], in West Virginia Using Morphometric Analyses. Thesis. Marshall University, Huntington, West Virginia. 101pp.
2010 Miller, Larry L. 2010 Investigation of the Checkered Garter Snake in Kansas with notes on other Amphibians, Reptiles, and Turtles encountered. Kansas Department of Wildlife and Parks, Pratt, Kansas. 31pp.
2011 McMartin, David C. U. S. Army 2011 Fort Leavenworth Herpetofaunal Survey: 23 April - 09 May 2011. Privately printed, Leavenworth, Kansas. 33pp.
2012 Rohweder, Megan R. Spatial conservation prioritization of Kansas for terrestrial vertebrates. Thesis. Fort Hays State University, Hays, Kansas. 151pp.
2016 Engelbert, Jared. Geographic distribution: Pantherophis obsoletus: Mitchell County, Kansas. Collinsorum 5(4):16
2016 Pittman, Galen L., Henry S. Fitch, and W. Dean Kettle Vertebrate animals on the Fitch Natural History Reservation (1948-2002) Kansas Biological Survey Report Number 188, Lawrence. 48pp.
Account Last Updated:
3/25/2019 8:11:30 AM


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