Diagnosis:
HARMLESS. The Common Watersnake is characterized by keeled scales, a divided anal scale, a dark brown, orange, yellow, red, and gray half-moon and speckled pattern widely spaced and scattered on the front part of a gray or whitish belly (these markings are closer together or fused on the rear portion of the belly, making it appear darker), and dark, complete bands on the front part of the body and alternating rows of dark blotches on the back and sides of the rear portion of the body. This snake may be gray or light brown, with dark gray or brown bands and blotches (young and young adults), or uniform dark gray with no pattern (old adults). Young specimens are more brightly colored and have a more contrasting pattern than adults. Adult males have longer tails than females. Adult females grow larger (twice the mass and 1.2 times the length) than males.
Adults attain 56.0-106.7 cm (22-42 inches) in total length. The largest specimen from Kansas is a sex undetermined (though certainly a female) (KU 288637) from Jackson County with a total length of 120.8 cm (47½ inches) collected by James Gubanyi on 21 October 1998. The maximum length throughout the range is 149.9 cm (59 inches) (Conant and Collins, 1998). The maximum weight for a Kansas specimen is 480 grams (1 pound, 1 ounce).
Fossil History:
Pleistocene fossil specimens are known from Meade, Rice, McPherson, and Jewell counties. Fossils from the Williams Local Fauna of Rice County (Pleistocene: Illinoian) (Preston 1979, Holman 1984; Holman 1995), Sandahl Local Fauna of McPherson County (Pleistocene: Illinoian) (Holman 1971; Preston 1979; Holman 1995), Mount Scott Local Fauna of Meade County (Pleistocene: Illinoian) (Preston 1979, Holman 1987; Holman 1995), Butler Spring Local Fauna of Meade County (Pleistocene: Illinoian) (Tihen 1962; Preston 1979; Holman 1995), Cragin Quarry Local Fauna of Meade County (Pleistocene: Sangamonian) (Hay 1917; Etheridge 1958; Etheridge 1960, Tihen 1960; Tihen 1962; Brattstrom 1967; Preston 1979; Holman 1995), Kanopolis Local Fauna of Ellsworth County (Pleistocene: Rancholabrean I) (Preston 1979, Holman 1972, Holman 1984; Holman 1995), and Courtland Canal/Hall Ash local fauna of Jewell County (Rogers, 1982; Eshelman and Hager, 1984) are referable to this taxon.
Natural History:
This snake is found is almost any aquatic situation, from fast -flowing rocky streams and rivers to swamps, lakes, and marshes. It appears to become active at a lower temperature than most other snakes and has a preferred optimal temperature near 77°F. Taggart (1992) observed an example of this snake sunning on the north bank of Shoal Creek in Cherokee County on 1 January at an air temperature of 47°F; the creek had a thin layer of ice extending three to four feet out from the shoreline.
The Common Watersnake is active from March to November, temperatures permitting. Like many snakes, it is active during the day in spring and fall and becomes more nocturnal in the summer. This species spends much of its time basking in the sun on branches and logs which overhang, or are near, water; it can be discovered easily by looking under rocks along streams in eastern Kansas.
Apparently, this snake spends the cold winter months in a variety of retreats, ranging from deep, dry crevices and holes on rocky, wooded hillsides to below water level in crayfish burrows in lowland areas.
Mating in this species occurs during the spring, and courtship involves the male positioning himself alongside the female and rubbing his chin on her neck while he spasmodically jerks his body to stimulate her to copulate. More than one male may copulate with a single female. The young are born from August to October. Number of young per litter varies from six to 66 (Fitch, 1985), with an average of 20- 25. Some females may produce young only every other year. Pilch (1982) recorded a brood of 33 young born in early September to a female from Douglas County.
Diener (1957) showed that fishes make up over 75 percent of the diet of the Common Watersnake. It also eats frogs and toads. Rundquist and Collins (1977) and Collins and Caldwell (1978) reported an adult Mudpuppy (KU 174546) discovered while being consumed by a Common Watersnake (Nerodia sipedon) in a shallow area of Shoal Creek at Schermerhorn Park, Cherokee County. Gray and Douglas (1989) recorded this snake preying on Southern Redbelly Dace in isolated pools on the Konza Prairie near Manhattan. The Common Watersnake uses an 'entrapment' behavior when preying on fishes in drying pools. Riedle (1998) examined the stomach contents of three Common Watersnakes from Montgomery County. One adult snake, estimated to be 700 mm TL, was observed swallowing a 120 mm Channel Catfish (Ictalurus punctatus). A juvenile snake, approximately 207 mm TL, contained an adult Blanchard's Cricket Frog (Acris blanchardi), and another juvenile, approximately 210 mm TL, contained a small sunfish (Lepomis sp.), which was 35 mm in length.
Remarks:
First reported in Kansas by Hallowell (1857) from specimens (no other associated data) received at the Academy of Natural Science, Philadelphia from William A. Hammond, post surgeon at Fort Riley. Hallowell(1857) described Tropidonotus obliquus (= Nerodia sipedon) (ANSP 5016) from among those specimens. The earliest existing specimen (MCZ 5913) was collected in 1879 J. Barbour. The MCZ catalog provides no other information, other than the specimen was received from the Smithsonian Institution in 1879 and penciled in notes questioning if the actual locality is Kearney County, Kansas (where this species occurs along the Arkansas River and adjacent sand pits).This record is a bit problematic as the while the listed state is Kansas the locality is Fort Kearney (=Nebraska). At this time, the shipping point was often used as the locality for specimens collected as far as 450 miles away. The Common Watersnake does occur along the Platte River near the site of Fort Kearney.
Beatson (1976) studied and analyzed the pattern and coloration of this snake in Chase County. He concluded that the change from contrasting bright body color and pattern of young Common Watersnake to the more uniform darker pattern of old adults is related to change in habitat and pressure from predators. Young specimens usually inhabit small, rocky, fast-flowing streams, and their color and pattern blend readily with surrounding debris. Adults tend to migrate to larger, more open bodies of water where contrasting pattern and bright colors would be too conspicuous. The reason for this change in color pattern with age undoubtedly holds for the Plain-bellied Watersnake as well.
Based on a captive specimen, Snider and Bowler (1992) reported a maximum longevity for this snake of nine years, seven months, and 24 days.