This snake was referred to as Natrix kirtlandi in older literature.

Listed as Near Threatened as its area of occupancy might not be much greater than 2,000 km², its distribution is severely fragmented, and the extent and quality of its habitat is declining, thus making the species close to qualifying for Vulnerable under criterion B2ab(iii).

This species is restricted to the north-central Midwest of the United States. The present range includes disjunct populations in Michigan, Ohio, Illinois, Indiana, and Kentucky. Most recent records for the Great Lakes region are clustered near the southern end of Lake Michigan (Cook County, Illinois; northwestern Indiana; and southwestern Michigan) and in Lucas County, Ohio (Toledo area) (Harding 1997). The Kentucky distribution is along the Ohio River valley (Barbour 1971). Historically, the range included northeastern and central Illinois, most of Indiana and Ohio, north-central Kentucky, southern Michigan, western Pennsylvania, and extreme northeastern Missouri. Records from southeastern Wisconsin and from eastern Pennsylvania have been regarded as erroneous (Conant 1943). The species was last recorded in Pennsylvania in 1965. Historically, Wisconsin and Missouri were at best extreme peripheral locations; known in Wisconsin from a single unsubstantiated report in 1883 (Hoy 1883, Vogt 1981); known in Missouri from a single record in 1964 (Jones 1967, Johnson 1987). The area of occupancy within its range is small.

Between 1980 and 1987, 48 extant occurrences were documented in Illinois, Indiana, Kentucky, Ohio, and Michigan (Wilsmann and Sellers 1988). In Illinois, the species is "known from only a few isolated populations" (Phillips et al. 1999). This snake is difficult to detect and all occurrences have probably not been documented. Failure to locate this snake at historical sites does not mean that the populations are extirpated. The uncertainty of site survey results and the ability of this species to survive in small urban and agricultural sites makes it difficult to identify it as extirpated, except where habitat destruction or other disturbances are obvious (Wilsmann and Sellers 1988). Accordingly, there may be as many as 100 total occurrences in the range. The total adult population size is unknown but is probably at least a few thousand. Fairly dense local populations exist in scattered locations (Harding 1997). Minton (1972) mentioned that some colonies near suburbs might be quite dense. Minton (2001) reported that 44 individuals were removed from a threatened inner-city site in two days, yet the snakes subsequently remained common there. The species was easiest to find during 1980s rangewide surveys in suburban areas with much litter. The largest number reported recently at a site was 24 found along 20 feet of a state road in Washington County, Indiana (Sellers pers. comm. 1993). This suggests that some sites may have fairly large populations. In general, population size at a site is difficult to determine, even with a mark-and-recapture study, because these snakes are so secretive. In Kentucky, Barbour (1971) stated that this species "now seems nowhere common." Kirtland's snake was once known from more than 100 counties in eight states. Since 1980, it has been observed in only one quarter of those counties (Wilsmann and Sellers 1988). Many urban populations have disappeared in recent years (Harding 1997). Once common in northern Illinois, it declined before the turn of the century and is now rare in Illinois and most of its present range (Wilsmann and Sellers 1988). Most records for Illinois are pre-1980 (Phillips et al. 1999). The species can be regarded as rare and declining across its entire historical range, despite fairly dense local populations (Harding 1997).

This snake inhabits relict Prairie Peninsula habitats: prairie fens, wet meadows, lakeplain wet prairies and associated open and wooded wetlands, seasonal marshes, open swamps, sparsely wooded hillsides, and the vicinity of ponds and sluggish creeks. In the more recently glaciated parts of the range, occurrences are on gently sloping pitted outwash, till plains, and former glacial lake plains; in the more highly dissected, recently unglaciated areas, the species occupied larger river valley drainages (Wilsmann and Sellers 1988). In Illinois and west-central Indiana, it is most often found on mollisols, soils that develop under grasslands and have excellent water retaining abilities (Wilsmann and Sellers 1988).

The current distribution of this snake is centered in metropolitan areas, often in vacant lots associated with streams or wetlands; these are remnants of much larger populations that have been reduced by urbanization and may now be rapidly dying out (Minton et al. 1983). However, this species can be locally abundant in inner city situations (Minton 2001). There are few records of this species from relatively undisturbed habitats (Minton 2001). This species is most readily found in habitats with abundant debris on the ground surface; open grassy habitats may harbour populations that are relatively difficult to detect and document. Individuals are secretive and usually are found under debris, but in general these snakes are likely most often below ground (Harding 1993, pers. comm.). They commonly use Chimney Crayfish (Cambarus diogenes) burrows as cover and underground passageways; the burrows provide moisture, less severe temperature extremes, and food resources (Wilsmann and Sellers 1988). Fossorial habits allow survival of grassland fire. Hibernation occurs apparently underground, possibly in crayfish burrows, in or near the wetlands that are inhabited the remainder of the year.

Mating has only been observed on the ground surface under cover in the spring (Sellers pers. comm. 1993).

Human activities, especially housing development and habitat alteration, are the major threats. Most of the former habitat has been lost to agriculture (Wilsmann and Sellers 1988). Grassy habitats are subject to succession when surrounding land use patterns change. Conversion of native prairie to agricultural uses is a threat. Many remnant populations inhabit small areas in urban or suburban areas where they are highly vulnerable to extirpation by development; colonies near housing developments may thrive for a time but eventually decline, according to Minton. Activities that negatively impact crayfishes and their burrows are detrimental. Other potential threats to this species are disease, predation, competition, pesticide use, road kills, long-term climatic changes and collecting for the pet trade. Collecting for the pet trade is a threat in urban populations (Harding 1997) where large amounts of litter and debris increase the chances of finding these snakes (Wilsmann and Sellers 1988).

Several occurrences are in protected areas. Protection needs include the following: 1) identify and protect a large number (perhaps at least 20) of suitable sites throughout the range; 2) do whatever it takes to curtail pet trade exploitation (state legislation); and 3) educate the public about conservation needs.