Clonophis kirtlandii - (Kennicott, 1856)
Kirtland's Snake
Other English Common Names: Kirtland's snake
Synonym(s): Clonophis kirtlandi
Taxonomic Status: Accepted
Related ITIS Name(s): Clonophis kirtlandii (Kennicott, 1856) (TSN 174216)
Unique Identifier: ELEMENT_GLOBAL.2.105161
Element Code: ARADB06010
Informal Taxonomy: Animals, Vertebrates - Reptiles - Snakes
 
Kingdom Phylum Class Order Family Genus
Animalia Craniata Reptilia Squamata Colubridae Clonophis
Genus Size: A - Monotypic genus
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Concept Reference
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Concept Reference: Collins, J. T. 1990. Standard common and current scientific names for North American amphibians and reptiles. 3rd ed. Society for the Study of Amphibians and Reptiles. Herpetological Circular No. 19. 41 pp.
Concept Reference Code: B90COL01NAUS
Name Used in Concept Reference: Clonophis kirtlandii
Taxonomic Comments: This snake was referred to as Natrix kirtlandi in older literature.
Conservation Status
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NatureServe Status

Global Status: G2
Global Status Last Reviewed: 30Aug2006
Global Status Last Changed: 12Sep2001
Rounded Global Status: G2 - Imperiled
Reasons: Confined to the Midwestern United States, with the range centered in Illinois, Indiana, and Ohio; distribution and abundance have declined due to loss of prairie wetland habitat; rare and local throughout range; little suitable habitat remains, and most of this is subject to human alteration.
Nation: United States
National Status: N2 (05Oct1996)

U.S. & Canada State/Province Status
United States Illinois (S2), Indiana (S2), Kentucky (S2), Michigan (S1), Missouri (S1), Ohio (S2), Pennsylvania (SH), Tennessee (S1)

Other Statuses

IUCN Red List Category: NT - Near threatened

NatureServe Global Conservation Status Factors

Range Extent: 20,000-2,500,000 square km (about 8000-1,000,000 square miles)
Range Extent Comments: Range is restricted to the north-central Midwest of the United States. The present range includes disjunct populations in Michigan, Ohio, Illinois, Indiana, Kentucky, and perhaps Missouri. 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 Alabama, and West Virginia are clearly erroneous (Conant 1943). Records from the Delaware Valley of eastern Pennsylvania and New Jersey are supported by correctly identified specimens collected in the 1800s, but no other records exist for the region; Conant (1943) found these records "difficult to explain" and stated that they might not represent natural occurrences, but he conceded that they could be valid and that the species may be extirpated in the region. A nonspecific record of the species in Ontario, Canada (Wright and Wrtight 1952), is unsubstantiated. The species is known in Wisconsin from two unsubstantiated records published in the late 1880s (Hoy 1883, Conant 1943, Vogt 1981). Kirtland's snake was last recorded in Pennsylvania in 1965 (Hulse et al. 2001). The species is known in Missouri from a single record in 1964 (Jones 1967, Johnson 2000).

Area of Occupancy: 126-2,500 4-km2 grid cells
Area of Occupancy Comments: Assuming that there are 100 extant occurrences (about twice as many as currently documented) and that occurrences average less than 4 square kilometers per occurrence, the area of occupancy may be less than 500 square kilometers.

Number of Occurrences: 21 - 300
Number of Occurrences Comments: 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 probably have 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 determine extirpation, 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.

Population Size: 1000 - 100,000 individuals
Population Size Comments: Total adult population size is unknown but likely is 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."

Number of Occurrences with Good Viability/Integrity: Unknown

Overall Threat Impact: High
Overall Threat Impact Comments: 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 include pesticide use, road kills (reviewed by Gibson and Kingsbury 2004), mowing operations, long-term climatic changes, and collecting for the pet trade. Collecting for the pet trade is a threat particularly in urban populations (Harding 1997) where large amounts of litter and debris increase the chances of finding these snakes (Wilsmann and Sellers 1988). Disease has not been identified as a significant threat (Gibson and Kingbury 2004).

Short-term Trend: Decline of 10-30%
Short-term Trend Comments: Trend over the past 10 years or three generations is uncertain, but probably the species can be regarded as rare and declining across its entire historical range, despite fairly dense local populations (Harding 1997, Gibson and Kingsbury 2003).

Long-term Trend: Decline of 50-90%
Long-term Trend Comments: Kirtland's snake is known from more than 100 counties in eight states. Since 1980, it has been observed in only 58 counties in five states; since 1990, it has been found in 39 counties (mapped by Gibson and Kingsbury 2004). Many urban populations have disappeared in recent years (Harding 1997). Once common in northern Illinois, Kirtland's snake declined before the turn of the century and is now rare in Illinois and most of its present range (Wilsmann and Sellers 1988, Edgren 2000). Most records for Ilinois are pre-1980 (Phillips et al. 1999).

Intrinsic Vulnerability: Moderately vulnerable

Environmental Specificity: Narrow. Specialist or community with key requirements common.

Other NatureServe Conservation Status Information

Inventory Needs: Viability of extant occurrences needs to be assessed throughout the range. USFWS Endangered Species Office is in the process of doing this. However, complete population information probably never will be obtained for this difficult-to-survey snake.

Protection Needs: Adequate conservation probably will require the identification and protection of a large number (perhaps at least 20) suitable sites throughout the range. Efforts to curtail pet trade exploitation are needed; this should include development of state wildlife regulations where those are not currently in place). The public should be informed about the species' conservation needs.

Distribution
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Global Range: (20,000-2,500,000 square km (about 8000-1,000,000 square miles)) Range is restricted to the north-central Midwest of the United States. The present range includes disjunct populations in Michigan, Ohio, Illinois, Indiana, Kentucky, and perhaps Missouri. 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 Alabama, and West Virginia are clearly erroneous (Conant 1943). Records from the Delaware Valley of eastern Pennsylvania and New Jersey are supported by correctly identified specimens collected in the 1800s, but no other records exist for the region; Conant (1943) found these records "difficult to explain" and stated that they might not represent natural occurrences, but he conceded that they could be valid and that the species may be extirpated in the region. A nonspecific record of the species in Ontario, Canada (Wright and Wrtight 1952), is unsubstantiated. The species is known in Wisconsin from two unsubstantiated records published in the late 1880s (Hoy 1883, Conant 1943, Vogt 1981). Kirtland's snake was last recorded in Pennsylvania in 1965 (Hulse et al. 2001). The species is known in Missouri from a single record in 1964 (Jones 1967, Johnson 2000).

U.S. States and Canadian Provinces
Color legend for Distribution Map
Endemism: endemic to a single nation

U.S. & Canada State/Province Distribution
United States IL, IN, KY, MI, MO, OH, PA, TN

Range Map
Note: Range depicted for New World only. The scale of the maps may cause narrow coastal ranges or ranges on small islands not to appear. Not all vagrant or small disjunct occurrences are depicted. For migratory birds, some individuals occur outside of the passage migrant range depicted.

Range Map Compilers: NatureServe, 2005


U.S. Distribution by County Help
State County Name (FIPS Code)
IL Christian (17021), Clinton (17027)*, Coles (17029), Cook (17031), De Witt (17039), DeKalb (17037)*, Douglas (17041), DuPage (17043)*, Effingham (17049)*, Fayette (17051), Ford (17053), Lake (17097)*, Mclean (17113), Piatt (17147), Sangamon (17167), Schuyler (17169), Shelby (17173)*, Will (17197)
IN Adams (18001)*, Allen (18003), Bartholomew (18005), Blackford (18009)*, Brown (18013), Carroll (18015), Clark (18019), Clay (18021), Decatur (18031), Delaware (18035)*, Elkhart (18039)*, Floyd (18043), Fulton (18049)*, Grant (18053)*, Harrison (18061)*, Henry (18065), Howard (18067)*, Jackson (18071), Jay (18075)*, Jefferson (18077), Jennings (18079), Johnson (18081)*, Kosciusko (18085), La Porte (18091), Lake (18089), Marion (18097), Marshall (18099)*, Monroe (18105), Montgomery (18107)*, Morgan (18109), Orange (18117)*, Parke (18121)*, Porter (18127)*, Pulaski (18131)*, Randolph (18135), Ripley (18137), Rush (18139)*, St. Joseph (18141), Starke (18149)*, Steuben (18151), Vigo (18167)*, Washington (18175), Wayne (18177), Wells (18179)*
KY Bullitt (21029), Campbell (21037)*, Graves (21083), Hardin (21093), Jefferson (21111), Kenton (21117)*, McLean (21149), Pendleton (21191)*
MI Berrien (26021), Cass (26027), Kalamazoo (26077), Lenawee (26091)*, Muskegon (26121), Ottawa (26139)*, Van Buren (26159)*, Washtenaw (26161)
MO Clark (29045), Marion (29127)
OH Butler (39017), Champaign (39021), Clark (39023), Clermont (39025), Erie (39043), Greene (39057), Hamilton (39061), Hancock (39063)*, Henry (39069), Hocking (39073), Jackson (39079), Lucas (39095), Montgomery (39113), Paulding (39125), Preble (39135)*, Warren (39165), Wayne (39169)*, Wyandot (39175)
PA Allegheny (42003)*, Butler (42019)*, Clarion (42031)*, Forest (42053)*, Jefferson (42065)*, Westmoreland (42129)*
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
04 Little Calumet-Galien (04040001)+*, Pike-Root (04040002)+*, St. Joseph (04050001)+, Black-Macatawa (04050002)+*, Kalamazoo (04050003)+, Pere Marquette-White (04060101)+, Muskegon (04060102)+, Huron (04090005)+, Ottawa-Stony (04100001)+*, Raisin (04100002)+*, St. Marys (04100004)+, Upper Maumee (04100005)+, Blanchard (04100008)+*, Lower Maumee (04100009)+, Cedar-Portage (04100010)+, Sandusky (04100011)+
05 Clarion (05010005)+*, Conemaugh (05010007)+*, Lower Allegheny (05010009)+*, Lower Monongahela (05020005)+*, Upper Ohio (05030101)+*, Connoquenessing (05030105)+*, Hocking (05030204)+, Tuscarawas (05040001)+*, Lower Scioto (05060002)+, Upper Great Miami (05080001)+, Lower Great Miami (05080002)+, Whitewater (05080003)+, Ohio Brush-Whiteoak (05090201)+, Little Miami (05090202)+, Middle Ohio-Laughery (05090203)+, Licking (05100101)+*, Lower Green (05110005)+, Pond (05110006)+, Upper Wabash (05120101)+*, Mississinewa (05120103)+*, Middle Wabash-Deer (05120105)+, Tippecanoe (05120106)+, Middle Wabash-Little Vermilion (05120108)+*, Sugar (05120110)+*, Middle Wabash-Busseron (05120111)+*, Embarras (05120112)+, Little Wabash (05120114)+*, Upper White (05120201)+, Lower White (05120202)+, Eel (05120203)+, Driftwood (05120204)+, Flatrock-Haw (05120205)+, Upper East Fork White (05120206)+, Muscatatuck (05120207)+, Lower East Fork White (05120208)+, Patoka (05120209)+*, Silver-Little Kentucky (05140101)+, Salt (05140102)+, Blue-Sinking (05140104)+
07 Bear-Wyaconda (07110001)+, North Fabius (07110002)+*, The Sny (07110004)+, Kankakee (07120001)+, Chicago (07120003)+, Des Plaines (07120004)+, Lower Fox (07120007)+*, Lower Illinois-Lake Chautauqua (07130003)+, Upper Sangamon (07130006)+, South Fork Sangamon (07130007)+, Salt (07130009)+, Upper Kaskaskia (07140201)+, Middle Kaskaskia (07140202)+*
08 Obion (08010202)+
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
Ecology & Life History
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Basic Description: A small (adults usually about 26-46 cm), nonpoisonous snake.
General Description: This snake has the following combination of characteristics: two rows of large dark spots (sometimes inconspicuous, especially the two central rows) along each side of the body; belly pink or red, with a row of dark spots on each side; sometimes appears to have a reddish-brown middorsal stripe; chin and throat yellowish; scales keeled; anal scale divided; eyes and head small, with a rounded narrow snout (Rossman and Powell 1985); adult total length is usually 36-46 cm (to 62 cm); young are dark, essentially unicolored, belly a deeper shade of red (Minton 1972), about 11-17 cm at birth (Holman et al. 1989, Conant and Collins 1991). A population with white ventral coloring has been documented by the Illinois Natural History Survey (Wilsmann and Sellers 1988).
Diagnostic Characteristics: Kirtland's snake differs from the red-bellied snake (Storeria occipitomaculata) in having conspicuous dark spots on the belly (and on the dorsum). Brown snakes (Storeria dekayi) lack the rich reddish belly color and conspicuous dark spots on the belly scales found on Kirtland's snake. Queen snakes (Regina septemvittata) have a uniformly brown dorsum, with a light stripe along each side of the body. Copper-bellied watersnakes (Nerodia erythrogaster neglecta) lack large dark spots on the dorsum and also lack the single row of round black spots that border the belly scales of Kirtland's snake. Gartesnakes (Thamnophis species) generally have pale lateral stripes and lack a reddish belly.

Ernst and Ernst (2003) includes an identification key.

Reproduction Comments: Courtship or mating have been noted in the field in February, March, May, August, and September (Minton 1972, 2001; Martin 1986; Brown 1987; Anton et al. 2003). Multiple males may attend one female (Anton et al. 2003). Gravid females can be found as early as May (Wilsmann and Sellers 1988). In Indiana, Minton (2001) found 6 gravid females in mid-June. The life cycle does not include a shelled egg stage; females give birth in summer or early autumn. Gravid females often share favorable gestation sites. Individuals reach maturity probably in their second year of growth (Ernst and Ernst 2003). Typical longevity is unknown.

The following information is from captive studies by Conant (1943), Minton (1972), Tucker (1976), Mierzwa (1985), Martin (1986) Brown (1987), and Anton and Mauger (2004). Parturition generally occurs in summer, recorded dates range from late July (Minton 2001) through late September (Conant 1943). Brood sizes range from 4 to 15 (Conant 1943, Tucker 1976; record of 22 young apparently is erroneous, Wilsman and Sellers 1988).

Ecology Comments: Potential predators include other snakes, birds, carnivorous mammals, and fish (Wilsmann and Sellers 1988).

Kirtland's snake occurs in association with many wetland, grassland, and forest edge reptiles including Butler's garter snake, brown snakes, eastern massassauga, water snakes, queen snakes, eastern fox snakes, spotted turtles, and the five-lined skinks. Too little is known of the ecology of most of these species to conclude that resource competition is occurring, except perhaps with Butler's garter snakes in Michigan and Indiana (Wilsmann and Sellers 1988).

Non-Migrant: Y
Locally Migrant: N
Long Distance Migrant: N
Mobility and Migration Comments: This snake does not exhibit significant migrations. Home range size and other movement characteristics are poorly known, but most evidence suggests that movements are not very extensive.
Palustrine Habitat(s): Bog/fen, HERBACEOUS WETLAND, Riparian, SCRUB-SHRUB WETLAND
Terrestrial Habitat(s): Grassland/herbaceous, Old field, Suburban/orchard
Special Habitat Factors: Burrowing in or using soil, Fallen log/debris
Habitat Comments: Kirtland's snake occurs in 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 harbor 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.). Kirtland's snake commonly uses crayfish burrows as cover and underground passageways (Wilsmann and Sellers 1988, Bavetz 1994, Anton et al. 2003); 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).

Adult Food Habits: Invertivore
Immature Food Habits: Invertivore
Food Comments: The diet includes mostly earthworms; also slugs and leeches (Conant 1943, Tucker 1977, Minton 2001, Wilsmann and Sellers 1988); sometimes insects (Thurow 1993) and crayfish (Bavetz 1993). Reports of amphibians and minnows in the diet (Minton 1972, Barbour 1971) have been discounted by other authors. Tucker (1977) stated that Kirtland's snake eats native slugs but not the introduced European slug (Limax maximus).
Adult Phenology: Hibernates/aestivates
Immature Phenology: Hibernates/aestivates
Phenology Comments: This snake is inactive during cold periods, but live individuals have been found on the surface in every month (Sellers, pers. comm., 1993; see also Gibson and Kingsbury 2004), with basking occurring on warm winter days. Annual emergence from hibernation is usually in early spring; activity peaks in April-May and October (Conant 1943, Minton 1972);
Length: 46 centimeters
Economic Attributes
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Economic Comments: Kirtland's snake has been collected for the pet trade in some areas (Wilsmann and Sellers 1988).
Management Summary
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Stewardship Overview: Kirtland's snake inhabits open damp grassy areas, wet meadows, wet prairie remnants, floodplains, fens, and the vicinity of ponds and swamps. In urban areas it can still be found in a few vacant lots associated with streams or wetlands. It now exists in 33 populations found in Michigan, Ohio, Illinois, Indiana and Kentucky (Sellers, pers. comm., 1993). This snake has declined in abundance over its entire range. The major threat to this species is habitat loss; much of its habitat has already been lost to development. It is vulnerable to extirpation by development. The existing populations and their habitats need to be protected. Surveys can be used to detect undiscovered populations, although this species is secretive and surveying may be difficult. Drift fences might be a useful surveying technique in spring and fall.
Species Impacts: Kirtland's snake is not known to significantly impact other species that may be of conservation concern.
Restoration Potential: Restoration potential depends upon the degree of habitat alteration. Permanent alterations such as pavement prevent restoration. Remaining wet prairie habitats that have not been altered can be used for restoration.
Preserve Selection & Design Considerations: Preserves that will benefit this species should include natural open areas, streams or ditchs, and upland hillsides with underground refuges. Adjacent managed open areas such as yards or parks need to be considered in overall management of the preserve, as the snakes may frequent these areas (Sellers, pers. comm., 1993).
Management Requirements: Effective management requires consideration of mowing schedules, foot and car traffic, potential environmental contaminants, hydrology, and ground cover (Wilsmann and Sellers 1988). One management concern is the modification of wetlands by flooding or draining. These practices may enhance habitat for other species but can make unsuitable habitat for this snake (Wilsmann and Sellers 1988), which requires unsaturated soil with a high subsurface water table (Sellers, pers. comm., 1993).

At many managed sites, controlled burns are used for maintenance of prairie species. The fossorial habits of Kirtland's snake and the typical cool burn near the ground in wetlands allows the snake to survive grassland fires.

A study of Killdeer Plains Wildlife Area in Ohio, which is a state-owned remnant of prairie managed for Canada geese, reported snake mortality from mowing and vehicle traffic. During the fall hunting season when both factors were heavy, snake mortality was high. The study recommended rescheduling mowing operations to coincide with the snakes' periods of inactivity, and rerouting traffic, placing speed bumps and signs to caution motorists to avoid hitting snakes. See Gibson and Kingsbury (2004) for further discussion of mortality from mowing and vehicle traffic.

If urban litter must be removed it should be replaced with litter from natural materials such as tree bark and limbs, leaves, cut brush, or hay and straw (Wilsmann and Sellers 1988).

Monitoring Requirements: Monitoring should be conducted during the prime seasonal, diel, and weather-related activity periods, with repeated visits to each site (Wilsmann and Sellers 1988). Natural areas may be difficult to survey because of the lack of cover under which snakes may be easily found. Open damp grassy areas may harbor populations, but these populations are relatively difficult to detect and document.

Some monitoring techniques include overturning of natural and artificial covers, shining with flashlights, seining in streams, drift-fencing, and searching roadways for dead and injured snakes (Wilsmann and Sellers 1988). Drift-fencing may be more successful earlier in the spring or fall when the snakes are moving to and from their hibernacula.

See Gibson and Kingsbury (2004) for further brief discussion of monitoring this species.

Management Research Needs: Information on response to fire and other management techniques is needed. Effective survey/monitoring techniques need to be developed.
Biological Research Needs: Studies of basic life history and population ecology are needed.
Population/Occurrence Delineation
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Group Name: Medium And Large Colubrid Snakes

Use Class: Not applicable
Minimum Criteria for an Occurrence: Occurrences are based on evidence of historical presence, or current and likely recurring presence, at a given location. Such evidence minimally includes collection or reliable observation and documentation of one or more individuals (including eggs) in or near appropriate habitat where the species is presumed to be established and breeding.
Separation Barriers: Busy highway or highway with obstructions such that snakes rarely if ever cross successfully; major river, lake, pond, or deep marsh (this barrier pertains only to upland species and does not apply to aquatic or wetland snakes); densely urbanized area dominated by buildings and pavement.
Separation Distance for Unsuitable Habitat: 1 km
Separation Distance for Suitable Habitat: 10 km
Separation Justification: Available information on movements of colubrid snakes is limited to a small minority of species. These data indicate that nearly all species have home ranges smaller or much smaller than 25 ha (e.g., less than 3 ha, Pituophis catenifer in California, Rodriguez-Robles 2003), with some up to about 75 ha (Heterodon platirhinos, average 50 ha, Plummer and Mills 2000), and the largest up to 225 ha in the biggest colubrids (Drymarchon, summer mean 50-100 ha, USFWS 1998).

Radiotelemetry data for Pantherophis indicate that residents of hibernacula that are 1-2 km apart (with suitable intervening habitat) probably interbreed (Prior et al. 1997, Blouin-Demers and Weatherhead 2002). However, "evidence of genetic structure even over short distances (e.g., 2-20 km) implies that gene flow among rat snake populations can be easily disrupted" (Prior et al. 1997). Loughheed et al. (1999) found evidence of substantial genetic exchange among local hibernacula (< 6 km apart), but gene flow over distances of 10s of km appears to be substantially less. Based on extensive radio-tracking data, Blouin-Demers and Weatherhead (2002) found that home range size of Pantherophis averaged 18.5 ha and ranged up to 93 ha; based on the most mobile individuals, Pantherophis from hibernacula up to 8 km apart can come together for mating. Pantherophis and probably other colubrids exhibit high fidelity to hibernacula and shift even to nearby sites only rarely (Prior et al. 2001).

Many of the several studies that report small home ranges for colubrids did not employ methods (e.g., radio telemetry) suitable for detecting full annual or multi-annual home range size, dispersal, or other long-distance movements, so these may have yielded underestimates of home ranges or activity areas.

At least some colubrids, including medium-sized species such as garter snakes, not uncommonly move between areas up to a few kilometers apart, and several species make extensive movements of up to several kilometers, so separation distances of 1-2 km for suitable habitat are too small for medium-sized and large colubrids.

A separation distance of 10 km for suitable habitat was selected as most appropriate for snakes assigned to this Specs Group because it seems generally unlikely that two locations separated by less than 10 km of suitable habitat would represent distinct occurrences.

For the purposes of these occurrence specifications, upland habitat is regarded as unsuitable habitat for aquatic and wetland snakes. For upland snakes, shallow or patchy wetlands are treated as unsuitable habitat whereas large deepwater habitats (subjective determination) are barriers.

Inferred Minimum Extent of Habitat Use (when actual extent is unknown): .5 km
Date: 12Feb2013
Author: Hammerson, G.
Notes: Separation distance for suitable habitat was changed from 5 km to 10 km based on comments from Dale Jackson (12 Feb 2013).
Population/Occurrence Viability
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U.S. Invasive Species Impact Rank (I-Rank) Not yet assessed
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Authors/Contributors
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NatureServe Conservation Status Factors Edition Date: 08Jul2011
NatureServe Conservation Status Factors Author: Soule, J. D., B. Van Dam, and G. Hammerson
Management Information Edition Date: 30Sep1993
Management Information Edition Author: VAN DAM, B.
Management Information Acknowledgments: Thanks to all the state Heritage Program personnel who responded to requests for information: IL - Jean Karnes; WI - Karen Gaines; OH - Pat Jones; IN - Michelle Martin; PA - Barb Barton; KY - Brainard Palmer-Ball. James Harding, Mark Sellers and Leni Wilsmann reviewed an earlier draft and provided many suggestions that added substantially to the final document.
Element Ecology & Life History Edition Date: 11Jul2011
Element Ecology & Life History Author(s): Van Dam, B., and G. Hammerson

Zoological data developed by NatureServe and its network of natural heritage programs (see Local Programs) and other contributors and cooperators (see Sources).

References
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  • Anton, T. G., D. Mauger, C. A. Phillips, M. J. Drezlik, J. E. Petzing, A. R. Kuhns, and J. M. Mui. 2003. Clonophis kirtlandii (Kirtland's snake). Aggregating behavior and site fidelity. Herpetological Review 34:248-249.

  • Anton, T. G., and D. Mauger. 2004. Clonophis kirtlandii. Reproduction. Herpetological Review 35:58-59.

  • Barbour, R. W. 1971. Amphibians and reptiles of Kentucky. Univ. Press of Kentucky, Lexington. x + 334 pp.

  • Bavetz, M. 1993. Geographic variation, distribution, and status of Kirtland's snake, Clonophis kirtlandii (Kennicott) in Illinois. M.S. thesis, Southern Illinois University, Carbondale, IL.

  • Bavetz, M. 1994. Geographic variation, status, and distribution of Kirtland's snake (Clonophis kirtlandii Kennicott) in Illinois. Transactions of the Illinois State Academy of Science 87(3-4):151-163.

  • Brandon, R. A., and M. Bavetz. 1992. Status of Kirtland's snake in Illinois. Final report submitted to Division of Natural Heritage, Illinois Department of Conservation, Springfield, IL.

  • Brooks, R. P., and W. J. Davis. 1987. Habitat selection by breeding belted kingfishers (Ceryle alcyon). Am. Midl. Nat.117:63-70.

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