Inventory Methods for Snakes
Standards for Components of British Columbia's Biodiversity No. 38

Table of contents

2. Inventory Group

The following is a list of the snakes found in British Columbia:

Family Boidae

Family Colubridae

Family Viperidae

2.1 Rubber Boa Charina bottae

Description

Adult TL: 355-830 mm

Body form: short and stout; blunt, prehensile tail; rounded, blunt head

Colour: dorsal: uniform brown, greyish or yellowish- or greenish-brown; ventral: yellow

Eyes: small with vertical pupil

Head scales: 9-11 upper labials; plates large and irregular; no chin shields

Body scales: small and smooth; usually 44 or fewer dorsal rows at midbody; anal plate single, with small spur in pit on either side (spur more conspicuous in males, may be absent in females); subcaudal scales single

Range and distribution

Occurs across southern British Columbia, as far north as Quesnel; range extends south to the San Bernadino Mountains, California, and east to western Montana, western Wyoming, and Utah.

Life history

Activity: adapted to burrowing; highly nocturnal; sluggish and inoffensive

Feeding: kills food by constriction: small mammals, occasionally birds and lizards; captive animals eat a wide variety of food, including fish and small snakes

Reproduction: viviparous; 2-8 young, 180-280 mm total length.

Habitat requirements

Appears to inhabit humid, mountainous regions; also occurs in drier lowlands and foothills with open vegetation.

Status

Provincial Blue List

Selected references

Hoyer 1974; Nussbaum and Hoyer 1974; Nussbaum et al. 1983; Smith and Brodie 1982; (map from Gregory and Campbell 1984)

2.2 Sharptail Snake Contia tenuis

Description

Adult TL: 205-455 mm

Body form: short, fairly stout; tail short, tapering, ending in sharply pointed scale; head wider than neck, with broad, rounded snout

Colour: dorsal: ground colour greyish, yellowish-brown, or reddish-brown (tending to be reddish on tail), sometimes with fine dots of black or slate and usually with a wide yellowish or reddish stripe along each side; scales below stripe dotted with black or darkened to form a continuous band in young individuals; ventral: whitish, greyish, or yellowish with conspicuous transverse dark bar on anterior edge of each plate; head: top dark brown, chin light

Eyes: small with round pupil

Head scales: 7 upper labials; 7 lower labials

Body scales: smooth; 15 dorsal rows at midbody; anal plate double; subcaudal scales divided

Range and distribution

In British Columbia, several scattered records have been made from Vancouver Island and the Gulf Islands, in the Coastal Douglas-fir Biogeoclimatic Zone; one additional record made from McGillivray Lake, in the Engelmann Spruce-Subalpine Fir Biogeoclimatic Zone. Elsewhere, range extends from western Washington and Oregon south to central California.

Life history

Activity: possibly nocturnal

Feeding: diet consists mainly of slugs

Reproduction: oviparous; 2-9 eggs per clutch; young about 75 mm long at hatching

Habitat requirements

Appears to inhabit woodlands and forests, especially near streams; moist environments.

Status

Provincial Red List

Selected references

Cook 1960; Nussbaum et al. 1983; Spalding 1993; (map from Gregory and Campbell 1984)

2.3 Racer Coluber constrictor

Description

Adult TL: 560-1980 mm

Body form: long and slender with long, whip-like tail; head large and distinct from neck

Colour: dorsal: uniform greyish or olive in adult; young with series of 70-85 brown cross- bands along back and smaller blotches on sides; ventral: yellow

Eyes: large with round pupil

Head scales: lower preocular wedged between upper labials; usually 8 upper labials; 9 lower labials

Body scales: smooth; 17 dorsal rows on fore- and mid-body; 15 dorsal rows on rear body; anal plate divided; subcaudal scales divided

Range and distribution

Occurs throughout the interior Dry Belt of British Columbia, especially in the area bounded by the Okanagan, Similkameen, Fraser, and Thompson Valleys. Range extends over most of the United States and adjacent parts of southern Canada.

Life history

Activity: fast and agile; aggressive; generally diurnal; climbs vegetation

Feeding: large, active predator: small mammals and insects; also frogs, lizards, snakes, birds

Reproduction: oviparous; 3-9 eggs (24-39 mm x 14-21 mm); young 205-305 mm at hatching

Habitat requirements

Inhabits open, sparsely treed country; may overwinter in more forested areas; den communally with rattlesnakes, gopher snakes, garter snakes.

Status

The subspecies, Coluber constrictor mormon, is on the Provincial Blue List.

Selected references

Brown and Parker 1976; (map from Gregory and Campbell 1984)

2.4 Night Snake Hypsiglena torquata

Description

Adult TL: 305-600 mm

Body form: slender; head somewhat flat and slightly triangular

Colour: dorsal: ground colour grey or yellowish-brown; numerous darker grey-brown spots; mid-dorsal row of more or less paired blotches; alternating row of smaller blotches on each side; second row of still smaller spots low on each side; three distinct dark brown blotches on back of neck, middle one widened posteriorly to cover most of nape; much variation in configuration and degree of connection of these blotches. ventral: white or yellowish. head: upper labials whitish; dark brown bar behind eye, running backward and downward; narrower bar running forward in front of eye.

Eyes: pupil vertical

Head scales: 8 or 9 upper labials; 10 lower labials

Body scales: smooth; 21 dorsal rows at mid-body; anal plate divided; subcaudal scales divided

Range and distribution

In British Columbia, the Night Snake has been recorded 5 times in the southern Okanagan valley; also a single report from the southern Similkameen valley. Range extends through central Washington, eastern Oregon, southern Idaho, Nevada, Utah, and across the southern United States from California to central Texas; south throughout Mexico and Central America to Costa Rica.

Life history

Activity: nocturnal

Feeding: venomous; rear-fanged (not thought to be dangerous to humans); diet probably lizards, small snakes, frogs

Reproduction: oviparous, 3-9 eggs; hatchlings 150-180 mm total length

Habitat requirements

Inhabit dry, sandy areas with abundant rock cover.

Status

Provincial Red List

Selected references

Diller and Wallace 1981; (map from Gregory and Campbell 1984)

2.5 Gopher Snake Pituophis catenifer

Description

Adult TL: 915-1800 mm (in British Columbia)

Body form: long and stout; tail moderately long; head slightly larger than neck; snout narrow and projecting beyond lower jaw

Colour: dorsal: ground colour usually pale yellow or greyish-yellow; keels on scales are dark brown; 45-55 dark brown blotches along back beginning behind head; on upper surface of tail, these become a series of 12-16 dark brown cross-bands; several series of smaller blotches or spots along body sides; ventral: yellow or yellowish-white with brown or black spots; head: dark line across head in front of eyes; dark band from eye to angle of jaw; dark vertical spot below eye

Eyes: large with round pupil

Head scales: 8 (7-10) upper labials; 12-13 lower labials

Body scales: lightly keeled on back; smooth on sides; anal plate single; subcaudal scales divided

Range and distribution

Occurs throughout the interior Dry Belt of British Columbia. Single records (of P.c. catenifer) from Galiano Island and Sumas, Washington. Range extends over most of the western and southeastern United States and parts of adjacent Canada.

Life history

Activity: good climber; aggressive; largely crepuscular

Feeding: large, active, constricting predator: small mammals; birds and eggs

Reproduction: oviparous; 3-24 eggs/clutch; hatchlings 204-455 mm long

Habitat requirements

Habitats range from forested areas to open sagebrush; usually den communally with rattlesnakes and other snake species.

Status

P.c. deserticola (Synonym: Pituouphis melanoleucus deserticola): Provincial Blue List

P.c. catenifer (Synonym: Pituouphis melanoleucus catenifer): Provincial Red List

Selected references

Parker and Brown 1980; Nelson and Gregory (in press); Nussbaum et al. 1983; (map from Gregory and Campbell 1984).

2.6 Western Terrestrial Garter Snake Thamnophis elegans

Description

Adult TL: 455-1065 mm

Body form: fairly long and robust; tail moderately long; head large and distinct from neck

Colour: dorsal: ground colour usually grey, black, to dark brown on Vancouver Island, and lighter brown elsewhere in B.C.; prominent yellow to orange mid-dorsal stripe along length of back, usually a wavy line but sometimes straight; yellow lateral lines running length of body (on 2nd and 3rd rows of body scales) less evident than mid-dorsal stripe; two rows of dark brown or black blotches between stripes on each side of body (upper row invades mid-dorsal stripe giving stripe a wavy appearance); blotches particularly obvious in Interior specimens but may not show clearly in coast specimens; series of small dark brown or black spots below lateral stripe (or even invading lateral stripe); rarely, specimens have tinge of red on sides of body; some coast specimens may have a generally bluish appearance with otherwise normal pattern. ventral: usually greyish, sometimes with black markings. head: top black or brownish with black markings in coast specimens, brown in Interior specimens; upper lip white or yellow; chin and throat whitish.

Eyes: moderately large with round pupil

Head scales: usually one preocular on coast, two east of Coast Range; 8 (7-8) upper labials; 10 (9-10) lower labials; posterior upper labials very large relative to other garter snakes

Body scales: strongly keeled; 21 dorsal rows at mid-body; anal plate single; subcaudal scales divided

Range and distribution

Occurs throughout the southern part of British Columbia, from Vancouver Island and the adjacent coast to the Alberta border, and as far north as the Peace River district. Range extends east through Alberta and southwestern Saskatchewan, south to central New Mexico and west to central California.

Life history

Activity: diurnal; aquatic; very active and aggressive

Feeding: diet highly varied: mainly slugs, small mammals, fish; also amphibians, earthworms, leeches, birds, other snakes; occasionally uses constriction to hold prey

Reproduction: viviparous; 4-19 young, 171-230 mm total length; mating takes place in spring

Habitat requirements

Usually found near water, including marine environments; may occupy terrestrial situations (open meadows and estuaries) where small mammals are abundant.

Status

Provincial Yellow List

Selected references

Gregory 1978, 1984; Gregory and McIntosh 1980; (map from Gregory and Campbell 1984)

2.7 Northwestern Garter Snake Thamnophis ordinoides

Description

Adult TL: 320-850 mm

Body form: long and fairly stout; tail moderately long; head small, fairly blunt in snout, not very distinct from neck

Colour: dorsal: extremely variable; typically: ground colour brown; yellow stripe and yellow lateral stripe (on 2nd and 3rd rows of body scales) on each side, running length of body; two rows of small black blotches between stripes; some specimens with dorsal and/or lateral stripes incomplete or lacking; many specimens with considerable red: sides of body may be reddish, dorsal stripe may be red; dark or completely black specimens fairly common; some specimens completely black with bright red dorsal stripe and/or belly; albino specimens are known. ventral: variable; yellowish, olive, brown, bluish, slatey, or black; commonly blotched with red and sometimes with black. head: variable; typically: top brown, upper lip white; chin white.

Eyes: small with round pupil

Head scales: 1-2 preoculars; usually 7 upper labials; 8-9 lower labials

Body scales: strongly keeled; 17 dorsal rows at mid-body; anal plate single; subcaudal scales divided

Note: markings are extremely variable; this species must be identified by scale count.

Range and distribution

Occurs along the coast of southwestern British Columbia, including the Gulf Islands and all of Vancouver Island, and inland to Manning Park. Elsewhere, ranges through western Washington and Oregon south to extreme northwestern California.

Life history

Activity: diurnal; highly terrestrial; not aggressive

Feeding: diet includes slugs and earthworms

Reproduction: viviparous; 2-19 young, 145-200 mm total length; mating in fall and spring

Habitat requirements

Inhabits meadows or ecotones between meadows and woods; sparse forests; found along estuaries and on beaches on the coast.

Status

Provincial Yellow List

Selected references

Gregory 1978; Gregory and McIntosh 1980; (map from Gregory and Campbell 1984)

2.8 Common Garter Snake Thamnophis sirtalis

Description

Adult TL: 460-1300 mm

Body form: long and slender; tail moderately long; head large and distinct from neck

Colour: dorsal: ground colour usually black or dark brown; skin between dorsolateral scales usually red producing series of red vertical bars or blotches on sides of body (red sometimes absent on Vancouver Island specimens); three yellow or greenish-yellow stripes running length of body; mid-dorsal stripe includes middle row of scales and half of row on each side, lateral stripes occupy second scale rows and lower half of the third scale rows. ventral: yellow to black. head: top usually uniform black, brown, or olive-green; upper lip yellow; posterior part of head often marked by considerable red, laterally (less so on Vancouver Island specimens); often red or dark blotch on posterior upper labials; chin and throat usually pale yellow.

Eyes: large with round pupil

Head scales: one preocular; usually 7 upper labials, 10 lower labials

Body scales: strongly keeled; 19 dorsal rows at mid-body; anal plate single; subcaudal scales divided

Range and distribution

In British Columbia, T.s. pickeringi is restricted to Vancouver Island and the immediately adjacent mainland coast, T.s. fitchi occurs across the province south from 300 km north of Prince Rupert, and T.s. parietalis occurs along the eastern side of the province, south from the Peace River district. Elsewhere, the Common Garter Snake is transcontinental from Fort Smith, Northwest Territories to the Gulf of Mexico, but is absent from the southwestern United States.

Life history

Activity: diurnal

Feeding: diet includes mainly amphibians and earthworms; also intertidal and freshwater fishes, leeches, small birds

Reproduction: viviparous; 2-85 young, about 200 mm total length; usually mates in spring near hibernacula

Habitat requirements

Inhabits a wide variety of habitats; most abundant near marshes, small lakes, rivers and ponds, fairly humid forests; often overwinters communally in large numbers, especially in northern parts of the range.

Status

Provincial Yellow List

Selected references

Gregory 1978; Gregory and McIntosh 1980; (map from Gregory and Campbell 1984)

2.9 Western Rattlesnake Crotalus viridis

Description

Adult TL: 600-1575 mm

Body form: long and stout; tail short, ending in a horny rattle or button; head broad (especially at back), triangular, distinct from neck

Colour: dorsal: ground colour brown, tan, olive, or grey, may be somewhat lighter towards tail; series of large dark brown blotches along back; these blotches typically have light-coloured edges and appear as cross-bands on the posterior part of the body and tail; series of smaller blotches on each side of body below large blotches; juveniles usually lighter in colour, with greater contrast of blotches with background. ventral: yellowish-white, sometimes brownish. head: top usually shows ground colour with dark band running from below eye to corner of jaw.

Eyes: moderate in size with vertical pupil; deep pit between eye and snout

Head scales: two preoculars; small on top of head; 15 (10-19) upper labials; 16 (11-20) lower labials

Body scales: strongly keeled (lower 1-3 may be smooth); 23-29 dorsal rows; anal plate single; subcaudal scales single

Range and distribution

Restricted to the interior Dry Belt in British Columbia, east to the Cascade Mountains, west to Lytton, and north to Kamloops and Cache Creek; a few specimens recorded as far west as Lillooet. Elsewhere, range extends over most of the western half of North America with few gaps.

Life history

Activity: mainly crepuscular, but active at any time of day or night if conditions suitable; active in B.C. between early April and early October

Feeding: venomous; diet mainly small mammals, birds

Reproduction: viviparous; 2-8 young (fully venomous), 240-270 mm TL; mate in late summer and early fall

Habitat requirements

Inhabit grassland and grassland-forest ecotone; den communally in talus slopes and rock outcrops

Status

Provincial Blue List

Selected references

Macartney 1985; Macartney and Gregory 1988; (map from Gregory and Campbell 1984)

2.10 Species Identification

Proper species identification is obviously very important. Most British Columbia species are readily identifiable from the key provided here (and in Gregory and Campbell 1984). Note that the identification of species solely on the basis of colour should definitely be avoided as colour can be quite variable between, and even within, populations. Records from localities in which the species has not previously been recorded should be verified by someone qualified to make a proper identification (e.g. at the Royal British Columbia Museum or the University of Victoria).

Key to the Snakes of British Columbia (modified from Gregory and Campbell 1984)

1a. Body scales all keeled............2
1b. Some or all body scales smooth............5
2a. Pit or cavity between nostril and eye;
button or rattle on end of tail
............Western Rattlesnake (Crotalus viridis)
2b. No pit or rattle............3
3a.17 rows of body
scales at mid-body
............Northwestern Garter Snake (Thamnophis ordinoides)
3b. More than 17 rows of body
scales at mid body
............4
4a.19 rows of body scales at mid-body ............Common Garter Snake (Thamnophis sirtalis)
4b.21 rows of body scales at mid-body............Western Terrestrial Garter Snake (Thamnophis elegans)
5a. Scales on back slightly keeled, all other
body scales smooth; 4 prefrontal scales; a series of dark brown
blotches down back; dark line across head in front of
eyes plus a dark band from eye to angle of jaw
............Gopher Snake (Pituophis catenifer)
5b. All body scales smooth............6
6a. Head and tip of tail blunt; 44-45 rows of
scales at mid-body:; no enlarged chin shields
............Rubber Boa (Charina bottae)
6b. Fewer than 44 rows of body scales at mid-body............7
7a.21 rows of body scales at mid-body; yellow- brown
background with numerous brown blotches, the mid-dorsal
row often occurring in pairs; 3 dark brown
blotches on back of the neck, pupil of the eye
vertically elliptical
............Night Snake (Hypsiglena torquata)
7b. Fewer than 21 rows of body scales at mid-body............8
8a. 15 rows of body scales at mid-body;
tail blunt with sharp, pointed scale at tip;
usually a yellowish or reddish stripe along each side
............Sharptail Snake (Contia tenuis)
8b.15-17 rows of body scales at mid-body;
head large with large eyes, tail long and whip-like;
dorsal colour grey-blue to olive, although small specimens may have a series of large brown blotches down the back
............Racer (Coluber constrictor)


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