Northern Brownsnake
Storeria dekayi dekayi

** Harmless **

  • Northern Brownsnake Venter
  • Northern Brownsnake Defensive Posture
  • Northern Brownsnake
  • Northern Brownsnake Neonate
  • Northern Brownsnake with Offspring
  • Northern Brownsnake with Offspring
Northern Brownsnake Venter1 Northern Brownsnake Defensive Posture2 Northern Brownsnake3 Northern Brownsnake Neonate4 Northern Brownsnake with Offspring5 Northern Brownsnake with Offspring6

Common Name: Northern Brownsnake
Scientific Name: Storeria dekayi dekayi
Etymology:
Genus: Storeria is in honor of David Humphreys Storer, an 18th-century,  zoologist from New England. <
 Species: dekayi is in honor of James Ellsworth Dekay, a 19th-century naturalists.
 Subspecies: dekayi is in honor of James Ellsworth Dekay, a 19th-century naturalists.
Vernacular Names: Brown grass snake, Dekay's snake, ground snake, house snake, little brown snake, rock snake, spotted adder, spotted brown snake.
Average Length: 9 - 13 in. (23 - 33 cm)
Virginia Record Length:  14.9 in. (37.9 cm)
Record length: 19.3 in. (49.2 cm)

 

PHYSICAL DESCRIPTION: In VA., maximum known SVL is 300 mm (11.8 in.) and max total length is 379 mm (14.9 in.) *10760*. Outside Virginia, the maximum known total length is 19.125 inches *11523*. The adults are usually 9-13 inches in length *11523*. Tail length/total length ratio is 15.0-30.5 (avg. = 21.9+/-2.7, n=132) *10760*.

SCUTELLATION: Ventrals 113-133 (avg. = 122.9+/-4.1, n=140); subcaudals 37-61 (avg. = 49.1+/-5.5, n=133); ventrals + subcaudals 158-186 (avg. = 171.9+/-5.2, n=133); dorsal scales keeled; scale rows 17 at midbody; anal plate divided; infralabials 7-7 (85.7%, n=126), other combinations of 6-8 (14.3%); supralabials 7-7 (90.6%, n=128), other combinations of 6-8 (9.4%); loreal scales absent; preoculars 1-1; postoculars 2-2; temporal scales usually 1+2/1+2 (72.0%, n=132), other combinations of 1-3 (28.0%).

COLORATION and PATTERN: dorsum of body and tail light brown or gray to dark brown or nearly black with a longitudinal series of small, paired, black spots; the area between the spots is lighter than the rest of the body, forming a tan middorsal stripe in some specimens; a variable number of pairs of spots (2-22) are connected by a thin black crossline; lateral scales tipped in black and white to form a checkerboard-like pattern in some specimens; venter cream to gray and usually patternless; one to several tiny black dots or areas of dark pigmentation lie at the edges of the ventral scales; dorsum of head light brown to dark brown (some are black in preservative) with a short, longitudinal, black streak on the temporal scales; supralabials have one to several dark vertical streaks or have variable amounts of dark pigmentation; chin and infralabials cream and patternless; head blunt.*10760*

SEXUAL DIMORPHISM: Sexual dimorphism occurs in body size and scutellation. Mature females average larger (232.3+/-28.2 mm SVL, 175-296, n=64) than mature males (199.6+/-27.0 mm SVL, 150-300, n=46), but the largest individual is a male (379 mm total length). Sexual dimorphism index is 1.16. Male offspring of a Powhatan Co. female averaged slightly smaller (61.7 mm SVL) than the female offspring (64.3 mm SVL). The tail length/total length ratio in females (15.0-24.9%, avg. = 20.2+/-1.8, n=76). is slightly lower than the ratio in males (19.6-30.5%, avg. = 24.3+/-1.8, n=56).*10760* Females have a higher average number of ventral scales (125.1+/-3.6, 113-133, n=79) than males (119.9+/-2.5, 114-125, n=61), but fewer average number of subcaudals (45.8+/-4.4, 37-61, n=76) than males (53.5+/-3.4, 47-61, n=57). Average counts of ventrals + subcaudals (males 173.3+/-4.4, 164-184, n=57; females 170.8+/-5.5, 158-186, n=76) are similar between sexes.*10760*

JUVENILES: Juveniles are uniform dark brown to black dorsally, with a narrow cream to yellow collar on the neck. This pattern changes in the first year of life to that seen in adults. At birth, S. dekayi is 57-77 mm SVL (avg. = 68.9+/-4.5, n=47), 80-1-6 mm total length (avg. = 91.3+/-6.0, n=46), and weigh 0.21-0.33 g (avg. = 0.28+/-0.05, n=means of 4 litters). Confusing Species: This specis may be confused with several other small VA. snakes. V. valeriae may have small black spots on the dorsum but has smooth scales. V. striatula has keeled scales and lacks the dorsal spots. Both of these species have more pointed heads than S. dekayi. Diadophis punctatus is uniform gray to nearly black with a conspicuous collar as adults. Tantilla coronata is uniform brown with a black head and collar on the neck. Thamnophis sirtalis has a distinct middorsal stripe, a dorsolateral checkerboard pattern, the spots of which occur on more than one scale, and a longer head. The congeneric Storeria occipitomaculata has a reddish venter and 3 light spots across the neck in adults and juveniles.*10760*

GEOGRAPHIC VARIATION: The average number of ventral scales is similar among physiographic regions in VA., ranging from 121.9+/-4.0 (116-130, n=34) in the northern Piedmont to 124.0+/-3.5 (119-131, n=18) in the southern Coastal Plain. The average # of subcaudals in the northern Piedmont (45.8+/-5.4, 40-61, n=34) is slightly less than elsewhere in the state (averages vary from 49.5+/-4.5-50.6+/-5.7). Consequently, counts of ventrals + subcaudals in northern Piedmont populations (167.7+/-5.5, 158-186, n=34) are lower than in other parts of the state (averages vary from 172.5+/-4.2 - 174.4+/-3.5). The low scale counts are most characteristic of S. dekayi from Fairfax Co. Trapido showed that there were few differences in scutellation and morphometrics in the range of S. d. dekayi.*10760* The Midwestern subspecies S. d. wrightorum, as described by Trapido, differs from the nominate subspecies S. d. dekayi by having the dorsal spots connected by black pigment forming a series of narrow crossbars. He listed one specimen from VA. (CM 13263, New Kent Co.) as S. d. wrightorum and indicated an intergrade zone in southeastern VA. Christman indicated an intergrade zone between these 2 forms that includes only southwestern VA. All populations of S. dekayi east of the New River drainage show considerable variation in presence, absence, and number of crossbars (14 of 45 specimens in all regions of the state have 2-22 crossbars).

REPRODUCTION: Storeria dekayi is viviparous. In VA., males reach maturity at a SVL of 150 mm and females at 175 mm SVL. Mating has not been observed in VA. but Ernst and Barbour noted that it occurs from late March through May. They also state that the gestation period is 105-113 days. Virginia females bear litters of 3-26 young (avg. = 10.8+/-4.3, n=26). Birth dates for nine litters were 22 July to 30 August, about evenly divided between the two months. Fitch, Ernst, and Barbour reported birth dates of 6 July - 14 September and litter sizes of 3-41 from throughout the range of this species *10760*. Gravid females are sometimes found in branches and vines overhanging streams *11517,11523*.

BEHAVIOR: This species is nocturnal in the spring *2075,2065*. Up to 20 living young are born from July-August. The gestation period is 109 days. It prefers a damp area with ground cover, i.e. logs, boards and rocks. This is a common snake in suburban yards and urban parks. It is harmless and does not bite *1014,1006*.

ORIGIN: This species is native *2075*. Northern brown snakes are active primarily between 13 March and 20 October (museum records), although this snake has been found in every month of the year (2 have been found in February). Noble and Clausen (1936) examined the aggregation behavior of S. dekayi and found that it occurs at all times of the year, but especially during winter hibernation. Hibernation sites include ant mounds and abandoned rodent burrows. Aggregations of more than 2 individuals have not been reported from VA.*10760* Thorp has found this species under logs and cover boards and crossing roads. He also has observed this species on late nights (around 10:00 pm) in the spring, when temperatures were in the low 60's (Fahrenheit degrees), crossing roads *11523*. Known predators of S. dekayi in VA. are free-ranging domestic cats, cottonmouths, (Agkistrodon piscivorous), black racers (Coluber constrictor), kingsnakes (Lampropeltis spp.), Virginia rails (Rallus limicola), loggerhead shrikes (Lanius ludovicianus), robin (Turdus migratorius), red shouldered hawks (Buteo lineatus), raccoons (Procyon lotor), skunks (Mephitis mephitis), weasels (Mustela spp.), and opossums (Didelphia virginiana). Linzey and Clifford mentioned that toads (Anaxyrus spp.) eat the young but provided no observations.*10760*

POPULATION PARAMETERS: The longevity record for this species is 7 years *11523*.

References for Life History

Photos:

*Click on a thumbnail for a larger version.

Fairfax County Fairfax County Venter Arlington Co. - Adult with neonates Arlington Co. - Neonate
Close-up - Lynchburg Adult Lynchburg Adult with neonates Lynchburg Cumberland Co. Fairfax County

 

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