Scientific Name: Crotalus horridus
Size: 36-60 inches (90-152 cm) in length
PA Status: Candidate Species

Habitat Type:
Upland forest with rocky outcroppings, talus slops, rock crevices,  rock ledges with vegetation, mature forest with numerous fallen logs, young forest with predominant leaf litter cover.

Colorations:
Adults:

• There are 2 distinct patterns in PA: Yellow Phase (light) and Black Phase (dark).
• The dorsal background is yellowish brown to dark brown.
• The dorsal has a bold pattern of dark brown, grey to black Chevron like “V” shaped body bands and blotches.
• The bands and blotches are set of from the background by a pale yellow to beige border.
• The tail is unpatterned and solid grey, brown or black.
• The bands continue to the tail.
• The ventral is cream to yellowish brown and may be mottled with small black stipples.
• The head has a dark stripe extending backwards from the eye to the corner of the mouth.
• Melanistic and Albino species have been found in PA.

Juveniles:

• Similar to adults

Characteristics:

• Large-sized, heavy bodied species.
• The head is large, flat and triangular in shape.
• The head is distinct and set off from the body by a narrow neck.
• Pupils are vertically elliptical.
• Deep set pits between the eyes and nostrils.
• The dorsal scales are strongly keeled.

Scale Counts:

• 23 or 25 scale rows at midbody.
• 25-27 scale rows at anterior.
• 19 scale rows at posterior.
• 154-183 ventral scales
• 13-31 subcaudals scales | Single row of subcaudals
• Higher than wide rostral scale
• 2 internasal scales
• 4 canthal scales
• 2 supraocular
• 2 nasal scales
• 2 loreal scales
• 2 preocular scales
• several subocular scales
• 4 postocular scales
• several temporal scales
• 13-15 supralabials
• 14-16 infralabials
• Anal plate is undivided

Confused with:

• Massasauga

Coloration/Pattern Photos:
Adults

Juveniles:

Range Map:

References:

• Hulse, C. and McCoy C. J. and Ellen Censky ,1998. Amphibians and Reptiles of Pennsylvania and the Northeast. 351-355pp.
• Ernst, Carl H. and Ernst, Evelyn M. ,2003. Snakes of the United States and Canada. 503-509pp.

Photo Credits:

• Jason Poston
• Dave Huskins
• Kyle Loucks