Appearance. This thick-bodied snake has a distinctive triangular head, which is unmarked and rust to brown in color. Its body is rust-orange to yellow, brown, or occasionally gray with dark brown to black chevrons, or cross bands. Its velvet-black tail ends in a cream-colored, segmented rattle. An adult rattlesnake can reach up to 54 inches in length, but averages 28 to 36 inches.
Range and Habitat. Timber rattlesnakes are found in the blufflands of southeastern Minnesota. They den in limestone rock cavities, where they can get below the frost line and hibernate communally for winter.
During their active period, typically May through early October, timber rattlesnakes bask on bluff prairies found on south- and west-facing slopes. In late May to June, males and nonpregnant females move off into surrounding forests to hunt. Pregnant (gravid) females tend to stay on the bluffs and bask on rocks to incubate their young. The DNR works on public and private lands to improve habitat for this and other bluff prairie species.
Diet. Minnesota has 17 native species of snakes, but only two are venomous. The timber rattlesnake is one. (The massasauga has not been reported here for more than 25 years.) It uses its hollow fangs to inject venom, which soon immobilizes its prey—rodents, squirrels, and other small mammals. The snake uses heat-sensing pits on its face to relocate prey, which it then consumes whole.
Life History. Females give birth to seven to 10 live young in September. Newborns, or neonates, are about 12 to 14 inches long. They are born with a button rattle and add a segment each time they shed their skin. Gray with black chevrons, neonates take on adult coloration as they grow and shed.
The female stays with her young for about two weeks and then moves off to feed before going into hibernation. The neonates feed, shed, and follow scent trails, left by adult snakes, back to the den.
Timber rattlesnakes are a long-lived species compared with some other snakes and reptiles. They live 20 years or more in the wild. In Minnesota, due to our northern climate, they do not reach reproductive maturity until they are 6 to 11 years old. They do not reproduce every year, so a female may produce only three to five litters in her life. This low reproductive rate makes recovery difficult for threatened populations.
Status. This species was once hunted because of bounties paid by local governments in Minnesota. Bounties ended in 1989. The timber rattlesnake has been listed as a threatened species in the state since 1996. Habitat changes and fragmentation are a threat, but human persecution is also a significant concern.
Jaime Edwards, DNR nongame wildlife specialist