On The Trail Of Timber Rattlesnakes

Posted by: Allen Canfield on Mon, 24 March 2003 00:03:50 (2384 Reads)

When wildlife biologist Jennifer Adams comes across a rattle-snake while doing fieldwork, she is having what she considers a very good day. While that prospect may not seem pleasant to others, Adams has been on the trail of the timber rattlesnake (Crotalus horridus) since this past spring in the Westvaco Wildlife and Ecosystem Research Forest (WERF) in Adolph, WV.

Her study, funded by a Nongame Wildlife and Natural Heritage Program research grant, is designed to determine the home range and behavior of timber rattlesnakes, as well as their transient ranges and summer ranges in a fragmented forest. It will also identify additional dens, rookeries and stopover points in the WERF.

"This study is providing important baseline data since very little is currently known about home range and behavior of this species in a fragmented forest," says Adams. Her experience with the rattlers has shown that "timbers are really innocuous or secretive; not as threatening as people think," dispelling the old myths of their danger.

Adams is hoping to capture 10 to 12 snakes and equip them with radio transmitters before the end of the field season. So far, nine have been radio-equipped. Snakes are monitored at regular intervals to determine their travel from the den site to summer range. Males are monitored closely to locate birthing areas or rookeries.

"I'm finding that the timbers are using multiple habitat types, including regenerating clear-cuts and shelterwood cuts," she says. Also, in early September, Adams found one of the newly radiod snakes had six young which were then PIT (Passive Integrated Transponder) tagged: microchips were inserted internally which allow the snakes to be scanned for identification. This discovery means she can potentially monitor a family group.

The location of the snakes with implanted transmitters is being carefully recorded using Global Positioning System technology and plotted on a cover map of the area. Adams spends long days tracking down the snakes, recording general habitat information, temperature, humidity and weather data. Including the hike to the sites, it usually takes about three hours to gather data per snake, she says.

Fortunately, Adams was already aware of three den sites while monitoring grouse in the WERF. She had located those dens by attaching radios to 10 snakes she had encountered last September. "Those dens were critical in doing the study," she says. "It provided a starting point for locating the snakes."

The 8,400 acre tract of land that makes up the research forest is comprised mainly of northern hardwoods ranging in elevation from 2,500- 3,500 feet. During the past five years a total of 12 timber cuts have been made in the WERF averaging 35-50 acres in size. The harvest plan over the next five years is to cut an average of four 35-acre blocks per year.

"This is a good opportunity to monitor the snakes' activities to and from the dens and determine their use of various habitats at different stages of growth," Adam Explains. "Since cutting takes place throughout the year on the Research Forest, the potential effects on den use after the cuts can be monitored."

The home ranges for rattlesnakes are surprisingly large, Adams points out, with the males having the larger range. Some studies indicate up to 500 acres. Generally, their reproductive capability is quite low with most females not reaching sexual maturity until four to six years of age and sometimes older.

While females commonly breed and produce an average of seven young at several year intervals, Adams feels that reprodution varies among regions and populations. "This study will allow us to determine these things for snakes of this region."

As Adams explains, this species' survival rate is also complicated by the fact that many states, including West Virginia do not protect the timber rattlesnake. Because of this, snakes are collected and killed.

The study will continue through next year in order to get a good interpretation of their home ranges and habitat uses. Adams is predicting that the results will "provide basic information on the rattlesnakes living on the WERF, and on their welfare and survival. This in turn will allow recommendations to be made that will minimize disturbance or loss of habitat, and provide protection of critical areas needed for their survival."

-Article reprinted from the Fall 2001 WV Nongame Wildlife & Natural Heritage News
- Author: Nanci Bross-Fregonara