Archives of The Cold Blooded News

The Newsletter of the Colorado Herpetological Society

Volume 31, Number 10;   October, 2004

Relocated Rattlesnakes Often Roam Home

by Jon Campbell

Erika Nowak, a USGS wildlife biologist in Flagstaff, Arizona, specializes in reptile and amphibian research, particularly the management of "nuisance" rattlesnakes (those snakes occurring in places where people don't want them) in national parks.

Most people are, shall we say, "concerned" about potential dangers associated with rattlesnake-human encounters. Park managers, however, take a professional approach to this apprehension for the benefit of both visitors and wildlife.

Typically when rattlesnakes are seen on trails in national parks, rangers pick them up and move (relocate) them, often for long distances or sometimes even outside of the park area. However, the effectiveness of such relocation practices has not been well understood.

Implanting radio-transmitters in 19 rattlesnakes enabled Nowak and many volunteers to track the relocated snakes every few days for over two years. The results were quite remarkable: relocated rattlesnakes traveled longer distances and more frequently than expected, and on the whole they had greatly increased home range sizes when compared to their ranges before relocation and to those of observed control snakes during the same time period. Relocated snakes also had higher mortality rates, even though over half of them returned back to their original home ranges.

An important finding of Nowak's research in the parks is that many rattlesnakes are using hibernation sites near or under park trails - not a welcome thought for most visitors. If large numbers of snakes are repeatedly seen in the spring and fall, it is likely they are migrating to and from nearby hibernation sites near the trail sides. Of even greater concern is the fact that many of the snakes have summer ranges near visitor centers or housing areas!

Preliminary research indicates that small mammal and bird prey abundance is higher in human-modified areas than in more native habitats. Continued removal of individual "nuisance" rattlesnakes in this context will not make the foraging sites any less attractive. Instead, Nowak recommends decreasing the attractiveness of developed areas to snakes and their prey by removing potential hiding places such as tall grass and woodpiles, and by not feeding or watering birds. If a snake does need to be moved from a public use area for safety reasons, Nowak feels the best solution is short-distance relocation (less than 100 meters) into the nearest area that provides adequate cover.

The perceived "aggressive" nature of rattlesnakes is widely overemphasized. The reality is that most rattlesnakes rely on a combination of camouflage and being motionless (procrypsis) for their first line of defense against predators, including humans. They do NOT usually rattle if under cover, and are not likely to be seen even when approached very closely. Although over half of the telemetered rattlesnake population spent significant amounts of time in the visitor center and housing areas at each research site, the snakes were almost never seen by visitors or park staff.

A focus on public education should be an integral part of any management plan for nuisance rattlesnakes, Nowak believes. She accepts at least one invitation a month to give rattlesnake talks and training sessions for national and state parks, fire districts, schools; the media, or scientific conferences. She has even been invited to present her research in Sweden.