More on Relocating Rattlesnakes – including a research bibliography

Here’s a more recent post on rattlesnake research by Dr. Erika Novak.

A reader and nature appreciator, Gary MacGrumbley from New Mexico, responded to my earlier article Rattlesnakes! Relocating them works just fine, saying there was not enough evidence to say that relocating rattlesnakes worked. I checked in with rattlesnake expert Dr. William Hayes who I had interviewed and he provided the update below, along with a complete bibliography on the subject.

Dr. Hayes said the following:

“As I stated and Linda wrote, snakes do travel more the first year after release and suffer higher mortality, but many do survive and settle down in time.”

He went on further: “There are just four options for dealing with “nuisance” rattlesnakes: (1) leave them alone (many homeowners won’t accept this); (2) kill them (I don’t like this option); (3) translocate them to another area and let them have a chance to live; (4) remove them from the wild and keep them in captivity for the rest of their lives. I personally think option #3 is perfectly legitimate and much preferable to and more humane than option #2.”

Hayes recommends releasing them 1-2 miles from your property whenever possible (and in different areas if more than one)

Gary says his community in New Mexico is encountering a high number of rattlesnakes this year, possibly because of the amount of rain this summer, a more typical “monsoonal” pattern that hits our Southwest each summer. He said his community is divided on how to deal with the snakes. “There are those that are adamant about relocation and those that are adamant about killing on sight and those that are open to either action depending on circumstances and those that argue do nothing, even if around the home. I don’t know that any information will change minds, but I appreciate being able to inform them that it is available for consideration/discussion,” he said. Also, despite living within 300’ of a rocky black-tailed rattlesnake den the last 24 years, they’ve only seen one (see caption below) outside their house.

Dr. Hayes provided the following annotated bibliography on the subject (12 relocation studies):

RATTLESNAKE RELOCATION STUDIES

Brown, J. R., C. A. Bishop, and R. J. Brooks. 2009. Effectiveness of short-distance translocation and its effects on Western Rattlesnakes. J. Wildlife Management 73:419–425. **C. o. oreganus in British Columbia translocated 500 m. Of 14 snakes, 85.7% returned on at least 1 occasion (range 1-7 times) to same area. Showed increase in total distance moved in active season compared to non-translocated snakes, but no increase in activity range size or effect on body condition, behavior, or mortality.

Brown, T. K., J. M. Lemm, J. Montagne, J. A. Tracey, and A. C. Alberts. Spatial ecology, habitat use, and survivorship of resident and translocated red diamond rattlesnakes (Crotalus ruber). Pp. 377-394 in W. K. Hayes, K. R. Beaman, M. D. Cardwell, and S. P. Bush (eds.), The Biology of Rattlesnakes. Loma Linda University Press, Loma Linda, California. **Translocated rattlesnakes used significantly more land, and had greater maximum-per-move distances and total distances traveled during the first year after relocation than did residents (non-translocated snakes) for the same time period. Snakes translocated a short distance (up to 314 m) showed a decrease over time in activity range sizes, annual distances moved, and mean movement speed. Some also showed up at their original capture site. Snakes translocated a long distance (856-1090 m) did not show a reduction in these behaviors over time, and none returned to their original location. There was no difference in survival between resident and translocated snakes.

Hardy, D. L., Sr., H. W. Greene, B. Tomberlin, and M. Webster. 2001. Relocation of nuisance rattlesnakes: problems using short-distance translocation in a small rural community. Newsletter of the Colorado Herpetological Society.**Up to 39% of 38+ C. m. molossus and 18+ C. atrox (sample sizes difficult to interpret) translocated 200-500 m returned to the areas of initial capture and were recaptured.

Hare, T. A., and J .T. McNally. 1997. Evaluation of a rattlesnake relocation program in the Tucson, Arizona, area. Sonoran Herpetol. 10:26-31. **I do not have a copy of this paper.

Holding, M. L., J. A. Frazier, E. N. Taylor, and C. R. Strand. 2012. Experimentally altered navigational demands induce changes in the cortical forebrain of free-ranging Northern Pacific Rattlesnakes (Crotalus o. oreganus). Brain, Behavior and Evolution 79:144-154. **Adult male C. o. oreganus radiotracked 2 months following 1) 225-m translocation, 2) 225-m walk-and-release at capture site, and 3) undisturbed control. Activity range (95% MCP) of translocated group larger than other two groups, volume of medial cortex larger than control group, but no difference in dorsal cortex or lateral cortex volumes or in numbers of labelled cells. Suggests causal relationship between navigational demands and greater medial cortex volume.

Johnson, B. 1993. Eastern Massasauga rattlesnake conservation program at the Metro Toronto Zoo. Pp. 89-93 in B. Johnson and V. Menzie (editors), International Symposium and Workshop on the Conservation of the Eastern Massassauga Rattlesnake. Toronto Zoo, Toronto, Ontario. **According to the brief article, “To date, 10 snakes translocated outside their home range have not only survived, but all our females have either given birth or been bred by resident males. The real test of survivorship will occur during the winter hibernation period…”

King, R., C. Berg, and B. Hay. 2004. A repatriation study of the Eastern Massasauga (Sistrurus catenatus catenatus) in Wisconsin. Herpetological 60:429-437. **After gravid female S. c. catenatus gave birth in captivity, adult of both sexes and neonates were released to restored habitats devoid of rattlesnakes. Snakes released during late July (4 adult males, 3 adult females, 8 subadults) had lower mortality rates, larger home ranges, and gained more mass than snakes released in early September (16 subadults, 2-yr-old). The July release cohort also successfully reproduced, while no breeding activity was observed with September release snakes. Analysis of all data (habitat use, mass gain, mortality, movement, and home range) indicates that a summer repatriation is preferred to an autumn repatriation. Regardless of release timing (autumn versus summer), the repatriated snakes had increased movement activity in the second month following release.

Mohr, J. R. 2010. Autecology of the Timber Rattlesnake (Crotalus horridus) in the South Carolina mountains. Unpubl. PhD dissertation, Clemson University. **Four Crotalus horridus translocated 949-2670 m. None returned to original capture site. One specimen died, one experienced transmitter failure, two adapted to new habitat and overwintered successfully for 2 and 3 winters, respectively.

Nowak, E. M., T. Hare, and J. McNally, J. 2002. Management of “nuisance” vipers: effects of translocation on Western Diamond-backed Rattlesnakes (Crotalus atrox). Pp. 525–552 in: Schuett, G.W., Hoggren, M., Douglas, M.E., Greene, H.W. (Eds.), Biology of the Vipers. Eagle Mountain Publishing, Eagle Mountain, Utah. **Compared 7 translocated C. atrox (2 km distance) with 7 control snakes at Montezuma Castle National Monument (MOCA), Arizona, and 7 additional translocated C. atrox (unreported distance) in the Tucson Rural Metro Fire District. Most snakes moved greater distances and more frequently after translocation, resulting in increased activity range sizes. At the protected MOCA site, there were few statistically significant negative effects of translocation, and >50% of the rattlesnakes returned to locations from which they were displaced. Nonetheless, the survival rate of translocated rattlesnakes was low. At the highly urbanized Tucson site, there were few recaptures of translocated snakes and mortality was high, mostly from human causes.

Reinert, H. K, and R. R. Rupert, Jr. 1999. Impacts of translocation on behavior and survival of timber rattlesnakes, Crotalus horridus. J. Herpetol. 33:45-61. **Translocated 11 C. horridus 8-172 km to new den area and compared to 18 resident snakes in same area. During 4-year study, 55% of translocated and 11% of resident snakes died, with 3 of 6 translocated snake mortalities occuring during hibernation. Translocated snakes selected habitats similar to those of residents, foraged successfully, and maintained body mass. However, translocated snakes exhibited 3-5 times greater movements than resident snakes in the first year, but appeared to establish more resident-like movements during the second year.

Sealy, J. 1997. Short-distance translocations of timber rattlesnakes in a North Carolina state park – A successful conservation and management program. Sonoran Herpetol. 10:94-99. **I do not have a copy of this paper.

Walker, M. L., J. A. Dorr, R. J. Benjamin, and G. R. Pisani. 2009. Successful relocation of a threatened suburban population of Timber Rattlesnakes (Crotalus horridus): combining snake ecology, politics, and education. IRCF Reptiles and Amphibians 16:211-221. **Apparently 9 rattlesnakes were fitted with radiotransmitters and translocated to a new site in Kansas “a few kilometers” from a den location to be bulldozed; however, there were two deaths, and data were reported from only five of these snakes over a two-year period (the other two snakes were not described). “The relocated snakes ranged, survived, and behaved seasonally in a fashion that mirrors undisturbed populations within 50 km.” The two females reproduced successfully.