How Far Should You Move a Nuisance Rattlesnake? At Great Basin, Inquiring Minds Want to Know

Great Basin rattlesnake. NPS photo.

When venomous snakes that endanger humans are moved elsewhere, translocation reduces survival rates. Snakes moved longer distances fare worse. At Great Basin National Park, wildlife biologists are studying translocated snakes to determine what translocation distance is “far enough.”

Venomous snakes, at least the native ones, are welcome in our national parks. But when these potentially dangerous reptiles turn up in the wrong places, such as park residential areas, campgrounds, visitors centers, busy trails and roads, and scenic overlooks, the potential for conflict often triggers intervention.

Killing a nuisance snake is not an option in a national park, so the normal procedure is to capture the snake and move it to a less problematic location. Park staff with appropriate training and experience can do this with little risk to themselves.

Unfortunately, studies have shown that translocated snakes have lower survival rates than snakes that are not moved. Distance matters, too. Snakes moved long distances – more than one kilometer (.62 miles) – have survival rates conspicuously lower than those moved shorter distances.

How far is “far enough”? Conceptually, it means a distance that is sufficient to eliminate the human-snake conflict that prompted the translocation without exposing the snake to unnecessary risk. Put into operation, it means that you stop after you reach an optimal distance because going further doesn’t make good sense.

Short distance moves of 100 meters or less are the preferred management option for rattlesnakes translocated in national parks. However, the argument for moves of this length rests mostly on anecdotal evidence or unstructured observation. Given a choice, wildlife managers would much rather base their managerial policies and practices on the results of empirical studies using scientific methods.

At Great Basin National Park, wildlife biologists are conducting such a study. The research findings will help to fine-tune current translocation guidelines for the park’s Great Basin rattlesnake (Crotalus lutosus). The Great Basin rattlesnake study is elegantly simple in design, if small in scale. Wildlife biologists had a veterinarian surgically implant temperature-sensing radio transmitters in three rattlesnakes, then released them within 100 meters of their capture sites. Each snake’s location and temperature (a key indicator of well-being) will be recorded weekly.

When scientists get good data, they try to make it serve as many useful purposes as practicable. Thus while the main goal here is put human-snake conflict reduction and associated tranlocation procedures on a more nearly scientific footing, the researchers expect the study to tell us useful things about rattlesnake natural history, movement patterns, and hibernacula (hibernation/overwintering shelters).

Postscript: And speaking of distance………. Go to this site and click on the speaker icon in the middle of the page about a third of the way down. .If you can hear this sound, you might consider putting some more distance between you and Crotalus lutosus.

Comments

Snakes moved long distances – more than one kilometer (.62 miles) – have survival rates conspicuously lower than those moved shorter distances.

Did any of the studies you read explain why the survival rates drop on longer moves? Thanks in advance.

I'm not sure what the issue is with Great Basin snakes, but I assume it's similar to problems with longer translocations of nuisance rattlers alluded to in a 2001 study Relocation of Nuisance Rattlesnakes: Problems Using Short-Distance Translocation in a Small Rural Community, which included this information:

Recent studies indicate rattlesnakes released well beyond their home range (LDT) become confused and tend to wander long distances. They apparently attempt to return to their home range where they grew up and knew their surroundings. Many snakes managed with LDT die within a year, unable to adapt to their new environment (Johnson et al. 2000 [massasaugas, Ontario], Hare and McNally 1997 [diamondbacks, Tucson], Reinert 1999 [timber rattlesnakes, Pennsylvania). Other studies indicate translocated snakes' aberrant activity patterns (Nowak 1998 [diamondback and blacktailed rattlesnakes, Montezuma Castle National Monument, Arizona], Sealy 1997 [timber rattlesnakes, North Carolina]). Our own long term studies (11 years) using radiotelemetry near Portal, Arizona, indicate blacktailed rattlesnakes know their home range intimately, seldom range out of it, and frequent the same refuges, hunting sites, and opposite sex meeting locations year after year (Hardy and Greene 1999).

I guess the bottom line here is that longer translocations leave the rattlers extremely upset, confused, and more likely to take lethaly dangerous risks while trying to find their way back to familiar habitat.

Thanks for the info, Bob. This is very interesting stuff. When I was a lookout, a massive rattle snake decided to sun on a step directly in front of the door. There were so many living in the splatter rampart the lookout was built on. I caught three and transported them to the bottom of the hill. Kinda bummed to find out this information now, though. While I'm extremely afraid of rattlers, and don't want to get bitten, I also don't want to see them die prematurely. There was an awful woodrat problem at the lookout, too, and they would urinate sticky pee all over the catwalk. Needless to say, rattlesnakes serve an important role in rodent population control.

While working in one of the densest population areas of timber rattlers in the east, we were made aware of the study noted in the above message conducted in North Carolina. We started to relocate rattlers found in visitor use areas much shorter distances. Although we did not have the time to conduct any semblance of a scientific study, it did not seem that the snakes were returning to the high visibility areas frequented by people. I would find it of interest to see a study conducted on the movement of snakes relocated and the frequency that they reappear in areas that are of concern.

Just a thought for consideration by one of those grad students looking for a research topic.