San Diego Management & Monitoring Program


Spatial ecology, habitat use, and survivorship of resident and translocated Red Diamond Rattlesnakes (Crotalus ruber)

Type: journal article

Article abstract: Red Diamond Rattlesnakes (Crotalus ruber) have a very restricted range in the United States and are considered a species of special concern in California. Over a five year period (1999-2004), we used radio-telemetry to collect data on the movement ecology and habitat use of this little-studied species on protected coastal sage scrub land managed by the San Diego Zoo’s Wild Animal Park. During the study we compared the movement patterns and survivorship of “Resident” snakes (N=11; 11,090 radio-days) to several C. ruber relocated by Park staff for safety purposes (“Relocates”; N=6; 3,858 radio-days). Among Resident snakes, activity range sizes varied greatly both between individuals, and between years within individuals. Male Resident activity ranges (minimum convex polygon) were typically triple the size of Resident females (2.80 ha vs. 0.88 non-gravid females or 0.76 ha gravid females), and Resident males moved nearly twice as far during an activity season (1.38 km, Resident males vs. 0.77 km, Resident females). Overall, Resident C. ruber have relatively restricted movements when compared to other similar-sized rattlesnakes, typically never occurring more than 300 m linear distance from their winter dens. Relocates used significantly more land (mean activity range size 5.86 ha), and had greater maximum per move distances and total distances traveled during the first year after relocation than did Residents for the same time period. Activity range sizes, annual distances moved, and mean movement speed decreased over time among short distance Relocates (n=3; translocated 97 to 314 m), yet was similar or increased among long distance Relocates (n=3; translocated 856 to 1090 m). Only short distance Relocates were found near (within 50 m) their original capture site at some point during the study (30 to 364 d). Unlike most previous studies of relocated rattlesnakes, there was no detectable difference in survivorship between Residents and Relocates. If translocation is necessary for nuisance rattlesnakes, we suggest only short-distance relocations; long-distance translocations may be a potential conservation tool for future repatriations of C. ruber. We highly recommend more education and public outreach to minimize the need for snake removal.

Authors: Brown, Tracey ; Lemm, Jeffrey; Montagne, J.P.; Tracey, Jeff; Alberts, Allison;

Journal title: The Biology of the Rattlesnakes

Year: 2008

Species: Red Diamond Rattlesnake

Vegetation communities: coastal sage scrub; chaparral