Effects of Relocation on the Movement, Home range size, and survival of eastern box turtles (Terrapene carolina)

Joy M. Hester, Steven J. Price, and Michael E. Dorcas
Above: One of the turtles with her transmitter and Ibutton (records temperature data)

Good background information

Box turtle populations are threatened by factors associated with urbanization such as construction, roads, railroad tracks, pets, and people. Relocating box turtles to a less threatening environment is one possible conservation strategy that could be used to address this problem. Box turtles are relocated by companies or other groups that wish to develop their habitat, as well as by well meaning individuals that find turtles in their yards or in roads.

Even though removing a box turtle from danger appears to be a good idea, box turtles relocation has not previously been successful due to the turtles' homing instinct that causes them to return to their established home range when displaced (Dodd, 2002). Therefore, the true effectiveness of box turtle relocation remains unknown. To study the effects of relocation on box turtles, we are using radio telemetry to determine the movement, home range size, and survival of resident and relocated box turtles. Hopefully, this information will allow us to assess the success of relocation as a conservation method.

Radiotransmitters and ibuttons (which record temperature every thirty minutes) have been attached to 10 relocated turtles and 10 resident (from the Ecological Preserve) turtles, all of which were released and re-released onto the Davidson Ecological Preserve. All turtles are radiotracked twice weekly and location and habitat selection are recorded.

The Abstract (the official summary)

HESTER, JOY M., STEVEN J. PRICE AND MICHAEL E. DORCAS. Davidson College – Effects of relocation on movements and home ranges of eastern box turtles (Terrapene carolina). Eastern box turtle (Terrapene carolina) populations are threatened by expanding urbanization, the resulting loss of habitat, and the introduction of threats such as roads, railroads, and pets. Individual box turtles are often captured by humans and relocated substantial distances from their capture location. Additionally, relocating populations of box turtles to a less threatening environment has been suggested as a possible conservation strategy. However, previous studies examining the effects of relocation on box turtles are limited. Thus, we used radio-telemetry to compare the home ranges and movement patterns of resident and relocated box turtles. We tracked ten relocated and ten resident female box turtles on the Davidson College Ecological Preserve, in Davidson, NC, twice weekly beginning in May 2004. Geographic coordinates were recorded during each tracking session. Results suggest that the majority of relocated box turtles have larger home ranges and move longer distances than resident box turtles. Additionally, relocated turtles had higher mortality and disappearance rates than resident turtles. Our preliminary results indicate that relocated box turtles do not quickly reestablish home ranges in a new habitat, and may attempt to leave their relocation site, thus, raising questions about the success of relocation as a conservation strategy for eastern box turtles.

What we have found so far....

So far it has been very difficult to determine how the turtles are being affected by relocation. Several of the relocated turtles have traveled fairly large distances, but we will be able to give you a better idea of how the turtles are responding after we finish collecting data in May, 2005.

Sample Data:

Figure 1 A and B: Examples of 50 and 95% probability kernel home range for a resident (A) and a relocated (B) box turtle, as calculated by the GIS. The dark green represents the 95% probability and the light green represents the 50% probability. Note that pictures are at the same scale.
Figure 2 A and B: Examples of movement vectors for a resident (A) and a relocated (B) box turtle, as calculated by the GIS. The yellow arrows represent the direction of the turtle’s movement between each tracking episode. Note that images are at a different scale. Box on B indicates scale of A.

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Email me with questions or comments @ johester@davidson.edu until May15, 2005

Updated on January 25, 2005

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