TSA 2008

 

Playing the Numbers Game: Massive Head-starting and Reintroduction of Mojave Desert Tortoises Utilizing the Reproductive Potential of Backyard Pets

 

James Juvik 1, A. Ross Kiester 2 and Kenneth Nagy 3

 

                                    1 Department of Geography-Environmental Science, University of  

                                                        Hawai`i-Hilo, HI 96720 (jjuvik@Hawaii.edu)

                                   2 Biodiversity Futures Consulting, 5550 Redtop Pl. Corvallis, OR 97333

                                                                       (rkiester@gmail.com)

 

                                                             3 Department of Ecology & Evolutionary Biology, University of 

                                         California, Los Angeles, CA 90095-1606  (kennagy@biology.ucla.edu)

 

 

Abstract

 

The potential exists for increasing the number of desert tortoises (Gopherus agassizii) being reintroduced into the California Mojave by orders of magnitude, ultimately to a level that will more than off-set continuing, anthropogenic and natural losses. This increase can be accomplished by leveraging the egg producing capabilities of the tens-of-thousands of captive desert tortoises in living Southern California backyards.  The State of California has issued more than 30,000 permits for desert tortoise possession. Due largely to disease transmission concerns, these captive tortoises can never be legally returned to the wild.  However, eggs from these privately held animals can provide a cost-effective source of disease-free hatchlings to be “head-started” to a “predator-resistant” size and released in large numbers (thousands). The ultimate aim is to reestablish wild populations in desert areas where tortoises have been recently extirpated or where they have suffered dramatic population declines.  This approach offers the potential for large-scale and long-term recovery of this threatened species. Project success will require consensus building in the tortoise conservation community (including biologists, conservationists, pet-owners, and State and Federal regulatory officials) on three key issues:

  1. Release Site Validation:  Can we develop a protocol for determining potential Mojave release sites that are environmentally suitable and compatible with landowner and management objectives?
  2. Meta-population Genetic Integrity: Can we agree on an acceptable range of genetic diversity for reintroduced tortoises?
  3. Marshalling Captive Tortoise Resources: Can the large (tens-of-thousands) and conservation-motivated, desert tortoise pet-keeping community in Southern California be organized in a way to annually provide large numbers of tortoise eggs and volunteer support for a large-scale and long-term egg donation and head-starting program?