Literaturdatenbank
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Bridges, A., & Bateman, H. L. , Habitat selection by juvenile sonoran desert tortoises (gopherus morafkai) in central arizona - abstract. Unpublished paper presented at Program and Abstracts of the Tenth Annual Symposium on the Conservation and Biology of Tortoises and Freshwater Turtles.
Added by: Admin (06 Jan 2014 18:22:40 UTC) |
| Resource type: Conference Paper BibTeX citation key: Bridges2012 View all bibliographic details  |
Categories: General Keywords: Habitat - habitat, Nordamerika - North America, Schildkröten - turtles + tortoises Creators: Bateman, Bridges Collection: Program and Abstracts of the Tenth Annual Symposium on the Conservation and Biology of Tortoises and Freshwater Turtles |
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| Abstract |
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Testudinidae Geographically separate populations of the Sonoran Desert Tortoise (Gopherus morafkai) can be found in varying habitat in Arizona, and studies differ in their explanations of the most significant habitat factors. Some studies report canopy cover as the parameter of highest importance; others list steep slopes with extensive outcrops and boulders, or slope and aspect as the main indicators of tortoise occupancy. Additionally, few studies focus on juvenile (<180 mm MCL) tortoise habitat selection. The need for both population-specific studies and age class-specific studies is needed to ensure a full understanding of the needs of the species throughout their range in Arizona. This study analyzes habitat selection of juvenile tortoises at the Sugarloaf Mountain site northeast of Phoenix. Eleven juvenile tortoises were followed using radio telemetry for 4 to 21consecutive months, and minimum convex polygons were created to describe each tortoise’s home range. Available habitat at the site was determined by creating a larger polygon, inclusive of all tortoises’ home ranges plus a 150 m buffer. Up to ten locations for each tortoise during the months of greatest activity (July - September, n ≤ 106) and one location for each tortoise during the months of little or no activity (December - February, n ≥ 11) were randomly chosen and 13 habitat variables measured at each location. These measures were repeated at an equal number of sites randomly generated within the available habitat for a total of 117 tortoise locations and 117 random locations. Preliminary analyses indicate a preference for moderate slopes, high shelter density, abundance of annual vegetation and canopy cover, and close proximity to boulders with no difference in selection between seasons. The addition of population-level characteristics from this site to the body of species-level research in Arizona will increase effective management for this species, which is listed as a Species of Greatest Conservation Need by the Arizona Game and Fish Department and a candidate under the Endangered Species Act, in part due to threats of habitat fragmentation and destruction from recreational land use and development.
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