Twenty-Fourth Annual Meeting and Symposium of the Desert Tortoise Council, March 5-8, 1999
Abstracts

Concerns about the demise of wild Central Asian tortoises (T. horsfieldi) have prompted studies of T. horsfieldi demographics and resource requirements in the Kyzylkum Desert (Bukhara Ecocentre, Uzbekistan). For part of these studies, we x-rayed 14 female T. horsfieldi (midline carapace length: 150 to 174 mm) weekly, from May 1 to June 14, 1998, to measure their reproductive output. The apparently high clutch sizes and clutch frequencies that we measured (up to 5 eggs and 3 clutches, respectively) may have been due to the high plant productivity in Spring 1998, but little is known about the reproductive output of wild T. horsfieldi. The average (± SD, range) clutch frequency and annual egg production (AEP, eggs produced per female) equaled 2.29 (± 0.47, 2 to 3) and 5.79 (± 1.63, 3 to 9 eggs), respectively. As for Gopherus agassizii, AEP was correlated to female size (midline carapace length: r2 = 0.414; body mass: P = 0.650), potentially influencing the impacts of poaching and conservation efforts. Also, female nutrient reserves and the ability to acquire nutrients for egg production may be size dependent. Measuring reproductive output, body condition and spring forage under a variety of conditions will help determine the relative importance of nutrient reserves and spring forage conditions to the reproductive output of T. horsfieldi. Field metabolism and water flux measurements made in conjunction with our x-ray analyses will help in assessing the importance of female reproductive output to the overall nutrient requirements of female T. horsfieldi.