Twenty-Third Annual Meeting and Symposium of the
Desert Tortoise Council, April 3-5, 1998
Abstracts

Studies in which desert tortoises are handled often result in the side effect of some tortoises voiding their bladders during processing. Water loss could result in serious health threats or compromise normal physiology, especially during the hot, dry summer months. I examined recapture and growth data for tortoises that voided and did not void their bladders when handled during annual surveys (1990-94) of three populations in Arizona. Proportions of tortoises that voided their bladders ranged from 0-38% and 20-100% among populations and years for individuals >180 mm and <180 mm MCL, respectively. Recapture rates of tortoises <180 mm from one year to the next (a measure of combined capture probability and survivorship) were only different (P<0.05) between the two groups in one out of 11 yearly tests among the three populations. However, the pooled data for tortoises <180 mm from one population indicated that those tortoises that voided in one year were less likely to be recaptured in the subsequent year (P<0.025). Recapture rates of tortoises >180 mm were not different between groups in 12 yearly tests (P>0.10) or for the pooled data for each population (P>0.05). Analysis of covariance (with carapace length and estimated volume of water lost during handling as covariates) indicated that volume of water lost did not affect tortoise growth between 1990 and 1994 (P=0.116). Observed effects of water loss on capturability/survivorship, as well as other potential effects, indicate that handling should be minimized as much as possible to prevent tortoises from voiding their bladders.