Using Scat to Estimate Body Size in Crocodilians: Case Studies of the Siamese Crocodile and American Alligator with Practical Applications

摘要

Models relating morphological measures to body size are of great value in crocodilian research and management. Although scat morphometrics are widely used for estimating the body size of large mammals, these relationships have not been determined for any crocodilian. To this end, we collected scats from Siamese Crocodiles (Crocodylus siamensis) and American Alligators (Alligator mississippiensis) to determine if maximum scat diameter (MSD) could be used to predict total length (TL) in these species. We obtained scats from 19 and 22 C. siamensis and A. mississippiensis, respectively, and evaluated the relationship between MSD and TL using logarithmic regression models. We found significant positive relationships between MSD and TL for both species. We attribute this relationship to anatomical constraints imposed on MSD by pelvic aperture width, which in turn correlates to body size. We found the MSD-TL relationship is similar for C. siamensis and A. mississippiensis. Our models can be used to increase precision of body size estimates in scat-based population surveys and dietary studies, and estimate the body size of nesting females.