Scope and Method of Study: This study investigated the potential tradeoffs between maternal bone density and the investment of calcium into offspring in the Texas tortoise ( Gopherus berlandieri ) and red-eared slider ( Trachemys scripta ). Specifically, this study examined the effects of season, sex, and age on bone density and plasma biochemicals associated with calcium physiology. Additionally, this study investigated the efficacy of dual-energy x-ray absorptiometry as a tool in the prediction of body composition in turtles.

Findings and Conclusions: Findings from this study suggest seasonal changes in calcium physiology that are associated with reproduction in female G. berlandieri . These physiological changes might have important implications for the maintenance of maternal bone density in this species. In the case of T. scripta , I did not document any reproductive influences on calcium physiology or bone density due solely to the production of the egg. This disparity is likely due to differing maternal investment of calcium between G. berlandieri and T. scripta . Additionally, I found that dual-energy x-ray absorptiometry is an effective predictor of bone mass in turtles.