Effect of Supplemental Heat in Captive African Leopard Tortoises (Stigmochelys pardalis) and Spurred Tortoises (CENTROCHELYS sulcata) on Growth Rate and Carapacial Scute Pyramiding

Carapacial scute pyramiding (CSP) is common in captive-raised turtles and tortoises. Several dietary and environmental hypotheses have been proposed to explain this phenomenon, but few have been scientifically investigated. The effect of increased heat exposure on CSP and growth was examined in juvenile African leopard (Stigmochelys pardalis) and spurred (Centrochelys sulcata) tortoises. Monthly measurements of individual tortoise surface temperature, length, height, width, weight, and pyramid height of treatment (heat) and control (no heat) groups for 2 years were higher in the treatment groups. Allometric comparison further revealed increased pyramiding in the treatment group. Humidity and diet did not differ between treatment and control groups. The results of this research investigation indicate that growth rate and CSP appear to be directly related and both increase with excess nocturnal heat. The significance of the atypical carapace growth and subsequent consequences for naturally occurring tortoise populations, especially in the context of global climate change, is unknown but requires further investigation.