Patterns of behavior in the Texas tortoise, Gopherus berlandieri: a multivariate ordination approach

Abstract

We compared the distribution of 19 categories of behavior exhibited by 47 adult Texas tortoises (Gopherus berlandieri) over 3 years with the use of detrended correspondence analysis (DCA) and canonical correspondence analysis (CCA). DCA revealed a gradient from passive to active behavior along axis 1. Tortoises were more active in 1994 and less active in 1996. This pattern was likely due to the extremely hot and dry conditions in 1996. Year was the most significant variable explaining variability in behavior when sex, age, size, year, and grazing treatment (pastures grazed versus ungrazed by cattle) were used as environmental variables in CCA. Age, size, and grazing treatment were not significant variables in CCA. Tortoises used proportionally more burrows, shallow surface depressions termed pallets, and cavity pallets, and ate more cactus in 1996. More foraging and active behaviors, like courtship, were observed in 1994. Sex was a significant variable in explaining behavioral variability after the effects of year were controlled for. Males tended to exhibit more active behaviors than females. Our analyses suggested that the grazing regime used in Chaparral Wildlife Management Area did not affect the patterns of behavior exhibited by this protected tortoise.