Home Range and the Influence of Shade Sources on the Movement Patterns of Ornate Box Turtles (Terrapene ornata ornata)
Home-range areas and daily movement patterns have been shown to scale with sex, body size, and metabolic rates but they also vary with extrinsic variables such as food availability and population density. In ectothermic animals, many of their key physiological functions (such as metabolic rate) are dependent upon environmental temperatures. For ectotherms, opportunities for behavioral thermoregulation, such as basking sites and cool dens, may be key determinants of activity. To our knowledge the impact of thermoregulation on home-range size has not been determined. To address this, 27 ornate box turtles (Terrapene ornata ornata) were located daily during their annual period of activity (May-August). Food and shade sources within 1m2 of the turtle were recorded at each location. The home-range areas ranged from 1 to 53 ha; a 50 fold difference. Home-range areas did not scale with body size or differ by sex. Instead, a turtle's home-range area was negatively correlated with the average number of shelter producing sources (primarily Yucca gluaca and Artemisia tridentata) per location. Surprisingly, the home-range area was positively correlated with the average number of food sources (primarily Opuntia macrorhiza and Tradescantia occidentalis) per location. Furthermore, the average number of shade sources and food sources was negatively correlated suggesting that turtles may be faced with a trade-off between time spent thermoregulating or foraging.