Effects of air temperature on habitat selection and activity patterns of two tropical imperfect homeotherms

In this study, we aimed to evaluate how air temperature is related to variation in activity patterns and habitat selection by two species of tropical armadillos, which are imperfect homeotherms. Although their behaviour is little studied, armadillos provide valuable models for understanding how physiology affects mammalian behaviour in response to environmental changes. We used GPS devices to track yellow armadillos, Euphractus sexcinctus, and southern three-banded armadillos, Tolypeutes matacus, at three sites of the Pantanal wetlands, Brazil. We used linear mixed-effects models to evaluate the variation in the timing and duration of activity patterns according to changes in air temperature. We fitted step selection functions to evaluate the effects of cover type, diel cycle and air temperature on armadillo habitat selection. Our models suggest that E. sexcinctus activity during the daytime decreases as air temperature increases. In contrast, T. matacus shows less variation, maintaining a predominantly nocturnal activity pattern. However, as air temperature decreases, activity periods of T. matacus are of shorter duration and peak earlier in the day. Both species should select forested areas when experiencing air temperatures outside their thermoneutral zones, as these areas act as thermal shelters. This study provides specific examples of the dynamic nature of activity patterns and habitat selection, and illustrates how thermal constraints, which vary dynamically over the daily cycle and among days, can alter behaviour. Our results highlight the importance of habitat heterogeneity for the long-term conservation of animal species that rely on behaviour to achieve adequate thermoregulation.