Beyond the burrow: Body condition and sex influence exploratory behavior in desert kangaroo rats (Dipodomys deserti)

Behavioral variation within a population can be influenced by physical factors such as size, sex, and body condition. This variation may contribute to intraspecific niche breadth by enabling individuals to exploit different niches. To examine how anatomy shapes behavior, we conducted open field tests on desert kangaroo rats (Dipodomys deserti, n=16) and compared their activity to sex, morphology, and body condition. We constructed an arena within the species' natural habitat to simulate ecologically relevant conditions and recorded behavior over 15 min. We quantified speed and distance traveled, used principal component analysis to explore behavioral patterns, and used linear models to test for associations between behavior, locomotor traits, and anatomical variables. We found that individuals with lower body condition scores spent more time exploring, males were more exploratory than females, and individuals with longer feet - a proxy for skeletal size - traveled further. However, behavior and locomotor performance were not significantly correlated. Lastly, individuals moved faster and farther on full moon nights compared to new moon nights, indicating that moonlight influences movement strategy - potentially reflecting trade-offs between foraging and predation risk. These findings highlight species-specific drivers of behavioral variation and underscore the importance of understanding behavioral variability of desert mammals.