Evaluating body condition of striped skunks using non-invasive morphometric indices and bioelectrical impedance analysis

Assessment of the body composition and body condition of animals in the wild is an important aspect of animal ecology. We were interested in understanding the seasonal changes in body condition in order to investigate the effects of adaptive strategies on life histories of animals. We investigated the merit of morphometric condition indices and bioelectrical impedance analysis (BIA) to predict fat reserves in striped skunks (Mephitis mephitis, n = 26). We took BIA and morphometric measurements following chemical immobilization in the field and completed chemical analyses of whole carcasses postmortem. We determined relationships between body lipid and water using multiple linear regression techniques and performed model selection using Akaike's Information Criterion (AIC). Bioelectric volume (L2/Rs) and chest circumference (CC) best predicted total body water (TBW = −1.1 + 0.058*CC + 0.25 * L2/Rs; r2 = 0.91, SEE = 0.15, P < 0.001). Lean dry mass (LDM) was significantly correlated with total body mass (LDM = 0.26 + 0.12 * TBM; r2 = 0.63, SEE = 0.13, P < 0.001). Total body fat (TBF) can then be estimated using total body water and lean dry mass by the equation TBF = TBM-TBW–LDM. We found condition indices to be poor indicators of body condition in striped skunks. Use of BIA on striped skunks has implications for a fast and accurate method to estimate body condition under field conditions.