What they do in the shadows : stable isotope analysis reveal that spatial and temporal heterogeneity explain dietary niche variation in Myotis lucifugus in Newfoundland

Abstract

Individuals must balance competitive and environmental pressures with obtaining the nutrients necessary to survive and reproduce. The goal of this project was to infer on individual dietary adaptations of adult female Myotis lucifugus from a maternity group. Therefore, I conducted stable isotope analysis on feces (n = 127), arthropods (n = 110), and hair (n = 120) collected from known individuals across two timescales (feces sampled May-August 2017; hair sampled 2012-2017). I used a Bayesian mixing model (MixSIAR) and an information-theoretic approach to determine models that best explained variation in isotopic niche. Isotopic niche variation across both timescales was strongly explained by spatial and temporal heterogeneity, with little explanatory power provided by inter-individual or reproductive group heterogeneity. Diets of individual bats were opportunistic, with strong dependence on the most abundant prey groups, although diets of most individuals contained a limited amount of all prey groups.