The data comprise 409 observations of ∆15N and ∆13C TDFs derived from controlled feeding trials on 26 bird and 27 mammal species. Explanatory variables that can be included in creating the predictive model are detailed in Table 1. Species taxonomic names follow those used in the Bininda-Emonds et al. (2007) and Jetz et al. (2012) phylogenies. Habitat was defined as either marine or terrestrial based on typical foraging habitat. Sampling tissues were reduced into categories that reflect the metabolic pathway and expected turnover of the tissue. For example, fur and whiskers were all defined under the heading of hair. Diet type is defined as either herbivore, carnivore, omnivore and pellet diets
