Abstract

The foods consumed by animals reflect their adaptations and ecological roles, which makes diet an important trait for ecological, evolutionary, and paleobiological research. Rodents are the most species-rich order of mammals and are also ecologically diverse, consuming a wide range of foods. To relate form with function, and to study diversification in the context of diet and feeding, researchers should follow classification schemes that capture diet composition. We evaluated existing diet datasets for mammals as well as previous classification schemes developed for rodents. To propose a suitable categorical scheme, we defined splits within plant-eating and animal-eating rodents, aiming to capture the intrinsic differences in diet composition in terms of the accessibility, nutrient content, and digestibility of various food items. Our proposal includes eight categories (Carnivore, Folivore, Frugivore, Granivore, Omnivore, Specialist Herbivore, Unknown, and Vermivore) in which species can be assigned with information from species accounts and field guides. To avoid ambiguity, we provide examples and detailed criteria for each diet category. For biologically tractable comparative research, we ask researchers to use our diet categories for rodent species. The categories can also be applied at other taxonomic levels or to different populations, sexes, or ontogenetic stages. We call for further study of the natural history of small mammals and the uptake of primary data into open databases.