Data for: Ingredient and nutrient composition of brown bear diets
Cite this dataset
De Cuyper, Annelies (2023). Data for: Ingredient and nutrient composition of brown bear diets [Dataset]. Dryad. https://doi.org/10.5061/dryad.dbrv15f64
Abstract
The dietary nutrient profile has metabolic significance and possibly contributes to species’ foraging behavior. The brown bear (Ursus arctos) was used as a model species for which dietary ingredient and nutrient concentrations as well as nutrient ratios were determined annually, seasonally and per reproductive class. Brown bears had a vertebrate- and ant-dominated diet in spring and early summer and a berry-dominated diet in fall, which translated into protein-rich and carbohydrate-rich diets, respectively. Fiber concentrations appeared constant over time and averaged at 25 % of dry matter intake. Dietary ingredient proportions differed between reproductive classes; however, these differences did not translate into a difference in dietary nutrient concentrations, suggesting that bears manage to maintain similar nutrient profiles with selection of different ingredients. In terms of nutrient ratios, the dietary protein to non-protein ratio, considered optimal at around 0.2 (on metabolizable energy basis), averaged around 0.2 in this study in fall and around 0.8 in spring and summer. We introduced the minimal non-fat to fat ratio necessary for efficient maintenance metabolism. This ratio varied across seasons but never fell beneath the theoretically estimated minimum to ensure metabolic efficiency. This population thus managed to ingest diets that never exerted a lack of glucogenic substrate, suggesting that metabolic efficiency may either be a driver of active diet selection or that natural resources available to bears did not constitute a constraint in this respect. Given the considerable proportion of fiber in the diet of brown bears, the relevance of this nutrient and its role in foraging behavior might be underestimated.
Methods
Datapoints (fecal samples from GPS-tracked brown bears) were collected by the Scandinavian Brown Bear Research Project (this study: years 2015 to 2018). The estimated dietary content (EDC; ingredient composition of the 'ingested' diet) was calculated from fecal dietary remains (but see Hewitt and Robbins (1996)) for every fecal sample. The associated nutrient composition was calculated via a collection of literature data on nutrient composition of different dietary ingredients. The raw data on ingredient and nutrient composition of the brown bear diet were used to evaluate the annual and seasonal diet composition as well as the diet compostion per reproductive class. Nutrient ratio's were also calculated.
Funding
Ghent University, Award: IOP031