Foods and nutritional components of diets of black bear in Rocky Mountain National Park, Colorado

Abstract

We used scat analysis to determine diets and relative nutritional values of diets for black bears (Ursus americanus Pallas, 1780) in Rocky Mountain National Park, Colorado, from 2003 to 2006, and compared foods consumed and nutritional components to identify important sources of fecal gross energy (GE), crude fat (CF), and fecal nitrogen (FN) in annual and seasonal diets. Patterns of use of food classes followed typical seasonal patterns for bears, although use of animal matter was among the highest reported (>49% annually). Use of animal matter increased after spring, although crude protein levels in bear diets were always >25%. GE was typically lowest for grasses and other herbaceous plants and highest for ants and ungulates; FN was strongly positively related to most animal sources, but negatively correlated with vegetative matter; and CF showed the strongest positive relationship with ungulates and berries, with the latter likely influenced by the presence of seeds. Compared with historic data (1984)(1985)(1986)(1987)(1988)(1989)(1990)(1991), contemporary diets included substantially greater prevalence of anthropogenic foods, which likely contributed to increases in size, condition, and productivity of the contemporary bear population. Management strategies are needed to increase quantity and quality of natural foods while minimizing dependence on anthropogenic sources. Résumé: Une analyse des fèces nous a servi à déterminer le régime alimentaire et la valeur nutritionnelle relative de ce régime chez des ours noirs (Ursus americanus Pallas, 1780) dans le parc national des Montagnes Rocheuses, Colorado, de 2003 à 2006; nous avons comparé les aliments consommés et les composantes nutritives afin d'identifier les sources importantes d'énergie fécale brute (GE), de lipides bruts (CF) et d'azote fécal (FN) dans les régimes alimentaires annuels et saisonniers. Les patrons d'utilisation des diverses classes d'aliments suivent les patrons saisonniers typiques des ours, bien que le taux d'utilisation de matière animale soit parmi les plus élevés (>49 % sur une base annuelle) jamais observés. L'utilisation de matière animale augmente après le printemps bien que les concentrations brutes de protéines soient toujours >25 %. Les valeurs de GE sont typiquement minimales pour les herbes et les autres plantes herbacées et maximales pour les fourmis et les ongulés; il y a une forte corrélation positive entre FN et la plupart des sources alimentaires animales et une corrélation négative avec la matière végétale; la plus forte relation positive existe entre CF et les ongulés et les baies, dans ce dernier cas vraisemblablement influencée par la présence de graines. Par comparaison aux données du passé (1984)(1985)(1986)(1987)(1988)(1989)(1990)(1991), les régimes alimentaires actuels comprennent une fréquence nettement plus élevée d'aliments d'origine humaine, ce qui contribue vraisemblablement à l'augmentation de la taille, de la condition et de la productivité de la population présente d'ours. Il faudrait établir des stratégies...

Using stable isotopes to assess dietary changes of American black bears from 1980 to 2001

“…Baldwin and Bender [51] found similar results through fecal nitrogen analysis and showed that black bears increased consumption of ants seasonally when berries and grasses were not available. This increase in fecal nitrogen [51] and δ 15 N stable isotope values (this study) could be due to a shift in increased consumption of animal matter (i.e.…”

Estimating population size and density of a low-density population of black bears in Rocky Mountain National Park, Colorado

“…For example, bears were observed more frequently at sites with a greater proportion of Table 3 (Baldwin 2008), with ants constituting the greatest volume of any food source consumed by bears in RMNP (Baldwin and Bender 2009a). Similarly, lodgepole pine was related to historic bear use in RMNP (1984RMNP ( -1991 L. Zeigenfuss, unpublished report).…”

Black Bears (Ursus Americanus) as Possible Vectors of Bi-directional Nutrient Transfer in Marine and Terrestrial Systems Inferred from their Late Summer Diets

“…If we consider that consuming Zostera spp. typically provides bears with relatively little energy compared to consuming animals (Baldwin and Bender, 2009), the presence of Zostera spp. in 36.36% of scats may also be due to incidental ingestion as bears forage for amphipods.…”

“…Scats are incredibly valuable resources for study that can allow researchers to gain insight into the diet, movement and range of animals (Darimont et al, 2008). Analysis of scats involves identifying food items and relating these items to diet through frequency and volume calculations (Baldwin and Bender, 2009), and inferring the diet of the animal based on faecal residue.…”

“…animal matter is more digestible than graminoids; Hewitt and Robbins, 1996), which could lead to under-or overestimations of dietary items. Knowledge of the EDC is pertinent when estimating nutrient transfer from forest to beach and vice-versa, as some nitrogenous compounds obtained from ingestion of marine resources may be expelled in urine (Hellgren, 1995) and would not be accounted for in FV calculations. The CFs used in this study were: We did not include gravel and rocks in EDC calculations as they are assumed to have been inadvertently ingested during foraging and do not contribute to any bi-directional nutrient transfer, nor provide any energy to the bears.…”