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Assessing Nutritional Parameters of Brown Bear Diets among Ecosystems Gives Insight into Differences among Populations.

López-Alfaro C, Coogan SC, Robbins CT, Fortin JK, Nielsen SE - PLoS ONE (2015)

Bottom Line: Food habit studies are among the first steps used to understand wildlife-habitat relationships.However, a recent decrease in consumption of trout (Oncorhynchus clarki), whitebark pine nuts (Pinus albicaulis), and ungulates, particularly elk (Cervus elaphus), in GYE bears has decreased the energy and protein content of their diet.The patterns observed suggest that bear body size and population densities are influenced by seasonal availability of protein an energy, likely due in part to nutritional influences on mass gain and reproductive success.

View Article: PubMed Central - PubMed

Affiliation: Department of Renewable Resources, University of Alberta, 751 GSB, Edmonton, T6G 2H1, AB, Canada; Departamento de Ciencias Ambientales y Recursos Naturales Renovables, Universidad de Chile, Av. Santa Rosa, 11315, Casilla 9206, Santiago Chile.

ABSTRACT
Food habit studies are among the first steps used to understand wildlife-habitat relationships. However, these studies are in themselves insufficient to understand differences in population productivity and life histories, because they do not provide a direct measure of the energetic value or nutritional composition of the complete diet. Here, we developed a dynamic model integrating food habits and nutritional information to assess nutritional parameters of brown bear (Ursus arctos) diets among three interior ecosystems of North America. Specifically, we estimate the average amount of digestible energy and protein (per kilogram fresh diet) content in the diet and across the active season by bears living in western Alberta, the Flathead River (FR) drainage of southeast British Columbia, and the Greater Yellowstone Ecosystem (GYE). As well, we estimate the proportion of energy and protein in the diet contributed by different food items, thereby highlighting important food resources in each ecosystem. Bear diets in Alberta had the lowest levels of digestible protein and energy through all seasons, which might help explain the low reproductive rates of this population. The FR diet had protein levels similar to the recent male diet in the GYE during spring, but energy levels were lower during late summer and fall. Historic and recent diets in GYE had the most energy and protein, which is consistent with their larger body sizes and higher population productivity. However, a recent decrease in consumption of trout (Oncorhynchus clarki), whitebark pine nuts (Pinus albicaulis), and ungulates, particularly elk (Cervus elaphus), in GYE bears has decreased the energy and protein content of their diet. The patterns observed suggest that bear body size and population densities are influenced by seasonal availability of protein an energy, likely due in part to nutritional influences on mass gain and reproductive success.

No MeSH data available.


Related in: MedlinePlus

Energy contribution from terrestrial meat on bear diets under different CFs for ungulates and proportion of ungulates on the diet.We simulated four diets composed of ungulates and four other common food items: green vegetation; roots; fruit; and pine nuts. Red lines show the energy contribution from ungulates for a diet with 50% of ungulates and 50% of a) green vegetation; b) roots; c) fruit or d) pine nuts.
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pone.0128088.g005: Energy contribution from terrestrial meat on bear diets under different CFs for ungulates and proportion of ungulates on the diet.We simulated four diets composed of ungulates and four other common food items: green vegetation; roots; fruit; and pine nuts. Red lines show the energy contribution from ungulates for a diet with 50% of ungulates and 50% of a) green vegetation; b) roots; c) fruit or d) pine nuts.

Mentions: As expected, the energy contribution from ungulates increased as the CFungulate and proportion of ungulates in the diet increased. This energy increase followed a logarithmic growth shape in most scenarios depending on the CFungulate used and the nutritional characteristics of other food items (Fig 5). When CFungulate was <6, the differences in energy contribution were higher, suggesting that using CFungulate for terrestrial meat below this threshold will have a stronger impact on dietary estimates (Fig 5).


Assessing Nutritional Parameters of Brown Bear Diets among Ecosystems Gives Insight into Differences among Populations.

López-Alfaro C, Coogan SC, Robbins CT, Fortin JK, Nielsen SE - PLoS ONE (2015)

Energy contribution from terrestrial meat on bear diets under different CFs for ungulates and proportion of ungulates on the diet.We simulated four diets composed of ungulates and four other common food items: green vegetation; roots; fruit; and pine nuts. Red lines show the energy contribution from ungulates for a diet with 50% of ungulates and 50% of a) green vegetation; b) roots; c) fruit or d) pine nuts.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4470632&req=5

pone.0128088.g005: Energy contribution from terrestrial meat on bear diets under different CFs for ungulates and proportion of ungulates on the diet.We simulated four diets composed of ungulates and four other common food items: green vegetation; roots; fruit; and pine nuts. Red lines show the energy contribution from ungulates for a diet with 50% of ungulates and 50% of a) green vegetation; b) roots; c) fruit or d) pine nuts.
Mentions: As expected, the energy contribution from ungulates increased as the CFungulate and proportion of ungulates in the diet increased. This energy increase followed a logarithmic growth shape in most scenarios depending on the CFungulate used and the nutritional characteristics of other food items (Fig 5). When CFungulate was <6, the differences in energy contribution were higher, suggesting that using CFungulate for terrestrial meat below this threshold will have a stronger impact on dietary estimates (Fig 5).

Bottom Line: Food habit studies are among the first steps used to understand wildlife-habitat relationships.However, a recent decrease in consumption of trout (Oncorhynchus clarki), whitebark pine nuts (Pinus albicaulis), and ungulates, particularly elk (Cervus elaphus), in GYE bears has decreased the energy and protein content of their diet.The patterns observed suggest that bear body size and population densities are influenced by seasonal availability of protein an energy, likely due in part to nutritional influences on mass gain and reproductive success.

View Article: PubMed Central - PubMed

Affiliation: Department of Renewable Resources, University of Alberta, 751 GSB, Edmonton, T6G 2H1, AB, Canada; Departamento de Ciencias Ambientales y Recursos Naturales Renovables, Universidad de Chile, Av. Santa Rosa, 11315, Casilla 9206, Santiago Chile.

ABSTRACT
Food habit studies are among the first steps used to understand wildlife-habitat relationships. However, these studies are in themselves insufficient to understand differences in population productivity and life histories, because they do not provide a direct measure of the energetic value or nutritional composition of the complete diet. Here, we developed a dynamic model integrating food habits and nutritional information to assess nutritional parameters of brown bear (Ursus arctos) diets among three interior ecosystems of North America. Specifically, we estimate the average amount of digestible energy and protein (per kilogram fresh diet) content in the diet and across the active season by bears living in western Alberta, the Flathead River (FR) drainage of southeast British Columbia, and the Greater Yellowstone Ecosystem (GYE). As well, we estimate the proportion of energy and protein in the diet contributed by different food items, thereby highlighting important food resources in each ecosystem. Bear diets in Alberta had the lowest levels of digestible protein and energy through all seasons, which might help explain the low reproductive rates of this population. The FR diet had protein levels similar to the recent male diet in the GYE during spring, but energy levels were lower during late summer and fall. Historic and recent diets in GYE had the most energy and protein, which is consistent with their larger body sizes and higher population productivity. However, a recent decrease in consumption of trout (Oncorhynchus clarki), whitebark pine nuts (Pinus albicaulis), and ungulates, particularly elk (Cervus elaphus), in GYE bears has decreased the energy and protein content of their diet. The patterns observed suggest that bear body size and population densities are influenced by seasonal availability of protein an energy, likely due in part to nutritional influences on mass gain and reproductive success.

No MeSH data available.


Related in: MedlinePlus