Fig 1.
The study area centered on Grand Teton National Park, Wyoming, USA, as defined by the spatial extent of all site visits during 2004–2006.
Colored areas depict locations of site visits by species: grizzly bear (yellow); sympatric black bear (blue); and allopatric black bear (pink).
Table 1.
Scat correction factors and food-specific energy values applied to food items identified in scats or from observation of feeding sign at site visits of grizzly and black bear locations, Grand Teton National Park and vicinity, Wyoming, USA, 2004–2006.
Total energy was calculated as the mean of individual foods identified to genus or higher taxonomic group (e.g., Formicidae [S1 Table]).
Table 2.
Body mass range (kg) and sample size (bear-days) for sex and species categories of bears monitored to estimate daily diets, Grand Teton National Park, Wyoming, USA, 2004–2006.
Fig 2.
Scatter plots of the first two principal components (PC) constructed from daily diets of grizzly and black bears, Grand Teton National Park and vicinity, Wyoming, USA, 2004–2006.
Top graph illustrates active variables, which were the daily percentages of total energy obtained from 7 food types (e.g., above-ground vegetation [AGVEG], below-ground vegetations [BGVEG]). Bottom graph illustrates supplementary variables of species (grizzly, sympatric black [black-S], allopatric black [black-A]), sex, and season (spring [1 May–30 Jun], summer [1 Jul–20 Aug], fall [21 Aug–31 Oct]).
Table 3.
Mean estimated percentages of daily digestible energy provided by seven primary food types within 14 diets of grizzly and black bears identified by principal components and cluster analyses of field data, Grand Teton National Park, Wyoming, USA, 2004–2006.
Homogenous diets were dominated by one particular food type, whereas mixed diets were composed of 2 or more principal food types. Within these categories, diets are ordered by number of bear-days observed.
Table 4.
Positive (+) and negative (-) associations of the 14 identified daily diet types with supplementary categorical variables for season, sex, and species (χ2 tests) and supplementary continuous variables for body mass and GPS fix interval (t tests), Grand Teton National Park, Wyoming, USA, 2004–2006.
The number of symbols corresponds to P: single (0.01 ≤ P ≤ 0.05), double (0.001≤ P ≤ 0.01), triple (P ≤ 0.001).
Fig 3.
Mean estimated macronutrient content, as a percentage of daily digestible energy, for the 14 daily diet types of grizzly and black bears identified by principal component and cluster analyses of foraging data collected during site visits of bear locations during a 24-hour period, Grand Teton National Park and vicinity, Wyoming, USA, 2004–2006.
Foods were categorized into 7 primary food types (e.g., above-ground vegetation [AGBVEG], below-ground-vegetation [BGVEG]). The dashed line depicts the optimal protein level (17 ± 4%) that has been shown to maximize body mass gain per unit of energy intake [8].
Fig 4.
Mean estimated percentage of daily digestible energy provided by seven primary food types (e.g., above-ground vegetation [AGBVEG], below-ground-vegetation [BGVEG]) among grizzly, sympatric black (black-S), and allopatric black (black-A) bears, as documented from site visits to bear locations during a 24-hour period, Grand Teton National Park and vicinity, Wyoming, USA, 2004–2006.
Fig 5.
Model-predicted mean percentage of protein (±95% confidence interval) within the daily digestible energy consumed by grizzly, sympatric black (Black-S), and allopatric black (Black-A) bears, by season and sex, Grand Teton National Park and vicinity, Wyoming, USA, 2004–2006.
The dashed line depicts the optimal protein level (17 ± 4%) that has been shown to maximize body mass gain per unit of energy intake [8].
Fig 6.
Model-predicted relationship between body mass and mean percentage of protein (± 95% CI) within the daily digestible energy consumed by bears (species combined), by season, Grand Teton National Park and vicinity, Wyoming, USA, 2004–2006.
The dashed line depicts the optimal protein level (17 ± 4%) that has been shown to maximize body mass gain per unit of energy intake [8].