Linking landscape-scale differences in forage to ungulate nutritional ecology

Area of Science:

• Wildlife Ecology and Management
• Ungulate Population Dynamics
• Nutritional Ecology

Background:

• Understanding habitat and nutrition is crucial for managing ungulate populations, especially with recovering carnivores and declining trends.
• Variations in forage availability and phenology complicate landscape-level nutritional assessments for ungulates.

Purpose of the Study:

• To develop a spatial model estimating landscape-level elk nutritional resources.
• To link nutritional resource differences to elk body condition and pregnancy rates in varying habitats.

Main Methods:

• Integrated spatial modeling to estimate digestible forage biomass as an index of nutritional resources.
• Comparison of nutritional resources between two study areas with differing habitat quality.
• Analysis of elk body condition (body fat) and pregnancy rates in relation to nutritional resources.

Main Results:

• Digestible forage biomass varied significantly by land cover type and study area, with fire-altered plant composition as a key driver.
• Elk in areas with lower summer nutritional resources exhibited poorer body condition entering winter.
• Lower nutritional resources were associated with significantly reduced pregnancy rates (72%) compared to areas with higher resources (89%).

Conclusions:

• Summer range nutritional resources can limit elk pregnancy rates and calf production.
• Nutritionally limited elk populations may be more vulnerable to predation and harvest.
• Wildlife managers must identify nutritionally limited ungulate populations for effective conservation and management strategies.