# Hierarchy in Structuring of Resource Selection: Understanding Elk Selection Across Space, Time, and Movement Strategies

## TL;DR

This study explores how elk select resources based on their movement strategies, showing that behavior varies across herds, seasons, and environmental conditions.

## Contribution

The study introduces a consistency score to quantify differences in resource selection behavior across movement strategies and environmental contexts.

## Key findings

- Elk avoid human development and roads at fine scales while selecting productive areas in summer.
- The greatest differences in resource selection behavior were found among herds, followed by seasonal variation.
- Elk show more uniform responses to productivity than to human-related factors.

## Abstract

Movement is a fundamental aspect of animal ecology that varies across space, time, and among individuals or groups within a population. Broad‐scale patterns of animal movement are often classified into different movement strategies, such as resident, nomadic, or migratory. While landscape‐level environmental patterns can predict the presence of different movement strategies in an area, elucidating how these patterns downscale to fine‐scale resource selection behaviors remains a challenge. Partially migratory systems, where both migrants and residents coexist, offer a unique opportunity to address these questions. Using tracking data from four Rocky Mountain elk (
Cervus canadensis) herds situated primarily within Colorado, USA, we assessed between‐herd, seasonal, and within‐herd variation in resource selection behavior. We modeled fine‐scale seasonal resource selection and compared strategy‐specific behaviors using resource selection functions. Additionally, we used a consistency score to quantify the extent of differentiation in resource selection behavior across strategies, seasons, herds, and groups of covariates. We found variation in strategy frequency within each herd and in selection behavior, highlighting the complexity and context‐dependence of strategy‐specific selection. Despite herd‐specific differences, some consistent trends emerged, with elk avoiding human development and roads at fine scales while selecting areas with higher productivity during summer. Our consistency analysis identified where elk most diverged in their selection behavior, revealing the greatest differences among herds, followed by variation between seasons, and lastly between movement strategies. Elk exhibited more uniform responses to productivity, contrasting with greater differentiation in responses to anthropogenic‐related covariates. Overall, our study improves our understanding of elk behavior across space, time, and movement strategies and sheds light on the hierarchical influences of space and time in constraining behavior.

We leveraged a unique dataset of over 500 elk from four herds living in very different environmental conditions, ranging from semi‐arid desert to high‐elevation mountains across the state of Colorado, USA. For each herd, we characterized broad movement strategies (whether individuals were migrant or resident) as well as fine‐scale resource selection during the winter (when residents and migrants overlapped in space) and summer (when residents and migrants did not overlap). Our work reveals nuances in elk behavior across space, herds, seasons, and movement strategies while also providing information on the hierarchy of those factors in constraining elk resource selection.