Density‐dependent habitat selection alters drivers of population distribution in northern Yellowstone elk

• Published in: Ecology letters 2023-02, Vol.26 (2), p.245-256
• Main Authors: Smith, Brian J., MacNulty, Daniel R., Stahler, Daniel R., Smith, Douglas W., Avgar, Tal
• Format: Article
• Language: English
• Subjects: Aerial surveys; Animals; Cervus elaphus; cougar; Deer; Density dependence; Ecosystem; Elk; Food; Food safety; Food selection; food‐safety tradeoff; Habitat selection; Habitats; Hypotheses; ideal free distribution; Letter; Letters; Northwestern United States; Parks, Recreational; Population Density; Population distribution; predation risk; Predatory Behavior; predator‐prey interactions; RSF; Safety; Seasons; spatial distribution; wolf; Wolves
• ISSN: 1461-023X; 1461-0248
• DOI: 10.1111/ele.14155

Although it is well established that density dependence drives changes in organismal abundance over time, relatively little is known about how density dependence affects variation in abundance over space. We tested the hypothesis that spatial trade‐offs between food and safety can change the drivers of population distribution, caused by opposing patterns of density‐dependent habitat selection (DDHS) that are predicted by the multidimensional ideal free distribution. We addressed this using winter aerial survey data of northern Yellowstone elk (Cervus canadensis) spanning four decades. Supporting our hypothesis, we found positive DDHS for food (herbaceous biomass) and negative DDHS for safety (openness and roughness), such that the primary driver of habitat selection switched from food to safety as elk density decreased from 9.3 to 2.0 elk/km2. Our results demonstrate how population density can drive landscape‐level shifts in population distribution, confounding habitat selection inference and prediction and potentially affecting community‐level interactions. Relatively little is known about how density dependence affects variation in population distribution. We found that density‐dependent habitat selection changes the relative drivers of elk distribution in northern Yellowstone, from food driving distribution at high density to safety driving distribution at low density. Our results demonstrate how population density can drive landscape‐level shifts in population distribution, confounding habitat selection inference and prediction and potentially affecting community‐level interactions.