Research: Elk

Sierra Madre Elk Project

Sierra Madre Elk Project


Widespread mortality of pine trees following the bark-beetle epidemic can change the ways wildlife and people interact with these formerly intact forest habitats. Elk, for example, rely on intact conifer forests for thermal refuge and escape from predation (e.g., natural predators and human hunters), but as beetle-killed trees fall, the subsequent changes to canopy cover and understory structure can alter forage abundance, thermal cover, and locomotive costs for elk. Behavioral responses of elk to changes in forest structure may, in turn, shift how people hunt them, affecting the way we manage this highly valued species and their habitats. We aimed to identify the ways beetle-kill in conifer forests altered forest structure and the interactive responses of elk and hunters to such changes.

Our hypothesis:

We hypothesized that downfall resulting from beetle-kill has changed the structure of the over- and understory of conifer forests in a way that shifts elk behavior and influences how hunters seek elk.

Elk selection for meadows, green (intact) conifer, and beetle-kill conifer forests throughout the day in the summer. Above the dotted line indicates selection for habitats, while below the line indicates avoidance. Elk generally avoided beetle-kill forests (red triangles) throughout the day but selected for intact conifer (green circles) during the heat of the day and meadows (blue squares) in the evening and nighttime.  

What's the issue?

As trees killed by pine-bark beetle begin to fall, canopy cover increases, exposing the understory to more sunlight which can promote growth of vegetation. At the same time, the increased downfall can inhibit animals from freely moving through the fallen obstacles of the understory and diminish the quality of thermal refuge for elk. Although these trends are often observed, rarely are the benefits and costs of structural change in forest evaluated in the context of what it may mean for elk.

How're we tackling it?

We characterized forest structure, including canopy cover, number of downed trees, and grass abundance and height, at known locations of GPS-collared elk.

What are our findings?

As beetle-killed trees fell, canopy cover decreased causing a modest increase in abundance of forage for elk, but the increase of solar radiation onto the forest floor potentially diminished the amount of thermal refuge for elk. Intuitively, the number of down trees in beetle-killed forests was 75% greater when compared with forests with no beetle-kill.

 

What's the issue?

As forest structure changes following beetle-kill, the tradeoff between accessing forage contained within the understory and getting needed cover from heat and predators may challenge the ways elk use these recently altered forests. In turn, elk responses to the changing structure of beetle-killed forests could influence the way hunters seek the animal they wish to harvest. Understanding the interplay between behavioral responses of elk and hunters to forests with beetle-killed trees is needed to effectively manage elk populations and their habitats in rapidly changing environments. Indeed, harvest by humans in many systems is the most effective, or sometimes only way to maintain a balance between elk abundance and healthy habitat.

How're we tackling it?

We tracked GPS-tagged elk and hunters to evaluate the interactions among their behaviors in beetle-killed forests and other habitats commonly used by elk and hunters.

Tracking elk: We fit 71 elk with GPS collars in the Sierra Madre Mountains and tracked their behavior relative to beetle-killed forests for two years.

Tracking hunters: During elk hunting seasons, we had 347 hunters ((both archery and rifle) volunteer to carry GPS units with them as they hunted.

What are our findings?

Summer elk behavior: Elk avoided beetle-killed forests at all times of the day. They selected for intact, green conifer during the day, when temperatures were warmer, and selected for grass meadows during the crepuscular times (i.e., twilight hours), which are generally characterized as prime feeding times for ungulates.

Elk and hunter behavior during hunting season: Elk increased selection for conifer forests with beetle kill during hunting season in autumn. This behavior is presumed to provide elk with increased concealment from hunters, but contrary to that notion, hunters too used beetle-kill conifer—especially archery hunters. Although rifle hunters generally avoided beetle-kill conifer while strongly selecting for grass meadows, they did increase use of beetle-kill conifer when elk use was greater in those habitats. In other words, both rifle and archery hunters followed elk to areas where they were most likely to occur.

People working on the project:

Bryan Lamont, Matthew Kauffman, Tony Mong, Kim Olson, Jerod Merkle, Matt Hayes, Shannon Albeke, and Kevin Monteith

Funders

Wyoming Game and Fish Department, Medicine Bow-Routt National Forest Resource Advisory Council, Rocky Mountain Elk Foundation, Wyoming Governors Big Game License Coalition, with additional contributions from the Saratoga, Encampment, Rawlins Conservation District, and Little Snake River Conservation District.

Publications

Lamont, B. G., K. L. Monteith, J. A. Merkle, Tony W. Mong, S. Albeke, M. Hayes, and M. Kauffman. 2019. Multi-scale habitat selection of elk in response to beetle-killed forestJournal of Wildlife Management

Find our other publications on elk Elk

Project updates

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