How Do Mule Deer Use Sagebrush?
February 5, 2019
Photo of mule deer in sagebrush by Susan Morse.
ASK AN EXPERT: Miles Moretti, President/CEO Mule Deer Foundation
Where do mule deer live?
Mule deer and their subspecies, black-tailed deer, range across most of western North America. They usually migrate, although there are also resident herds that don’t move during the year.
Mule deer spend the summer in the mountains and forests where it’s cooler. During the winter they live in lower elevation, wide-open sagebrush country, where it’s easier to forage for food.
They spend a lot of time on private land in the winter, since valley bottoms are usually agricultural lands, and more time on forested public lands during the summer.
How do mule deer use sagebrush?
They rely almost exclusively on sagebrush or bitterbrush as their food source to survive the winter.
Mule deer will eat a broad range of plants found in the sagebrush ecosystem. The native perennials provide just enough protein to sustain them until they can build up their fat reserves in the summer.
They also utilize sagebrush range during the spring and fall as they transition between summer and winter range.
Do mule deer and sage grouse habitat overlap?
Yes, as much as 16-19 million acres of mule deer and sage grouse range overlap. In fact, recent research shows that many of the most critical mule deer migration corridors fall within core sage grouse habitat.
Like sage grouse, mule deer flock to rangelands near water, especially in the fall. These areas tend to be irrigated alfalfa fields on ranches.
To help conserve the birds’ and the herds’ mutual habitat, the Mule Deer Foundation has focused on working collaboratively to create healthy sagebrush rangelands on both public and private lands.
What is the main threat to mule deer populations?
Development of any kind that chops up habitat—energy facilities, highways, housing subdivisions. This is especially a threat on sagebrush rangelands, since most development takes place in valleys.
It’s a high priority for our organization to restore or conserve sagebrush country for mule deer and other wildlife. Keeping rangelands healthy—and working ranches working—benefits all sorts of wildlife, plus it helps agricultural families remain on their land.
How does the Mule Deer Foundation restore sagebrush habitat?
We have a variety of proactive, partnership-based conservation projects. For instance, in southern Idaho we’ve been planting sagebrush and bitterbrush in an area that was burned badly in a wildfire—and we’ve seen good progress restoring perennials.
Across the range, we help landowners get rid of fences that are no longer needed and are harmful to wildlife. We also partner with SGI to flag fences that are high risk for collisions.
In Colorado, we work on thinning juniper trees to improve wildlife habitat. Not only are we seeing the native vegetation come back where the landscape was opened up, we’ve also seen wildfires slow down in the thinned areas where we removed fuel loads.
In fact, we worked to include a policy in the recently-passed Farm Bill that will expedite pinyon-juniper removal for mule deer and sage grouse. This will accelerate our work restoring sagebrush rangelands.
Why are pinyon-juniper trees bad news?
Pinyon-juniper are invading into sagebrush habitat at a rapid pace due to drought, overgrazing, and fire suppression. Though they’re native, this rapid conversion of diverse perennial forage to trees threatens wildlife, since most sagebrush-dependent species rely on nutritious rangeland plants.
Plus, when these trees get too thick they burn really hot, creating mega-wildfires that leave nothing behind but cheatgrass, which has little to no value for wildlife—or people.
As a last resort, mule deer will eat pinyon-juniper if it’s the only thing left above the snow. However, it’s the least nutritious item on their menu. They do use conifers to stay out of the wind, so when we remove advancing conifers we like to selectively leave a few islands of trees.
Sage grouse are pickier and avoid trees. So, if we’re working in sage grouse habitat, we’ll remove more trees in that area and balance it out across the landscape.
What do you view as priorities for sagebrush conservation?
We want to keep the conservation partnerships working together long term. Working collaboratively across fence lines and across whole watersheds helps maintain connectivity across the range. That holistic approach is the key for addressing what both critters—mule deer and sage grouse—need to thrive.
As for the Mule Deer Foundation, we plan to focus on the “stopover areas” that deer use as they migrate. Mule deer often stop to rest for a week or more at certain sites as they follow the “green wave” of emerging spring vegetation into their higher elevation summer range.
If we can figure out why they stop in these areas, we can hopefully replicate that high-quality mule deer habitat elsewhere.
How can NRCS help benefit mule deer habitat in the future?
I can’t say enough good about the NRCS and its role funding proactive conservation on private lands. We’ve been able to use Farm Bill programs and then extend the conservation work out to the public lands where ranchers have grazing permits.
The key, I think, is providing the flexibility to tailor conservation programs across such a large range. Meeting the needs of producers in New Mexico is much different than in Montana.
MEET THE EXPERT
How did your career lead you to the Mule Deer Foundation?
I was raised in southwest Wyoming during the “golden age” of abundant mule deer and sage grouse. After earning my degree in wildlife management from Utah State University, I went on to receive a Master’s from Brigham Young University. I worked for 30 years with Utah Division of Wildlife Resources, focusing on endangered species, non-game and big game management.
When I retired as deputy director of the department 12 years ago, I wasn’t ready to quit working. This position with the Mule Deer Foundation came up and it’s been a great fit.
What are your hobbies?
I really like to bass fish from my boat here in Utah. While fly fishing is fun, too, I like to eat what I catch and you often have to release trout when fly fishing.
I also like to hike and hunt. In fact, I just got the grand slam for turkeys this year.
ABOUT OUR PARTNER
The Mule Deer Foundation ensures the conservation of mule deer, black-tailed deer, and their habitat. This non-profit organization is comprised of over 150 local chapters across the country and 25,000 active members, many of whom volunteer for on-the-ground habitat improvement projects.
MDF focuses on restoring, improving and protecting mule deer habitat to create healthy and huntable deer populations. In addition to partnering on habitat projects, MDF works closely with state and federal wildlife agencies to ensure mule deer are a priority, and we also advocate for funding to support wildlife management.
Learn more: www.muledeer.org
The Sage Grouse Initiative is a partnership-based, science-driven effort that uses voluntary incentives to proactively conserve America’s western rangelands, wildlife, and rural way of life. This initiative is part of Working Lands For Wildlife, which is led by USDA’s Natural Resources Conservation Service.