Saving Idaho Winter Range
By: Jessie Shallow (MDF Idaho Partner Biologist)
The importance of Sagebrush for Idaho Mule Deer
The “grey ghost”, aka mule deer, is synonymous with the grey year-around aromatic shrub known as sagebrush. The two will nearly always be found occurring together on the same landscape in Idaho. Let’s take a scientific dive into how important sagebrush really is to mule deer.
That scientific dive will take us into the depths of what a deer chooses to put in their mouth, which we can uncover by looking at what comes out in their scat. MDF helped fund research into the diets of Mule Deer in Idaho in 2011, and this revealed that mule deer not only chose to bed under sagebrush, but that sagebrush is also a huge part of what they eat during critical times.
Even when other plants are available, mule deer are selecting for sagebrush at a higher rate than many other plants on the landscape. Maternal females with fawns must be the most selective of nutritious plants, because their bodies need extra calories to support their nursing fawns. Scat samples were gathered and analyzed under microscopes to determine diet selection from 40 does with nursing fawns. Diet selection was analyzed in Southwest Idaho aspen landscapes and compared to high-elevation, dry sagebrush dominated landscapes in Central Idaho. Even in the best habitat, sagebrush and bitterbrush were the most important plants in the diets of mule deer. In more arid Central Idaho, some mule deer diets were made up of up to 90% sagebrush.
Why sagebrush? Sagebrush is both high in protein content and digestible enough for mule deer.
- Protein content – deer need this to put on fat in summer, so they can survive on their fat storage through cold, snowy winters.
- Digestibility – this is how many calories it takes to break down food into useable nutrients.
Turns out there is a threshold for maternal mule deer before they will choose to eat a plant and gain calories. For plants to be selected by lactating maternal deer in 2 study sties in Idaho, the minimum % of digestibility was 55% and protein content was 10% (Jessie Shallow graduate research thesis 2012).
Shrubs that met the threshold for digestibility and protein content in the two study sites in Idaho were: bitterbrush, sagebrush, buffaloberry, chokecherry, willow, buckbrush, Wood’s rose, aspen, snowberry, maple, and green rabbitbrush.
Both bitterbrush and sagebrush are considered important food sources for mule deer in summer, but these plants are also selected during winter months. Nearly all forbs are highly digestible and have high protein content, but they are not typically available outside of the warm growing season. Grasses are not very digestible for mule deer, but a few species have higher protein content compared to other grasses (e.g. fescue, some sedges, and pinegrass have greater than 10% protein content).
Sagebrush provides two things a mother deer desperately needs
1.) Cover for her young fawns
2.) Food to chow on that provides sufficient protein content and is highly digestible.
Survival of fawns before 3 months of age is higher in sagebrush compared to other types of forage cover based on the study in 2010-2011. Before a fawn is 3 months old, they are not fast enough to outrun predators. Therefore, their best survival strategy is to stay hidden in cover. During the time that fawns are vulnerable, the mother deer is the most nutritionally stressed an animal can be. She is making milk to nurse 2 young fawns, and must consume nutritious foods often.
Unlike cattle and elk who are grazers, mule deer are browsers; therefore, they eat primarily shrubs and forbs that are highly digestible and contain adequate protein to produce milk.
The value of sagebrush landscapes goes beyond mule deer to other important species like sagegrouse, pronghorn, and numerous other wildlife that depend on these landscapes. The increase in wildfire frequency and intensity are changing the sagebrush landscape, and MDF along with several federal and state partners are returning this important plant to the landscape post-fire.
Sagebrush is not adapted to burn and return every 25 years like lodgepole pine. In high-elevations, fire is often good to reduce tree canopy and allow forage to become available to mule deer. For example, mule deer enjoy the flush in brush and forbs that expand after dense tree-canopy burns. In contrast, at lower elevations where sagebrush exists, after an intense fire, it may take sagebrush several hundred years to return on its own after a fire.
What is MDF doing about it!
Highly skilled hand-planters are hired by MDF each year to plant sagebrush in the cold Fall months. The MDF crew is made of 20 restoration planters and two seasoned crew bosses. Hal Hering and Steve Belinda formed this mighty MDF crew in 2015.
These individuals are in excellent shape, and spend their year working in the conservation industry in the West. Some work in timber management, while others gather pine-cones for fire rehab. This crew of skilled hand-planters just completed their 9th year of shrub planting in Idaho. This past year, MDF crews planted a total of 235,000 sagebrush, bitterbrush, and rabbitbrush seedlings in Idaho alone. Another 12,000 sagebrush were hand-planted in Colorado. All sites had prior high-intensity fires and all were located in prime mule deer winter range.
In Idaho, 4 sites were planted, which improved about 4,000 acres of winter range habitat. In SE Idaho, MDF and Idaho Fish and Game (IDFG) teamed up to plant 33,110 sagebrush on the Tex Creek Wildlife Management Area which is one of Idaho’s largest WMAs managed by the State of Idaho for the protection of wildlife, fisheries, habitat, and hunting heritage. In Central Idaho, 107,176 shrubs were planted in the Wedge Butte fire, located just south of Ketchum, Idaho. In Eastern Idaho, IDFG and MDF responded quickly and planted 42,740 sagebrush, bitterbrush, and rabbitbrush in the ash left behind by this year’s Paddock Fire. Another 52,246 shrubs were planted in the Owyhee desert in the scar of the Soda fire that burned 280,000 acres back in 2015.
What are other ways to be proactive and protect sagebrush and bitterbrush landscapes
MDF, USFS, BLM, IDFG, NRCS, and FWS have teamed up to attack the invasive plant that is often leading to fires spreading rapidly and burning hotter in sagebrush landscapes. These groups are using chemicals specially targeted to treat cheatgrass, and other invasive annual grasses. Before the expansion of the invasive grasses, sagebrush would have bare spaces on the ground – these are called interstitial spaces.
These spaces serve as a natural fire break when a fire roles through. When cheatgrass invades, it will take advantage of and fill in those interstitial spaces. Now, when a fire occurs, the fuel load is high enough that sagebrush and other natives burn hotter and faster – often leaving behind just the skeleton of a plant.
The Wedge Butte fire was stopped by a “cheatgrass treatment line”. The fire was rapidly burning to the west, assisted by strong winds, but when the fire hit a line where cheatgrass had been treated the year before, the fire dropped to the ground vs. continuing as a rolling ball of flame. At that point, engines could suppress the desert fire. The preemptive treatment by BLM to remove cheatgrass during the prior season kept that fire in check. After fire, the BLM often treats cheatgrass, which helps lower the competition for the precious hand-planted sagebrush seedlings.
Good Luck
Good luck this winter and remember to send any success pictures or stories from the field to [email protected] and you could be featured on our website or in our magazine. If this article or any of our articles have helped you become a better hunter or conservation steward, consider becoming a member of the Mule Deer Foundation for only $35 dollars a year. Click here to join: https://muledeer.org/product-category/membership/
