Mountain fires can spark the growth of new vegetation that, for several years, can provide as much nutrition to elk as irrigated agricultural fields.
“We found out they have access to some good food up high and down low,” said Kristin Barker of the Montana Cooperative Wildlife Research Unit at the University of Montana, the lead author of a recently published study.
The analysis took place at the northeast end of the Bitterroot Valley where a resident elk herd’s population has climbed by 350 percent since the 1960s. The study, conducted in Hunting District 240, is one of several performed as part of Montana Fish, Wildlife and Parks’ Northern Sapphire Elk Research Project.
The advantage of fire on the landscape was not unexpected, given that the West has long experienced fire as part of the environment.
“Fire is the big disturbance factor that a lot of the Western ecosystems evolved with,” said Tom Toman, director of conservation programs for the Rocky Mountain Elk Foundation, based in Missoula. RMEF was one of the groups that funded the research.
Wildland fire can remove the buildup of pine needles on the forest floor, opening up the ground so grasses, forbs and browse species elk like to eat can grow, he noted. RMEF conducted its first prescribed burn in 1986, he said, and has continued to use fire as a management tool, sometimes in conjunction with forest thinning.
Barker’s study found that “ … Recently burned (1-6 year prior) dry forests at higher elevations provided forage quality approximately equivalent to that of irrigated agriculture.”
She collaborated with three other scientists over two years (2014-2015) to track 45 collared cow elk (48 in 2015) and the vegetation they ate to examine how nutritious feed was for resident agricultural elk versus those that migrate to higher elevations in the summer.
“The objectives of our study were to determine which native vegetative communities provided forage of similar quality to that of irrigated agriculture during late summer and whether female elk that exhibited different migratory behaviors had access to different qualities of forage during late summer,” according to the study, which was published in the “Journal of Wildlife Management.”
The study, and the overall project, is significant in that landowners would prefer to keep elk out of their fields so they don’t eat cash crops like alfalfa and corn. Some elk also carry the bacteria that causes brucellosis, which can cause young female cattle to abort. Keeping elk and cattle separate, especially in the spring when elk give birth, can help prevent the disease from spreading to cattle. Birthing material is suspected of being the main way elk infect cattle.
Elk that gather on farmland also make it difficult for the Montana Department of Fish, Wildlife and Parks to reduce elk populations to the agency’s objectives, since public hunting is the main way FWP has to decrease elk numbers. Some private landowners don’t allow public hunting so elk will congregate on those lands during the hunting season. Once the season is over, the elk may disperse to surrounding lands, including those private properties where public hunting was allowed, frustrating the landowners who allowed public hunting.
Toman also said some new landowners may not even be running cattle or working their fields, meaning humans aren’t pushing elk off the landscape like traditional ranchers and farmers in the past. One family that eliminated livestock on their ranch saw the local elk herd jump from 30 to 300, he said, as “word got out” among the elk that the land was a sanctuary.
“Elk are a smart animal and if they don’t have to walk to the top of the mountain, it makes a lot of sense,” he said.
Barker’s study may point to one possible way to urge some elk to leave agricultural fields — using prescribed fires in certain forested areas to spark the growth of more desirable vegetation.
“We did find burning has a benefit under some circumstances and for a certain amount of time,” said Mike Mitchell, a University of Montana professor and leader of the Montana Cooperative Wildlife Research Unit. Mitchell was one of the co-authors of the study, which also included the unit’s Jesse DeVoe and Montana Fish, Wildlife and Parks biologist Kelly Proffitt.
“Land management can help play a role in the quality of elk forage up high,” Barker said.
In the past, and as studies of elk and deer in Wyoming have shown, wildlife migrate to higher elevations in pursuit of newly growing vegetation, which contains more protein. This has been termed “surfing the green wave.”
Good nutrition in cow elk is essential to calf production, so it’s no wonder elk seek out the best food source.
“If summer nutrition is bad, they won’t have a calf,” Toman said. “It takes summer nutrition to drive that elk herd.”
As predator populations have grown — with more grizzly bears, mountain lions and wolves in places like the Greater Yellowstone Ecosystem — some elk have chosen to forego the summer migrations in the region, as well as elsewhere.
“It appears that agriculture on winter ranges is changing the cost and benefit” for elk to migrate, Mitchell said. “Why leave because this is a pretty good gig.”
In the Bitterroot Valley, the elk studied were divided into three groups. The majority of the animals (49 percent) were in the middle — sometimes migrating into the North Sapphire Mountains and sometimes not. Another 24 percent were classified resident elk, while 27 percent were deemed migrants.
“The elk populations in Montana have these historic patterns of migration,” Mitchell said. “But it turns out to be more complex than we thought.”
Deciding whether to migrate “appears to be based on nutrition,” he added. But even the attraction of irrigated alfalfa, which Mitchell compared to “ungulate candy,” may not be enough if there’s heavy competition for that resource, he said.
“It’s a bit of a gamble because they don’t know what’s available on the summer range,” Mitchell said.
More info needed
Findings from the project note, “World-wide, loss of migration is a growing trend that can threaten resiliency of populations and ecosystems,” hence the importance of the work.
Some of the outcomes of such reliance on agricultural fields could be that better-nourished cow elk that don’t migrate could produce healthier calves. As that resident elk population grows, fewer elk would learn to migrate.
On the other hand, migrants may be able to expend less energy because they aren’t walking from bedding areas to ag lands to feed every day, the study noted.
“We certainly saw resident elk make big moves every day,” Barker said. “They need a safe place to hold up while they are digesting.”
In contrast, migratory elk made smaller daily moves once they found the feed they were seeking, she added.
More work is needed to help give researchers better insight to elk behavior, Mitchell said. And, as the study points out, scientists need a better understanding of how different logging techniques and thinning practices may compare to fire management for opening up the forest to grow higher quality elk forage.
“Differences in available nutritional resources have strong potential to influence elk distributions and migratory behaviors,” the project’s executive summary states. “Changing or decreasing migratory behaviors may affect natural ecosystem processes and may result in increasing property damage issues on private lands and lack of elk availability on public lands during the fall hunting season.”