Stepping Lightly in the Sage
Researchers Learn Moderate Grazing Has No Effect on Sage Grouse Nest Success
Rancher Richard Ward grew up alongside greater sage grouse and observed their spring mating, or lekking displays, in the open land around the Jim Sage Mountains of southern Idaho.
He heard the ethereal pulsing of sage grouse mating calls on cold spring mornings and watched the birds’ lumbering flight across open country. And he is aware that sage grouse have for many years been considered for the endangered species list.
The 74-year-old rancher, whose family has raised cattle for five generations on either side of the mountains that sprawl south to Utah, grazes close to 200 head. Like most producers, Ward depends on lush spring pastures on federally leased land to sustain his operation.
But spring grazing on federal allotments has for decades been the focus of those who contend that cows sharing greater sage grouse nesting habitat are detrimental to the birds and may result in low nesting success in the bird’s former range.
A recent study by University of Idaho shows the claim is unfounded.
The Grouse and Grazing Project
The 10-year study led by U of I Professor Courtney Conway shows that cows sharing nesting habitat with grouse on federal lands has no influence on nest success of greater sage grouse if grazing intensity is kept at current levels.
In fact, according to the research, there are upshots for grouse living alongside cows. Having bovines on the land results in a greater abundance of insects, especially in the spring, when chicks rely on bugs for food.
"Nesting success doesn’t seem to be affected by current levels of cattle grazing, and insect biomass increases with grazing,” said Conway, who directs the USGS research unit and led the decade-long research project which wrapped up in August 2023.
The idea for an extensive grouse and cattle grazing research project was spurred after opposition to spring cattle grazing on federal land picked up steam. Conway knew there was a dearth of science to inform the debate. He joined forces with Prof. Karen Launchbaugh, the director of the Rangeland Center, biologists in the Bureau of Land Management — the agency that oversees much of the sage grouse habitat in southern Idaho — Idaho Fish and Game, and Idaho ranchers to bring scientific data to the debate.
“Many decisions regarding sage-grouse and cattle were being made by land managers, but there wasn’t a lot of science to rely on,” Conway said. “We just didn’t know what effect spring grazing had on nesting grouse, brood production or anything else.”
Conway’s group of researchers wanted to know how grazing affected sage grouse populations, and whether current levels of cattle grazing increased nest predation. Many people had assumed that increased visibility in grazed pastures would make sage grouse eggs easier to find by common nest predators like coyotes and ravens.
Scientists also wondered if spring grazing affected the abundance of insects. Arthropods are a key food source for greater sage grouse chicks. Research shows that more than 90% of the diet of one to four-week-old chicks is comprised of arthropods.
After collecting and analyzing data annually from five sites in southern Idaho’s sage lands, researchers found spring cattle grazing increase the abundance of arthropods favored by sage grouse chicks, including ants, crickets and several types of beetles.
“Spring grazing resulted in a greater number of insects, a greater variety of insects and the insects found under the spring grazing treatment generally are bigger, which could provide more food for sage grouse,” said entomologist Grace Overlie, a U of I master’s student on the project.
Scientists also learned that the presence of cattle in places where sage grouse nested, and grazing of spring grass, had no effect on nest success.
Master’s student Nolan Helmstetter, whose research focused on sage grouse nest predators, found that coyotes were the primary nest predators on five study sites and higher shrub canopy cover decreases the probability of nest predation by coyotes. But whether cattle grazed the area did not affect predation.
“I think this is a significant outcome for the ranching community, which has wondered all along what they would do if scientists learned that spring grazing was bad for grouse,” said Launchbaugh, the co-lead investigator of the study. “Had we found that spring grazing had a negative effect on grouse populations, it could have resulted in the loss of grazing allotments on federal land, something cattle ranchers, especially smaller operations, need for their businesses to survive.”
A Research Cooperative
Going back to the late 1990s, critics of cattle grazing on federal land pushed for more stringent restrictions on ranchers, arguing that cows aren’t good for sage grouse, an iconic Western species that teetered on the federal threatened species list. They argued that because grazing was the main use of federal rangelands, grazing was likely the culprit behind grouse declines.
“A lot of people just don’t want us on these lands,” said Ward, whose ranch is home to a sage grouse lek — a spring mating site to which birds flock for annual courtship rituals in March and April. “We’ve been battling this for a long time, and I hope now that we got the science behind us, we can put the spring grazing issue to rest.”
Ward, who lives and ranches on the eastern slope of the Jim Sage near Malta, was among a group of ranchers approached more than a decade ago by the research team because their grazing lands, or the federal allotments they leased, were ideal sage grouse habitat.
Conway said his team extensively examined southern Idaho ranchlands using maps, GPS and satellite imagery as well as historical data to find five study sites spanning Idaho — all of it home to the greater sage grouse, the largest North American grouse that ranges across the high plains of the western U.S. and Canada.
Snow conditions at the sites, the abundance of Wyoming big sage — a smaller, drought tolerant and high value forage plant important to sage grouse, as well as the abundance of water and spring grazing allotments were considered before choosing potential study sites.
“There wasn’t a lot of science to rely on.”
— Courtney Conway, Professor
“It took us about a year to pinpoint land we thought contained the right mix of grouse and spring grazing before we even approached ranchers who used the land,” Conway said. “Many of the ranchers wanted nothing to do with our study.”
The tracts they chose included remote sites such as Sheep Creek, southeast of Grasmere along the Nevada border, Brown’s Bench south of Twin Falls, the Jim Sage acreage near Malta. A high altitude flat near Arco called Big Butte was added as a study area as well as a chunk of the Pahsimeroi Valley south of Salmon.
Annual studies conducted at the sites began with the capturing and radio-collaring of sage grouse hens in late winter. The radio transmitters helped biologists locate nests. Cattle were rotated on and off the research allotments where hens nested based on a rigorous, randomized study design. Researchers collected insects at the sites, measured grass abundance and height, and tracked fate of sage grouse nests.
By the Numbers
- The 10-year grouse and grazing project:
- Included more than 30 scientists.
- Measured vegetation at 500 sampling plots.
- Annually measured height, percent biomass removed on 31,000 grass plants at 700 nest or random plots.
- Included 19 BLM grazing pastures measuring a thousand-plus acres.
- Captured and marked more than 150 female sage-grouse annually.
- Followed 80 hens captured in previous years.
- Measured grass height, percent biomass removed, and other metrics on 31,000 grass plants annually within almost 700 plots.
- Conducted invertebrate sampling at more than 100 locations.
- Collected almost 2,000 pitfall samples and 1,000 sweep-net samples.
Mark and Wendy Pratt’s cow-calf operation lies between the Snake and Blackfoot rivers southeast of Big Butte. The Pratt family has been raising cattle there since 1904, and annually run 600 head between wintering grounds on the Snake River plain and summer grazing on the Blackfoot mountains.
A drop in sage grouse numbers across their Idaho range over the past few decades had many ranchers concerned for the birds. They also worried proposed mitigation efforts could adversely affect their agri-business.
“We first got involved in this project after learning of the sage grouse declines,” said Wendy Pratt, who was tapped to join a working group called the East Idaho Uplands Group more than a decade ago to learn about threats to sage grouse, and how to offset them. “It became an issue with a lot of ranchers, us included, because we have sage grouse on our summer range.”
Pratt was eventually asked to serve on a statewide advisory committee to provide a cattle producer’s perspective to sage grouse discussions.
“I had friends in the sage grouse community, biologists and range ecologists,” Pratt said. “We just knew how important it would be to actually find out how sage grouse and grazing either worked or didn’t work together.”
The group members agreed lack of information was a primary threat to the birds.
“We just didn’t know a lot about them as a species,” Pratt said. “Through this research project, we know more about them than we did, and we’ll learn something from this study that will help us be better land managers.”
South of Twin Falls near the small, one gas station community of Rogerson, lies a narrow chunk of sage land that is pressed between the Salmon Falls Creek Reservoir and a steep, mountain wall. Known as Brown’s Bench, the approximately 30 square miles is a mix of Bureau of Land Management grazing allotments and private ranchland where Bert Brackett’s family has raised cattle for generations. The land rolls south 18 miles to the Nevada border.
Bracket was a member of the Idaho legislature when he was asked to support an initiative to study the effect of cattle grazing on sage grouse.
“Spring grazing was being blamed for the decline of sage grouse, but it was mostly based on personal opinions because there wasn’t any data to support it,” Brackett said. “We thought that the university, as the state’s land grant institute, could provide us with some basic research to address the question. It was one of those deals where no one knew what the results would be.”
The sage land at Brown’s Bench, home to several large leks, was chosen for the grouse and grazing project.
“We built a contingent in the ranching community and the legislature who supported the research and pledged to stand behind it regardless of the outcome,” Launchbaugh said.
Family owned and privately held since 1929, Idaho’s J.R. Simplot Company is an international food and agriculture company with cattle operations headquartered in Grand View. The livestock operation uses federal and private rangelands in surrounding states and includes permits for grazing livestock on more than two million acres, averaging 30,000 cows on the spring and summer range.
Cows share habitat with sage grouse on much of the range, said Darcy Helmick, the Grand View operation land manager. Simplot joined the U of I study to find answers that could help settle the grazing debate.
Conway and his researchers approached Simplot after locating two major leks visited on Simplot allotments.
“We were excited to participate,” said Helmick, a U of I alumna with a rangeland degree. “We have seen and observed through our management and our time on the land, the interaction and correlation between grouse and cattle, specifically in spring grazing, but we didn’t have any good scientific literature to support the observations on the ground.”
Cowboys and land managers noticed that grouse numbers increased in areas used by cattle, said Helmick. When researchers asked Simplot to manipulate grazing patterns to accommodate the 10-year study, the cattle company agreed.
“We thought it was a good idea for the researchers to come out and document what we were seeing on a daily basis,” Helmick said. “There appeared to be a symbiotic relationship between livestock raising and wildlife, especially sage grouse.”
Scientists documented hatch dates and clutch sizes across the study sites, tracked broods and measured brood survival.
“This 10-year-study was designed to be the Cadillac of studies,” Conway said. “What we found so far is there is no effect of cattle grazing on sage grouse nesting success, and that is an important result because most of the management guidelines and the lawsuits and litigation so far have been completely based on the premise that livestock grazing reduces sage grouse nesting success. So, our study is going to completely revolutionize how grazing management guidelines are going to be written throughout the West.”
For Ward study results confirm what he and other ranchers had surmised.
“With the results of this study, I think we’ll be able to continue with the cattle out there on the range as we have been, pretty much,” Ward said. “If there’s a conflict, we’ll be able to find ways to minimize that and keep cattle out there and grouse out there, and have them both thrive.”
“I am not aware of a project that has had so much cooperation across such a wide range of groups,” Conway said.
Collaborated with ranchers and cattle groups, Idaho Fish and Game and the Bureau of Land Management, the U.S. Fish & Wildlife Service, Western Association of Fish and Wildlife Agencies, Great Basin Landscape Conservation Cooperative, Public Lands Council, Idaho Cattle Foundation, Idaho Governor’s Office of Species Conservation and Natural Resource Conservation Service (NRCS).
The Idaho Cattle Association and the University of Idaho provided administrative support.