New Study Measures Fire Impacts on Wildlife, Livestock in NM

When members of the Bureau of Land Management’s Pecos District fire team put on their fire gear, it’s almost always to fight a fire. In early March, though, they were starting fires, and they did a picture-perfect job of it.

“This region used to see fire on a six- to ten-year cycle,” said Scott Carleton, an ecologist with the United States Geological Survey’s New Mexico Cooperative Fish & Wildlife Research Unit at New Mexico State University (NMSU). “This is a fire-adapted community, with a species assemblage that evolved with fire.”

Member of the fire team lights a backburn on the BLM Sand Ranch ACEC (photo courtesy Scott Carleton).

Member of the fire team lights a backburn on the BLM Sand Ranch ACEC (photo courtesy Scott Carleton).

Carleton is part of a research effort to assess the effects of prescribed fire on lesser prairie-chickens at Sand Ranch, a 58,600-acre federally owned parcel 35 miles east of Roswell managed by the Bureau of Land Management (BLM).

Designated as an Area of Critical Environmental Concern, Sand Ranch is specifically managed as habitat for the lesser prairie-chicken, a species of grouse whose range and population numbers have declined dramatically as a result of many factors, including row-crop agriculture and fire suppression. In 2015, their total range-wide numbers were estimated at 29,000.

Sand Ranch is the only parcel within the lesser prairie-chicken’s five-state range that meets the US Fish and Wildlife Service criteria for a habitat “stronghold” for this uncommon grouse of the Southern Great Plains. A stronghold provides long-term protection to at least 25,000 acres of high-quality habitat for lesser prairie-chickens.

Before settlement, regularly occurring fires and periodic, intensive grazing by large herbivores shaped the Great Plains. BLM wildlife biologist Randy Howard notes that the prescribed fire treatment is part of a carefully planned effort to reintroduce these historic disturbance patterns on Sand Ranch.

“We’ve got this big chunk of real estate set aside for [lesser prairie] chickens,” Howard explained. “Instead of just throwing fire and grazing at it, we’re doing it carefully, and hoping that, as a result, we’re going to know the management path forward that’s best for the chicken.”

On March 4, they took a big first step, carrying out the first-ever prescribed burn on the parcel. The BLM fire team burned two management units totaling 3,100 acres. The results were exactly what Carleton and Howard had hoped for.

The prescribed fire snaked through the prairie, burning some areas, leaving other areas untouched or very lightly burned.

The prescribed fire snaked through the prairie, burning some areas, leaving other areas untouched or very lightly burned.

“We got a beautiful mosaic burn,” said Carleton. “I couldn’t have asked for better. The fire snaked through the prairie, with areas that didn’t burn and areas that did. We had chickens out foraging in it, right after the burn, and within two weeks we had a lek move from an adjoining unburned area to the recently burned area.”

Over the next three years, the BLM plans to burn the rest of the central part of the ranch, which is bracketed by roads that serve as fire breaks. By burning portions of the ranch each year, they’ll help create the varied habitat structure that lesser prairie-chickens need throughout the year.

During mating season lesser prairie-chickens gather on leks, also called booming grounds, where males display and spar as they vie to mate with females. Leks generally form at sites with low vegetation, where males are most visible to one another and to females. For nesting, the females seek out the shelter of sites with taller, denser grasses and low prairie shrubs. When chicks hatch, females guide them to less dense vegetation, where the chicks can forage more easily but still have good hiding cover. Burning small portions of the ranch each year will help create this habitat mosaic.

A male lesser prairie-chicken displays at the BLM Sand Ranch prescribed burn site just a few days after the fire.

A male lesser prairie-chicken displays at the BLM Sand Ranch prescribed burn site just a few days after the fire.

The lesser prairie-chicken is what’s referred to as an umbrella species. Because the prairie chickens need large tracts of healthy prairie habitat to survive and reproduce, conserving habitat for them benefits many other prairie species as well.

During the prescribed burn, Carleton said, they watched Cooper’s and Swainson’s hawks circling at the head of the fire, hunting for small animals. Since then, they’ve seen plenty of wildlife on the burned acreage, including pronghorn and scaled quail.

Historically, fire and grazing acted in tandem to shape the prairie. Fire fingered across the grasslands, and the burned grasses resprouted vigorously in its wake. The fresh growth attracted herds of bison. Their grazing kept the fuel load low, ensuring that the next fire would burn the older, denser growth. And so the cycle went.

The BLM management study on Sand Ranch is carefully planned to fully explore how fire, grazing, and prairie habitat interact. Carleton describes how the six-year study will build from what he and his graduate students have already learned about Sand Ranch from studies over the past three years. “We know where they’re nesting, where they’re moving their broods, and where they are the rest of the year,” he says.

“Now we’re going to study how the birds’ movements change in response to fire,” Carleton continued. “At the end of three years, we’ll begin to implement grazing, but we’ll start with fire alone, so we can tease out the effects of each management practice.”

Howard notes that the research team will also assess whether increased grassland vigor from fire affects the quantity and quality of forage for livestock.

“If we do find that prescribed fire is beneficial to chickens,” Howard said, “we have to figure out a way to make it work for ranchers. We need to know, do the cows benefit?”

Cattle graze on recently burned prairie grassland in Kansas (photo: Jeremy Roberts, Conservation Media).

Cattle graze on recently burned prairie grassland in Kansas (photo: Jeremy Roberts, Conservation Media).

With 95 percent of the lesser prairie-chicken’s range on private land, conservation efforts hinge on engaging private landowners in habitat conservation practices that also improve ranch sustainability.

Studies over the past 50 years on the effects of fire on livestock forage in other parts of the country have shown that prescribed fire improves the palatability, nutritive value, and abundance of herbaceous plants and results in greater cow and calf weight gains. The Sand Ranch study will put that question to the test on New Mexico’s grasslands.

The BLM and NMSU are two of more than 25 organizations collaborating in a range-wide conservation partnership led by the Natural Resources Conservation Service, known as the Lesser Prairie-Chicken Initiative (LPCI).

LPCI provides financial and technical assistance to help private landowners voluntarily improve lesser prairie-chicken habitat. Working through Pheasants Forever, another partner organization, LPCI is helping to fund the six-year study, along with the BLM, USFWS, and New Mexico Department of Game and Fish.

“This study will help us quantify the impact of fire and grazing on lesser prairie-chickens in the shinnery-oak ecoregion,” said LPCI Science Advisor Christian Hagen. “What’s more, it will serve as a model for applying prescribed burns to private land, in a region where it’s not an established part of the range management toolbox.”