Livestock grazing affects wildlife habitat, but whether that impact is a positive or a negative has a lot to do with management and the environment.
Type and location of grassland, range productivity and precipitation all play a role. Of those elements, Lance McNew, an assistant professor of wildlife habitat ecology at Montana State University, says precipitation is probably the most significant mediator of livestock grazing effects on an area’s wildlife.
“Because … the host of mediating factors vary over time and space, the ‘silver bullet’ of proper grazing management for all but the most geographically restricted species of wildlife is a myth,” he says.
MULTIPLE STRATEGIES. McNew points to the spatial extent of the prairie ecosystems in North America. Rangeland-management actions implemented within the tallgrass prairies of Iowa, Kansas and Nebraska will not produce similar results when applied to the northern, mixed-grass prairies of North Dakota, South Dakota and eastern Montana.
“Even within a single prairie ecosystem, annual variability in precipitation from one growing season to the next has been shown to significantly affect the range vegetation structure and composition. Without accounting for these differences, management actions may not improve range condition for wildlife habitat quality,” he notes
Grassland-associated wildlife, especially grassland birds, have declined in the last 60 years as the number of acres of grassland has decreased across North America during this same time. McNew says these birds serve as literal “canaries in the coal mine” of prairie ecosystem health.
McNew strongly believes the interests of both grazing livestock producers and grassland wildlife overlap. The positive effect of grazing can lead to both increased ecological functionality for wildlife and improved rangeland for grazing.
On the other end of the spectrum, improper livestock grazing can have a negative effect on wildlife. This includes decreasing plant biodiversity and having less biomass and residual cover, which will have long-term effects on range condition. These issues have led to an uptick in research over the last 10 to 15 years, McNew adds.
DIVERSITY THE KEY. John Kraft, a research assistant with the Kansas Cooperative Fish and Wildlife Research Unit, says many contemporary grazing-management strategies, such as the use of smaller pastures, shorter grazing periods and higher stocking densities, are growing in popularity. This creates uniform grazing but sacrifices habitat heterogeneity (diversity) and biodiversity for wildlife.
Kraft supports a shift to more wildlife-friendly grazing-management practices, including patch-burn grazing. In this strategy, a portion of grassland is burned. Grazing animals are attracted to the burned regions, allowing previously burned patches to recover. The patch-burn practice is designed to improve wildlife habitat quality by increasing habitat diversity.
Kraft explains the lesser prairie-chicken requires heterogeneous grassland habitats and is an ideal case study for evaluating effects grazing strategies have on a species.
“The findings showed the lesser prairie-chicken hens used a large range of forage utilization values,” he says. “Breeding females did not place nests with pasture grazed at rates greater than 40% forage utilization, and most nests were placed on sites with forage utilization rates between 0 and 20%.”
STOCKING RATES MATTER. Regardless of forage utilization, bird habitat increased as stocking densities decreased.
“In large pastures with relatively low-stocking densities, the lack of competition for high-quality forage by grazing livestock created variable grazing distribution. This distribution produces a desired habitat,” Kraft says.
Despite the positive effects for grasslands, some grazers avoid burning grasslands. Fire is commonly not included in grazing management as a tool because of a culture of skepticism and fear, he adds.
McNew says a grazing-management practice popular in Montana is rest-rotation grazing, where forages are grazed until seed heads are present; then the land is rested for up to a year. This practice is not done for wildlife but grassland health, but it might affect wildlife, as well.
STUDY RESULTS. A recently completed study by McNew and his research team from Montana State examined at this method of grazing management.
Specifically, the group wanted to find the effects of the practice on the sharp-tailed grouse, other grassland birds and mesocarnivores (skunks, badgers and coyotes).
For the grouse, the study showed no benefit in terms of nest survival, home range size or habitat selection and movement. McNew says there was even a case to be made where season-long grazing might be better for the birds.
With songbird populations, however, the grazing-management program produced a potentially positive increase. This included the vesper sparrow, the grasshopper sparrow and the western meadowlark.
In all cases, conservation-minded systems increased the mesocarnivore population.
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