A recent modeling study that looked at livestock grazing and sage grouse has been getting a lot of play in the media with headlines like “Livestock Grazing Can Benefit Sage Grouse, Study Says.”
And not surprisingly, representatives of the livestock industry are quick to pounce on the study as evidence that livestock grazing is compatible with recovery of sage grouse.
Basically, the study concluded that grazing early in the season in most locations tended to be correlated with declining sage grouse numbers, while grazing late summer and fall had more “positive” influences.
From an ecological perspective, this is a no-brainer. Grazing early in the season removes grass cover that protects nesting sage grouse hens, and can also reduce the quantities and quality of forbs that can result in higher quality eggs and faster growth among grouse chicks.
Even a minor decline in forage quality can set back chick’s growth. So a chick maturing say 2-3 days earlier might avoid predators by flying while a chick on grazed rangelands might delay maturation and thus be more vulnerable to predators.
However, there are more problems with the headlines and the study’s conclusions than reported in the media.
First, the entire study was based on modeling with no empirical field work or field verification. Modeling is notorious for errors—the old cynical line “garbage in—garbage out” is often an accurate description of the problems with modeling.
Second, the study did not gather its own data on range condition, instead relied on grazing data from the BLM which is notorious for optimistic reporting on range conditions to avoid antagonizing the livestock industry.
Third, there was no “control” with no grazing as a comparison. Yes, changing the timing of grazing might benefit sage grouse, but this does not suggest that livestock grazing benefits sage grouse as the headline proclaims.
For instance, the study authors suggest that “higher grazing levels after the peak in vegetation production corresponded with a positive response from sage grouse populations.” However, what that may indicate is that grazing later in the summer and fall gave grasses sufficient time to grow and recover height lost from grazing, thus providing hiding cover for grouse in the nesting spring months.
This again begs the question of whether no grazing would not lead to even greater sage grouse population growth? We don’t know the answer because there was no control without livestock grazing.
Livestock production has multiple impacts on sage grouse that were not investigated as part of this study and proclaiming that livestock can benefit sage grouse is an exaggeration. Indeed, livestock production is the single greatest factor in sage grouse decline across the West.
Sage grouse are poor fliers and livestock fences are a well-known mortality source for the bird.
Trampling of soil crusts by livestock hooves, destroys soil crusts which are important for precluding the invasion of cheatgrass, an annual that burns readily and contributes to a loss in sagebrush habit because of heightening fire frequency.
Livestock watering troughs are a major breeding ground for mosquitoes that carry West Nile Virus which has devastated some sage grouse populations.
Livestock presence has been correlated with higher raven populations, which often consume sage grouse eggs.
Even livestock grazing later in the season can reduce hiding cover for birds, making them more vulnerable to predators. At the minimum sage grouse require 7 inches of grass after grazing to have effective hiding cover, and obviously taller grass is even better. In many active grazing allotments, 7 inches of stubble is seldom found after the cattle have passed through the area.
Livestock trample wet meadows and riparian areas which are critical to chicks as foraging areas early in life. Chick seek out insects and forbs in these areas, but the loss of these areas, and/or degradation (cows often graze wet meadows down to golf course height stubble) makes chicks more vulnerable to predators.
For these reasons, the proclamation that livestock “benefits” sage grouse must be taken with a grain of salt. There is no denying that changing the timing and intensity of grazing can improve survival for sage grouse—but even with these changes, sage grouse numbers will continue to decline. If we are serious about bringing about the recovery of this species, then the best solution is to eliminate livestock grazing from all prime sage grouse habitat.