Effects of rotational grazing management on nesting greater sage‐grouse

Abstract

Grazing by domestic livestock is a ubiquitous land use in the sagebrush (Artemisia spp.) biome of western North America. Widespread, long-term population declines in greater sage-grouse (Centrocercus urophasianus) have elicited concern about potential negative effects of livestock management practices on sage-grouse populations. We evaluated how recently implemented rotational grazing systems affected sagegrouse nesting habitat quality as part of a large-scale, replicated, natural experiment in central Montana, USA. We used Bayesian methods to assess support for effects of rotational grazing management and rest from grazing on daily survival rates of nearly 500 sage-grouse nests monitored over 6 years, and mixed effects models to test for effects of rotational grazing and rest on vegetation structure. Though nests on rotationally grazed ranches displayed a trend toward greater daily survival rates, the evidence for an effect was weak. There was no evidence that rest from grazing (!12 months) increased daily survival rates. Furthermore, rotational grazing systems and rest had negligible effects on herbaceous vegetation height and cover relative to other grazing strategies used in the study area. Results do not support the hypothesis that rotational grazing systems or rest from grazing increase nest success in the northern Great Plains. Estimated nest success, however, was comparable to range-wide averages, suggesting concealing cover for nests is unlikely to be limiting growth of this population regardless of grazing strategy. In light of these results and recent research questioning reported relationships between grass height and nest survival, maximization of hiding cover may be overemphasized in grazing management guidelines and policies. Rather, our findings suggest a variety of locally appropriate grazing strategies focused on fundamental range health principles may provide adequate habitat quality for nesting sage-grouse. Ó 2017 The Wildlife Society.

Are Sage‐Grouse Fine‐Scale Specialists or Shrub‐Steppe Generalists?

“…This could include large‐scale management experiments or observational studies of actual management actions (Walters and Holling 1990). Fortunately, such investigations are increasingly common (Monroe et al 2017, Smith and Beck 2018, Smith et al 2018 b , Olsen 2019). For example, recent management studies have affirmed the effectiveness of watershed‐scale restoration of conifer‐invaded sagebrush rangelands (Severson et al 2017, Olsen 2019) but have failed to demonstrate clear benefits of managing fine‐scale vegetation structure, e.g., via grazing management (Smith et al 2018 b ) or other treatments (Smith and Beck 2018) intended to increase herbaceous understory cover.…”

“…Second, inference from fine‐scale habitat studies may be wholly inadequate to predict outcomes of large‐scale management manipulations on vital rates of populations (Bro et al 2004). With few exceptions (Smith and Beck 2018, Smith et al 2018 b ), effects of extensive vegetation manipulation on sage‐grouse demography are poorly studied. Habitat management guidelines and monitoring assessments thus rest on the assumption that fine‐scale habitat relationships scale up to predict effects of manipulating vegetation at management scales (e.g., pastures, ranches, allotments; Fig.…”

“…We limited our analysis to nesting habitat because, as the most thoroughly studied seasonal habitat, many studies with similar protocols and reporting comparable data were available. Furthermore, nest success is among the most important factors influencing population growth in sage‐grouse (Taylor et al 2012, Dahlgren et al 2016) and hence a common management target (Doherty et al 2014, Severson et al 2017, Smith et al 2018 b ). The scale of our analysis is novel for this species and confers several advantages.…”

Unintended habitat loss on private land from grazing restrictions on public rangelands

“…However, the benefits of these guidelines are unproven and the relationships between livestock grazing and sage‐grouse persistence remain obscure. Few studies have directly examined the role of grazing management on sage‐grouse demography and these have failed to produce unambiguous evidence that a reduction in grazing provides benefits (Monroe et al., ; Smith, Tack, Berkeley, Szczypinski, & Naugle, ).…”

Arthropod Abundance Associated with the Natural Resources Conservation Service: Implications for Greater Sage-Grouse Management

“…However, the effect of grazing on insects depends upon both the vegetation type of the grazed habitat and the insect group considered (O'Neill et al 2003). Smith et al 2017 also reports that ranches that enrolled their land in NRCS SGI rotational grazing system varied in size and cattle numbers so individual grazing plans were generated to take account of these differences and individual landowner needs and that all ranch plans did adhere to the NRCS Montana Prescribed Grazing conservation practice standards. For a more detailed description of the SGI-Rotational Grazing System see Smith et al (2017).…”