Greater Sage-Grouse and Severe Winter Conditions: Identifying Habitat for Conservation

doi:10.2111/REM-D-11-00223.1

Rangeland Ecology & Management

Volume 66, Issue 1, January 2013, Pages 10-18

https://doi.org/10.2111/REM-D-11-00223.1 Get rights and content

Abstract

Developing sustainable rangeland management strategies requires solution-driven research that addresses ecological issues within the context of regionally important socioeconomic concerns. A key sustainability issue in many regions of the world is conserving habitat that buffers animal populations from climatic variability, including seasonal deviation from long-term precipitation or temperature averages, and that can establish an ecological bottleneck by which the landscape-level availability of critical resources becomes limited. We integrated methods to collect landscape-level animal occurrence data during severe winter conditions with estimation and validation of a resource selection function, with the larger goal of developing spatially explicit guidance for rangeland habitat conservation. The investigation involved greater sage-grouse (Centrocercus urophasianus) that occupy a landscape that is undergoing human modification for development of energy resources. We refined spatial predictions by exploring how reductions in the availability of sagebrush (as a consequence of increasing snow depth) may affect patterns of predicted occurrence. Occurrence of sage-grouse reflected landscape-level selection for big sagebrush, taller shrubs, and favorable thermal conditions and avoidance of bare ground and anthropogenic features. Refinement of spatial predictions showed that important severe winter habitat was distributed patchily and was constrained in spatial extent (7–18% of the landscape). The mapping tools we developed offer spatially explicit guidance for planning human activity in ways that are compatible with sustaining habitat that functions disproportionately in population persistence relative to its spatial extent or frequency of use. Increasingly, place-based, quantitative investigations that aim to develop solutions to landscape sustainability issues will be needed to keep pace with human-modification of rangeland and uncertainty associated with global climate change and its effects on animal populations.

Section snippets

INTRODUCTION

Climatic seasonality, or within-year variability in precipitation and temperature (Williams and Middleton 2008), is a prominent feature of temperate rangelands. In regions with a pronounced winter season, climatic seasonality is gauged in terms of winter severity or deviation from long-term temperature and precipitation averages. For animal populations, periods of below-average temperature and above-average snow depth can reduce landscape-level availability of food resources or cover, causing

Study Area

The 4 328-km² study area included portions of the Great Divide Basin in south-central Wyoming, United States (Fig. 1). The terrain was characterized by rolling sagebrush steppe, gently sloping flats, vegetated sand dunes, and badland hills ranging in elevation from 1 933 m to 2 385 m. Average maximum and minimum temperature during winter (1 November–31 March) is 1.7°C and -10.9°C, respectively; average monthly precipitation is 0.81 cm (Western Regional Climate Center 2011). Dominant vegetation

RESULTS

Minimum, maximum, and total (summed) transect length was 12.3, 73.4, and 563.6 km, respectively. We recorded 68 observations of sage-grouse in the study area during aerial surveys. Detection probability ranged from 1.0 on the transect to 0.53 at a perpendicular distance from the transect of 200 m. We estimated location error to be ≤ 100 m given the slow, low flight protocol, and based on visual examination of locations relative to the field notes and the transect buffer. The Hosmer and Lemeshow

DISCUSSION

Conservation of habitat such as severe winter range is a landscape sustainability issue because such habitat functions disproportionately in the persistence of animal populations relative to its spatial extent or frequency of use. Without a place to go when conditions become insupportable, a single climatic event can significantly reduce population size (Barrett 1982; Young 1994), potentially establishing or exacerbating issues that affect conservation in the long term such as genetic

IMPLICATIONS

Management strategies that include identifying and conserving habitat that buffers populations from climate-induced limitation on habitat availability would have general application across taxa and landscape types. Here critical habitat for sage-grouse during severe winter conditions was characterized by an intermediate density of tall sagebrush and other shrubs at the landscape level throughout places where there was little bare ground, a favorable thermal environment, moderately rough

ACKNOWLEDGMENTS

We thank F. Blomquist, M. Read, and R. Etzelmiller of the Bureau of Land Management, Rawlins Field Office, F. Blackgoat, C. Hedley, and two anonymous reviewers for guidance and helpful suggestions throughout this effort.

References (0)

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Research was funded by energy industry operators associated with the Continental Divide–Creston Environmental Impact Statement.

Current address: Larry D. Hayden-Wing, PO Box 1690, Laramie, WY 82073, USA.

Current address: Stephen L. Webb, Department of Scientific Computing, Samuel Roberts Noble Foundation, 2510 Sam Noble Parkway, Ardmore, OK 73401, USA.

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Research ArticleGreater Sage-Grouse and Severe Winter Conditions: Identifying Habitat for Conservation