Identifying and Prioritizing Greater Sage-Grouse Nesting and Brood-Rearing Habitat for Conservation in Human-Modified Landscapes

Abstract

BackgroundBalancing animal conservation and human use of the landscape is an ongoing scientific and practical challenge throughout the world. We investigated reproductive success in female greater sage-grouse (Centrocercus urophasianus) relative to seasonal patterns of resource selection, with the larger goal of developing a spatially-explicit framework for managing human activity and sage-grouse conservation at the landscape level.Methodology/Principal FindingsWe integrated field-observation, Global Positioning Systems telemetry, and statistical modeling to quantify the spatial pattern of occurrence and risk during nesting and brood-rearing. We linked occurrence and risk models to provide spatially-explicit indices of habitat-performance relationships. As part of the analysis, we offer novel biological information on resource selection during egg-laying, incubation, and night. The spatial pattern of occurrence during all reproductive phases was driven largely by selection or avoidance of terrain features and vegetation, with little variation explained by anthropogenic features. Specifically, sage-grouse consistently avoided rough terrain, selected for moderate shrub cover at the patch level (within 90 m2), and selected for mesic habitat in mid and late brood-rearing phases. In contrast, risk of nest and brood failure was structured by proximity to anthropogenic features including natural gas wells and human-created mesic areas, as well as vegetation features such as shrub cover.Conclusions/SignificanceRisk in this and perhaps other human-modified landscapes is a top-down (i.e., human-mediated) process that would most effectively be minimized by developing a better understanding of specific mechanisms (e.g., predator subsidization) driving observed patterns, and using habitat-performance indices such as those developed herein for spatially-explicit guidance of conservation intervention. Working under the hypothesis that industrial activity structures risk by enhancing predator abundance or effectiveness, we offer specific recommendations for maintaining high-performance habitat and reducing low-performance habitat, particularly relative to the nesting phase, by managing key high-risk anthropogenic features such as industrial infrastructure and water developments.

Incorporating within- and between-patch resource selection in identification of critical habitat for brood-rearing greater sage-grouse

“…Identifying resources necessary for critical life-history phases (e.g., brood-rearing, nesting, and roosting) and survival are important for managing landscapes (Dzialak et al 2011b), especially when landscapes are exposed to large-scale modification from climatic and anthropogenic sources. The needs of brooded hens and their chicks revolve around nutrition acquisition, protection from predation, water needs, and favorable thermal environments.…”

“…The needs of brooded hens and their chicks revolve around nutrition acquisition, protection from predation, water needs, and favorable thermal environments. Brood-rearing areas for sage-grouse include moderate shrub coverage with a prominent sagebrush component, proximity to mesic areas, and herbaceous vegetation such as forbs that also harbors insects (Hagen et al 2007;Dzialak et al 2011b;Harju et al 2013a). However, less is known about how behavior structures the use of resources during critical seasons.…”

“…One of the most useful and prevalent applications of species occurrence modeling is spatial prioritization of management activity, wherein habitat that is identified as having a high probability of importance to wildlife is managed differently than habitat that is predicted to be used with low frequency or otherwise of less importance (Margules and Pressey 2000; Aldridge and Boyce 2007;Sawyer et al 2009;Dzialak et al 2011b). Efforts to identify and prioritize important wildlife habitat are particularly relevant in human-modified areas where wildlife conservation may be one of the several valued land uses or where protecting large contiguous areas of unmodified habitat is not an option (Moilanen et al 2005).…”

“…Behavioral mode is a variable that the investigator may wish to characterize before conducting further analysis (Van Moorter et al 2010) or incorporate as a latent process into structural equation or time-series models (Patterson et al 2008). Depending on the scale of investigation, dominant breeding season behavioral modes of sage-grouse might include pre-nesting behavior such as lek attendance, nest-site selection, nesting off-bout behavior, and between-versus within-patch movement of the brooded female (Aldridge and Brigham 2002;Aldridge and Boyce 2007;Doherty et al 2010;Dzialak et al 2011b). Global positioning system (GPS) data at a fine temporal scale make transitions between these modes readily observable (Dzialak et al 2011b).…”

“…Depending on the scale of investigation, dominant breeding season behavioral modes of sage-grouse might include pre-nesting behavior such as lek attendance, nest-site selection, nesting off-bout behavior, and between-versus within-patch movement of the brooded female (Aldridge and Brigham 2002;Aldridge and Boyce 2007;Doherty et al 2010;Dzialak et al 2011b). Global positioning system (GPS) data at a fine temporal scale make transitions between these modes readily observable (Dzialak et al 2011b). Identifying behavioral mode within the context of current management establishes the opportunity to quantitatively assign observed data to a defined mode as an initial analytical step.…”