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Sage grouse population connectivity and landscape change

Date: July 30, 2015

Electrical transmission power lines have an unexpectedly large impact on sage grouse


Greater sage-grouse (Centrocercus urophasianus) occupy a small fraction of their former range and are now threatened by extinction. Recent connectivity assessments for the greater sage-grouse in the Columbia Basin, Washington, provide an opportunity to (1) evaluate approaches for parameterizing resistance models based on sage grouse specifically or the concept of landscape integrity, (2) derive parameters from expert or empirical data, and (3) explore the influence of scale on model accuracy. This study looked at various models to try and better understand landscape resistance (i.e., how landscape features affect movement or gene flow of species) for sage grouse. Specifically, the study expored the ability to predict greater sage-grouse movement paths, genetic isolation, and patterns of lek occupancy.

Methods

For the study, two opinion-based models and two sets of empircal, data-driven models were evaluated. One of the opinion-based models was based on opinions of leaders in the field and the other was based on a landscape integrity model based on expert opinion that assumed lower human footprint areas would provide less landscape resistance for sage grouse.

Two groups of empirical models were also evaluated. Within these models there were numerous hypothesis. One empircal model focused on the relationship of gene flow to landscape features, and the other considered lek (i.e., breeding) occurrence and the influence of environmental and human factors on breeding sites.

Findings

  • The empirical models (breeding and gene flow) were very similar to each other in terms of results but were different than expert models. The empirical models predicted the occurrence of sage grouse more accurately.
  • Resistance models based on fine-scale spatial data and tailored to sage grouse tended to exhibited stronger relationships to empirical data than models based on coarse-scale spatial data or landscape integrity parameters.
  • Sage grouse occupancy and movement were highly impacted by electrical transmission line corridors in Washington state, an unexpected result not previously reported for sage grouse.

Can this information be extrapolated to other sage grouse populations outside of Washington? Across the West, sage grouse populations are the same species and transmission lines are nationally standardized. That said, research has not yet been conducted on populations outside of Washington to scientifically determine if transmission lines would offer the same level of resistance. 

View the press release for the project »

Featured Publications

Shirk, Andrew J. ; Schroeder, Michael A. ; Robb, Leslie A. ; Cushman, Samuel A. , 2015


Principal Investigators: 
External Partners: 
Principal Investigator: Andrew J. Shirk, University of Washington
Michael A. Schroeder, Washington State Department of Fish and Wildlife
Leslie A. Robb, Washington State Department of Fish and Wildlife