Assessing greater sage-grouse breeding habitat with aerial and ground imagery

Authors: BECK, J - University Of Wyoming; BOOTH, D - Retired ARS Employee; Kennedy, Carmen

Submitted to: Rangeland Ecology and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/20/2014
Publication Date: 3/15/2014
Citation: Beck, J.L., Booth, D.T., Kennedy, C.L. 2014. Assessing greater sage-grouse breeding habitat with aerial and ground imagery. Rangeland Ecology and Management. 67:328-332.

Interpretive Summary: Sagebrush-dependent species, including greater sage-grouse, are at risk due to habitat losses from a variety of man-made disturbances, wildfires, and weedy-plant invasions; thus, the selection of habitat inventory methods are an important part of the conservation and management of these species both for the data produced and for the cost to management budgets. We compared data from ground, aerial, and space photography to assess key habitat characteristics known to be important to sage-grouse breeding habitat (lekking, nesting, and brood-rearing). Measurements from ground and high-resolution aerial photography produced information not available from space photography and allowed development of cost figures for comparison with costs of conventional monitoring methods. We conclude that high-resolution photographic monitoring is a cost-effective means for detecting changes in sagebrush habitats across large landscapes and should be considered for complimenting and extending data from other habitat-monitoring methods.

Technical Abstract: Anthropogenic disturbances, wildfires, and weedy-plant invasions have destroyed and fragmented sagebrush (Artemisia L. spp.) habitats. Sagebrush-dependent species like greater sage-grouse (Centrocercus urophasianus; hereafter, sage-grouse) are vulnerable to these changes, emphasizing the importance of habitat monitoring to management. Conventional ground-based habitat inventory methods are expensive and time consuming, hindering data collection to support management decisions. Our study evaluated the feasibility of ground and aerial imagery to assess ground cover, plant taxa such as big sagebrush (Artemisia tridentata Nutt.), and vegetation functional groups known to be important to sage-grouse breeding habitat (lekking, nesting, and brood-rearing). We surveyed ~526 km2 of the upper Powder River watershed in Natrona County, Wyoming, USA, in a region dominated by Wyoming big sagebrush (Artemisia tridentata Nutt. ssp. wyomingensis Beetle & Young) communities interspersed with narrow riparian corridors. Our study area included 16 leks and provided year-round habitat to sage-grouse. In June 2010, we systematically-acquired aerial images for 3,228 locations; additional images were acquired as rapid-succession bursts where aerial transects crossed riparian areas, and for 39 riparian and upland ground stations within 3.2-km of leks. We used SamplePoint to quantify cover for plant taxa and functional groups using all ground images and a systematic sampling of aerial images. Our findings included canopy cover of sage-grouse food forbs within 3.2 km of leks, which—as averaged across aerial and ground imagery around all leks—was 1.8% and 7.8% in riparian areas and 0.5% and 4.0% in upland areas, respectively. Big sagebrush cover was 8.7% from upland aerial images and 9.4% from upland ground images. One-mm aerial and 0.3-mm ground imagery provided fine-scale data such as food-forb cover that compliments wider field-of-view scenes from lower resolution imagery. This and other image-derived archival data imply that image-based habitat surveys are cost-effective methods for monitoring changes in sagebrush habitats across large landscapes.