Greater Sage-grouse 'lek kernels' in the SageCon study area, southeastern and central Oregon

This dataset is a component of habitat connectivity analyses for Greater Sage-grouse (GSG) in southeastern and central Oregon conducted by The Nature Conservancy in Oregon (TNC) – see Jones (2015). Spanning the SageCon Assessment Area within Oregon plus a 10-mile buffer, the data demarcate areas of local landscape around leks that are modeled as the most accessible to a female sage-grouse moving outward from the lek in search of a suitable nesting site. These ‘lek kernels’ (the nodes of the analysis network) serve as both source and destination habitat patches between which habitat connectivity for sage-grouse movement was analyzed with reference to a related dataset, the cost-weighted distance (CWD) surface using the Linkage Mapper toolbox (McRae and Kavanagh 2011).

Lek kernels were ‘seeded’ at each specified lek and ‘grown’using the resistent kernel algorithm as a function of the CAPS traversability metric, one of three metrics of potential functional connectivity described in Compton et al (2007) and McGarigal et al (2012). The algorithm, which is a hybrid approach between the standard kernel estimator and least-cost paths (LCPs), estimates the realized ecological neighborhood around each target cell (lek) as a GIS focal operation (neighborhood statistic) using a dispersal parameter (bandwidth, measured as the standard deviation of the kernel, in meters), a cost (resistance) matrix, and a search distance (indicating the maximum spread of the kernel as a multiple of bandwidth). The bandwidth and search distance parameters were set to simulate a 5 km nesting movement distance, i.e. the distance from leks within which approximately 80% of sage-grouse nests were found to occur (Hagen 2011). Towards this goal, bandwidth was set to a value of 1705 and the search distance parameter to 3 so as to approximate (assuming a normal distribution) the desired radial kernel spread of 5 km. The resistance surface developed for sage-grouse across the SE Oregon study area served as the cost surface.

Lek kernels were delineated for a designated analysis set of leks in the study area. In Oregon, this comprised all leks within lek complexes in addition to those with a Conservation Status of ‘Occupied’, ‘Occupied pending’, ‘Unoccupied pending’, or ‘Unknown’. In areas of California, Nevada, and Idaho within the SageCon study area’s 10-mile buffer, all leks were included except those of ‘historic’(presently unoccupied) status.