Timing of Vegetation Sampling at Greater Sage-Grouse Nests

Habitat management guidelines for greater sage-grouse, Centrocercus urophasianus, have been formulated, in part, based on studies of nest site selection. However, these guidelines may not represent conditions when the female initiates nesting because sampling occurs posthatch (> 30 days after nest initiation) to avoid disturbing incubating females. In 2002, we investigated differences in 22 habitat variables at initiation and hatch. Sampling was at 30 randomly selected active nests marked in 2001. There was no significant difference in structural or cover data (P > 0.05). Grass height and percent grass cover differed (P < 0.05) based on timing of sampling. Grass heights at the nest bowl and at 1m from the edge of the nest bowl were 10 and 9cm at initiation and 16 and 13cm at hatch, respectively. Percent grass cover increased from 4% to 6% cover from initiation to hatch. Sampling occurred in a dry year; differences in grass heights and percent cover may be more pronounced in years of normal precipitation. Preliminary results indicated current habitat sampling techniques conducted posthatching adequately described selection of structural components of shrub height, visual obstruction, and percent cover of shrubs, bare ground, litter, and forbs at the nest site at initiation. Data need to be verified for other study areas and under different climatic conditions.