In order to sample the distribution of these four species across the National Forests of the Sierra Nevada, we are using a
standardized point count method (Ralph et al. 1995, Ballard et al. 2003) where a single observer estimates the distance to
the location of each individual bird they detect within a five minute time span from a fixed location. Call-playback surveys
are also conducted (for Hairy Woodpecker and Mountain Quail) on a subset of the point count locations by broadcasting the
vocalizations of these species and then listening for a response. Point counts were conducted during the spring/summer
breeding season in early to mid-morning when weather conditions were mild. To minimize observer bias, we had different
observers conduct surveys on each of the two visits per year, and all biologists were thoroughly trained in survey
techniques and bird identification.
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We used a generalized random-tessellation stratified (GRTS) sampling scheme to distribute survey locations evenly
across the region to avoid clustering in any given area (one particular forest for example) while remaining random at the
local level to avoid bias due to natural spatial patterns of habitat and physiographic conditions. We selected survey sites
in two separate samples based upon habitat. The first sample includes upland montane chaparral and 'green forest', which
encompass the habitats for Mountain Quail, Hairy Woodpecker, and Fox Sparrow. The second sample includes only riparian
areas to target Yellow Warbler habitats. We defined our range of habitats broadly so that any CWHR types that are currently
considered appropriate habitat or could transition to them through natural processes or management actions (e.g. fire,
silvicultural treatments) are included in the sample. Thus we chose to include all conifer forest regardless of age structure,
since even old-growth stands have the potential to become early-seral forest, and we include all riparian habitat and
meadows even when shrubs are not present to ensure that if succession takes place we will have the potential to detect the
establishment of MIS populations in those areas. In order to efficiently locate our field sites, we limited the set of
potential survey locations to areas within 1 kilometer of roads, elevations between 1000 and 2800 meters, and on slopes less
than 30%.
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