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Table 2 Variables considered important to greater sage-grouse nest survival in central Wyoming

From: Landscape features and weather influence nest survival of a ground-nesting bird of conservation concern, the greater sage-grouse, in human-altered environments

Variable

Covariate

Scale (m)

Vegetation

   Shrub height (-)

Height of shrub (cm) at nesta

15b

   Bare ground (-, +)

Percentage (%) of bare groundc

30d

   Litter (-, +)

Percentage (%) of litterc

30

   Forbs (+)

Percentage (%) of forb covera

15

   Grass (-)

Percentage (%) of grass covera

15

   Total herbaceous (-)

Percentage (%) of total herbaceous covera

15

   Sagebrush (-, +)

Percentage (%) of sagebrush coverc

15

   Shrubs (+)

Percentage (%) of total shrub cover a

15

   Mesic (+)

Distance (m) to mesic habitat year of nest e

N/A

Topography

   Elevation (-, +)

Elevation (m)c

30

   Slope (+)

Slope (%)a

30

   Roughness (+)

Roughness index (SD of elevation)a

1,590d

Anthropogenic

   Oil and gas wells (+)

Distance (m) to wells year of nest e

N/A

   Structures (-)

Distance (m) to structures year of neste

N/A

   Ancillary features (-)

Distance (m) to ancillary features year of neste

N/A

   Roads (-)

Distance (m) to roads year of nest a

N/A

Others

   Initiation date (+)

Julian date for first day of nest incubation a

N/A

   Nest age (-)

Age of nest (in days) a

N/A

  1. aLinear term. bRefers to on-the-ground measurements of vegetation at the nest site using either Daubenmire plots (forbs, grass, and total herbaceous vegetation) or line transects (percentage of sagebrush and shrub canopy cover). cLinear + quadratic term. dSpatial scales depicted as an area (e.g., 30 or 1,600 m) using remotely sensed imagery and heads-up digitizing to estimate variables. eNatural log-transformed variable to allow for a decreasing magnitude of influence with increasing distance. Variables selected from a suite of variables at multiple spatial scales (the spatial scale for each variable with the lowest AICc was retained) that were considered to influence nest survival of female greater sage-grouse in the Wind River Basin in central Wyoming, USA. Variables in italicized text were entered into a landscape model after variable reduction based on AICc, correlation (PROC CORR; SAS® 9.2), and non-significance (P > 0.1), and used as a null landscape model for testing the influence of weather on daily nest survival. Signs (positive or negative) in parentheses next to landscape variables represent the relationship between the particular variable and the probability of DSR (when two signs occur, the first represents the linear relationship and the second represents the quadratic relationship). SD, standard deviation; N/A, not applicable.