HABITAT_{SAVS}: the sum of the proportions of
the landscape within 500 m of the survey stations in each of the following
grassland types: pastures, alfalfa, grass and mixed grass/alfalfa hayfields,
fallow fields, and old fields.HABITAT_{BOBO}: the sum of the proportions of the landscape within 500 m of the point count stations in each of the following grassland types: pastures, grass and mixed
grass/alfalfa hayfields, and old fields. PROPOPEN500: the sum of
the proportions of the landscape within 500 m that is not forested or
developed based on digitized maps. WOODEDEDGEDENSITY500: edge
density of forest cover within 500 m, serving as an indication of the
"brokenness" of the landscape based on digitized maps. PROPOPEN2500: the sum of the proportions of the landscape
within 2500 m that is not forested or developed, based on the LCLU data
set. WOODEDEDGEDENSITY2500: edge density of forest cover within
2500 m, serving as an indication of the "brokenness" of the
landscape, based on LCLU data set. LEGUME: the percent cover of
the alfalfa, trefoil, and clover. FORB: the percent cover of forbs,
including dandelions (excluding legumes). LITTERDEPTH: vertical
depth of litter. AREA: the size of the field in hectares (see
text for field size definition). WOODEDPERIMETER: the proportion
of AREA that is bordered by trees (see text for
details). DAYSSINCECUT: the number of days since the field was
mowed, or the number of days since May 1, 2002 if the field was
uncut. NUMBERCUTS: the number of cuts performed on the field
during the study period; serves as an indicator of management intensity on
the field. CUT: a categorical variable describing whether a field
had been cut in the previous 2 weeks; used in removal analyses.
VEGHEIGHT: mean height of vegetation in the survey area on a
given count; used in removal analyses. FIELDPERIMETER: the
perimeter of the field in which the survey point was located (meters); used in
removal analyses.
