Life history parameters
A birds’ lifestyle and environment likely affect needs for feathers, and
so we attempted to quantify many life history and environmental
parameters for each species. All calculations of life history and
environmental parameters were conducted in R version 3.3.1 (R Core team
2016). Spatial data were extracted using shapefiles of species
distributions provided by Birdlife International and NatureServ
(Birdlife International 2016). We worked with the shapefiles of spatial
distributions of Parulidae using the packages GISTools (Brunsdon and
Chen 2014), maptools (Bivand and Lewis-Koh 2016), raster (Hijmans 2016),
and geosphere (Hijmans et al. 2005) in R. We chose to quantify life
history and environmental parameters that reflect factors that may
result in feather wear from solar exposure due to distribution and
migratory behavior, as well habitat use and foraging stratum. These
parameters are migratory distance, breeding latitude, wintering
latitude, day length experienced throughout the year, breeding and
winter habitat, breeding and winter foraging stratum, nest type,
intensity of solar radiation experienced over the year, intensity of
solar radiation experienced in the breeding and wintering range
(separately), and precipitation, minimum maximum and mean temperature,
and elevation, on the breeding and wintering ranges, separately. We also
calculated body mass. Below, we detail how we measured or scored these
parameters.