DOI: 10.5061/dryad.ks53j
title: Data from: Feather melanin and micro-structure variation in dark-eyed junco (Junco hyemalis) across an elevational gradient in the Selkirk Mountains

description: Variation in feather melanism and microstructure can arise through sexual
 selection and ecological functional drivers. Melanin-based plumage traits
 are associated with sexual dichromatism and the intensity of sexual
 selection in many avian species, but also have several ecological benefits
 such as protection against ultra-violet (UV) radiation, camouflage, and
 feather strength. Additionally, feather microstructure influences
 thermoregulation. Plumage variation across species is well documented;
 however, the relative role of sexual selection and ecological drivers in
 intra-specific and within-population variation is less established. We
 investigated UV reflectance, melanism, and feather microstructure in a
 population of Oregon dark-eyed juncos Junco hyemalis oreganus between high
 (1900–2200 m a.s.l.) and low (450–800 m a.s.l.) elevations in the Selkirk
 Mountains to evaluate potential sexual selection and ecological drivers of
 variation. We found no difference in UV reflectance or lightness
 (melanism) of head feathers between elevations, but individuals at high
 elevation had lighter (less melanism) and less brown (less pheomelanin)
 body contour feathers than at low elevations. High elevation individuals
 also had longer contour feathers with more pronounced plumulaceous
 regions. Sexual dichromatism did not vary between elevations, leading us
 to reject sexual selection in favour of ecological functional drivers of
 plumage variation in this system. To our knowledge, this is the first
 study to identify within-population differences in feather melanism and
 microstructure between different elevations.
description: Plumage colour
 measurements for Dark-eyed juncos in the Selkirk
 MountainsA combination of
 morphological and body condition data collected in the field, as well as
 LAB colour space data measured in Adobe Photoshop for head and dorsal
 regions. Column heading abbreviations: FWS is the unique individual
 identifier; std.l, std.a, and std.b are the L*A*B* colour variables for a
 black standard colour chip included in each photo; head.l, head.a, head.b
 are the L*A*B* colour variables for the mantle; back.l, back.a, back.b are
 the L*A*B* colour variables for the dorsal region.colour
 data_JAV-01050_R1.csvFeather microstructure
 measurements for Dark-eyed junco in the Selkirk
 MountainsA combination of body
 condition data and feather microstructure variables. Originally, all
 microstructure variables were measured twice on two separate feathers.
 After finding there was no difference between variables measured on
 separate feathers (P&gt;0.33), we pooled the variables within individual
 and the averaged values are depicted in this data set (i.e., one row per
 individual). Column heading abbreviations: penn.length & plum.length
 are the linear measurements of the pennaceous and plumulaceous feather
 regions respectively; penn.barb is the number of pennacous barbs counted
 to measure density; penn.density.length is the length over which the barbs
 were counted; penn.density is penn.barb/penn.density.length;
 penn.barbules: this series is the same as the penn.barb columns but for
 barbule densities measured twice (on two separate barbs); barbule.length:
 measurements of individual barbule length from 5 randomly selected
 barbules on the section of the barb that barbule density was
 measured.feather microstructure data _
 JAV-01050_R1.csvPlumage reflectance data
 for Dark-eyed junco in the Selkirk MountainsA combination of body
 condition data collected in the field and plumage reflectance data derived
 from the R package 'pavo' (Maia et al. 2013) which is based on
 Stoddard and Prum (2008)'s 'Tetracolourspace'. The data was
 generated using an average avian visual and achromatic cone system. Column
 heading abbreviations: u.p, s.p, m.p, l.p: proportion of ultra-violet,
 short wave, medium wave, and long wave reflectance, respectively; u.r,
 s.r, m.r, l.r: relative reflectance for each wavelength category; the
 remaining variables (x, y, z, h.theta, h.phi, r.vec, r.max, and
 r.achieved) were ultimately not used in the final analysis but serve to
 place individuals in a 3D Tetracolourspace and also allow calculation of
 variables such as brilliance and chroma which tend to be more important
 for carotenoid colours (see Stoddard and Prum 2008 for a more detailed
 description).Reflectance_JAV-01050_R1.csv