DOI: 10.5061/dryad.w3r2280mw
title: Divergence in plumage, voice, and morphology indicates speciation in Rufous-capped Warblers (Basileuterus rufifrons)

description: The biodiversity of the Neotropics is considerable, but it is likely
 underestimated owing to gaps in sampling effort and a focus on using
 morphological features of animals to determine species differences rather
 than divergence in their mating signals and behavior. Recent multi-trait
 analyses incorporating morphological, plumage, and vocal data have allowed
 for more accurate quantification of tropical biodiversity. We present a
 comprehensive study of morphological features, plumage, and vocalizations
 of the Neotropical resident Rufous-capped Warbler (Basileuterus
 rufifrons). This species’ taxonomic status is controversial because the B.
 r. salvini subspecies is intermediate in plumage coloration between the
 neighboring B. r. delattrii and B. r. rufifrons subspecies. Using
 morphological and spectral plumage measurements of field and museum
 specimens, as well as analyses of vocalizations from field recordings and
 sound libraries, we compared phenotypes of all eight currently recognized
 Rufous-capped Warbler subspecies, with an emphasis on delattrii,
 rufifrons, and salvini. We found that delattrii and rufifrons differ
 significantly in morphology and plumage, and that salvini is similar to
 rufifrons in morphology and some plumage features. Vocalizations fall into
 two distinct groups, delattrii and rufifrons-salvini, which differ in
 multiple spectro-temporal characteristics with no overlap between them,
 even among individuals in the delattrii-rufifrons zone of sympatry. Our
 results therefore suggest that Rufous-capped Warblers comprise two
 distinct groups: Rufous-capped Warblers (B. r. rufifrons and salvini as
 well as B. r. caudatus, dugesi, and jouyi) and Chestnut-capped Warblers
 (B. r. delattrii as well as B. r. actuosus and mesochrysus). Future
 genomic analysis of samples from multiple sites in Mexico and Central
 America will further refine our assessment of range-wide phenotypic and
 genetic divergence in this species complex.
description: Morphology data: Wing, tail, tarsus, and bill measurements were
 collected from museum specimens and live birds caught in the
 field. Plumage coloration data: Spectrometry
 measurements were collected from 10 body regions for each museum specimen
 included in the analysis. Song data: Recordings of
 singing birds were obtained in the field, and from the Macaulay and
 University of Florida natural sound archives. The audio files were
 high-pass filtered and spot-filtered to remove non-target background
 sounds. The associated audio files included are minimally processed
 versions (unprocessed or high-pass filtered only).
description: <strong>Morphology:</strong> Data
 spreadsheets: (1) RCWA_morphology.csv (all analyses except DFA for
 females: all subspecies); (2) FemalesDFA.csv (DFA for females: all
 subspecies) R script: RCWA_morphology.R
 <strong>Plumage coloration:</strong>
 Data spreadsheets: (1) RCWA museum data summary_all.csv (raw
 spectral data); (2) RCWA.spec_processed_2.csv (data summarized by
 individual) R script: (1) RCWA spectral analysis_3spp.R
 (3-subspecies analysis); (2) RCWA spectral analysis_plumage_grps.R
 (plumage groups analysis) Raw data (folder): AUK-19-195
 RCWA spectrometry (spectrometry data)
 <strong>Song:</strong> Data
 spreadsheets: (1) RCWA_vocal analysis.csv (measurements summarized
 for each song); (2) RCWA songs_average.csv (data summarized by
 individual) R script: RCWA_vocal analysis.R
 Raw data (folder): RCWA song audio files