Meeting Abstract
The Bell’s Sparrow (Artemisiospiza belli) and Sagebrush Sparrow (A. nevadensis) were split recently based on genetic, morphological, and ecological differences. These species meet in a narrow contact zone in eastern California where the Mojave Desert meets the Great Basin. The Bell’s Sparrow is smaller than the Sagebrush Sparrow, occupies a different ecological niche, and migrates shorter distances. We add to prior work by examining song differences at two scales: (1) among populations of A. nevadensis and three of four subspecies of A. belli; and (2) in detail across the contact zone. We studied over 8900 songs from 427 individuals and 27 sites, and measured a number of variables on sound spectrographs to quantify the frequency and temporal characteristics of songs. On a broad scale, songs reflect ecological similarity versus phylogenetic relatedness. Songs of A. b. belli are distinctive from a cluster that includes A. nevadensis, A. b. canescens, and A. b. clementeae. Within that cluster, A. nevadensis songs are distinctive from the other taxa. The endemic, threatened island subspecies (A. b. clementeae) has songs more typical of the ecologically similar A. b. canescens than the geographically proximate A. b. belli. At both scales, A. nevadensis and A. belli show marked differences in song frequency and temporal characteristics. Songs across the contact zone generally matched patterns of mtDNA and morphology, with more typical A. nevadensis songs at the northern end of the zone, more typical A. b. canescens songs at the southern end of the zone, and genetically mixed populations showing song characteristics of both taxa.
