DOI: 10.5061/dryad.gmsbcc2tp
title: Mojave Bell's Sparrow (Artemisiospiza bellii canescens) and Sagebrush Sparrow (Artemisiospiza nevadensis) captures at western Arizona sites, February 2014

description: Bell’s Sparrows (Artemisiospiza belli)) have only recently been recognized
 as distinct from Sagebrush Sparrows (A. nevadensis), and the “Mojave”
 subspecies (A. b. canescens) shares an overlapping wintering distribution
 with Sagebrush Sparrow in the Mojave and Sonoran deserts of southeastern
 California and western Arizona. We lack understanding of the 2 species’
 respective wintering habitat preferences and the degree to which they
 interact or segregate on their wintering grounds due to the difficulty in
 separating them in the field and to their previous classification as one
 species. We captured and sampled 74 Artemisiospiza sparrows from 5 sites
 across western Arizona, supporting field identifications with genetic
 analyses of mitochondrial DNA to confirm species and molecular sexing of
 sampled individuals. Bell’s Sparrows and Sagebrush Sparrows segregated
 into different habitat types across our study area, with only one species
 detected at 4 of 5 study sites. Bell’s Sparrows comprised 82 percent (n =
 33) of Artemisiospiza sparrows captured at the 5th site at Robbins Butte.
 Broadly, Sagebrush Sparrows were found in more upland, well-drained
 locations that were sparsely vegetated with xerophytic scrub. Bell’s
 Sparrows were found in more vegetated locations with halophytic Mojave
 seablite (Suaeda nigra) and saltbush (Atriplex) adjacent to mesquite and
 tamarisk woodlands. Bell’s Sparrow sex ratios were significantly
 female-biased (binomial test: n = 56, observed k = 48 females, expected k
 = 28 females for assumed p = 0.5, Pr (k ≤ 8 or k ≥ 48) &lt; 0.0001;
 95% CI = 0.369 – 0.631 for assumed p = 0.5) at Fort Mohave and Robbins
 Butte, the 2 sites where Bell’s Sparrows were found. Our observed
 sex-ratios and well-documented year-round presence of Bell’s Sparrows on
 and near the breeding grounds suggest that Bell’s Sparrow males and
 females employ different migration strategies, a phenomenon not previously
 documented for this taxon.
description: This data set includes photographs for Bell's Sparrows and
 Sagebrush Sparrows at 5 sites across western Arizona, captured and
 photographed from February 6–16, 2014. The data set also includes habitat
 photographs at the 5 sites. 
 <em>Artemisiospiza</em> sparrows were captured
 following a flush-netting method described in Gordon (2000). Scouting was
 required at each site, given that a) preceding reports of recent
 <em>Artemisiospiza</em> sightings were vague as to the precise
 location of potential captures, the reports occasionally dated, and b)
 wintering <em>Artemisiospiza</em> are nonterritorial (Martin
 and Carlson 2020a). Presence of <em>Artemisiospiza</em>
 sparrows determined where nets were placed; all vegetation types were
 scouted at sites with multiple vegetation assemblages (Robbins Butte, Fort
 Mohave, Boundary Cone), and the yellow-outlined capture areas depicted in
 Figures 2a – 2e correspond to where <em>Artemisiospiza</em>
 sparrows were found. Upon locating
 <em>Artemisiospiza</em> sparrows during scouting, we aligned 4
 to 6 mist nets (2 x 10 m, 32- and 36-mm mesh) from end to end in a line
 near sighted birds, with care taken to hide nets in natural gaps in shrub
 cover when possible. We spaced ourselves and typically 8 to 15 volunteers
 into a large C-shaped semi-circle then slowly herded sparrows toward the
 net line. The net line was then dismantled and placed in a new location,
 contingent on where uncaptured birds moved while herding them toward nets
 or where new groups of potential captures were found. Two to approximately
 12 net placements were attempted at each site, depending on the success of
 preceding flushing attempts. Photographs were processed
 in Adobe Lightroom. We photographed captured
 <em>Artemisiospiza</em> with a Nikon digital single-lens
 reflex camera and 300 mm lens. We photographed each individual’s back,
 tail, nape, crown, profile, front, and opened wing. Each individual's
 set of photographs is provided in a file bearing the individual's
 unique USGS numbered aluminum band. File names include processing settings
 (e.g., sharpness, exposure) in Adobe Lightroom.
description: These are easily opened .jpg files.