Wintering Artemisiospiza sparrows: patterns of segregation between Sagebrush Sparrow ( A. nevadensis ) and Mojave Bell's Sparrow ( A. belli canescens ) across Lower Colorado Desert vegetation assemblages, with evidence for differential migration in Mojave Bell's Sparrow

Bell’s Sparrows (Artemisiospiza belli) have only recently been recognized as distinct from Sagebrush (A. nevadensis), and the “Mojave” subspecies b. canescens) shares an overlapping wintering distribution with Sparrow in Mojave Sonoran deserts of southeastern California western Arizona. We lack understanding two species’ respective habitat preferences degree to which they interact or segregate on their grounds due difficulty separating them field previous classification one species. captured sampled 74 Artemisiospiza sparrows 5 sites across Arizona, supporting identifications genetic analyses mitochondrial DNA confirm species molecular sexing individuals. segregated into different types our study area, detected at four five sites. comprised 82% (n = 33) 5th site Robbins Butte. Broadly, were found more upland, well-drained locations that less vegetated xerophytic scrub. halophytic seablite (Suaeda nigra) saltbush (Atriplex) adjacent mesquite tamarisk woodlands. sex ratios significantly female-biased (binomial test: n 56, observed k 48 females, expected 28 females for assumed p 0.5, Pr [k < 8 > 48] 0.0001; 95% CI 0.369 – 0.631 0.5) Fort Mohave Butte, 2 where found. Our sex-ratios well-documented year-round presence near breeding suggest males employ migration strategies, a phenomenon not previously documented this taxon.