We used mitochondrial DNA to study the population structure and genetic diversity of the northern bobwhite (Colinus virginianus) west of the Mississippi River. We observed a lack of phylogeographic structure, high haplotype diversity, and low nucleotide diversity for northern bobwhites in this part of their geographic range. Despite the discordance between geographic patterns of mtDNA diversity and subspecies designations, we detected significant genetic differentiation among 4 subspecies, the plains (C. v. taylori), eastern (C. v. virginianus), Texas (C. v. texanus), and masked (C. v. ridgwayi) bobwhites. Evidence of significant isolation by distance and a latitudinal gradient with regard to the geographic distribution of haplotypes was also apparent. Neutrality tests, Bayesian skyline plots, and test of spatial expansion provided evidence of demographic and range expansion following the end of the last Pleistocene glaciation. Lack of phylogeographic structure indicates that morphological differences that are the basis of subspecies designations are of recent origin. Ecoregions may provide a better basis for management units than subspecies taxonomy for northern bobwhites in the western part of their geographic range. Our results indicate that much of the northern bobwhite's geographic range in the United States is the result of relatively recent colonization, which was a response to climate and habitat changes at the close of the Pleistocene. The northern bobwhite may be as vulnerable to fluctuations in climate as it has been to habitat and landscape changes during the past century. Ó 2014 The Wildlife Society.

The flight behavior and cover use of northern bobwhite (Colinus virginianus) have been examined in several studies, but the current data lack quantitative measures of how bobwhites respond to natural threats. We examined aspects of bobwhite behavior in response to 4 threat categories: researcher, hunter, raptor, and mammal. We found that bobwhite flight distance is best predicted by threat type and covey size, and bobwhite flight speed is best predicted by threat type. Bobwhites flushed by the hunter threat and the raptor threat selected for significantly taller obstruction at landing sites than was randomly available, with average heights of 6.2 cm taller (P = 0.034), and 38.1 cm taller (P < 0.001), respectively. Raptor‐flushed bobwhites also selected for significantly denser shrub cover (42.2%, P < 0.001) and a lower angle of obstruction (70.4°, P < 0.001) at landing points than was randomly available. In the process of data collection, we also observed bobwhite roost locations have lower visual height obstruction (7.3 cm, P = 0.03), lower shrub intercept (10.1%, P = 0.02), and greater angles of obstruction (18.5°, P = 0.005) than bobwhite diurnal locations; this may facilitate escape from nocturnal mammalian predators. Our results suggest that bobwhite escape strategies and cover use vary among threat types. These results support current management recommendations of creating a patchwork of vegetation covers for bobwhites but also suggest how a more complete understanding of bobwhite behavior would improve management and conservation efforts. © 2014 The Wildlife Society.

Distance sampling during aerial surveys has been used extensively to estimate the density of many wildlife species. However, practical issues arise when using distance sampling during aerial surveys, such as obtaining accurate perpendicular distances. We assembled a computerized, electronic system to collect distance‐sampling data (e.g., transect length, detection location, and perpendicular distance) during aerial surveys. We tested the accuracy of the system in a controlled trial and a mock survey. We also evaluated the electronic system during field surveys of northern bobwhite (Colinus virginianus) conducted in the Rio Grande Plains and Rolling Plains ecoregions of Texas, USA, during December 2007–2008. For comparison, we evaluated the accuracy of visual estimation of distance during a mock survey. A strong linear relationship existed between estimated and actual distances for the controlled trial (r2 = 0.99) and mock survey (r2 = 0.98) using the electronic system. Perpendicular‐distance error (i.e., absolute difference between estimated distance and actual distance) for the electronic system was low during the controlled trial (1.4 ± 0.4 m; ${\bar {x}}$ ± SE) and mock survey (3.0 ± 0.5 m) but not during the visual estimation of distance (10 ± 1.5 m). Estimates of bobwhite density obtained using the electronic system exhibited reasonable precision for each ecoregion during both years (CV < 20%). Perpendicular‐distance error slightly increased with target distance (0.7‐m increase in error for every 10‐m increase in target distance). Overall, the electronic system appears to be a promising technique to estimate density of northern bobwhite and possibly other terrestrial species for which aerial‐based distance sampling is appropriate. © The Wildlife Society, 2012

Small populations are vulnerable to increased genetic load and drift that can lead to reductions in fitness and adaptive potential. By analyzing 66 individual whole genomes of Montezuma Quail (Cyrtonyx montezumae) from multiple populations, we illustrate how genetic load is dynamic over evolutionary time. We show that Montezuma Quail are evolving like a ring species, where the terminal extant populations from Arizona and Texas have been separated for ~16,500 years. The Texas populations have remained small but stable since the separation, whereas the Arizona population is much larger today but has been contracting for thousands of years. Most deleterious mutations across the genome are young and segregating privately in each population and a greater number of deleterious alleles are present in the larger population. Our data indicate that ancestral load is purged during strong bottlenecks, but the reduced efficiency of selection in small populations means that segregating deleterious mutations are more likely to rise in frequency over time. Forward-time simulations indicate that severe population declines in historically large populations is more detrimental to individual fitness, whereas long-term small populations are more at risk for reduced adaptive potential and population-level fitness. Our study highlights the intimate connections among evolutionary history, historical demography, genetic load, and evolutionary potential in wild populations.

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