The northern bobwhite (Colinus virginianus) decline has become a cause ce´le´bre of wildlife conservation during the past 2 decades. With few exceptions, current broad-scale population trends show ongoing erosion in bobwhite numbers across most of the species' range. The causes of these declines are ultimate factors exacerbated by certain proximate factors. Ultimate factors are centered on the loss and fragmentation of habitat. Proximate factors such as predation and disease also may be present. The impacts of some factors, such as climate change, remain unknown but may influence bobwhite population trajectories over the long term. Progress has occurred in bobwhite conservation efforts since 1990 and has culminated in the formation of the National Bobwhite Technical Committee and the publication of the Northern Bobwhite Conservation Initiative. The vast majority of prevailing agricultural, forestry, and to some extent rangeland land uses in the United States continue as threats to bobwhite population persistence in the foreseeable future. Land-use patterns that once sustained widespread abundance of northern bobwhite during the early 20th century clearly are past and likely never to return. Landscape features that sustain and elevate northern bobwhite populations will only be maintained as a function of purposeful management actions directed at saving and creating usable space. ß 2012 The Wildlife Society.KEY WORDS adaptive management, bobwhite, Colinus virginianus, conservation planning, northern bobwhite, Northern Bobwhite Conservation Initiative, quail.Two decades ago, Brennan (1991) published an article titled, ''How can we reverse the northern bobwhite population decline?'' The publication outlined a series of observations and issues related to factors that were responsible for the nearly range-wide decline of the northern bobwhite (Colinus virginianus). Northern bobwhites had been declining at a considerable rate across their geographic range prior to 1991, but very few conservationists had taken notice. The publication of Brennan (1991) seemed to awaken a complacent quail profession that did not appreciate the general status of northern bobwhite in the United States at the time.Since the publication of Brennan (1991), considerable effort has been directed at the conservation of northern bobwhite and its habitat. When cast in a broader context of the past 2 decades, it is clear that bobwhite conservation efforts have gained traction, and perhaps even an element of critical mass, that will provide a basis for further achievement. We examine what has happened to the northern bobwhite over the past 20 years in the context of ultimate and proximate factors that influence their mostly declining populations. We identify ongoing and emerging threats to bobwhite conservation and discuss the initiatives that wildlife professionals, landowners, quail hunters, and conservationists have developed in an effort to stop the decline. Lastly, we use this paper as a forum to clarify some misunderstandings that were ...

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.

A landscape-scale assessment of how bobwhite productivity varies in relation to weather does not exist for northern bobwhite (Colinus virginianus). We collected age and sex ratio and body mass data from hunter-harvested bobwhites in 16 counties of South Texas (n ¼ 72,797 bobwhites) during 2001-2009 hunting seasons. We evaluated annual bobwhite production (juvenile:adult age ratios) as a function of cumulative April-August rainfall using National Oceanic and Atmospheric Administration (NOAA) weather station data from Falfurrias and Hebbronville, Texas. We observed minimal among-year change in percent males harvested (51.0-54.5% male) and mean mass (156-160 g) of bobwhites across South Texas. We found no relationship between percent male or body mass and weather. We documented a positive, linear relationship between cumulative April-August rainfall and bobwhite age ratios (r 2 ¼ 0.94); we also documented a negative, linear relationship between summer (Jun-Aug) mean maximum daily temperature and bobwhite age ratios (r 2 ¼ 0.38). Our results suggest that rainfall is a landscape-scale indicator of annual bobwhite production in South Texas and can thus be used to manage annual expectations of quail hunters prior to the hunting season. ß 2012 The Wildlife Society.

Since the 1950s, many south Texas rangelands have been seeded with buffelgrass, a perennial C4 bunchgrass native to Africa that is believed to contribute to reductions in biodiversity. Forb species represent a critical habitat component throughout the breeding period for many wildlife species as seed (summer to fall), as green vegetative material (spring to summer), and as habitat for arthropods (spring to summer). Reductions in richness and diversity of crucial ecosystem components such as forbs and arthropods have large implications for grassland birds and other wildlife. We sampled annual and perennial forbs within 1-m2 quadrats on 15 study plots (1 ha; n = 20 quadrats/plot) at Chaparral Wildlife Management Area, in LaSalle and Dimmit counties, Texas, during 2005 and 2006. Study plots were divided into five light-buffelgrass plots (0 to 5% buffelgrass canopy coverage), five moderate-buffelgrass plots (5 to 25% buffelgrass canopy coverage), and five heavy-buffelgrass plots (> 25% buffelgrass canopy coverage). Buffelgrass in study plots was composed of naturalized plants, and was not deliberately planted. During 2005 we observed that plots with > 25% buffelgrass had a 73% reduction in forb canopy of native species, a 64% reduction in native forb species richness, and a 77% reduction in native forb stem density compared to plots with 0 to 5% buffelgrass. These trends in native forb reduction (−79% native forb canopy, −65% forb species richness, −80% forb stem density) were nearly identical in 2006, even with greatly reduced rainfall. Simple linear regression revealed negative relationships between buffelgrass cover, total exotic grass cover (buffelgrass and Lehmann lovegrass), and total grass cover and the richness, coverage, and density of forbs/m2. Reductions in diversity may have larger implications regarding ecosystem function and available useable space and densities of desired bird species such as northern bobwhite.

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