Temporal and Spatial Trends of Northern Bobwhite Survival and Nest Success

The northern bobwhite (Colinus virginianus) has been declining in abundance across North America for many years. It is unknown, however, if other population variables also exhibit this downward trajectory. We conducted a retrospective-analysis of annual survival and nest success based on a literature review of 64 studies and compared these estimates temporally and spatially. We hypothesized that increased management efforts influenced bobwhite survival in the 1990s. Evidence from linear splining indicated survival trends changed in 1994. Thus, we compared trends across 3 periods: before 1994, after 1994, and overall. Mean (6 SD) annual survival was 13.9 6 9.4% across 31 studies from 1970 to 2007. Annual survival decreased 0.534% per year during 1970–1994 and stabilized thereafter. This stabilization in survival occurred along latitudinal and longitudinal gradients in which survival decreased at the northern and western periphery of the bobwhite range. Our linear splining models did not support the hypothesis that trends in nest success changed in the 1990s; thus, we only compared trends across the overall, 1924–2008 range of studies. Mean nest success across 33 studies was 44.4 6 15.2% during this interval and increased slightly across the 1924–2008 range of studies. We observed latitudinal gradients in nest success. Nest success was lowest at the northern periphery of the bobwhite range; it decreased 0.90% per degree of latitude. Annual survival stabilized after 1994 despite monotonic declines in bobwhite abundance since at least the 1960s. Range-wide survival and nest success trends may not parallel trends in abundance, particularly after 1990, which suggests biologists may not fully understand the range-wide population ecology of bobwhites. This lends support for the need to monitor other aspects of the bobwhites range-wide population dynamics as supplements to range-wide abundance

The Forgotten Quail Decline: The Plight of Scaled Quail in Texas

Several quail species are experiencing range-wide declines in the United States. The northern bobwhite (Colinus virginianus) has garnered the most attention, both from a research and conservation perspective. The bobwhite decline in Texas, has resulted in considerable time and effort being devoted to research and management on the species due to its status as a highly popular and economically important game bird. This attention has been beneficial to bobwhite conservation and management but, an unfortunate consequence of this focus has been neglect of the scaled quail (Callipepla squamata) that has been declining at even a more alarming rate. Scaled quail, according to Breeding Bird Survey (BBS) data, have declined at a rate of 5.1% per year in the Tamaulipan Biotic Province (southern Texas), the greatest of any region surveyed in its geographic range. Anecdotal reports of landowners have long noted the gradual disappearance of scaled quail and concomitant replacement with northern bobwhite throughout southern Texas, beginning since about the 1990s. Analysis of BBS data provides evidence for this replacement. Percent of quail detections in the core of the scaled quail range in the Tamaulipan Biotic Province were 80:20 (scaled quail: bobwhite) during the 1960s but currently represent about 5:95. In addition, the range of scaled quail has been contracting, moving progressively west with time. The species is no longer detected on the easternmost BBS routes in southern Texas

Spatial Analysis of Predator Abundance and Northern Bobwhite Nest Success in Southern Texas

Northern bobwhites (Colinus virginianus) have low nest success across their geographic range, and predation is the primary cause of failure. We evaluated the influence of relative abundance of predators on northern bobwhite nest success. We used data from a long- term radiotelemetry study conducted on 3 sites (800 ha each) in Brooks County, Texas during 2000–2007. We located bobwhite nests (n 1⁄4 456) using radiotelemetry and estimated Mayfield nest success each year. We also estimated relative abundance of nest predators using scent stations (400 3 400 m grid/site) during the nesting season (May–Aug). We developed a gradient map of predator relative abundance and correlated this variable with location-specific bobwhite nest success. Mayfield nest success during the incubation period (23 days) varied between 0.43 and 0.60 during the study. Scent-station visitation rates (% stations visited/night) ranged from 0 to 67%

Summer Whistle Counts, Roadside Counts, and Fall Abundance of Northern Bobwhite

Reliable information on fall abundance of northern bobwhite (Colinus virginianus) is important for proper harvest management. Aerial surveys can provide reliable estimates of abundance, but can be expensive. Alternatively, whistle counts and roadside counts are indices of abundance that are relatively inexpensive, simple, and commonly used by biologists. We compared whistle and roadside counts conducted during summer to fall relative abundance (coveys/km) estimates obtained using helicopter surveys. All data were collected at the pasture scale (mean 1⁄4 1,716–2,762 ha) on the King Ranch (334,000 ha), which is comprised of 4 divisions across South Texas. Average survey effort was 245 km/year (1999–2001) and 1,194 km/year (1999–2007) for whistle and roadside counts, respectively, and 48 km/pasture/year (1999–2009) for fall helicopter surveys. Preliminary analyses demonstrate a moderate correlation between whistling bobwhite males and fall relative abundance (r 1⁄4 0.68). We collected age-based (i.e., chicks, juveniles, and adults) and population structure-based (i.e., singles, pairs, or coveys) data for roadside counts. Correlations between roadside counts and fall relative abundance varied by age and population structure. We found moderate correlation between total juveniles and fall relative abundance (r 1⁄4 0.49); all other correlations were low (r 1⁄4 ,0.36). We explore the feasibility of using summer whistle and roadside counts as a surrogate for fall relative abundance and discuss optimum timing to conduct surveys

Habitat, Climate, and Raptors as Factors in the Northern Bobwhite Decline: A Multi-Scale Analysis

Landscape-level processes such as habitat loss and fragmentation are primarily responsible for the declines in northern bobwhite (Colinus virginianus). These landscape processes generally occur at a scale beyond that of traditional quail studies and may involve not only habitat loss and fragmentation but also broad-scale changes in climate trends and predation risk. However, reductions in usable space and changes in habitat configuration at smaller scales may also reduce population viability. It is therefore imperative to study relationships to bobwhite populations at multiple scales. The objective of our research is to quantify to what extent habitat loss and fragmentation, climate, and predators are affecting quail populations at multiple scales within Texas. Our study area will include the Rolling Plains and Rio Grande Plains ecoregions, which are historic strongholds of bobwhite, though each has seen recent declines. We will examine the relative contributions of 3 general factors (habitat, climate, and predators) on quail populations at multiple scales (ranch, route-level, and landscape). Specifically, these factors include total habitat amount, degree of fragmentation, raptor relative abundance, temperature, and precipitation. We will obtain data from multiple sources to determine quail trends (Breeding Bird Survey and ranch-level data) and relate habitat trends (National Land Cover Database and Texas Ecological Systems Classification Project), raptor abundance (Breeding Bird Survey), and climate factors (PRISM) within a multiple linear regression framework. This study will provide an understanding of 1) to what degree habitat loss and fragmentation are affecting quail populations on Texas rangelands, 2) how other factors such as climate and predators may be compounding these effects, and 3) how these relationships vary at multiple scales

Effects of Tanglehead Expansion on Bobwhite Habitat Use in South Texas

Usable space for northern bobwhite (Colinus virginianus) has been reduced across a large portion of South Texas rangelands due to the spread of non-native, invasive grasses. A native grass, tanglehead (Heteropogon contortus) has rapidly expanded its dominance in the western Sand Sheet of South Texas within the last 10-15 years. It has formed high-density monocultures, similar to non-native grasses, which are associated with losses of forb and grass diversity as well as bare ground, which are key components of bobwhite habitat. The objectives of our research were to 1) determine selection-avoidance of habitat features by bobwhites, and 2) determine the effects of tanglehead cover on vegetation characteristics. We detected 488 coveys across 20,103 ha on helicopter surveys conducted December 2014 in South Texas. We measured 6 vegetation characterstics (grass and forb species richness, vegetation height, woody-plant cover, tanglehead cover, and non-native grass cover) at all covey detections and an equal number of random locations. We developed continuous selection ratios based on probability density functions of used and random points derived using Simple Saddlepoint Approximations to determine habitat selection by bobwhites. We also used quantile regression at the 10th, 50th, and 90th quantiles to determine relationships between tanglehead and vegetation factors. Bobwhite avoided areas of high canopy cover (\u3e20%) of all invasive grasses measured. Brush cover was selected for up to 47%, after which it was avoided. We found significant negative relationships between tanglehead cover and forb and grass species richness, bare ground, and shrub cover, and a positive relationship with vegetation height at all quantiles modeled. Our results demonstrate the negative effects of increased tanglehead cover on native rangeland habitats. Further expansion by tanglehead has the potential to significantly reduce usable space for bobwhites in South Texas

Landscape-Scale Effects of Habitat and Weather on Scaled Quail Populations

Scaled quail (Callipepla squamata) have declined over the last half century; however, there is spatial variation within their geographic distribution. Interior populations have increased and peripheral populations have generally decreased. Declines have been attributed to habitat loss and degradation. Scaled quail populations also show interannual fluctuations related to precipitation. Our objective was to determine the relative impact of habitat and weather (i.e., precipitation and temperature) on scaled quail population dynamics. Our hypothesis was that habitat metrics would be more important for decreasing populations whereas weather metrics would be more important for increasing populations. We used publicly available datasets for scaled quail abundance measures (Breeding Bird Survey, Christmas Bird Count), weather (PRISM), and land cover (National Land Cover Data) collected over 3 5-year time periods (1990–1994, 1999–2003, 2009–2013). Data were collected at 2 scales: a route scale (5-km route buffer) and region scale (25-km circular buffer). We developed 25 a priori models that fit into 4 “model classes” (habitat amount, habitat fragmentation, matrix quality, weather). Model selection followed a 2-stage approach, where models were initially evaluated within each individual model class, then top models from each class were evaluated in combination to determine a global model. We used mixed-effects models with a negative binomial response distribution, treating route as a random effect. Weather variables were the primary explanatory factor for increasing populations at both scales. Similarly following our hypothesis, habitat variables were generally the most important for decreasing populations, but only at the route scale; weather variables dominated at the region scale. Both abundance datasets provided similar results and explanatory power (R2 ≈ 0.10 for route scale; R2 ≈ 0.27 for region scale), for both increasing and decreasing populations. Comparisons of land cover variables showed increasing populations to have higher amounts of habitat (p = 0.0028), higher mean patch area of habitat (p = 0.0446), and lower urban cover (p = 0.0287). Our hypothesis that weather variables account for more variation of increasing scaled quail populations was generally supported, likely because of increased amounts of habitat in these areas. However, given the low overall explanatory power of our models, it is likely that other factors such as habitat quality may be more important to scaled quail. Increasing temperature and reduced precipitation associated with climate change are likely to exacerbate scaled quail declines both directly and through continued habitat degradation, even within areas with increasing populations

MP758: East Regional Potato Trials 2006: Summary of NE1014 Regional Project Field Testing of New Potato Clones

The objectives of this regional potato trial are (1) to develop pest-resistant, early-maturing, long-dormant potato varieties that will process from cold storage; (2) to evaluate new and specialty variet­ies developed in the Northeast; (3) to determine climatic effects on performance to develop pre­dictive models for potato improvement; and (4) determine heritability/linkage relationships and improve the genetic base of tetraploid cultivated varieties. The results presented in this report reflect a portion of the activity directed toward objectives 1, 2 and 3.https://digitalcommons.library.umaine.edu/aes_miscpubs/1017/thumbnail.jp

MP760: East Regional Potato Trials 2007: Summary of NE1014 Regional Project Field Testing of New Potato Clones

The objectives of this regional potato trial are (1) to develop pest-resistant, early-maturing, long-dormant potato varieties that will process from cold storage; (2) to evaluate new and specialty variet­ies developed in the Northeast; (3) to determine climatic effects on performance to develop pre­dictive models for potato improvement; and (4) determine heritability/linkage relationships and improve the genetic base of tetraploid cultivated varieties. The results presented in this report reflect a portion of the activity directed toward objectives 1, 2 and 3.https://digitalcommons.library.umaine.edu/aes_miscpubs/1016/thumbnail.jp

MP757: Eastern Regional Potato Trials 2005: Summary of NE1014 Regional Project Field Testing of New Potato Clones

The objectives of this regional potato trial are (1) to develop pest-resistant, early-maturing, long-dormant potato varieties that will process from cold storage; (2) to evaluate new and specialty variet­ies developed in the Northeast; (3) to determine climatic effects on performance to develop pre­dictive models for potato improvement; and (4) determine heritability/linkage relationships and improve the genetic base of tetraploid cultivated varieties. The results presented in this report reflect a portion of the activity directed toward objectives 1, 2 and 3.https://digitalcommons.library.umaine.edu/aes_miscpubs/1018/thumbnail.jp