Quail and rain in semiarid rangelands: Does management matter?

Rainfall is a strong driver of quail populations on southwestern rangelands and can account for a large portion (~70–95%) of the variability in regional quail production and abundance. Landowners have attempted to moderate these boom-and-bust fluctuations via management; however, presently it is unknown whether management can increase or stabilize quail populations in semiarid environments or whether rainfall remains as influential at small spatial extents. Our objectives were to evaluate the efficacy of management at mitigating the effects of rainfall on northern bobwhite (Colinus virginianus) populations on semiarid rangelands and to quantify the influence of rainfall on bobwhite density at smaller spatial extents. We conducted a study to evaluate these objectives during 2014–2020 in the Rio Grande Plains (n = 11 sites; 1,100‒6,500 ha) and Rolling Plains (n = 4 sites; 1,900‒4,000 ha) of Texas, USA. We estimated bobwhite density during late autumn (Dec‒Jan) on all sites using helicopter surveys within a distance-sampling framework. We also obtained site-level seasonal rainfall (Apr‒Aug) and quantified management intensity via landowner surveys and a scoring rubric to categorize sites into 3 classes (low, medium, and high management intensity). Bobwhite populations during this study experienced a boom-bust cycle in both the Rio Grande Plains and Rolling Plains, with mean bobwhite density fluctuating considerably (0.57‒2.96 bobwhites/ha and 0.02‒2.88 bobwhites/ha, respectively). In the Rio Grande Plains, mean bobwhite density significantly increased from low to high management intensity in 2015 (1.12 ± 0.17 bobwhites/ha vs. 2.87 ± 0.39 bobwhites/ha, respectively), 2016 (1.06 ± 0.20 bobwhites/ha vs. 2.96 ± 0.36 bobwhites/ha, respectively), 2017 (0.73 ± 0.16 bobwhites/ha vs. 1.91 ± 0.32 bobwhites/ha, respectively), and 2019 (0.42 ± 0.14 bobwhites/ha vs. 1.01 ± 0.26 bobwhites/ha, respectively; P < 0.05). In addition, rainfall at the site level accounted for a low amount of the variation in bobwhite density (r² = 0.09; P < 0.01). Similarly, in the Rolling Plains, mean bobwhite density significantly increased from low to high management intensity in 2015 (1.30 ± 0.27 bobwhites/ha vs. 2.20 ± 0.29 bobwhites/ha, respectively) and 2016 (1.26 ± 0.26 bobwhites/ha vs. 2.88 ± 0.34 bobwhites/ha, respectively; P < 0.05). Rainfall at the site level also accounted for a low amount of the variation in bobwhite density (r² < 0.02; P = 0.82). Our findings suggest that management can increase bobwhite density beyond that of less-managed properties but does not completely eliminate inter-annual fluctuations in semiarid environments. In addition, rainfall appears to exert less of an influence on bobwhite density at a site level (e.g., 2,000 ha) than has been documented at a regional level (e.g., ≥8 million ha).     

Impacts of weather on northern bobwhite sex ratios,body mass,and annual production in South Texas

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 = 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 (r² = 0.94); we also documented a negative, linear relationship between summer (Jun–Aug) mean maximum daily temperature and bobwhite age ratios (r² = 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. © The Wildlife Society, 2012     

Effect of Radiotransmitters on Northern Bobwhite Annual Survival

Abstract: Radiotelemetry has been widely used in northern bobwhite (Colinus virginianus) research to estimate survival rates and other demographic parameters. Biologists have used this knowledge to study bobwhite ecology, develop management theory, and base management actions. We tested the assumption that radiotransmitters do not bias survival rates of bobwhites by comparing survival rates of banded bobwhites with and without radiotransmitters on Tall Timbers Research Station (TTRS) from 1999 to 2004. We used Burnham's model in Program MARK and model-selection procedures to determine relative importance of year, gender, and radiotagged status on annual survival rates and recovery processes. Three plausible models (relative quasi-likelihood Akaike's Information Criterion [ΔQAIC_c] < 3) included year dependence in survival and an additive effect of gender but no radiotransmitter effect. Models including a radiotransmitter effect in survival were >8 ΔQAIC_c from the top models, had low Akaike model weights (w_i < 0.007), and low importance weight (S̀w_i(radio) = 0.01). We also compared band—recapture survival estimates from the QAIC_c minimizing model to staggered entry Kaplan—Meier (KM) survival estimates from 2000 to 2003. Annual KM survival estimates of male and female bobwhites were within the 95% confidence interval of band—recapture estimates in 7 of 8 comparisons. We conclude that radiotelemetry is a reliable technique for determining bobwhite survival. Managers should view information from properly conducted telemetry research as reliable and useful for management.     

A population model to simulate northern bobwhite population dynamics in southern Texas

Models are important tools that can help managers and researchers understand the population dynamics of a species and how different habitat or population management scenarios impact that species. We used radio-telemetry data from northern bobwhites (Colinus virginianus) in southern Texas from 2000 to 2005 to develop a stochastic simulation model for bobwhite populations. Our model is based on difference equations, with stochastic variables drawn from normal and Weibull distributions. We simulated bobwhite populations to 100 yr and evaluated our model by comparing results with independent estimates of 4 population parameters (spring and fall density, finite rate of increase in the fall population [λ], and winter juv:ad age ratios). Using a quasi-extinction criterion of ≤40 birds (density = ≤0.05 birds/ha), probability of persistence to 100 yr was 88.3% (106 of 120 simulations) for the spring population and 96.7% (116 of 120 simulations) for the fall population. Using a less restrictive quasi-extinction criteria (≤14 birds), probability of persistence was 93.3% (112 of 120 simulations) for the spring population and 98.3% (118 of 120 simulations) for the fall population. Simulated population parameters were similar to independent estimates for 4 of 4 population parameters. Winter age ratios differed between our model ( juv:ad, n = 120, SE = 0.32) and empirical age ratios from harvested bobwhites on our study area ( juv:ad, n = 25, SE = 0.24). However, when we corrected harvest age ratios for bias in juvenile harvest ( juv:ad, n = 25, SE = 0.32) simulated and empirical estimates were similar. Our model appears to be a reliable predictor of bobwhite populations in the southern Texas. Our simulation results indicate that bobwhite hunters and managers can expect excellent bobwhite hunting (fall populations ≥2.2 birds per ha) in about one of 10 yr. © 2011 The Wildlife Society     

Northern Bobwhite Chick Survival and Effects of Weather

Reliable vital rates for all life stages are necessary to identify limiting factors in wildlife populations and inform sound wildlife management. The difficulty associated with capturing and tagging precocial young, such as northern bobwhite chicks (Colinus virginianus), and linking variation in recruitment to ecological conditions has contributed to significant knowledge gaps in their population ecology. During 1999–2017, we captured and patagial-tagged ≤12-day-old bobwhite chicks (n = 3,576) and estimated their survival from time of capture (Jun–Sep) to fall and winter (Nov and Jan) recapture and winter (Feb) recovery. We used Burnham's model implemented in Program MARK to integrate mark-recapture and dead-recovery (via harvest) data to estimate survival for the 19-year study. By including weather covariates, we also evaluated explicit hypotheses related to temperature and precipitation effects on chick survival. We found inter-annual, intra-annual, and intra-seasonal variation in chick survival with an average annual daily survival estimate of 0.9887 (95% CI = 0.9321, 0.9918). Precipitation amount and number of precipitation (>0.635 cm) events during the first 4 weeks post-tagging decreased the daily survival rate of chicks curvilinearly. Average minimum daily temperature and maximum daily temperature effects on survival were negligible, but an interaction between minimum temperature and cumulative precipitation during the first 14 days post-tagging affected survival. We recommend population modelers incorporate intra- and inter-annual variation in chick survival to improve predictions. Observed variation in chick survival rates portends a significant opportunity to improve population management for bobwhites and other game birds. © 2019 The Wildlife Society     

Northern Bobwhites and Postfire Succession

ABSTRACT Our study evaluated the effects of prescribed fire on northern bobwhites (Colinus virginianus) occupying native rangelands in Rolling Plains of Texas, USA, during 2002 and 2003. Prescribed fires were conducted during February of 1996, 1998, and 2000; pastures with no recent treatment history served as controls. We quantified bobwhite densities from line transects using distance sampling. We used a repeated-measures analysis of variance to test for treatment-year differences in bobwhite densities. We measured postfire herbaceous and woody vegetation attributes and evaluated vegetation relationships to bobwhite density using simple linear regression. We found significant between-year differences in fall bobwhite densities (F = 13.05, df = 3, P = 0.036) but no differences among treatments or controls. Fall bobwhite densities were inversely related to visual obstruction (r² = 0.179, df = 15, P = 0.058) and positively associated with increasing heterogeneity of grass cover (r² = 0.416, df = 15, P = 0.004). Our results suggest prescribed fire at large spatial scales may be a neutral practice for managing bobwhite habitat on semiarid rangelands.     

Combining Breeding Bird Survey and Christmas Bird Count Data to Evaluate Seasonal Components of Population Change in Northern Bobwhite

Abstract Annual surveys of wildlife populations provide information about annual rates of change in populations but provide no information about when such changes occur. However, by combining data from 2 annual surveys, conducted in different parts of the year, seasonal components of population change can be estimated. We describe a hierarchical model for simultaneous analysis of 2 continent-scale monitoring programs. The Christmas Bird Count is an early winter survey, whereas the North American Breeding Bird Survey is conducted in June. Combining information from these surveys permits estimation of seasonal population variance components and improves estimation of long-term population trends. The composite analysis also controls for survey-specific sampling effects. We applied the model to estimation of population change in northern bobwhites (Colinus virginianus). Over the interval 1969–2004, bobwhite populations declined, with trend estimate of −3.56% per year (95% CI = [−3.80%, −3.32%]) in the surveyed portion of their range. Our analysis of seasonal population variance components indicated that northern bobwhite populations changed more in the winter and spring portion of the year than in the summer and fall portion of the year. (JOURNAL OF WILDLIFE MANAGEMENT 72(1):44–51; 2008)     

Simulating density-dependent relationships in south Texas northern bobwhite populations

Density dependence influences northern bobwhite (Colinus virginianus) reproduction and overwinter mortality. However, the functional forms of these density-dependent relationships or the factors that influence them during the annual life cycle events of this bird are not clear. We used a systems analysis approach with a compartment model based on difference equations (Δt = 3 months) for bobwhites in South Texas to simulate population behavior using 16 different functional forms of density-dependent production and overwinter mortality. During the reproductive season, a weak linear density-dependent relationship resulted in the longest population persistence (up to 100.0 yr), whereas a reverse-sigmoid density-dependent relationship had the worst population persistence (2.5–3.5 yr). Regarding overwinter mortality, a sigmoid or weak linear density-dependent relationship and a weak linear or no density-dependent reproduction relationship had the longest population persistence (87.5–100.0 yr). Weak linear density-dependent reproduction with either sigmoid or weak linear overwinter mortality produced stable fall population trends. Our results indicated that density dependence may have a greater influence on overwinter survival of bobwhites than previously thought. Inclusion of density-dependent functional relationships that represent both density-dependent reproduction and overwinter mortality, were critical for our simulation model to function properly. Therefore, integrating density-dependent relationships for both reproductive and overwinter periods of the annual cycle of bobwhite life history events is essential for conducting realistic bobwhite population simulation analyses that can be used to test different management scenarios in an integrated and interdisciplinary manner. © 2012 The Wildlife Society.     

Northern Bobwhite Non-Breeding Habitat Selection in a Longleaf Pine Woodland

Efforts to halt the decline of the northern bobwhite (Colinus virginianus; bobwhite) across its distribution have had limited success. Understanding bobwhite habitat requirements across the annual cycle and at varying scales is essential to aid efforts to conserve bobwhites. We monitored radio-tagged bobwhites from 2016 to 2018 on a 165-km² portion of Fort Bragg Military Installation in the Sandhills physiographic region of North Carolina, USA, to determine factors influencing non-breeding bobwhite habitat selection at multiple scales. We used generalized linear models (GLM) and generalized linear mixed models to assess bobwhite habitat selection at the microsite scale (the immediate vicinity of an animal) and the macrosite scale (across the study area), respectively, by comparing used points to available random points. At the microsite scale, bobwhites strongly selected areas with greater woody understory cover. Also, bobwhite selection increased with greater forb and switchcane (Arundinaria tecta) cover, but this effect plateaued at 65% forb cover and 50% switchcane cover. At the macrosite scale, bobwhites generally selected areas with greater understory cover within a 200-m radius but avoided areas with >55% understory cover; these areas primarily were located in the core areas of drainages with extensive ericaceous vegetation. Bobwhites selected areas with 3–6 m²/ha hardwood basal area in uplands, potentially because of the availability of mast, but avoided uplands when pine (Pinus spp.) or hardwood basal area exceeded 20 m²/ha or 12 m²/ha, respectively, likely because high basal area is associated with increased shading and subsequent loss of understory cover. In addition, bobwhites selected uplands 1 growing season (≥2-month period falling entirely between 1 Apr and 1 Oct) post-fire regardless of burn season. Overall, managers seeking to improve habitat quality for bobwhites in longleaf pine (Pinus palustris) woodlands should employ management practices that maintain available woody understory across the landscape to provide cover during the non-breeding season. © 2020 The Wildlife Society.     

Variation in northern bobwhite demography along two temporal scales

Quantification and understanding of demographic variation across intra- and inter-annual temporal scales can benefit from the development of theoretical models of evolution and applied conservation of species. We used long-term survey data for northern bobwhites (Colinus virginianus) collected at the northern and southern extent of its geographic range to develop matrix population models which would allow investigation of intra- and inter-annual patterns in bobwhite population dynamics. We first evaluated intra-annual patterns in the importance of a seasonal demographic rate to asymptotic population growth rate with prospective perturbation analysis (elasticity analysis). We then conducted retrospective analysis (life table response experiments) of inter-annual patterns in the contribution of observed changes in demography to the observed change in population growth rate. Survival in the earliest age class during the nonbreeding season had the greatest potential influence in both the northern and southern populations. Examination of inter-annual variation in demography indicated that variation in nonbreeding season survival in the earliest age class contributed the most to observed changes in population growth rate in the northern population. In contrast, changes in fertility in the earliest age class in the southern population had the greatest influence on changes in population growth rate. Prospective elasticity analyses highlight the similarities in bobwhite demography throughout different parts of its geographic range, while retrospective life table response experiments revealed important patterns in the temporal differences of bobwhite life history at the northern and southern extent of its geographic range.     

Effects of Landscape Composition on Winter Survival of Northern Bobwhites

Abstract: In a manipulative experiment, we tested effects of select elements of landscape structure and composition on winter survival of northern bobwhites (Colinus virginianus) at Ames Plantation, Tennessee, USA. We hypothesized that abundance of closed canopy forested habitats (52% of the landscape) on Ames diminished usable space for bobwhite and provided usable space for a suite of important predators, thereby contributing to low winter survival. To test this hypothesis we divided a 2,217-ha portion of the property into 4 approximately equal areas. We altered landscape structure and composition by converting approximately 33% of the timber to early successional herbaceous plant communities on 2 treatment sites, which reduced percentage of landscape and edge density of closed canopy forest and increased percentage of landscape in early successional herbaceous communities, and left 2 control sites in their former composition. During one pretreatment year (1998–1999) and 3 posttreatment years (1999–2000, 2000–2001, 2001–2002), we estimated winter (15 Oct-10 Apr) survival on treatment and control sites from a radiomarked sample of 920 bobwhites. We used Cox Proportional Hazard models to test for effects of treatment (forest conversion) and covariates describing landscape structure and composition (% closed canopy forest, % early successional herbaceous, wooded edge density) on winter survival at multiple spatial scales. Winter survival on the treatment sites pooled across the 4 winter seasons was 41% compared to 32% for control sites. Additionally, for each 1 m/ha increase in closed canopy woods edge density within winter covey ranges, risk of mortality increased 0.3%. Our results suggest composition at the landscape scale and landscape structure at the local scale influence winter survival of bobwhite. Management strategies that alter composition and structure and increase usable space may be effective in mitigating winter mortality thereby altering population trajectories. Typical bobwhite management plans focus on improving quality of herbaceous vegetation structure within existing herbaceous patches, however, population processes may work at larger spatial scales influencing design and implementation of conservation programs.     

Simulating northern bobwhite population responses to nest predation,nesting habitat,and weather in south Texas

Nest predation is thought to be one of the major factors limiting northern bobwhite (Colinus virginianus) populations. We examined the relative impact of altering nest-predation rate, nesting habitat, and weather (i.e., temp and precipitation) on northern bobwhite population dynamics in a hypothetical 15,000-ha subtropical-rangeland ecosystem in south Texas using a simulation model. The systems model consisted of a 3-stage (i.e., eggs, juv, and ad) bobwhite population with dynamics influenced by variables affecting production, recruitment, nest predation, and mortality. We based model parameters on data collected from a 3-yr nest-predator study employing infrared-camera technology, from ongoing field research using a radio-marked population of wild bobwhites, and from the literature. The baseline simulated bobwhite population dynamics corresponded closely to empirical data, with no difference between medians of simulated (n = 30 yr) and observed bobwhite age ratios over a 28-yr period. Similarly, a time-series comparison of simulated and observed age ratios showed most (89%) observed values fell within the 5th and 95th percentiles of the simulated data over the 28-yr period. We created simulated population scenarios representing 1) baseline historical conditions, 2) predator control, 3) low precipitation, 4) low precipitation with predator control, 5) high temperature, 6) high temperature with predator control, 7) reduced nest-clump availability, and 8) reduced nest-clump availability with predator control that resulted in considerably different median bobwhite densities over 10 yr. For example, under simulated predator control, populations increased by about 55% from the baseline scenario, whereas under simulated reduced nest-clump availability, populations decreased by about 75% from the baseline scenario. Comparisons of time-series for each scenario showed that reduced nest-clump availability, low precipitation, and high temperature reduced bobwhite densities to a larger degree compared to a natural nest predation rate. Reduced nest-clump availability resulted in the most substantial decline of simulated bobwhite densities. Simulations suggested that management efforts should focus on maintaining adequate nest-clump availability and then possibly consider nest predator control as a secondary priority. © 2010 The Wildlife Society     

Factors Influencing Survival of Radiotagged and Banded Northern Bobwhites in Georgia

Abstract: Numerous studies of behavior and ecology of northern bobwhites (Colinus virginianus) have depended on radiotagging and telemetry for data collection. Excluding the presumably short-term effects of trapping, handling, and attaching radiotransmitters, researchers often assume that little bias is associated with estimating survival and behavioral parameters associated with this technique. However, researchers have not adequately examined these effects on organisms being investigated and have thus assumed demographic information obtained from such methods are valid. In light of this conjecture, it is imperative to evaluate methodological assumptions to ensure research is statistically valid and biologically meaningful. Therefore, we used Burnham's model and program MARK to analyze survival estimates of individually banded and radiotagged bobwhites during an 8-year period (1997–2004) consisting of 6,568 individuals (2,527 radiotagged) via combined analysis of mark—recapture, dead recovery (via harvest), and radiotelemetry data to test the effects of radiotransmitters on bobwhite survival. We also compared band—recapture survival estimates to Kaplan—Meier survival estimates, and we examined the effects of various other factors (e.g., temporal, spatial) on bobwhite survival. Based on Akaike's model selection criterion, the best model including the radiotransmitter covariate (Akaike's Information Criterion adjusted for small sample size bias and overdispersion relative value = 0.72) did not explain more of the variation in survival than models without this effect. Thus, we found the effect of radiotransmitters as negligible. Bobwhite survival varied relative to spatial (e.g., site), temporal (e.g., yr and season), and gender effects. Average annual survival for the 8-year period was 22.76% (1.50 SE) for banded-only and 21.72% (1.49 SE) for radiotagged birds. Survival rate varied annually, ranging from 12.42% (7.51 SE) to 37.16% (8.27 SE), and seasonally, ranging from 23.82% (2.71 SE) to 65.06% (3.23 SE); however, between group (banded-only, radiotagged) survival differences were still inconsequential. We conclude that for our study, radiotelemetry provided reliable survival estimates of an intensively managed bobwhite population, where supplemental food was provided, and this information provided useful data to make practical habitat management decisions. We believe that future radiotelemetry studies would benefit as a whole if researchers conducted similar analyses prior to presenting their results from radiotelemetry data, especially for populations that are more food limited.     

Evidence for Regionally Synchronized Cycles in Texas Quail Population Dynamics

Abstract: Knowledge of the possible role of cyclic behavior in wildlife dynamics assists in understanding and managing populations. Using spectrum, we analyzed time series (1978-2002) on the abundance of northern bobwhites (Colinus virginianus) and scaled quail (Callipepla squamata) in several ecological regions in Texas, USA, to test for the presence of cycles; we also tested whether drought severity (Modified Palmer Drought Severity Index) exhibited cyclic dynamics and whether quail and drought cycles were synchronized among regions. We found evidence of population cyclicity in all ecoregions we tested (5 for bobwhites, 4 for scaled quail) based on both Texas Parks and Wildlife and North American Breeding Bird Survey count data. Periods of the observed cycles generally were 5-6 years (bobwhites) or 2-3 years (scaled quail), depending on ecoregion and data source. Cyclicity was most pronounced for bobwhites in the Rolling Plains (north TX) and the South Texas Plains. The Palmer Index exhibited a roughly 5-year cycle in 5 of 6 regions we tested. A 5-year bobwhite and Palmer Index cycle were synchronous in 3 contiguous ecoregions totaling 27,200,000 ha. Wet-dry cycles seemed to synchronize bobwhite cycles in Texas. Our results suggest that habitat manipulations aimed at improving habitat conditions during dry periods, such as reducing livestock stocking rates, could provide ground cover similar to that available in wet periods.     

Home range and habitat selection of northern bobwhite coveys in an agricultural landscape

Northern bobwhites thrive in fine-grained landscapes with a diversity of early succession woodland, grassland, and agriculture-associated habitat types. Bobwhite conservation has proved challenging in the increasingly coarse-grained Midwestern landscape as simplified agricultural cropping systems are implemented at larger spatial scales. Regardless, managing agricultural landscapes on private lands is the primary opportunity to restore bobwhite populations in the Midwestern United States. Although bobwhite habitat requirements are well understood, habitat selection in contemporary Midwestern landscapes is not well understood, especially on private lands where populations are declining. We used compositional analysis to investigate second- (study area) and third- (home range) order habitat selection by radiomarked bobwhite coveys on 4 private land study areas in southwestern Ohio. Mean covey home range size was 26.1 ± 2.2 ha (n = 48). Although home ranges were established in areas with more grassland cover, bobwhites most strongly selected early succession woody habitat (e.g., fencerows and ditches) at all scales, and selection for grassland diminished between the study area and home range scales. Grassland selection varied among sites and was strongest on sites with more row crop area. Woodlots were avoided at the study area scale, but were selected within home ranges. Grassland cover, like that provided by contemporary conservation programs, is an essential component of bobwhite habitat in the Midwest, but our results suggest more emphasis should be placed on early succession woody cover. Woody cover associated with fencerows, ditches, and woodlots adjacent to food sources and breeding habitat will likely improve non-breeding season survival, which is an influential vital rate in northern populations. © 2012 The Wildlife Society.     

Home range, movement, and site fidelity of translocated northern bobwhite (Colinus virginianus) in southwest Georgia, USA

During 1997 and 1998, we compared home range, movement, and site fidelity characteristics of translocated wild northern bobwhite (Colinus virginianus) to resident birds using radiotelemetry. We captured wild bobwhites (n=74) in southwest Georgia, USA just before the breeding season and relocated them (>1.6 km from capture sites) to sites nearby where previous density estimates revealed that populations were low compared to surrounding areas. Translocated birds were equipped with radiotransmitters and released in groups of 8 to 12. Resident birds (n=166) were also captured and simultaneously monitored via radiotelemetry. We found no difference in home range size (F ₁=0.08, P=0.78), mean daily movements (F ₁=0.04, P=0.84), or distance moved from trap or release sites to arithmetic centers of home ranges (F ₁=1.58, P=0.21) between translocated and resident bobwhites. These results suggest that translocating wild bobwhites over relatively short distances into suitable habitat does not negatively influence bobwhite movement and renders site fidelity as reasonable. Therefore, translocation of wild bobwhites before breeding season can result in enhanced numbers of adult breeders in a target location and potentially augments fall populations via reproductive yield.     

Aspects of northern bobwhite ecology on south Florida US pastureland

During 2004 and 2005, we monitored breeding season survival, home range, habitat use, density, and reproduction of northern bobwhite (Colinus virginianus) in the peninsular region of Florida, USA. We radio-tagged 81 birds across a 20-km² cattle ranch consisting predominately of rotationally grazed pastureland. Birds were radio-tracked three to five times per week until mortality or the transition to nonbreeding season. We found no difference in home range size among the sexes, ages, or their interaction. Mean home range size pooled for years, sexes, and age class was 56.28 ha (±7.87 SE). Home ranges of bobwhites were not distributed among habitats randomly (second order: Λ?=?0.10; 7, 35 df; P?=?0.002). In addition, bobwhites did not use the habitats within their home range at random (third order: Λ?=?0.14, 5, 35 df; P?=?0.02). Estimated seasonal survival was 0.28 (±0.12 SE) and was best explained by the time-dependent model. Reproductive metrics indicated adequate reproduction and values consistent with the bobwhite literature. Bobwhite density (birds per hectare) in 2004 was 0.52 (±0.54 95 % confidence interval [CI]) and 0.75 (±0.51 95 % CI) for 2005. These results suggest that pastureland landscapes managed with rotational grazing can support bobwhite populations, albeit at low densities. More conservation attention should be directed towards improving these systems for bobwhite restoration.     

Survival and growth of northern bobwhite offspring post-translocation

Continual population declines in northern bobwhites (Colinus virginianus) have prompted the use of population restoration techniques in conjunction with habitat management to restore their populations. We tested the site familiarity hypothesis to determine if translocation to new environments affected offspring survival and growth rates of bobwhites. We used bobwhites from north Florida and translocated them to a study site in Brunswick County, North Carolina, USA, and monitored birds during April−October 2016 and April−October 2017. We used the corral capture method and modified-suture technique to capture and radio-tag chicks to evaluate offspring growth and survival rates of resident and translocated bobwhites. Offspring survival varied by year and age. We did not find any difference in offspring survival rates of resident and translocated individuals, lending no support to the site familiarity hypothesis with regards to survival. Offspring of resident bobwhites did not grow at a faster rate than offspring of translocated bobwhites, indicating a lack of support for the site familiarity hypothesis in terms of physiological development. Survival, however, is a more important metric for determining post-translocation population dynamics, and our results indicated that translocated bobwhites can reproduce and raise offspring similar to resident counterparts, but both had low survival. © 2019 The Wildlife Society.     

Life on the edge: Northern bobwhite ecology at the northern periphery of their range

Over the past 40 years, Northern bobwhite (Colinus virginianus) populations have declined range-wide. The Mid-Atlantic once held the highest densities in the country and now shows some of the worst declines. Although population parameters have been quantified throughout most of the bobwhite range, Mid-Atlantic populations have been largely unstudied. To better quantify the dynamics of this declining system, we sought to not only gather annual data on home range, movement, and habitat selection, but also examine how some of these metrics might impact survival. We captured and radio-tracked 154 bobwhites between May 2006 and April 2008 on a 125 km² area of Cumberland County, New Jersey, USA. Seasonal daily movement ranged from 146 m to 158 m but several extreme movements were notable. Across seasons, grassland habitat was used in greater proportion to its availability, shrub-scrub and agriculture habitats were used equally with their availability and forests and other habitats were used less than their availability. Differences in second-order selection occurred between seasons with lower use of shrub-scrub and forest habitats and higher use of other habitat in breeding seasons. Pooled breeding season survival was 0.343, nonbreeding season survival was 0.183, and annual survival was 0.063. Although mortality was dominated by avian predators, house cat mortalities were noteworthy. Cox proportional hazard analysis revealed that risk of breeding season mortality risk was increased by longer daily movement, lower grassland use, and higher forest and other use. During the nonbreeding season, risk of mortality increased with shorter daily movement and proximity to occupied buildings and barns. This information could inform management decisions in the greater Mid-Atlantic as well as other areas of their range where they exist at very low abundances. © 2010 The Wildlife Society.     

Spatial Variation in Lesser Prairie-Chicken Demography: A Sensitivity Analysis of Population Dynamics and Management Alternatives

ABSTRACT The lesser prairie-chicken (Tympanuchus pallidicinctus) is currently considered a candidate for protection under the Endangered Species Act. To identify potential limiting factors for lesser prairie-chicken populations, we developed an age-based matrix model of lesser prairie-chicken population dynamics to compare the relative importance of components of reproduction and survival, and determine if various management alternatives stabilize or increase rates of population change. We based our analyses on an intensive 6-year population study from which demographic rates were estimated for each age class in Kansas. We used deterministic models and elasticity values to identify parameters predicted to have the greatest effect on the rate of population change (λ) at 2 study sites. Last, we used life-stage simulation analysis to simulate various management alternatives. Lambda was <1 for both populations (site 1: λ = 0.54, site 2: λ = 0.74). However, we found differences in sensitivity to nest success and chick survival between populations. The results of the simulated management scenarios complemented the lower-level elasticity analysis and indicated the relative importance of female survival during the breeding season compared with winter. If management practices are only capable of targeting a single demographic rate, changes to either nest success or chick survival had the greatest impact on λ at site 1 and 2, respectively. Management that simultaneously manipulated both nest success and chick survival was predicted to have a greater effect on λ than changes in survival of adult females. In practice, our demographic analyses indicate that effective management should be based on habitat conservation measures to increase components of fecundity.