Hunting as a recreational pursuit provides an important ecosystem service worldwide. Harvest management plays a vital role in regulating wildlife take to ensure long-term population sustainability and meet value-based objectives (e.g. hunter satisfaction). However, managers rarely have complete control or observability of harvest mortality. A particularly uncertain component is the number of animals killed but not recovered, known as crippling loss. We examined this issue in a commonly hunted species in the USA, the northern bobwhite Colinus virginianus, which shares life-history traits with many game birds. Using an extensive dataset spanning three hunting seasons across four sites, we parameterized a multistate survival model to estimate survival, hunter-recovered mortality, and crippling loss. We also explored field-observed crippling rates to estimate the difference between realized and perceived rates of crippling. Estimated total mortality from harvest was 0.11 (95% CrI = 0.10-0.13). The probability of a bobwhite being harvested and recovered was 0.08 (95% CrI = 0.07-0.09), while the probability of being shot but not recovered (i.e. crippled) was 0.03 (95% CrI = 0.02-0.05). Crippling represented 29% (95% CrI = 22-38%) of total harvest. For field-observed crippling, the average observer reported that 25% of total harvest was due to crippling loss, though this was underestimated compared to the multistate model for some sites and years. This may reflect the limited ability of hunters/observers to detect birds that were wounded but died later. Our findings demonstrate that crippling loss can represent a substantial and overlooked component of total harvest mortality. If unaccounted for, this source of mortality may lead to overharvest. The modeling framework presented here offers an approach for estimating crippling loss for species lacking direct estimates. In the absence of species-specific data, our estimates may serve as provisional values to support conservative harvest management.

Investigating resource selection patterns of declining species is critical to developing effective conservation strategies and mitigating negative population trends. We trapped and radio‐collared northern bobwhite Colinus virginianus and recorded the location of each individual three times per week during the northern bobwhite breeding season (April–September) to infer resource selection by non‐brooding adults. We defined 13 vegetation communities with varying fire histories and assessed their relative use via a distance‐based logistic regression model within a Bayesian framework. We found reliable evidence that non‐brooding northern bobwhite preferred supplemental feed lines, recently burned natural pine stands, one‐year rough in shrub/scrub, and one‐year rough in hardwood/pine stands. Conversely, we found they avoided one‐year rough in natural pine stands, recently burned shrub/scrub, and recently burned hardwood/pine stands. Our data suggest that non‐brooding bobwhite's successional stage preference may vary between vegetation communities within the same study area, and adds further evidence to the importance of fire and vegetation interspersion in bobwhite management. Results from our study may be applied to enhance habitat for non‐brooding northern bobwhite and potentially increase adult survival, an important metric correlated with bobwhite population growth.

Indirect effects of hunting can lead to changes in population dynamics, which can be caused by trait‐mediated effects such as, but not limited to, changes in behavior, reproduction, and physiological responses. Our understanding of the effects of activities associated with hunting such as dog training may incur trait‐mediated effects, and ultimately indirect effects to wildlife populations are underrepresented. We conducted a two‐year study on a relatively high‐density wild bobwhite population to identify potential impacts of disturbance caused by the most common levels of spring dog training on bobwhite survival and reproduction. About 34% of coveys across all training events were not available to be encountered. Those remaining for possible encounters were typically encountered once (39%) or not at all (32.5%), whereas 14.6% and 12.8% were encountered twice or three times, respectively. We found no effect of the categorical effects of treatment or encounters on adult or nest survival, clutch size, hatchability, or nest propensity. Additionally, we found no effect of treatment or encounters on fecundity for both years and for both treatments. The neutral results of our study are likely attributed to intentionally low encounter rates. Future studies should focus on scenarios where disturbances are more frequent, and food resources are likely more limited.

Management of wildlife populations is most effective with a thorough understanding of the interplay among vital rates, population growth, and density-dependent feedback; however, measuring all relevant vital rates and assessing density-dependence can prove challenging. Integrated population models have been proposed as a method to address these issues, as they allow for direct modeling of density-dependent pathways and inference on parameters without direct data. We developed integrated population models from a 25-year demography dataset of Northern Bobwhites (Colinus virginianus) from southern Georgia, USA, to assess the demographic drivers of population growth rates and to estimate the strength of multiple density-dependent processes simultaneously. Furthermore, we utilize a novel approach combining breeding productivity and post-breeding abundance and age-and-sex ratio data to infer juvenile survival. Population abundance was relatively stable for the first 14 years of the study but began growing after 2012, showing that bobwhite populations may be stable or exhibit positive population growth in areas of intensive management. Variation in breeding and non-breeding survival drove changes in population growth in a few years; however, population growth rates were most affected by productivity across the entire study duration. A similar pattern was observed for density-dependence, with relatively stronger negative effects of density on productivity than on survival. Our novel modeling approach required an informative prior but was successful at updating the prior distribution for juvenile survival. Our results show that integrated population models provide an attractive and flexible method for directly modeling all relevant density-dependent processes and for combining breeding and post-breeding data to estimate juvenile survival in the absence of direct data.

Community dynamics are essential for ecosystems as they support the functioning of food webs and maintain biodiversity. However, the fluctuations of species abundances are rarely analyzed simultaneously despite their interconnectedness across space and time. We developed a Bayesian multi-species model that estimates community- and taxon-level parameters related to dynamics, abundance, detection probability, and environmental stochasticity. From this model, we analyze the variability of populations of a community of raptors composed of accipiters (sharp-shinned hawk [Accipiter striatus], and Cooper's hawk [A. cooperii]), buteos (red-tailed hawk [Buteo jamaicensis], and red-shouldered hawk [B. lineatus]) and owls (great horned owl [Bubo virginianus], and barred owl [Strix varia]). We show that migration pulses of accipiters, buteos, and dispersal of fledging owls drive variation in raptor abundances, indicating a defined production and dispersal period. Also, large-scale climatic processes such as the North Atlantic Oscillation (NAO) influenced the variation in abundances of raptors. When the NAO was in a positive phase, the abundance of raptors decreased, and inversely. Local weather did not affect raptor population abundances. Our approach facilitated the modelling of species-specific effects of environmental variation and guild-level dynamics that could be used for ecosystem-based conservation measures.

Our understanding of synchrony between populations from different taxonomic groups has been centered on predator–prey dynamics in simple systems but has rarely been examined in complex predator–prey systems. In addition to trophic interactions such as predator–prey dynamics, there is some evidence that exogenous factor such as climatic variation may facilitate synchrony between different taxonomic groups. Using three longitudinal datasets on quail (Colinus virginianus) and cotton rats (Sigmodon hispidus) we examined 1) the consistency of synchrony across time and space, 2) the relative influence of trophic interactions vs. exogenous factors on synchrony and 3) if trophic interactions were positively associated with synchrony between populations. We found evidence of consistent synchrony in cotton rat and bobwhite populations at both the site and regional levels. We found that trophic interactions between cotton rats and bobwhite were associated with relative synchrony between these populations, but these interactions appeared to weaken in years of greater synchrony. We did not find evidence that exogenous factors influenced relative synchrony at the regional level. Given the lack of a clear mechanistic explanation of the patterns observed in our data, we propose an alternative climate-mediated predation framework to explain synchrony in complex predator–prey systems. This framework includes both classic bottom-up theories of regulation while integrating trophic interactions via components of the shared predator hypothesis.

Abstract Private landowners who operate multifunctional landscapes play a critical role in the conservation of native and imperiled species, and the restoration of native ecosystems. In the southeastern United States, both northern bobwhite (Colinus virginianus) and pine savanna ecosystems are imperiled and heavily reliant on conservation efforts by private landowners. Engaging private landowners in the restoration and management of pine savannas and grasslands is essential to the recovery of northern bobwhite, which is also managed as a game species. Since the early 1900s, the cultural tradition of wild bobwhite hunting has motivated landowners to manage their properties to increase bobwhite populations. However, the costs and revenues associated with intensive wild bobwhite management and hunting are imperfectly understood. From May 2021 to February 2022, we conducted semistructured interviews with landowners and land managers of 37 wild bobwhite hunting properties (total of 65,317 ha in bobwhite management) in Alabama, Georgia, Florida, and South Carolina to enumerate the costs and revenues associated with intensive wild bobwhite management. Landowners spent an average of $154/acre/year (~$381/ha/year; median of $142/acre/year or ~$352/ha/year) to manage for northern bobwhite. These costs included salaries and benefits for labor, depreciated equipment and infrastructure expenditures, and other supplies (e.g., fuel, seed) needed to maintain wild bobwhite populations and their habitat. Few properties offset their bobwhite management costs with revenues generated on the property, including hunting revenues. Non‐financial motivations for owning a bobwhite property included a strong land stewardship ethic, the desire to maintain rural lifestyles and family heritage, and securing hunting and recreational opportunities. Through wild quail management, private landowners are helping to secure critical habitat for threatened and endangered species and increasing the landscape's overall resilience to climate change without the use of public funding.

Demographic rates of northern bobwhite (Colinus virginianus; hereafter, bobwhite) may vary spatially and temporally, and understanding the significance of these individual rates to population performance is critically important to bobwhite management. We present descriptive evidence from 2 populations that were simultaneously monitored from 2015–2020 that suggests different demographic rates can be more important to population performance than other demographic rates within the same region. Our objective was to understand the relative importance of various demographic rates to population performance in separate and seemingly stable populations. We monitored bobwhite seasonal survival and reproductive demographics on 2,475 bobwhites via radio-telemetry and estimated fall density using fall covey counts. Both sites maintained high densities (i.e., ≥3.45 birds/hectare) and remained relatively stable throughout the study period. On one site in the Red Hills region near Monticello, Florida, USA, bobwhite experienced comparatively low seasonal survival, but higher reproduction, including more frequent multiple-brood production. One hundred and twenty-nine kilometers away on a study site near Albany, Georgia, USA, bobwhite demonstrated consistently higher survival and lower reproductive output, including less multiple-brooding compared to the Red Hills population. This suggests, at a minimum, that compensatory or density-dependent reproduction may be occurring in these populations and regional population dynamics can vary locally even among stable populations.

Adaptive resource management (ARM) is an approach to managing that allows decision makers to learn about a system and subsequently change management actions based on new information about system processes (i.e., adapt) to better meet fundamental objectives. This is not to be confused with changing management actions when the state of the system changes. For example, changing a harvest regulation when populations decline is not ARM. This dynamic decision making may be fortuitously optimal, but if the effect of harvest is uncertain then changing regulations may be suboptimal—for example, weather may have caused the decline. Adaptive resource management can be implemented along a spectrum of passive to active to reduce system uncertainty. Active ARM is when explicit hypotheses are posited then implemented to test them, and monitoring occurs to elucidate whether the effect of the management action achieved a given result. Passive ARM uses current management practices, natural variation in the system, and monitoring to reduce uncertainty. Even though northern bobwhite (Colinus virginianus) have been studied for a century, uncertainty regarding optimal management strategies still exists. The Albany Quail Project (AQP) has used both modes of ARM to learn about northern bobwhite populations to better meet the hunting objectives of stakeholders. Between 1992 and 2019 the AQP radio-tagged 5,182 unique individuals and banded an additional 5,008 birds on the primary study area near Albany, Georgia, USA. Additionally, 1,724 nests have been monitored and population surveys conducted in the spring and autumn. Active ARM occurred with tests of supplemental feeding, hardwood cleanup, and predator control whereas passive ARM was used to learn about prescribed fire regimes, brood habitat preferences, small mammal cycles, and raptor migrations. We built an integrated population model (IPM) that combined known-fate survival data, nesting records, dead recoveries from harvest, and population surveys to model the system. The preliminary results of the IPM demonstrated that populations have increased during the project. The 5 most abundant autumn populations have occurred in the most recent 10 years of the project when bobwhite populations throughout their range have continued to decline. Unlike typical ARM applications, the AQP has not had an explicit model to predict consequences of future management actions; nonetheless, the essence of ARM has been followed. Since its inception uncertainty has been reduced, management actions have been changed, and bobwhite populations have responded. Improvements to AQP and similar projects could include explicit hypotheses and predictive models about the system to facilitate the transfer of knowledge to future bobwhite managers.

Understanding interactions between prey species and their predators is essential to discerning the ecology and management fundamentals of a species. Great-horned owls (Bubo virginianus) have long been considered an opportunistic predator of northern bobwhite (Colinus virginianus; hereafter, bobwhite) and recent studies have demonstrated that bobwhite survival is reduced at higher great-horned owl densities (Rectenwald et al. 2021). Managers on quail properties often mechanically remove live oak (Quercus virginiana) hammocks as part of larger predation management plans to reduce the amount of suitable predator habitat. While scattered live oaks are typically left for aesthetic purposes, these serve as preferred day roosts and hunting perches for great-horned owls. To improve bobwhite survival and fitness, managers on quail properties broadcast supplemental grain along designated trails at a density of 2.4 km/40.5 ha of upland habitat. From the peak of bobwhite brooding season to the end of the breeding season (i.e., Jun–Sep), it is common for managers to switch from broadcasting grain from feed trails to broadcasting grain from mowed roads to reduce tractor activity in obscured cover where broods or nests may be run over and destroyed. Bobwhite are potentially at higher risk for predation where live oak hammocks are intersected by feed trails due to increased exposure time in areas with higher predator occurrence. Additionally, bobwhite may be at higher predation risk when feeding on mowed roads in the summer, particularly when in close proximity to live oaks, due to the lack of screening cover from opportunistic owls perched above.

Widespread changes to breeding bird phenology in response to climate change have been apparent in North America for several decades. While the impact of an earlier breeding season may be minimal by itself, changes in community-level interactions can be greatly influenced because of varying responses to climate change in different trophic levels. Climate change has been shown to alter the onset of breeding season and chick survival, and lead to population declines for game birds in high latitudes, at high elevations, and on the periphery of their range. The topic of climate change in relation to northern bobwhite (Colinus virginianus; hereafter, bobwhite) populations has attracted interest in the past 2 decades. Some researchers have hypothesized that climate change has the potential to cause the breeding season to initiate sooner and have a shorter duration. Using a 29-year dataset (1992–2020) with 1,171 individual bobwhites, we analyzed how temperatures prior to the breeding season affected the timing of nest initiation and clutch size, and how the length of the breeding season varied over time. We determined that the average minimum daily temperatures 30 days prior to the breeding season warmed by 0.07° C/year from 1992–2020. For any given year, we found that nest initiation could occur 1.12 days earlier for every 1° C increase in temperature. Overall, we determined that the timing of the nesting season had not changed from 1992–2020. The overall average breeding season length (135 days) or last average initiation date (27 Aug) did not change over the course of our study. We did not find that clutch sizes have changed over time and they were not correlated to pre-laying temperature. We attribute the lack of significant change in nesting chronology to plasticity of populations within the core of the range and the intensity of bobwhite management on the landscape.

AbstractInvasive species are a major driver of native species declines, frequently resulting in a reduction of ecosystem function. Though control of invasive species is often beneficial, it can create other ecological issues. However, studying the results can give insight into the benefits of removal and most effective management techniques. A model invasive species to test the effects of removal is the red‐imported fire ant (Solenopsis invicta, hereafter RIFA), which depredates and competes with native species. We hypothesized that following removal, RIFA would recolonize treated areas from untreated borders, resulting in reinvasion and higher densities due to elimination of competition from native species that would also be extirpated by treatments. To test our hypothesis, we compared RIFA relative abundance on large sites (>400 ha) treated with a granular insecticide (Extinguish Plus, Central Life Sciences, Schaumburg, IL) in southwest Georgia, USA. Extinguish Plus effectively removed RIFA, but the treated sites were reinvaded approximately 14 months after treatment with higher densities of RIFA than on untreated areas, potentially reflecting release from competition from native ants removed by treatments. Invasive species removal may elicit a rapid recolonization via a density‐dependent response mechanism and potentially increase abundance of the target species. Management strategies integrating temporal and spatial replication of control measures and multiple management techniques will be most successful in controlling invasive species.

The demographic behavior of northern bobwhite (Colinus virginianus; hereafter, bobwhite) populations at high densities could provide important insights into why bobwhite populations fluctuate. Therefore, we documented breeding season demographics of bobwhites to understand how prebreeding density influenced reproductive effort and postbreeding density on an intensively managed property in Leon County, Florida, USA, 2002–2006. We estimated prebreeding bobwhite density each April using multi-observer strip-transects and postbreeding densities each November using covey call grid surveys. We radio-tagged 217 bobwhites in March and located bobwhites at least 5 days/week, 15 April–30 September to determine vital rates. Prebreeding density ranged from 1.5–8.6 birds/ha, peaking in 2002, declining through 2005, then increasing in 2006. Breeding season survival was 0.55, 0.17, 0.20, and 0.59, and nesting rate was 0.47, 0.67, 0.80 and 0.89, 2002–2005, respectively. Postbreeding density ranged from 5.2–13.6 birds/ha, also peaking in 2002 and declining through 2004 before increasing beginning in 2005 and 2006. High breeding season survival and nesting success (>0.55) resulted in greater chick production during periods of population growth. Nesting rate was inversely related to prebreeding density. Declines in bobwhite nesting rate at high prebreeding densities appeared to regulate population growth near population peaks. Lower adult survival and nesting success appeared to cause population declines. We suggest density-dependent intraspecific competition limited population growth at high bobwhite densities by reducing nesting rate while predation of adults and nests explained population fluctuations.

Understanding how predators affect prey species is a central endeavor in applied ecology. Game birds are a culturally and economically important group of birds throughout the world. Specifically, northern bobwhite (Colinus virginianus) is an imperiled game bird native to North America that has declined precipitously over the past 65 years. Concurrently, raptor populations increased substantially as a result of pesticide bans and legal protections. However, relationships between raptors and bobwhites are not well-understood because of limited long-term data. We analyzed long-term raptor survey and bobwhite survival datasets from 2008 to 2018 to determine if oscillations in raptor abundance affected bobwhite survival. We used a novel open multi-species dynamics hierarchical distance sampling model to estimate the abundance of raptors. We used a known-fate survival model to determine if variation in raptor abundance affected bobwhite survival. We had multiple working hypotheses regarding biological relationships between raptor abundance and bobwhite survival. Raptors affected bobwhites in every biological season but were more influential in the breeding season and late winter supporting the notion of bobwhite behavior and raptor migration were driving observed patterns. Our results suggest that even in areas with abundant habitat, predators exert top–down influences on vital rates suggesting similar or greater influences on populations under poor habitat conditions.

Efforts to remove invasive species may benefit native species, but the effects can be complex and unpredictable. Thus, studies of invasive-species removal provide important information for guiding management and providing insight about variation in post-removal impacts within the community. Using southern pine-grassland ecosystems as a model system, we hypothesized that removal of the long-established red-imported fire ant (Solenopsis invicta, hereafter RIFA) would positively influence altricial Peromyscus species, due to increased survival of young in the nest and thus increased recruitment to the population, but would not impact semi-precocial hispid cotton rats (Sigmodon hispidus), which are mobile more quickly after birth and thus at less risk of depredation by RIFA. We compared small mammal populations on sites treated with a granular insecticide (Extinguish Plus) to remove RIFA in southwestern Georgia, United States, from April 2018 to December 2019. As expected, we detected no difference in cotton rat recruitment. However, contrary to our prediction, the same was true for cotton mice (Peromyscus gossypinus) and oldfield mice (Peromyscus polionotus). We found RIFA removal increased survival both of cotton rats and cotton mice, increasing average population rate of change (λ) on treated sites during the study period. In contrast, we observed lower survival of oldfield mice, with similar λ estimates on treated and untreated sites, but low sample sizes were problematic for this species. Our results show that removal of invasive species can have positive impacts for native species, but both the magnitude of RIFA effects on small mammals and mechanisms by which impacts occur are complex.

ABSTRACTDensity dependence, immigration, and emigration can considerably influence wildlife population demographics. Population models used to evaluate common actions like predator management and harvest in the absence of these processes may lead to poor management decisions. We built a novel population simulation model for the northern bobwhite (Colinus virginianus; bobwhite) that included implicit spatial structure (ingress and egress of individuals), density dependence, and harvest. We used 42 years of data (1970–2012) from a relatively stable population to create and validate the simulation model. We then used this simulation model to predict the effect of meso‐mammal trap and removal, a management action that increases bobwhite fecundity, on population abundance, cumulative harvest through 50 years, and extirpation risk. We conducted a population sensitivity analysis to understand the implications of meso‐mammal trap and removal to populations with varying vital rates. Incorporating ingress and egress of individuals and density dependence improved the understanding of bobwhite population dynamics and reduced the uncertainty about the efficacy of predator management across a range of environmental conditions. Increased number of immigration sources decreased extirpation risk and increased bobwhite abundance. A key outcome of our modeling process was that density‐dependent processes did not fully compensate for harvest. Cumulative harvest through 50 years increased with increasing harvest rate but started to decline when harvest rate was >0.35 for populations with meso‐mammal removal and 0.25–0.30 for populations without meso‐mammal removal. Meso‐mammal removal increased the harvest capacity of populations and produced greater harvest opportunity over time. Meso‐mammal removal also buffered populations from extirpation risk resulting from too few immigration sources. Practitioners often ignore the contribution of immigration and emigration to local demographics or assume density‐independent vital rates; however, recent literature reviews and our study indicate that these processes are important to the understanding of animal ecology and management. In the interest of the conservation of species that are hunted and at risk of extirpation in some geographies, predator management may increase hunter success and be a tool to reduce extirpation risk, although the degree of effectiveness likely varies geographically. This manuscript could serve as a framework for predicting the effects of management on bobwhite at the population level. © 2020 The Wildlife Society.

ABSTRACTNest predation is the major cause of nest failure in northern bobwhites (Colinus virginianus; i.e., bobwhites). Control of mid‐sized mammalian nest predators (i.e., meso‐mammals) is often conducted to increase reproductive success on lands managed for bobwhites. Nest predation by meso‐mammals, however, is only one part of a complex predator‐prey trophic system. There is limited understanding of the effect of nest predators on bobwhite demographics, which creates uncertainty about the efficacy of nest predator control. We quantified demographic effects on bobwhite populations from reducing meso‐mammals on 4 study areas managed for bobwhites in northern Florida and southwestern Georgia, USA, during 2000–2006. After 1 year of pre‐treatment monitoring (2000), we reduced meso‐mammal nest predator abundance through trapping over 3‐year intervals, March to September, on 2 sites using a crossover design. Efficacy of trapping was demonstrated by a 43% reduction in scent station visitation rates of meso‐mammals. Meso‐mammal control increased all demographic metrics including a 30% increase in nesting propensity, a 10% increase in nest success, and a 43% increase in chicks produced. Despite significant regional variation in breeding season survival rates, this equated to an average 18% increase in autumn density on trapped sites. Decision‐makers should weigh the tradeoffs between bobwhite population goals and costs of meso‐mammal control, where those that value maximum bobwhite density and reduced annual variation should likely implement control of meso‐mammals. © 2019 The Wildlife Society.

Perceived changes in predator—prey dynamics along with documented declines of northern bobwhite Colinus virginianus have created a renewed interest from biologists and managers about the role meso‐mammals play in shaping bobwhite population trajectories. Therefore, we evaluated the efficacy of meso‐mammal trap and removal (MMTR) at reducing meso‐mammal activity and increasing bobwhite reproductive success; thus testing the predation limitation hypothesis. During 1999–2006, we monitored bobwhite reproduction on 11 sites in three states across the southeastern United States. Combined, there were 37 site—year combinations when MMTR occurred and 20 combinations when it did not occur. We conducted 57 predator surveys and calculated an index of meso‐mammal activity (i.e. predator index), for each site, as the average number of station visits per night by raccoons Procyon lotor, nine‐banded armadillos Dasypus novemcinctus, Virginia opossums Didelphis virginiana, bobcats Lynx rufus and foxes Vulpes vulpes, Urocyon cinereoargenteus. The average predator index (predator visits per trap night) across sites was 0.13. We collected bobwhite reproductive information from a total of 3935 radio‐tagged bobwhites resulting in 2499 nests. We used generalized linear mixed models to evaluate the relationships between MMTR, predator activity, and bobwhite reproduction. The mean predator index for non‐trapped sites was 0.21 (95% CLs: 0.18, 0.24) compared to 0.10 (95% CL: 0.07, 0.13) for trapped sites. Bobwhite nests were 1.33 times (Odds ratio, 95% CL: 1.09, 1.62) more likely to be successful on trapped sites than non‐trapped sites. Meso‐mammal trap and removal had a positive effect on nests per hen (βtrapped= 0.25 ± 0.06; 95% CL: 0.13, 0.37), broods per hen (βtrapped = 0.37 ± 0.08; 95% CL: 0.21, 0.53), and chicks per hen (βtrapped = 1.09 ± 0.52; 95% CL: 0.07, 2.11). Our results show that MMTR reduces meso‐mammal activity and positively affects bobwhite reproduction.