Waterfowl Harvest Research Articles

Migration tracking assists harvest management of overabundant Canada geese in Manitoba, Canada

AbstractSimilar to other jurisdictions across North America, populations of temperate‐nesting giant Canada geese (Branta canadensis maxima) have increased to unprecedented levels in Manitoba, Canada, causing extensive damage to crops and property, posing risks to human safety, and mostly avoiding mortality risk from fall hunting seasons. As a result, this population in southern Manitoba was declared overabundant in 2019, through an amendment to the Canada Migratory Birds Regulations. Management authorities sought to increase harvest rates by introducing an additional hunting period in spring, or conservation season, wherein harvest could be concentrated on this population. An important consideration was the need to avoid additional harvest on non‐target populations that do not meet the criteria to be classified as overabundant, specifically, sub‐arctic nesting Canada geese (Branta canadensis interior) and mid‐continent cackling geese (Branta hutchinsii hutchinsii). To investigate differences in migration timing of populations, and ultimately determine start and closure dates for the spring conservation season, we deployed light‐level geolocators on adult females of each population between 2016 and 2018. We used Bayesian approaches to derive locations from light‐level data and generalized linear mixed models to investigate potential differences in timing of international border crossing among goose populations. Migration data confirmed that movement of these populations overlapped extensively in fall, but in spring, a narrow period existed where mainly the target population was present. Our findings provide the basis for decisions about timing of spring conservation seasons for overabundant temperate‐nesting Canada geese in Manitoba, the first season of its kind for this population in North America. Additionally, our work represents the first large‐scale use of light‐level geolocator technology for assisting with waterfowl harvest management decisions.

Harvest of waterfowl and Sandhill Crane in rural Alaska: Geographic and seasonal patterns.

We estimated the annual harvest of waterfowl and Sandhill Crane Grus canadensis and their eggs by Alaska's rural residents and described seasonal and geographic patterns. Subsistence in Alaska refers to patterns of resource use typical of rural, remote regions where Indigenous people are a high proportion of the population. Rural communities in Alaska rely on the legally-allowed spring-summer harvest of migratory birds for food and socio-cultural wellbeing, in addition to harvests in the fall-winter general hunting season. We based harvest estimates on a large dataset (637 community-years) composed from multiple sources. The estimated annual average harvest of waterfowl and Sandhill Crane by rural residents was 270,641 birds/year (68% in spring-summer, 32% in fall-winter) and 36,692 eggs/year in the 2004-2015 reference period. Harvest estimates for ducks, swans, and Sandhill Crane were lower than in the 1980s-1990s. Harvest amounts, seasonality, and species composition distinguished regional patterns for the Pacific-Aleutian mainland and islands, Bering Sea mainland, St. Lawrence-Diomede islands, North Slope, and Interior Alaska-Upper Copper River. Rural residents accounted for 79% of the total waterfowl harvest in Alaska and high proportions of the total Pacific Flyway harvest for several species of sea ducks, geese, swans, and Sandhill Crane. Alaska's Indigenous people are important partners in harvest management and conservation of migratory birds. Harvest data are needed to inform efficient and appropriate decisions to achieve management goals. This study can facilitate collaboration for harvest management and conservation across Alaska and the flyways by helping diverse users to understand their contributions to the total harvest.

Influence of sanctuary disturbance, weather, and landscape characteristics on waterfowl harvest opportunity in western Tennessee

AbstractThe North American Waterfowl Management Plan (NAWMP) recognizes waterfowl hunters and non‐consumptive users as important stakeholders to sustain waterfowl populations through economic and political support for habitat conservation initiatives. Opportunities to shoot at and harvest ducks are key determinants of achievement‐oriented hunt satisfaction and quality. Therefore, identifying factors influencing harvest opportunity would help hunters and wildlife managers identify optimal days afield and promote hunter recruitment, retention, and reactivation (R3) efforts in support of NAWMP. Waterfowl extensively use spatial sanctuaries during hunting seasons, especially diurnally, which could limit their perceived availability to hunters. Thus, a possible management action to support R3 is allowing limited public access on sanctuaries, which could offer diverse recreational opportunities for non‐consumptive users and potentially increase harvest opportunities for hunters in traditional hunting areas if the limited disturbance caused waterfowl to leave sanctuaries. Therefore, we evaluated to what extent experimental sanctuary disturbance, landscape characteristics, and weather influenced local harvest opportunities. We conducted disturbance treatments including travel by a covered truck (i.e., truck with enclosed cab), a pedestrian on foot, and an uncovered vehicle (e.g., motor boat or all‐terrain vehicle [ATV]). To measure harvest opportunity, we used autonomous recording units (ARU) to enumerate daily shotgun volleys at a landscape‐scale across western Tennessee, USA, during 2019–2021 waterfowl hunting seasons. We identified 339,391 distinct shotgun volleys ( = 73 shotgun volleys/day/ARU). Shotgun volleys decreased 50% within 2 weeks of opening day and did not notably increase for the remainder of the hunting season. Contrary to our predictions, sanctuary disturbance decreased harvest opportunity. Specifically, the pedestrian disturbance and covered vehicle disturbance decreased daily shotgun volleys by 32% and 31%, respectively. Additionally, harvest opportunity decreased 20% with every 5‐km increase in distance from a sanctuary. Harvest opportunity increased 2% for every 1°C decrease from mean low temperatures and 9% with every 10‐hPa increase in barometric pressure from the previous day. Conversely, harvest opportunity was unaffected by changes in cloud cover, daily precipitation, waterfowl abundance, or surface water inundation. Our results suggest disturbing sanctuaries decreases harvest opportunity and, in turn, may reduce hunt quality and satisfaction. If increasing harvest opportunity is a primary management objective, we recommend limiting sanctuary disturbance to maximize local harvest opportunities. Furthermore, greater harvest opportunity nearer sanctuaries indicates that additional disturbance‐free areas may increase local harvest opportunities and hunter satisfaction.

The effect of individual harvest on crippling losses

AbstractCrippling loss (waterfowl downed, but not retrieved) is a recognized component of waterfowl harvest, but there are few contemporary estimates. We used a zero‐inflated negative binomial model to account for false reporting of zeros and estimated waterfowl crippling losses from harvest data reported in a 2018–2019 survey of waterfowl hunters in Illinois, USA. We found that crippling rates declined rapidly with increasing harvest and moderately with increasing days afield. For the most active hunters (days afield), the probability of falsely reporting zero crippling loss increased with the number of ducks they reported harvesting, whereas for the least active hunters we found the reverse. We suggest that modest improvements in hunter skill could produce significant reductions in crippling loss.

The effect of a ban on the use of lead ammunition for waterfowl hunting on duck and goose crippling rates in Illinois

Globally, there is increasing effort to transition away from the use of lead ammunition to mitigate its known risks to wildlife and human health. Whenever this transition is stated hunters frequently cite concerns about the effectiveness of non‐lead ammunition, how it will result in greater crippling rates, and associated animal welfare costs. This area has been little studied, but recent studies have found no differences in crippling rates using lead and steel ammunition. Using segmented linear regression we evaluated 37 years of waterfowl harvest data in Illinois, United States, overlapping the transition to non‐lead shot for waterfowl hunting in order to assess how crippling rates changed following the ban. The average crippling rate prior to the lead shot ban was 23% for both ducks and geese and reduced to an average of 15% and 11% for ducks and geese (respectively) following the ban. In addition, the annual trend in the proportion of ducks and geese crippled reversed following the ban, from a significant annually increasing to a significant annually decreasing trend. We offer hypotheses on behavioural and technological changes which may explain these changes and predict that crippling losses will not increase in Europe following a ban on the use of lead ammunition over wetlands in 2023.

Winter Survival of Female Ring‐Necked Ducks in the Southern Atlantic Flyway

ABSTRACTNorth American waterfowl harvest regulations are largely guided by the status of breeding populations. Nonetheless, understanding the demographics of wintering waterfowl populations can elucidate the effects of hunting pressure on population dynamics. The ring‐necked duck (Aythya collaris) breeds and winters in all North American administrative flyways and is one of the most abundant and most harvested diving ducks in the Atlantic Flyway. But few studies have investigated the winter ecology of ring‐necked ducks. We used a known‐fate analysis to estimate period survival probability using data from 87 female ring‐necked ducks marked with satellite transmitters in 2 regions of the southern Atlantic Flyway during winters of 2017–2018 and 2018–2019. Winter (128‐day) survival probability was higher for individuals in the Red Hills region of southern Georgia and northern Florida (0.875, 95% CI = 0.691–0.952) than individuals in central South Carolina (0.288, 95% CI = 0.082–0.514). We attribute the regional disparity in winter survival probabilities to differences in hunting pressure, which are reflected in the number of harvests we observed in each region. Our findings warrant further investigation into regional variation in winter survival of southern Atlantic Flyway ring‐necked ducks, and, specifically, the relationship between variable harvest pressure and winter survival and its influence on ring‐necked duck population dynamics and adaptive harvest management decisions. © 2020 The Wildlife Society.

Factors affecting waterfowl hunting and harvest at the Evros delta, Greece

The Evros delta is one of the most important wetlands for wintering waterfowl in Greece and the most popular among waterfowl hunters. This study addresses hunting activity and harvest while also investigating the relationship between weather conditions and hunting activity to suggest ways of improving waterfowl management. We counted wintering waterfowl and hunter numbers, and conducted hunter bag surveys during December–February over four hunting seasons. We calculated a 10-day goose and duck Preferential Shooting Index (PSI), which is the ratio of observed number of shot birds to the number of birds expected to have been shot if the birds were shot in proportion to their availability. Common Teal, Mallard and Greater White-fronted Goose were the most abundant species both in the field and in hunter bags. The mean number of hunters/day was 99.9, with each one shooting on average 2.5 birds/day. The overall waterfowl harvested accounted for 1.3% of the total waterfowl population. For geese this proportion was six times higher (8.7%), while for ducks alone and protected species was 1.2% and 1.4% respectively. Geese were shot more often than expected (PSI 6.55), while ducks and protected species were shot according to their availability (PSI 0.86 and 1.02, respectively). Wind speed, precipitation and geese number in the field were the best predictors of overall harvest and number of hunters. To reduce goose overshooting and the probability of protected species being accidentally shot, we suggest habitat management actions for the geese feeding areas and hunters’ awareness raising.

Influence of advanced notice record cards on waterfowl hunting participation and harvest distributions

ABSTRACTWildlife management often requires accurate estimates of hunter participation and species harvested. Sending pre-season hunting cards for recording activity can improve the accuracy of estimates. This research note examined the influence of record cards on the shape of waterfowl hunting survey response distributions. Data were obtained from a 2013–2014 mail survey of 1,796 waterfowl hunters in Illinois. Results indicated that individuals who received a record card were: (a) more likely to report small harvest and days hunting values (beginning of distribution), and (b) less likely to give responses that contributed to heaping (middle of distribution) compared to non-record card recipients. Record cards did not influence the end of the distribution, as frequency functions for all respondents were long-tailed distributions. Results imply that record card responses are more accurate than non-record card responses. Non-record card estimates were approximately 10% biased. Results supported continued use of record cards to limit bias.

Site preferences and participation of waterbird recreationists: Using choice modelling to inform habitat management

Recreationists utilizing wetland birds for hunting or birdwatching contribute significantly to local economies and conservation efforts. The waterfowl management community, through the 2012 North American Waterfowl Management Plan (NAWMP), has explicitly recognized the need to increase recruitment and retention of wetland bird recreationists to help halt the national decline in social support for conservation. Achieving this goal requires that waterfowl and wetland managers consider how recreation site characteristics and management impact participation and support for wetland conservation. The outdoor recreation management and natural resource economics fields have extensive experience with similar problems and frequently use recreational site choice models to link attributes of recreational areas to use by recreationists. The waterfowl management community has several publicly available, long-term data sets that can be used in site choice models. We introduce U.S. Fish and Wildlife Service waterfowl harvest survey data, U.S. Geological Survey band encounter data, and Cornell Lab of Ornithology eBird data and use those data to summarize travel characteristics of wetland bird enthusiasts. We used harvest survey and eBird data in choice models to predict and compare the impacts of three seemingly similar proposed habitat acquisitions on use by recreationists in the state of Georgia; the proposal that had the greatest increase in predicted trips would result in twice as many additional hunting trips and >10 times more additional birdwatching trips than the proposal that generated the fewest additional trips. This case study demonstrates the potential of these and similar data and analytical methods for incorporating recreation participation and site preferences into habitat planning and delivery under the NAWMP. We encourage the outdoor recreation management and economics communities and the waterfowl management community to build partnerships and cooperative projects to improve our understanding of the relationships between wetland bird users and habitat conservation. Management implications•Results from our site choice models can provide a natural and intuitive metric that can be used to evaluate the relative merits of alternative management actions in achieving social objectives. An improvement over current proposals evaluated on a qualitative description of public access might be achieved through using the choice modeling approach to obtain quantitative estimates of the expected increase in public use resulting from a proposal.•Future research efforts that utilize finer resolution recreation site choice information would allow for a better understanding of recreationists’ decision processes and could provide managers with valuable insights into the benefits of quality improvements at state parks, managed areas, and other management units of interest.•Researchers should also work with state agencies to identify sources of finer resolution site characteristic data, such as the distribution and availability of public land, recreational regulations, and presence of infrastructure.•Researchers should explore interdisciplinary collaborations with ecological modelers to model expected sightings or expected harvest as a function of spatially-explicit environmental and landscape characteristics. Such a model could then be linked to a recreation site choice model, allowing the tracing of wetland restoration/enhancement benefits through a change in the biological system, and ultimately the change in trip locations, total trips, and/or economic benefits.•We encourage the natural resource management and economics professionals to build partnerships and cooperative projects with the NAWMP community to improve our understanding of the preferences, participation, and motivation of wetland bird users and their relationships to habitat conservation and management.

Incorporating human dimensions objectives into waterfowl habitat planning and delivery

ABSTRACTThe 2012 revision of the North American Waterfowl Management Plan (NAWMP) explicitly recognized the need to increase recruitment and retention of waterfowl hunters, birdwatchers, and other conservationists to maintain support for wetland conservation. The incorporation of human dimensions objectives within the NAWMP has compelled waterfowl and wetland managers to consider whether and to what extent landscape characteristics such as public land access; the type, amount, and location of wetlands; and site infrastructure will increase support for wetland conservation among user groups. Further, it has forced the waterfowl community to consider the possible trade‐offs between managing land to achieve biological versus social objectives. We used publicly available, long‐term data sets to illustrate a method of incorporating human dimensions into waterfowl habitat planning and management. We used United States Fish and Wildlife Service waterfowl harvest survey data, United States Geological Survey band encounter data, and Cornell Lab of Ornithology eBird data to summarize travel characteristics of wetland bird enthusiasts (i.e., waterfowl hunters and birdwatchers) in the Atlantic Flyway. Greater than 90% of all trips by wetland bird enthusiasts occurred within their state of residence. We used data from New York, USA, to demonstrate how to construct discrete choice recreation demand models to identify factors that influence site selection and participation. We demonstrate how model outputs, such as the expected change in the number and geographic distribution of recreational trips (i.e., hunting or birdwatching), can be used as an objective metric to evaluate the benefits of alternative habitat acquisition and restoration projects relative to the human dimensions objective of the NAWMP. These data and methods show promise for incorporating human dimensions objectives into habitat delivery and understanding potential trade‐offs relative to biological objectives. Published 2017. This article is a U.S. Government work and is in the public domain in the USA.

Waterfowl populations are resilient to immediate and lagged impacts of wildfires in the boreal forest

Summary Wildfires are the principal disturbance in the boreal forest, and their size and frequency are increasing as the climate warms. Impacts of fires on boreal wildlife are largely unknown, especially for the tens of millions of waterfowl that breed in the region. This knowledge gap creates significant barriers to the integrative management of fires and waterfowl, leading to fire policies that largely disregard waterfowl. Waterfowl populations across the western boreal forest of North America have been monitored annually since 1955 by the Waterfowl Breeding Population and Habitat Survey (BPOP), widely considered the most extensive wildlife survey in the world. Using these data, we examined impacts of forest fires on abundance of two waterfowl guilds – dabblers and divers. We modelled waterfowl abundance in relation to fire extent (i.e. amount of survey transect burned) and time since fire, examining both immediate and lagged fire impacts. From 1955 to 2014, >1100 fires in the western boreal forest intersected BPOP survey transects, and many transects burned multiple times. Nonetheless, fires had no detectable impact on waterfowl abundance; annual transect counts of dabbler and diver pairs remained stable from the pre‐ to post‐fire period. The absence of fire impacts on waterfowl abundance extended from the years immediately following the fire to those more than a decade afterwards. Likewise, the amount of transect burned did not influence waterfowl abundance, with similar pair counts from the pre‐ to post‐fire period for small (1–20% burned), medium (21–60%) and large (>60%) burns. Policy implications. Waterfowl populations appear largely resilient to forest fires, providing initial evidence that current policies of limited fire suppression, which predominate throughout much of the boreal forest, have not been detrimental to waterfowl populations. Likewise, fire‐related management actions, such as prescribed burning or targeted suppression, seem to have limited impacts on waterfowl abundance and productivity. For waterfowl managers, our results suggest that adaptive models of waterfowl harvest, which annually guide hunting quotas, do not need to emphasize fires when integrating climate change effects.

Spatial and temporal variation in harvest probabilities for American black duck.

Assessing spatial variation in waterfowl harvest probabilities from banding data is challenging because reporting and recovery probabilities have distinct spatial patterns that covary temporally with harvesting regulations, hunter effort, and reporting methods. We analyzed direct band recovery data from American black ducks banded on the Canadian breeding grounds from 1970 through 2010. Data were registered to a 1-degree grid and analyzed using hierarchical logistic regression models with spatially correlated errors to estimate the annual probabilities of band recovery and the proportion of individuals recovered in Canada. Probability of harvest was estimated from these values, in combination with independent estimates of reporting probabilities in Canada and the USA. Model covariates included estimates of hunting effort and factors for harvest regulation and band reporting methods. Both the band recovery processes and the proportion of individuals recovered in Canada had significant spatial structure. Recovery probabilities were highest in southern Ontario, along the Saint Lawrence River in Quebec, and in Nova Scotia. Black ducks breeding in Nova Scotia and southern Quebec were harvested predominantly in Canada. Recovery probabilities for juveniles were correlated with hunter effort, while the adult recoveries were weakly correlated with the implementation of stricter harvest regulations in the early 1980s. Mean harvest probability decreased in the northern portion of the survey area but remained stable or even increased in the south. Harvest probabilities for juveniles in 2010 exceeded 20% in southern Quebec and the Atlantic provinces. Our results demonstrate fine-scale variation in harvest probabilities for black duck on the Canadian breeding ground. In particular, harvest probabilities should be closely monitored along the Saint Lawrence River system and in the Atlantic provinces to avoid overexploitation.

Assessing Effectiveness of Innovative Waterfowl Hunting Decoys

New waterfowl hunting decoy technologies warrant rigorous assessment of their effects on wildlife harvest. Recent development of several UV-reflecting paints employed on waterfowl hunting decoys are designed to appear more like real duck feather colours in an attempt to better attract waterfowl. In two concurrent field experiments over a four year period, we tested the ability of UV-painted decoys to attract waterfowl within ∼ 50 m (i.e., potential shotgun range) of a duck blind and their success when employed waterfowl hunting, compared to traditionally painted, non-UV reflecting decoys. While UV decoys did attract, on average, more ducks and flocks compared to non-UV decoys during non-hunting observational trials, these differences were not reflected in harvest of waterfowl during typical hunting situations, which were nearly identical among the two decoy types. From a resource management perspective, our results suggest that UV decoys do not have a profound impact on waterfowl harvest, although broader harvest assessment is warranted.

Multilevel Learning in the Adaptive Management of Waterfowl Harvests: 20 Years and Counting

ABSTRACTIn 1995, the U.S. Fish and Wildlife Service implemented an adaptive harvest management program (AHM) for the sport harvest of midcontinent mallards (Anas platyrhynchos). The program has been successful in reducing long‐standing contentiousness in the regulatory process, while integrating science and policy in a coherent, rigorous, and transparent fashion. After 20 years, much has been learned about the relationship among waterfowl populations, their environment, and hunting regulations, with each increment of learning contributing to better management decisions. At the same time, however, much has been changing in the social, institutional, and environmental arenas that provide context for the AHM process. Declines in hunter numbers, competition from more pressing conservation issues, and global‐change processes are increasingly challenging waterfowl managers to faithfully reflect the needs and desires of stakeholders, to account for an increasing number of institutional constraints, and to (probabilistically) predict the consequences of regulatory policy in a changing environment. We review the lessons learned from the AHM process so far, and describe emerging challenges and ways in which they may be addressed. We conclude that the practice of AHM has greatly increased an awareness of the roles of social values, trade‐offs, and attitudes toward risk in regulatory decision‐making. Nevertheless, going forward the waterfowl management community will need to focus not only on the relationships among habitat, harvest, and waterfowl populations, but on the ways in which society values waterfowl and how those values can change over time. © 2015 The Authors. Wildlife Society Bulletin published by The Wildlife Society.

Transnational Ecosystem Services: The Potential of Habitat Conservation for Waterfowl Through Recreational Hunting Activities

This article explores transnational ecosystem services in North America, provided by winter habitat for waterfowl in western Mexico coastal lagoons, and the hunting industry supported by these birds in the United States. This article shows that the number of waterfowl harvested in the United States is related to the abundance of waterfowl wintering in Mexico. On average, this flow of ecosystem services annually yields US$ 4.68 million in hunting stamp sales in the western United States. A demand curve, fitted to duck hunting licenses as a function of stamp price and previous-year waterfowl harvest, estimated US$3–6 million in consumer surplus produced in addition to governmental stamp sales revenue. This strongly suggests that waterfowl wintering habitat in western Mexico is economically valuable to U.S. hunters. Because hunters may benefit substantially from these habitats they may be willing to pay for conservation efforts in western Mexico that can result in transnational benefits received in the United States.

Conservation of wildlife populations: demography, genetics, and management

List of boxes. List of symbols. Preface. Acknowledgments. PART I: Background to applied population biology. 1. The Big Picture: Human population dynamics meets applied population biology. Introduction. Population ecology of humans. Extinction rates of other species. Humans and sustainable harvest. The big picture. Further reading. 2. Designing studies and interpreting population biology data: how do we know what we know?. Introduction. Obtaining reliable facts through sampling. Linking observed facts to ideasmind leads to understanding. Ethics and the wildlife population biologist. Summary. Further reading. 3. Genetic concepts and tools to support wildlife population biology. Introduction. What is genetic variation?. Genetic markers used in wildlife population biology. Insights into wildlife population biology using genetic tools. Summary. Further reading. 4. Estimating population vital rates. Estimating abundance and density. Survival estimation. Estimation of reproduction. Sex ratio. Summary. Further reading. PART II: POPULATION PROCESSES: THE BASIS FOR MANAGEMENT. 5. The simplest way to describe and project population growth: exponential and geometric change. Introduction. Fundamentals of geometric or exponential growth. Causes and consequences of variation in population growth. Quantifying population growth in a stochastic environment. Summary. Further reading. 6. Density dependent population change. Introduction. Negative density dependence. Positive density dependence. The logistic: one simple model of negative density-dependent population growth. Some counterintuitive dynamics: limit cycles and chaos. Summary. Further reading. 7. Accounting for age and sex-specific differences: population projection models. Introduction. Anatomy of a population-projection matrix. How timing of sampling affects the matrix. Projecting a matrix through time. Adding stochasticity to a matrix model. Sensitivity analysis. Case studies. Summary. Further reading. 8. Predation and wildlife populations. Does predation affect prey numbers?. Factors affecting how predation impacts prey numbers. Summary. Further reading. 9. Genetic Variation and Fitness of Wildlife Populations. Introduction. Long-term benefits of genetic variation. What determines levels of genetic variation in populations?. Quantifying the loss of heterozygosity: the inbreeding coefficient. When does inbreeding lead to inbreeding depression?. What to do when faced with inbreeding depression?. General Rules. Summary. Further reading. 10. Dynamics of Multiple Populations. Introduction. Connectivity among populations. Measuring connectivity among wildlife populations. Multiple populations are not all equal. Options for restoring connectivity. Summary. Further reading. PART III: APPLYING KNOWLEDGE OF POPULATION PROCESSES TO PROBLEMS OF DECLINING, SMALL, OR HARVESTABLE POPULATIONS. 11. Human Perturbations: Deterministic Factors Leading to Population Decline. Introduction. General effects of deterministic stressors on populations. Habitat loss and fragmentation. Introduced and invasive species. Pollution. Overharvest. Global climate change. Synergistic effects among deterministic stressors. Summary. Further reading. 12. Predicting the dynamics of small and declining populations. Introduction. Ecological characteristics predicting risk. The extinction vortex. Predicting risks in small populations. Population viability analysis: quantitative methods of assessing viability. Other approaches to assessing viability. Some closing thoughts about assessing viability. Summary. Further reading. 13. Bridging applied population and ecosystem ecology with focal species concepts. Introduction. Flagship species. Umbrella species. Indicator species. Keystone species and strong interactors. Summary. Further reading. 14. Population biology of harvested populations. Introduction. Effects of hunting on population dynamics. Long term effects: hunting as a selective force. Models to guide sustainable harvests. Waterfowl harvest and adaptive harvest management. Management of overabundant and pest populations. Summary. Further reading. Epilogue. References. Species lists. Subject index.

Assessment of bias in US waterfowl harvest estimates

Context North American waterfowl managers have long suspected that waterfowl harvest estimates derived from national harvest surveys in the USA are biased high. Survey bias can be evaluated by comparing survey results with like estimates from independent sources. Aims We used band-recovery data to assess the magnitude of apparent bias in duck and goose harvest estimates, using mallards (Anas platyrhynchos) and Canada geese (Branta canadensis) as representatives of ducks and geese, respectively. Methods We compared the number of reported mallard and Canada goose band recoveries, adjusted for band reporting rates, with the estimated harvests of banded mallards and Canada geese from the national harvest surveys. We used the results of those comparisons to develop correction factors that can be applied to annual duck and goose harvest estimates of the national harvest survey. Key results National harvest survey estimates of banded mallards harvested annually averaged 1.37 times greater than those calculated from band-recovery data, whereas Canada goose harvest estimates averaged 1.50 or 1.63 times greater than comparable band-recovery estimates, depending on the harvest survey methodology used. Conclusions Duck harvest estimates produced by the national harvest survey from 1971 to 2010 should be reduced by a factor of 0.73 (95% CI = 0.71–0.75) to correct for apparent bias. Survey-specific correction factors of 0.67 (95% CI = 0.65–0.69) and 0.61 (95% CI = 0.59–0.64) should be applied to the goose harvest estimates for 1971–2001 (duck stamp-based survey) and 1999–2010 (HIP-based survey), respectively. Implications Although this apparent bias likely has not influenced waterfowl harvest management policy in the USA, it does have negative impacts on some applications of harvest estimates, such as indirect estimation of population size. For those types of analyses, we recommend applying the appropriate correction factor to harvest estimates.

A modeling framework for integrated harvest and habitat management of North American waterfowl: Case-study of northern pintail metapopulation dynamics

We developed and evaluated the performance of a metapopulation model enabling managers to examine, for the first time, the consequences of alternative management strategies involving habitat conditions and hunting on both harvest opportunity and carrying capacity (i.e., equilibrium population size in the absence of harvest) for migratory waterfowl at a continental scale. Our focus is on the northern pintail ( Anas acuta; hereafter, pintail), which serves as a useful model species to examine the potential for integrating waterfowl harvest and habitat management in North America. We developed submodel structure capturing important processes for pintail populations during breeding, fall migration, winter, and spring migration while encompassing spatial structure representing three core breeding areas and two core nonbreeding areas. A number of continental-scale predictions from our baseline parameterization (e.g., carrying capacity of 5.5 million, equilibrium population size of 2.9 million and harvest rate of 12% at maximum sustained yield [MSY]) were within 10% of those from the pintail harvest strategy under current use by the U.S. Fish and Wildlife Service. To begin investigating the interaction of harvest and habitat management, we examined equilibrium population conditions for pintail at the continental scale across a range of harvest rates while perturbing model parameters to represent: (1) a 10% increase in breeding habitat quality in the Prairie Pothole population (PR); and (2) a 10% increase in nonbreeding habitat quantity along in the Gulf Coast (GC). Based on our model and analysis, a greater increase in carrying capacity and sustainable harvest was seen when increasing a proxy for habitat quality in the Prairie Pothole population. This finding and underlying assumptions must be critically evaluated, however, before specific management recommendations can be made. To make such recommendations, we require (1) extended, refined submodels with additional parameters linking influences of habitat management and environmental conditions to key life-history parameters; (2) a formal sensitivity analysis of the revised model; (3) an integrated population model that incorporates empirical data for estimating key vital rates; and (4) cost estimates for changing these additional parameters through habitat management efforts. We foresee great utility in using an integrated modeling approach to predict habitat and harvest management influences on continental-scale population responses while explicitly considering putative effects of climate change. Such a model could be readily adapted for management of many habitat-limited species.

Spinning‐wing decoy use and reported duck harvest in Illinois: Implications for adaptive harvest management

AbstractUse of battery‐powered spinning‐wing decoys (SWDs) by duck hunters has generated questions as to the effect these decoys may have on duck harvests. I used data from the annual Illinois Waterfowl Hunter Survey for duck hunting seasons 1999 through 2003 to compare mallard (Anas platyrhynchos) and total duck harvest, reported days afield, and duck crippling rates between hunters using and not using SWDs. For the each of the 5 years reported, mean mallard harvest was greater among hunters using SWDs than among hunters not using the decoys and effect size was substantial (1999: F = 355.01, P < 0.001; 2000: F = 567.92, P < 0.001; 2001: F = 333.25, P < 0.001; 2002: F = 321.58, P < 0.001; 2003: F = 299.00, P < 0.001). Mean reported total ducks harvested was greater for decoy users than non‐users, and I found effect sizes to be substantial for all years (1999: F = 301.80, P < 0.001; 2000: F = 607.76, P < 0.001; 2001: F = 369.49, P < 0.001; 2002: F = 321.59, P < 0.001; 2003: F = 335.82, P < 0.001). Decoy users reported hunting more days than non‐users (1999: F = 71.00, P < 0.001; 2000: F = 716.50, P < 0.001; 2001: F = 486.75, P < 0.001; 2002: F = 410.72, P < 0.001; 2003: F = 466.09, P < 0.001). I observed substantial effect size for days hunted by decoy use for each year except for 1999–2000, for which effect size was typical. Hunters using SWDs reported greater crippled ducks than for hunters not using the decoys, with typical effect sizes observed for each year I examined (1999: F = 168.42, P < 0.001; 2000: F = 361.34, P < 0.001; 2001: F = 163.05, P < 0.001; 2002: F = 153.29, P < 0.001; 2003: F = 169.18, P < 0.001). I did not observe significant relationships between years of hunting experience and decoy use (R2 range = 0.051–0.071). My findings support claims that SWDs lead to increased duck harvests. Recent actions by some state wildlife management agencies have resulted in a mixed approach toward regulating use of SWDs, ranging from prohibiting their use to removing all restrictions. This study seeks to provide managers with greater understanding of potential impacts of SWD use on waterfowl harvests. © 2011 The Wildlife Society.

Climate change, uncertainty, and natural resource management

AbstractClimate change and its associated uncertainties are of concern to natural resource managers. Although aspects of climate change may be novel (e.g., system change and nonstationarity), natural resource managers have long dealt with uncertainties and have developed corresponding approaches to decision‐making. Adaptive resource management is an application of structured decision‐making for recurrent decision problems with uncertainty, focusing on management objectives, and the reduction of uncertainty over time. We identified 4 types of uncertainty that characterize problems in natural resource management. We examined ways in which climate change is expected to exacerbate these uncertainties, as well as potential approaches to dealing with them. As a case study, we examined North American waterfowl harvest management and considered problems anticipated to result from climate change and potential solutions. Despite challenges expected to accompany the use of adaptive resource management to address problems associated with climate change, we conclude that adaptive resource management approaches will be the methods of choice for managers trying to deal with the uncertainties of climate change. © 2010 The Wildlife Society.