Journal of Wildlife Management最新文献

In the early 1900s, wood duck Aix sponsa populations experienced severe declines due to unregulated hunting and habitat destruction. Federal protection under the Migratory Bird Treaty Act of 1918 and the implementation of nest box programs facilitated their recovery such that sport harvest resumed in 1941. In 2008, the bag limit for wood ducks during the general duck season increased from two to three daily, a change projected to increase the harvest rates. However, estimating harvest and survival rates of adult females remains challenging due to the difficulty of capturing them during preseason banding operations. We analyzed data from 2001–2014 from box-nesting female wood ducks in Louisiana using a live-dead model to estimate survival and calculate harvest rates. Our results indicate the bag limit increase had minimal impact on the survival and harvest rates of box-nesting females. The mean annual survival rate was 68%, with no changes after the increase in bag limit in 2008. Harvest rates also remained consistent across the study period, averaging 3%. Our findings suggest the increase in bag limit has not adversely affected survival of box-nesting wood ducks in Louisiana, allowing for additional hunting opportunities without compromising conservation goals for adult female wood ducks in the state.

Due to the steady decline of waterfowl hunters, several studies have investigated means to bolster the waterfowl hunter population. Documented declines in waterfowl hunter participation are particularly worrisome because funding for the conservation of North American waterfowl habitat is dependent on the annual purchase of Federal Migratory Bird Hunting Conservation Stamps by migratory bird hunters. One method of recruiting new waterfowl hunters is through mentoring by existing members of the hunter population. These mentors serve an important role in the propagation of waterfowl hunting participation and the continued funding of waterfowl conservation. Given the importance of mentors to hunter participation, we sought to discover at what age hunters were most likely to mentor new individuals. Using data from a survey of Central Flyway waterfowl hunters, we found that during the time of the survey, individuals between the ages of 20 and 50 years had a ~0.50 probability of taking someone waterfowl hunting who had never gone before. Hunters in their sixties, seventies, and eighties had a 0.20, 0.24, and 0.18, respectively, probability of mentoring a new hunter. If increasing the waterfowl hunter population remains a goal for wildlife agencies, recruitment programming may wish to consider the promotion of mentoring activity by existing hunters well before the age of 60 years.

Beaver Castor canadensis create ecological refugia against drought, heat stress, and fire, and policies to support beaver conservation and recolonization in regions where they have been historically extirpated are increasingly common. Between prolonged periods of drought, arid regions are increasingly challenged by extreme precipitation events that promote flash floods, debris flows, and mudslides—a phenomenon known as whiplash weather. Understanding how beaver wetlands respond to whiplash weather will help inform the development of restoration policies targeting the species as a natural climate solution. We used remotely sensed normalized difference vegetation index data to characterize the influence of beaver complexes on riparian greenness dynamics under whiplash weather by comparing three complexes and five nearby reference areas along the Salinas River, California. Our study region is within a remanent patch of the historical range of beaver and is highly impacted by agricultural and urban uses. Despite these limitations to expansion and their low density due to historical extirpation, the Salinas River beaver complexes demonstrated greater riparian greenness resistance to drought and resilience to flood disturbance than the watershed reference areas. Thus, policies supporting beaver re-colonization—even within highly fragmented and anthropogenically impacted habitats—may confer both riparian resistance and resilience to increasingly erratic climatic conditions.

In arid urban ecosystems, oases support both agricultural livelihoods and biodiversity. Given their importance, understanding factors influencing wild boar (Sus scrofa) distribution and their subsequent effects on crops is crucial. We explored the occurrence and ecological impacts of wild boars in the oasis agroecosystems of southern Tunisia, focusing on the Gabès and Kébili regions. We tested the hypothesis that wild boar occurrence was related to regional differences in agroecosystem characteristics that reflect variations in habitat suitability and management practices. Our measurements focused on oasis size, irrigation practices, cereal density, proximity of oases to wild boar refuge areas and roads, accessibility of oases to wild boars, and palm height. We assessed wild boar presence through systematic field surveys at each sampling site, using direct observations and the identification of tracks, scat, and rooting signs, which served as a key indicator of wild boar damage. We assessed biodiversity on standardized sampling plots where we recorded plant species richness and abundance across the study sites. We detected wild boars in 66.7% (±8.54 [SD]) of sampling plots in Gabès and 48.95% (±13.33) in Kébili on average, with signs of damage detected in 30.52% (±13.30) of plots in Gabès and 26.05% (±4.02) in Kébili on average, with no significant differences observed between regions or seasons. Wild boar occurrence increased with vegetation complexity (2-layered oases) and organic fertilization (manure application), and was marginally greater closer to refuge zones. Conversely, disturbance from boars decreased with increasing oasis size, irrigation, distance to road, and cereal density but was greater in oases farther from refuge zones and with taller palm trees. Our results highlight the complex interactions between human activities and wild boar impacts, stressing the need for integrated wildlife management and sustainable agricultural practices in arid environments.

The successful conservation and management of North American waterfowl relies upon an adaptive harvest management framework that accounts for changes in the system state and critical uncertainties related to the dynamics of waterfowl populations and habitats. Increasing recognition of the importance of the human dimensions of the harvest process, particularly those related to hunters, has motivated calls for the integration of social objectives into waterfowl conservation programs and decision making. We introduce a framework for modeling the dynamics of hunter populations and behavior alongside those of waterfowl populations. Using Bayesian estimation, we fit a dynamic state space model to observational data from the Mid-Continent mallard (Anas platyrhynchos) system over a 20-year period and estimated parameter values for the relative effects of a set of hypothesized drivers of hunter recruitment, retention, reactivation, participation, and success rates. We then made projections across 3 future scenarios to examine the continuation of current trends, the potential effects of a shift to a moderate regulatory framework as informed by expert elicitation, and increased hunter recruitment to maintain a stable hunter population. We found that a theoretical stable state exists for Mid-Continent mallard and hunter populations but that the influence of broader sociocultural shifts and increasing hunter mortality from an aging base pose significant challenges for efforts to stabilize the ongoing decline of active hunter numbers, even under favorable regulatory conditions. This modeling framework and results from it can be used to inform decision processes in the management of game populations that seek to include social objectives and assess the potential trade-offs of prioritizing across social and ecological objectives. We emphasize the need for focused human dimensions expertise throughout the process of fully integrating goals for waterfowl populations, habitats, and people in waterfowl conservation.

The South African lion (Panthera leo) metapopulation is distributed over a network of small, fenced protected areas and requires intensive management to mimic ecological processes. As the metapopulation grows, coordinated management—supported by reliable, cost-effective monitoring—is increasingly important. However, monitoring programs to support improved metapopulation management can be resource intensive, and optimal sampling regimes are desirable, wherein expenditure of resources is minimized without compromising the reliability of estimates and the ability to detect population trends. In this study, we conducted a follow-up lion population survey in a small, fenced reserve in South Africa, 2 years after a management-driven population reduction. Using optimal sampling guidelines from an initial survey in 2020, we applied Bayesian spatial capture-recapture (SCR) models to estimate current density at 5.24 individuals/100 km² (95% highest posterior density interval = 4.22–6.43), a 40% decline since the 2020 estimate. By following recommendations on survey effort and minimum data objectives, informed by the 2020 survey, we demonstrate how an initial survey can be used to optimize subsequent survey effort and strike a balance between precision and resource expenditure. Our study highlights how SCR models and search-encounter methods can be used to guide lion management in small, fenced reserves and help to inform a more coordinated approach to lion metapopulation management in South Africa.

Semi-aquatic mammal species play important roles in terrestrial and aquatic ecosystems. Understanding of their current distributions and how they are influenced by environmental variables is important for management. From October 2021 to January 2022, we deployed camera traps at 48 sites along 10 waterways on 6 study areas in central and northeast Ohio, USA, to assess the distribution, relative abundance, co-occurrence, and habitat associations of beavers (Castor canadensis), minks (Neogale vison), muskrats (Ondatra zibethicus), and river otters (Lontra canadensis). We sorted photos by species and used a multispecies occupancy model for interacting species to assess the impact of environmental factors on species occupancy and co-occupancy. River otters were only detected in one study area, while minks, muskrats, and beavers occurred in all 6 study areas. Mean occupancy probability was 0.11 (95% CI = 0.04–0.56) for river otters, 0.73 (95% CI = 0.42–0.94) for minks, 0.40 (95% CI = 0.21–0.74) for muskrats, and 0.45 (95% CI = 0.20–0.81) for beavers. None of the variables we evaluated affected beaver occupancy. River otter occupancy increased as the proportion of wetland within 100 m of the survey site increased. Mink occupancy along waterways declined as available wetland within a 500-m buffer of the survey site increased, and muskrat occupancy increased as the proportion of developed cover within 100 m of the site increased. Occupancy probability for minks was higher when muskrats were present; however, mink–muskrat co-occupancy declined as woody cover in the area increased. Our results suggest that if trying to manage for both mink and muskrat populations, maintaining many smaller wetlands along a forested waterway may be more beneficial than a single large wetland.

The Interior Population of trumpeter swans (Cygnus buccinator) has expanded substantially since initial reintroduction efforts. Given recent trends following multiple successful releases beginning in the 1980s, we predicted continued expansion, especially into the nearby Prairie Pothole Region. To support management, we developed a landscape suitability model and range expansion estimates (2023‒2033) to help jurisdictions anticipate future swan distribution. We assessed landscape suitability for breeding trumpeter swans with a use-available study design based on global positioning system (GPS) collar data (2019‒2023) from swans in the western Great Lakes region of the United States and Canada. We related occurrence and pseudo-absences to landscape-scale summaries of upland and wetland conditions in a logistic mixed-effects model. We then incorporated landscape suitability into a range expansion model, which used logistic regression to estimate the probability of 50-km grid cells being occupied by 2033, where time-series citizen-science data summaries (2004–2023) of newly occupied range cells and unoccupied cells were related to year, survey effort, landscape suitability, and distance to previously occupied cells. Landscape suitability was positively related to greater amounts of wetland perimeter and foraging areas. Range expansion was positively associated with landscape suitability and survey intensity and negatively associated with year and distance to previously occupied cells. We estimated a 4.4% (95% CI = 2.0–6.9%) annual range expansion rate from 2023 to 2033, with expansion occurring in the Prairie Pothole Region of the Dakotas and the Boreal Shield and James Bay Lowlands of Canada. Our models can support proactive conservation planning by identifying priority areas for habitat management and public outreach. Notably, North Dakota and South Dakota permit tundra swan (Cygnus columbianus) hunting but not trumpeter swan hunting, emphasizing the need for targeted hunter education to prevent unintended take of the similar-looking species and support the establishment of persistent trumpeter swan populations.

The Eastern Population of sandhill cranes has expanded rapidly from near extirpation in the early twentieth century. Rapid population recovery and range expansion have resulted in the increased take of the Eastern Population through crop depredation permits and hunting. To provide a better biological foundation for managing the Eastern Population, the management community desired a scientifically informed evaluation of take to maximize the protection and use of this species for 3 major purposes: wildlife viewing, control of crop depredation, and sport hunting. We used a prescribed take approach, which uses data from population, demographic, and management parameter estimates to determine the allowable take. Furthermore, we used 2 different methods of estimating growth rates to control for demographic uncertainties. We estimated a maximum growth rate of 0.092 to 0.123 for demographically informed and demographically invariant methods, respectively. Depending on management objectives, median take ranged from 3,123 birds at a low take management goal to 6,245 at the maximum sustained yield management goal. We found that this species can sustain current reported take and likely can sustain additional take if needed. Owing to inherent differences in productivity, driven by small clutch size and lower fledging success, sandhill cranes need to be more closely monitored for take compared to more fecund species.