Journal of Wildlife Management最新文献

Expansion of boreal species into tundra ecosystems is a consequence of climate change and human exploitation that threatens local species through increased predation, competition, and pathogen transmission. Under these circumstances, efficient control of expanding boreal species may be necessary, but the efficiency of such action depends on understanding the ecological influences of expansion. The red fox (Vulpes vulpes) is expanding into the tundra across the Arctic. In Scandinavia, red foxes threaten local tundra species and communities including the endangered Arctic fox (V. lagopus). The ecological dynamics in the tundra are influenced by small rodent cycles (classified into different phases based on seasonal abundance fluctuations), which can affect red fox expansion, distribution, and abundance. We used a 17-year (2004–2020) dataset from the tundra in Sweden, consisting of raw snow track data, to test how cyclic prey influenced red fox distribution and abundance, and subsequently red fox control. The winter abundance of red fox was influenced by small rodent phase, with higher abundance during high prey availability (i.e., increased number of prey numbers) with no support for a time lag between red fox and small rodent abundance. This suggests that high prey availability attracts red foxes to the tundra and that higher immigration from the boreal zone can be expected in response to increased prey abundances. There was no relationship between red fox control and small rodent availability, but control was influenced by red fox abundance during the previous year, which highlights an opportunistic control strategy. We recommend an adaptive management strategy where authorities include small rodent dynamics in the planning and execution of red fox control.

Species-specific management strategies have been implemented to address persistently low continental populations of several duck species, including the northern pintail (Anas acuta). In the Canadian Prairie Pothole Region (PPR), addressing threats from spring-seeded cereals on pintail productivity may provide sufficient gains to recover populations. Research on pintail duckling ecology has revealed that duckling survival may be greater in grassland-dominated landscapes than in annual cropland-dominated landscapes, possibly limiting the benefits of fall-seeded cropping practices. Winter wheat crops increase nest success and may assist nesting pintail populations through provision of nesting refuges from spring tillage operations, earlier hatch, and greater nest densities compared to traditional spring-seeded cereal crops. Yet inadequate duckling survival may reduce these benefits. Our principal objective was to examine if pintail reproductive success in winter wheat in cropland-dominated landscapes was comparable to grassland-dominated landscapes or, alternatively, if duckling survival rates in cropland-dominated landscapes offset the gains of greater nesting success in winter wheat. We captured and radio-marked 104 nesting female pintails in grasslands and croplands of southern Saskatchewan, during 2011–2012. We modeled cumulative survival to 30 days post hatch in relation to landscape composition and land cover type, specifically, the influence of nesting in fall-seeded crops. Predicted 30-day survival for ducklings hatched in perennial cover (40.8% [85% CI = 40.0–44.6%]) in grassland-dominated landscapes and winter wheat (38.2% [32.0–44.4%]) in cropland-dominated landscapes was more than double survival of ducklings hatched in spring-seeded cropland (16.9% [12.6–21.6%]) in cropland-dominated landscapes. Ducklings moving through local environments with more perennial cover and seasonal wetlands, but less wetland edge, had increased survival. The benefit of greater nest survival in winter wheat was not completely superseded by reduced duckling survival for broods raised in intensive agricultural landscapes. The retention of grassland landscapes and expansion and promotion of fall-seeded crops in cropland-dominated landscapes can benefit northern pintails across broad regions of the PPR.

Brushlands support a diverse suite of bird species, including species of conservation concern in the western Great Lakes region of central North America. Information on how to effectively manage lowland brushlands for birds and associations between breeding birds and local-scale vegetation structure and composition is lacking. We surveyed lowland brushlands from 2016–2018 in Minnesota, USA, to assess bird-habitat associations using avian point-count surveys and fixed-radius vegetation plots. We used Poisson regression models to assess the associations between breeding bird species richness, total abundance, and abundance of frequently detected species (using counts as an index for abundance) to woody stem density and height, patchiness of woody stem density, variation of woody stem height, and number of woody plant species. Sedge wrens (Cistothorus stellaris), the most abundant species, were negatively associated with multiple woody plant metrics and positively associated with patchiness. Common yellowthroats (Geothlypis trichas) were the second-most abundant species and associated with low-stature woody plants (<1 m based on average heights in study sites). Bird species richness, alder flycatchers (Empidonax alnorum), chestnut-sided warblers (Setophaga pensylvanica), swamp sparrows (Melospiza georgiana), veeries (Catharus fuscescens), and yellow warblers (Setophaga petechia) increased with woody vegetation height. Chestnut-sided warbler and Nashville warbler (Leiothlypis ruficapilla) abundances also increased with woody stem density. We suggest that managing lowland brushlands to promote diverse woody plant structure, including tall shrubs and areas with patchy, open herbaceous cover, by implementing temporally and spatially variable disturbance regimes, may benefit bird species that rely on lowland brushlands with a range of vegetation structure requirements.

The United States Fish and Wildlife Service in Alaska, USA, conducted a species status assessment for a petition to list the Alexander Archipelago wolf (Canis lupus ligoni) under the Endangered Species Act in 2020-2022. This federal undertaking could not be adequately prepared without including the knowledge of Indigenous People who have a deep cultural connection with the subspecies. Our objective is to communicate the authoritative expertise and voice of the Indigenous People who partnered on the project by demonstrating how their knowledge contributed to the species status assessment. The Indigenous knowledge applied in the assessment is the cultural and intellectual property of those who have shared it. We employed rapid appraisal research to expeditiously develop a preliminary and qualitative understanding of Indigenous People's cultural and ecological knowledge of Alexander Archipelago wolves. We used semi-directed interviewing and inductive coding from grounded theory for text analysis. Indigenous knowledge contributed to the agency's understanding of the Alexander Archipelago wolf in Southeast Alaska and helped the agency with their classification decision. Indigenous research partners explained the rich cultural significance and position of wolves in Tlingit society and described human–wolf relationships and ecological interactions. The agency used a single-species assessment approach based in species ecology and conservation biology, whereas the Indigenous wolf experts applied a multi-species, community ecology approach based in a sociocultural context of balance and respect. The Indigenous wolf experts successfully addressed knowledge gaps identified by the agency. The partners were challenged by a short regulatory timeframe that did not allow for comprehensive study of Indigenous knowledge and constrained review and feedback by Indigenous experts. The United States Fish and Wildlife Service learned that its assessment framework was not designed to account for an Indigenous worldview. To level the playing field, the agency and Indigenous experts should discuss how to co-develop an assessment framework that equitably applies both perspectives.

Amphibians are declining worldwide, and research on their habitats and ecology is important for their conservation. The endangered dusky gopher frog (Rana sevosa) breeds exclusively in isolated, open canopy wetlands, usually with extensive herbaceous growth. Larvae of the dusky gopher frog have higher growth and survival under open canopy than under closed canopy conditions. The mechanisms whereby this occurs are poorly understood, however. In the summer of 2021 in Harrison County, Mississippi, USA, we conducted a complete factorial experiment in mesocosms to compare the relative influence of factors differing between open and closed canopy ponds on larvae. A heat and light treatment consisted of one third of tanks being exposed to full sunlight, one third of tanks being shaded with 70% shadecloth, and the final third being shaded with 70% shadecloth but heated to mimic the temperature of the full sun tanks. In addition, tanks received a closed canopy tree leaf litter mixture or an open canopy herbaceous vegetation mixture, and vertical vegetation-like structure made of polypropylene rope or not. Cool shaded tanks and heated shaded tanks had identical survival to metamorphosis at 74.7% and produced frogs with an average mass of 2.21 g and 2.09 g, respectively, while tanks in full sunlight achieved significantly higher 93.4% survival to metamorphosis and an average mass of 2.64 g. The open canopy vegetation mixture yielded an average tank survival of 88.3% and mass of 2.94 g, compared to closed canopy vegetation tanks with a significantly lower survival of 73.5% and average mass of 1.61 g. Added structure had no effect on survival or mass. These results indicate that sunlight (not heat alone) and herbaceous plants are important in increasing dusky gopher frog survival and mass in open canopy conditions and suggest that management for these characteristics receive priority in captive-rearing programs and habitat restoration.

Understanding the phenology of migration is fundamental to management of migratory gamebirds, in part because of the role migratory timing plays in setting harvest regulations. Migratory timing is particularly important for determining appropriate dates for hunting seasons, which may be selected to coincide with major periods of migration, according to local management objectives. We used global positioning system (GPS)-transmitters to track American woodcock (Scolopax minor), characterize the timing of woodcock migration, and identify sources of variation in timing relative to current hunting season structures in eastern North America. We captured 304 woodcock in 3 Canadian provinces and 12 states from 2017 to 2020, primarily within the Eastern Woodcock Management Region. Using locations collected every 1.7 days on average, we assessed whether initiation, termination, or stopover timing of woodcock migration during fall and early spring varied geographically, differed among age and sex classes, or was influenced by individual body condition. During fall, woodcock migrating from summer use areas farther north and west (e.g., Ontario, Quebec, Canada) initiated and terminated migration earlier than woodcock migrating from areas farther south and east (e.g., Rhode Island, USA). Adult woodcock made multiday stopovers that were 3 days longer on average than juveniles and females made more stopovers on average (8.0 stopovers) compared to males (6.1 stopovers). During the onset of spring migration, woodcock that wintered farther west initiated migration before birds that spent the winter farther east, and males initiated migration on average 6 days earlier than females. Under the current 45-day harvest regulatory framework in the United States, hunting seasons in northern breeding and southern wintering areas are generally consistent with migration phenology. At more intermediate latitudes, however, periods of migration are generally longer than 45 days, resulting in many circumstances where migrating woodcock are present during periods when hunting seasons are closed. Managers in mid-latitude states could consider opening hunting seasons later, allowing hunters to harvest more migrant woodcock.

Motion-sensitive cameras are commonly used to monitor wildlife occupancy rates; however, few studies have assessed whether data from cameras are correlated with density estimates obtained from more traditional labor-intensive methods such as those based on capture-mark-recapture. We used data from a boreal forest community to test whether camera data were correlated with densities estimated from independent monitoring methods. We placed 72 covert cameras in the forest around Lhù'ààn Mân' (Kluane Lake), Yukon, Canada, for 7 years and tracked changes in population densities by camera hit rates. We independently estimated population densities of snowshoe hares (Lepus americanus) and red squirrels (Tamiasciurus hudsonicus) using capture-mark-recapture via live trapping, and Canada lynx (Lynx canadensis), coyotes (Canis latrans), and moose (Alces americanus) by snow track transects. Density estimates obtained from conventional aerial surveys were also periodically available for moose. Except for red squirrels, camera hit rates were highly correlated with population density estimates obtained by traditional methods, including across a large range of estimated densities corresponding to cyclic population dynamics in several species. Accordingly, we infer that motion-sensitive cameras could supplement or replace traditional methods for monitoring key species in boreal forest food webs. Using cameras to monitor population change has several advantages; they require less effort in the field, are non-invasive compared to live-trapping, include multiple species at the same time, and rely less on weather than either aerial surveys or snow track transects. Tracking changes across the vast boreal forest is becoming increasingly necessary because of climate and landscape change and our data validate the use of motion-sensitive cameras to provide a useful quantitative method for state-of-the-environment reporting.

Mojave desert tortoise (Gopherus agassizii) populations in some regions have declined by >50% since 2004, prompting the need for more research on ways to recover populations. One possible recovery tool is head-starting (i.e., the act of protecting and raising juvenile tortoises to sizes that increase survival upon release); however, head-starting can have high start-up and maintenance costs that can limit its feasibility. Strategies that reduce cost and rearing duration may foster broader and more effective use. We released and radio-tracked 60 juvenile tortoises in the Mojave National Preserve in California, USA, that had been reared under 2 treatments: those reared 1 year indoors after hatching, then 1 year outdoors (combo) and those reared just 1 year indoors (indoor-only). We tested whether indoor-only rearing alone could be a more efficient means of producing robust head-started tortoises. We examined the behavior, movement, and survival of tortoises after release into the wild from 2020 to 2021 to determine whether these outcomes differed between husbandry treatments. Combo tortoises tended to perform settling behaviors (mean ± 1 SE days to building first burrow = 6.7 ± 0.8, entering dormancy = 23.3 ± 2.1, and emerging from dormancy = 189.6 ± 4.4) earlier than indoor-only tortoises (7.4 ± 0.9, 31.5 ± 2.6, and 193.9 ± 5.9, respectively), but this difference was not significant, suggesting the rearing method did not greatly alter settling behavior. Indoor-only tortoises dispersed at least twice as far from their release site (156.2 ± 26.3 m compared with 77.3 ± 20.6 m for combo tortoises), had larger mean use areas (3.7 ± 0.1 ha compared with 2.8 ± 0.3 ha for combo tortoises for 95% Brownian bridge movement model estimates), and greater variability in their movements than combo tortoises (daily average step length post-emergence: 4.3 ± 0.2 m compared with 2.8 ± 0.1 m for combo tortoises). Despite differences in their movements, indoor-only and combo tortoises had similar survival rates over the study, 51% versus 42%, respectively, during a period of extreme drought in 2021. The similarity in survival between groups gives head-starting practitioners freedom in their rearing methods. The indoor-only group had lower site fidelity, which should be considered when this is an undesirable trait for released tortoises.