Journal of Wildlife Management最新文献

Urbanization and expanding road networks threaten some avian populations through habitat loss and degradation. Barn owls (Tyto alba) have been particularly affected through roadway mortality, loss of grassland, and conversion or destruction of nesting sites. To combat declines and bolster reproduction, and as part of integrated pest management to reduce crop damage, some land managers provide supplemental owl nesting sites via the installation of nest boxes. If nearby habitat and land cover characteristics are not considered when placing boxes, such as major roads or other anthropogenic features, owls could be attracted to locations that could hinder populations further. We investigated the effects of roads and urban areas on barn owl breeding occupancy and productivity to provide information to help guide the placement of nest boxes. We monitored >300 nest boxes over the 2020 and 2021 breeding seasons in southwestern Idaho, USA, where substantial roadway mortality of barn owls occurs. Barn owls occupied >60% of nest boxes, but the likelihood of breeding occupancy decreased with increasing proximity of nest boxes to roads. Boxes 500 m from roads had a predicted probability of occupancy of over 0.9, which was nearly double that of boxes within 100 m. Proximity to roads also was associated with reduced productivity such that boxes within 100 m of roads were predicted to produce approximately 1 fewer fledgling than those 500 m away. There was no evidence that the proportion of urban area surrounding nest boxes substantially influenced breeding occupancy or productivity. Thus, land managers can consider placing nest boxes for barn owls farther from roads when possible as a potential tactic to increase the probability of breeding occupancy and to foster higher productivity.

Wood turtles (Glyptemys insculpta) are a species of conservation concern throughout their geographic distribution. Several studies have investigated individual-level habitat selection of wood turtles in the Upper Midwest in the United States, but the effects of habitat characteristics on abundance are poorly understood. This information is needed to improve landscape-level habitat management and conservation initiatives for the species. Our study aimed to identify important aquatic and terrestrial habitat characteristics and quantify their influence on abundance dynamics of adult wood turtles in the Laurentian Mixed Forest Province ecoregion of Wisconsin and Minnesota, USA. We collected standardized population survey data at 57 sites within the ecoregion between 2016 and 2022. We used N-mixture models with a multi-stage model selection procedure to assess the influence of aquatic and terrestrial predictors on abundance, including several 3-dimensional forest structure metrics derived from airborne Light Detection and Ranging (LiDAR) data. Several aquatic and terrestrial habitat characteristics influenced local abundance patterns of adult wood turtles. The most influential aquatic predictors were stream velocity and stream width, and the most influential terrestrial predictors were mean return height and vertical coefficient of variation of height. Abundance was high at sites containing comparatively narrow streams with moderate velocities. The most supported terrestrial predictors were derived from LiDAR and indicate that complex forest structures support larger wood turtle populations. Our results can be used in forest management strategies to improve habitat quality for wood turtles, such as selective tree harvesting to increase structural diversity, and potentially identify robust populations in under-surveyed areas.

The moose (Alces alces; mooz in Anishinaabemowin, Ojibwe language) population has recently declined in Minnesota, USA, and gray wolf (Canis lupus; ma'iingan) predation is likely a contributing factor. We analyzed diet composition of gray wolves in northeastern Minnesota during 2011–2013 to evaluate the importance of moose as prey and seasonal and regional variations in wolf diet. We identified frequency of occurrence of prey items and biomass consumed in 1,000 wolf scats collected on and adjacent to the Grand Portage Indian Reservation and Voyageurs National Park and within the 1854 Ceded Territory (greater northeastern Minnesota). White-tailed deer (Odocoileus virginianus; waawaashkeshiwag [plural]), moose, and beaver (Castor canadensis; amikwag [plural]) composed the majority of wolf diet, with moose as the primary prey in Grand Portage (35–54% of diet by biomass across seasons) and deer the primary prey in the 1854 Ceded Territory (46–62%) and Voyageurs (63–79%). Relative importance of prey species differed by study area and season. Moose calves were an important prey item in spring in the 1854 Ceded Territory (12% of diet by biomass) but not in Grand Portage or Voyageurs. Although calves were not a majority of wolf diet by biomass, many calves were preyed upon by wolves (30% of calves born each year in Grand Portage), thus affecting recruitment in a declining moose population. Deer fawns composed 12% of wolf diet in spring and 10% in summer in Grand Portage and 19% in summer in Voyageurs. Beaver composed 16% of wolf diet by biomass in spring and 14% in summer in Grand Portage and composed 22% of wolf diet in spring and 30% in summer in Voyageurs. At most prey densities, moose were preferred and deer avoided in Grand Portage and the 1854 Ceded Territory and beaver were preferred in Voyageurs. Our results can be used in conjunction with predation and prey studies to evaluate the effect of wolves on prey populations.

Epizootic events of pneumonia, presumably caused by Mycoplasma ovipneumoniae, in bighorn sheep (Ovis canadensis) have been observed in the western United States and Canada. Until recently, it was thought that populations of Mexican (O. c. mexicana) and Nelson's (O. c. nelsoni) desert bighorn sheep in Texas, USA, had not been exposed to Mycoplasma. Evidence of disease and potential population decline from outbreaks of M. ovipneumoniae are now known from several populations across the Trans-Pecos Ecoregion with documented instances of pneumonia and bluetongue in desert bighorn sheep from the Van Horn Mountains and Black Gap Wildlife Management Area. These disease events, especially those in 2019–2021, may be a result of increasing populations of aoudad (Ammotragus lervia), an introduced and invasive ungulate, in the region. With large population sizes and similar movement patterns as desert bighorn sheep, aoudad potentially are the reservoirs for bacterial and viral diseases, such as pneumonia and bluetongue, and are possibly contributing to the decline of desert bighorn sheep. Herein, we optimized the multi-locus sequence typing (MLST) with modifications in the Taq polymerase and annealing temperatures to determine the genetic identity of Mycoplasma strains or species within the nasal passages of desert bighorn sheep and aoudad in the Trans-Pecos Ecoregion of Texas. Four loci (small ribosomal unit, 16S; 16S-23S intergenic spacer region, IGS; RNA polymerase B, rpoB; gyrase B, gyrB) were characterized using MLST. Based on results from the modified MLST technique, we identified 9 desert bighorn sheep and 5 aoudad with M. ovipneumoniae, 9 aoudad with bacterial sequences genetically similar to M. conjunctivae, and 10 aoudad with bacterial sequences genetically similar M. hyopneumoniae. Of these, 9 aoudad possessed bacterial sequences genetically similar to both M. conjunctivae and M. hyopneumoniae. Among the 4 diagnostic loci, genetic divergence of M. ovipneumoniae ranged from 0.00–0.90% among desert bighorn sheep and aoudad. Future sampling efforts of seemingly asymptomatic aoudad, and asymptomatic, visibly sick, or deceased desert bighorn sheep, are important to monitor the spread of disease in desert bighorn sheep populations across mountain ranges in western Texas. It is imperative that aoudad removal plans are implemented to reduce and eliminate current infections and putative transmission of M. ovipneumoniae, prevent future disease outbreaks of pneumonia, and ultimately conserve desert bighorn sheep for future generations.

Wild pigs (Sus scrofa) are a highly adaptable species that have invaded many regions and cause significant damage throughout the world. Ungulate-proof fencing is increasingly used in conjunction with other control techniques to manage wild pig populations. However, little is known about how fencing affects wild pig space use behaviors and whether any changes may be exploited to increase efficacy of control activities. Our goal was to understand how wild pigs altered their space use behaviors in response to newly constructed fencing. Specifically, we examined for changes in space use area (home range and core area), increases in overlap with conspecifics, and shifts in space use as ungulate exclusion fencing was constructed on northern Guam from February 2021 to March 2022. Wild pigs closer to the fence had decreased space use. For every 200 m nearer newly constructed fence, home ranges and core areas decreased approximately 15% and 16%, respectively. When individual wild pigs were enclosed by the fence, those animals increased their home range overlap with conspecifics by approximately 76% compared to wild pigs outside the fence. Wild pigs shifted their home ranges 3 to 9 times more during the first part of fence construction when 68% of the fence was completed compared to all other time periods, with male wild pigs shifting greater distances than females by 1.15 times. The construction of ungulate fencing led to smaller space use areas of wild pigs on both sides of the fence and intensified use of the area inside the fence by wild pigs contained within (i.e., more overlap). Management activities nearer the fence should account for decreases in home range and core area size to maximize population control efforts (i.e., more densely spaced trap sites). Enclosed wild pigs should be eradicated quickly to minimize damages to sensitive flora and fauna and decrease disease risk from intensified movement behaviors inside the fence.

Owing to the increasing intensity and frequency of wildfires in the western United States, the removal of woody debris (downed dead wood and snags) from fire-prone landscapes is being evaluated for wildfire mitigation. Consequently, the study of the ecological value of coarse woody debris to sustain dependent species has become of foremost importance. From 2004–2009, we used a before-after control-impact (BACI) study design to assess the effects of downed wood removal on a population of big-eared woodrats (Neotoma macrotis) in an oak woodland (Quercus spp.) in coastal-central California, USA. Using Pollock's robust design mark-recapture analyses (with 12 primary capture occasions represented by trapping each spring and fall, and secondary occasions composed of 3 trap nights), we estimated survival and emigration rates. Further, applying mixed-effects models, we evaluated the effects of 7 habitat attributes on woodrat abundance and reproduction. Following the experimental removal of downed wood from the 11 randomly selected treatment plots, woodrat survival was higher (P = 0.013), and emigration was lower (P = 0.007) among 11 control plots on which downed wood was retained. Woodrat abundance within plots was best predicted by stem density, demonstrating positive demographic associations with habitat complexity. Plot-level reproductive success (i.e., the presence of juveniles within a plot during spring) was more likely with increasing snag density. These findings indicate that snags and downed dead wood are key components of high-quality habitat for big-eared woodrats. Management of woody debris to mitigate wildfire risk should consider the ecological value of this habitat attribute for big-eared woodrats and other dependent species.

Each year in the United States, fall-winter (sport) harvests of goose species are estimated from federal surveys coordinated by the United States Fish and Wildlife Service, including the Migratory Bird Harvest Survey to estimate total goose harvest and the Parts Collection Survey (PCS) to estimate the species and age composition. For the PCS, randomly selected hunters collect tail and wing feathers of each goose shot during the hunting season, and then biologists determine the age class and species of each sample at organized events (Wingbees) in each of the 4 flyways (Pacific, Central, Mississippi, and Atlantic). For similarly colored goose species, cackling (Branta hutchinsii) versus Canada (B. canadensis) geese (dark geese) and Ross's (Anser rossii) versus snow (A. caerulescens) geese (light geese), different protocols evolved among Wingbees to differentiate samples into groupings of management interest, leading to difficulties in estimating species-level harvests among the 4 flyways or nationally. We conducted a study among the United States flyways during 2019–2022 to derive thresholds of central tail feather length to discriminate between dark geese and between light geese. We compared morphological- and genetic-based approaches. There was support for 2 distinct mitochondrial DNA (mtDNA) clades in dark and light geese, but only dark goose clades corresponded with central tail feather lengths (morphological size and species identification). Derived thresholds for central tail feather lengths of dark geese in the 3 westernmost flyways using genetic-based species' discrimination were 145 mm for adults and 134 mm for juveniles, approximately 13 mm and 9 mm less, respectively, than thresholds using morphological-based species' discrimination. There was limited ability to discriminate light geese based on either mtDNA or central tail feather lengths. We suggest managers use our derived thresholds based on genetic-based species' discrimination to classify dark goose PCS samples. More advanced genome analyses should be conducted before changing current Wingbee protocols for light geese. Lastly, we encourage more studies to incorporate genetic analyses to complement morphological discrimination.

Tackling the global threat of antimicrobial resistance (AMR) requires joint efforts according to the principles of the One Health approach. In this context, wildlife, and especially wild birds, are recognized as an important bridge between environment, humans and livestock in perpetuating AMR. Over the last decades, important progress has been made in understanding the role of wild birds as carriers of antibiotic-resistant bacteria and their genes (ARGs) within ecosystems; however, there are still many knowledge gaps regarding transmission sources and routes. This commentary summarizes studies from recent years focusing on AMR in wild birds, highlighting the most frequently found zoonotic bacteria harboring ARGs and the possible exchange scenarios between humans, livestock, and wild birds. We emphasize the need to standardize and optimize a wild bird monitoring approach for AMR surveillance that includes non-invasive sampling methods, culture-independent techniques for identification of ARGs, database integration and implementation, and machine learning technology. This multidisciplinary perspective, which could involve veterinarians, biologists, ornithologists, conservationists, and managers, may represent part of the solution, not only for wildlife conservation but also for global health, considering that the goal is to reverse the route of AMR.

There is limited information available on wolverine (Gulo gulo) population density and trends in the boreal forest of North America. We estimated wolverine density using spatial capture-recapture methods across 2 boreal forest study areas in Red Lake, Ontario (26,568 km²) and Rainbow Lake, Alberta (19,084 km²), Canada. We also used radio-telemetry data to estimate annual survival of adult and sub-adult wolverines and evaluated population trends with a stage-based matrix model. We used an array of run poles and live traps to detect wolverines. In Red Lake over 3 winter field seasons (2019–2022), we detected 56 individual wolverines (17 females, 32 males, and 7 unknown sex), and in Rainbow Lake over 2 field seasons (2014–2016), we detected 48 individuals (19 females, 18 males, and 11 of unknown sex). Average densities in Red Lake and Rainbow Lake were 3.64 and 6.74 wolverines/1,000 km², respectively. Adults and sub-adults occurred at equal abundance. Spring snow cover, roads, and industrial developments were not associated with spatial patterns of wolverine density. Most deaths occurred near roads; wolverines were killed in fur traps set along roads, by wolves using roads to travel, and by vehicles. The largest source of death was from incidental (n = 6 in Red Lake) or licensed fur trapping (n = 8 in Rainbow Lake) and we report 8 injuries from fur trapping sets. Red Lake survival estimates for adults (0.87) and sub-adults (0.86) contributed to a stable population trend. Rainbow Lake survival estimates for adults (0.66) and sub-adults (0.50) contributed to a declining population trend based on a relatively low sample of radio-days. Red Lake and Rainbow Lake combined survival estimates for adults (0.77) and sub-adults (0.73) also contributed to a declining population trend. Our survival and population modeling suggests that human-caused mortality is a significant risk to these populations. Our results can be applied to wolverine status assessments and used as benchmarks for future monitoring. Wolverine population stability or growth might be achieved by reducing incidental trapping deaths or injury and hindering human access to wolverine habitats through decommissioning or limiting development of industrial roads or other anthropogenic linear features.