Journal of Wildlife Management最新文献

Non-target animal sensitivity remains a concern when treating Laurentian Great Lakes streams with 4-nitro-3-(trifluoromethyl)phenol (TFM), the main pesticide used to control Sea Lamprey Petromyzon marinus as part of the bi-national Great Lakes Fishery Commission's Sea Lamprey Control Program. Populations of Burbot Lota lota, a historically and culturally important fish, inhabit some of the streams that are treated with TFM. While many species of fish inhabiting the Great Lakes streams have been assessed for sensitivity to TFM, we are not aware of previous research to assess the risk to Burbot. We assessed the sensitivity of Burbot to TFM using replicate 12-hour flow-through diluter toxicity tests. We found Burbot to have a median lethal concentration (LC₅₀) of 9.74 mg/L, while the minimum lethal concentration (LC_99.9) for Sea Lamprey was predicted to be 2.5 mg/L in similar waters. The resulting toxicity ratio (LC₅₀ of non-target organism/LC_99.9 of Sea Lamprey) of Burbot was 3.90, well above the toxicity ratios for known sensitive species. Our results suggest Burbot are not expected to be adversely affected during a typical TFM stream treatment.

Electrofishing is commonly used to assess the abundance of stream fish. Estimating the absolute population size in a sampled stream reach requires repeated sampling and use of either a mark-recapture estimator or a removal estimator. Population estimates are then often converted to an estimate of density (number per area sampled) or the number per length of stream sampled. Alternatively, a single electrofishing event may be used to develop an index of relative abundance in some form of catch per unit effort, often expressed as catch per area sampled, catch per length of stream sampled, or catch per minute of shock time. The objective of this analysis was to determine which catch per unit effort index best described absolute estimates of Brook Trout Salvelinus fontinalis density (number/100 m²) and number per length of stream (number/100 m). Electrofishing data from ten Brook Trout streams in the Sinnemahoning Creek watershed of northcentral Pennsylvania from 2010–2018 were included in the analysis. I analyzed data with linear mixed effects models, with individual streams as random effects, to determine which index of catch per unit effort best predicted Brook Trout density or number per length of stream sampled. Results indicated that if interest lies in density, catch per area was the best index of relative abundance, and if number per length of stream is of interest, catch per length was the best index. Catch per minute of shock time may be a less useful index of relative abundance because of multiple factors that could influence the unit of effort used in its calculation.

Understanding the distribution and selection of breeding habitat is important for effective conservation and management of wildlife species. Advances in global positioning system (GPS) tracking technology allow for the collection of high-resolution location data and analysis of habitat selection in remote areas. We investigated home range selection of breeding sandhill cranes (Antigone canadensis) in the boreal forests of Ontario and Quebec, Canada, using high-resolution GPS tracking data across a gradient of land cover and land use classes. We quantified breeding home range selection using resource selection functions and developed spatial maps to predict the distribution of breeding home ranges across the boreal forest landscape. Sandhill cranes arrived at their breeding home ranges in late April and departed in late August, remaining on breeding grounds for approximately 4 months. The size of breeding home ranges varied considerably among individuals, with an average size of 14.12 ± 21.70 (SD) km². Our models revealed selection for home ranges containing greater proportions of cropland, forest disturbance, and wetland. Management efforts should focus on enhancing the quality and connectivity of selected cover types, particularly wetlands, to support sandhill crane conservation in the boreal forest ecosystem. These findings highlight the importance of integrating landscape-level analyses with detailed patterns of habitat selection to inform the development of effective management strategies that support the long-term conservation of breeding sandhill cranes.

Post-release monitoring is key to ensuring that conservation interventions like reintroduction, reinforcement, and headstarting are effective. However, for long-lived species, monitoring over sufficiently long time periods to confirm successful maturation and reproduction can be challenging. We use long-term monitoring data to document post-release maturation and reproduction by headstarted Blanding's turtles Emydoidea blandingii, a long-lived late-maturing species threatened by habitat loss and degradation, road mortality, and increased predation. We found that among headstarted Blanding's turtles, adult mass was attained in as little as 7 years, 3 years earlier than among non-headstarted turtles. We documented successful reproduction by 29 headstarted females and courtship by 2 headstarted males, the youngest of which were each 10 years old. In comparison, the youngest reproductive non-headstarted female and courting male were 11 and 12 years old, respectively. We found no difference in clutch size or reproductive frequency between headstarted and non-headstarted females (mean clutch size = 12.5 vs. 13.5; reproductive frequency = 0.964 vs. 0.943). Hatch success differed between headstarted and non-headstarted females depending on whether clutches were obtained by hormonal induction in enclosures (headstarts: 0.52; non-headstarts: 0.83), by hormonal induction in the field (headstarts: 0.73; non-headstarts: 0.74), or in maternity pens without hormonal induction (headstarts: 0.80; non-headstarts: 0.98). We found no effect of female age on clutch size, hatch success, or reproductive frequency. Our results add to a growing body of evidence for the success of headstarting as a conservation intervention.

The Rocky Mountain Population (RMP) of trumpeter swans Cygnus buccinator (hereafter, swans) in North America includes breeders in the Greater Yellowstone Area (GYA) and other western states (together, United States segment) and western provinces of Canada (Canada segment). Conservation concern for the United States segment stems from its slow population growth and the resident nature of GYA swans, which intermingle with migrating Canada segment swans in wintering habitats. Thus, understanding variation in migratory behavior and habitat use by swans in the two population segments can inform how management actions may affect the RMP. We used telemetry data from 55 RMP swans captured in the western United States to understand their movements and habitat use. For 45 swans (60 swan-years) that spent the summer in the United States, distance traveled between breeding and wintering areas ranged from 0 km (i.e., no migration in 22% of swan-years) to 473 km, with an average of nonzero movements of 118 ± 95 km (SD). Swans traveled farther distances when maximum temperatures were lower. For 10 swans (16 swan-years) that spent the summer in Canada, five appeared to molt but not to nest, and four appeared to nest in one or more years. Migration timing was similar for molting and nesting swans. All five molting swans and one nesting swan spent at least one previous summer in the GYA. Migratory connectivity of all birds was weaker in years when more swans migrated to Canada for the summer. During the breeding season, Canada swans used low-elevation lakes, but United States swans used high-elevation lakes. Both groups of swans increased use of crop fields outside of the breeding season. Our study shows interchange between the United States and Canada segments, a finding that challenges the efficacy of existing population designations. Furthermore, variation in movement behavior of GYA swans suggests possible actions, such as restoring winter habitats to increase swan distribution and migration, to support swan conservation.

Understanding Sauger Sander canadensis movement can inform focused management on large reservoir systems by providing insight into movement patterns, entrainment, exploitation, and apparent survival. However, fish movement patterns have not been assessed in Lewis and Clark Lake since 2006, and unprecedented floods that changed the reservoir's morphology and aging have occurred since the last assessment. We conducted a contemporary analysis of Sauger movement patterns, exploitation, entrainment, and apparent survival to inform management. We implanted adult fish (n = 79) with acoustic tags between 2021–2024 and assessed movement patterns during 2021–2024. Receivers (n = 14) distributed throughout the entire length of Lewis and Clark Lake and the 63-km river reach below Fort Randall Dam enabled quantification of the amount of movement into each management zone. We related environmental factors and flow characteristics to variation in weekly mean movement distance using multiple linear regression. We derived exploitation estimates from angler-reported tags. We estimated entrainment from angler-reported tags and receivers placed below Gavins Point Dam, documenting entrainment through the dam. We used a multistate live-dead model approach to determine that resight probabilities (mean = 0.71, range = 0.44–1.00) varied among strata, and apparent survival (mean = 0.83, range = 0.80–0.86) did not vary between sexes. Approximately 32% of females and 18% of males tagged in the delta zone never left this zone over the study duration. Mean weekly fish movement was driven primarily by reservoir storage, discharge through Fort Randall Dam, mean temperature, and precipitation. Increased reservoir storage was correlated with decreased mean weekly male movement. Exploitation and entrainment were sources of loss for adult fish in the reservoir, with annual exploitation estimates ranging from 0–15%, and annual entrainment estimates ranging from 0–2.5%. Examination of adult Sauger movement patterns enables fisheries managers to focus management on important spawning areas, whereas quantifying exploitation and entrainment informs the effectiveness of current harvest regulations.

Anthropogenic disturbance of stream ecosystems is a widespread North American issue that is especially acute in fall line streams of the southeastern United States. Disturbances have resulted in the loss or degradation of bedrock shoals, and many species endemic to shoals have declined concurrently. One particularly imperiled and ecologically important species is the shoals spider lily Hymenocallis coronaria. The spider lily plays an essential role in creating the heterogeneous physical structure of fall line stream ecosystems, but its habitat characteristics have not been quantified. The goal of our study was to apply a multiscale analysis to determine what stream characteristics predicted spider lily habitat. We examined characteristics at both the microhabitat and shoal scale in Stevens Creek, South Carolina, using a combination of field and remote sensing survey methods, which we analyzed using generalized linear models. Additionally, we monitored physiochemical parameters in three shoals with varying spider lily density to further characterize spider lily habitat. Shallow stream depth and coarse substrate were the most important predictors of spider lily presence at the microhabitat scale. At the shoal scale, shoal length had the greatest effect on spider lily density. Our physiochemical monitoring results indicated that stream depth and coarse substrate also appear to influence spider lily density at the shoal scale. We recommend that long shoals with shallow water depths throughout the growing season be targeted for conservation and restoration, with microhabitats that contain coarse substrate being of particular importance. The cultural value of the shoals spider lily makes it a great candidate to be an umbrella species for shoal conservation and restoration for the benefit of a wide variety of shoal-endemic biota and ecosystem services.

Despite their crucial role in ecosystems, few studies have addressed attitudes toward mesocarnivores, even though their impact on human activities often leads to social conflicts. The Egyptian mongoose (Herpestes ichneumon) is expanding its distribution in the Iberian Peninsula, raising concerns among stakeholders, particularly hunters concerned with impacts on small-game species. We assessed hunters' preferences for various mongoose management strategies through a discrete choice experiment with 1,009 hunters from central-southern Spain between October 2021 and April 2022. Participants evaluated several mongoose management scenarios regarding mongoose distribution, abundance, and effects on other predators. Hunters exhibited a strong preference for reducing mongoose abundance, and a moderate preference for limiting its range of expansion and for controlling other predator species, particularly those that are also game species. Spatial differences emerged regarding preferences for managing mongoose abundance, distribution, and other predators. In a region where mongoose range has recently expanded, respondents advocated for prevention strategies to contain the species' distribution. In regions where the mongoose has been more widespread for a longer period, hunters favored abundance reduction. While there was consensus among participants on the need for mongoose management, our results warrant regional-specific approaches that are likely to be more acceptable for hunters. Overall, hunters' preferences reflect a complex interplay of ecological perceptions and management strategies. Future management plans should integrate diverse stakeholder perspectives to develop effective and socially acceptable wildlife management policies.

Fish egg studies provide insights into reproductive health, hatchery success, and population dynamics. Metrics for assessing egg quality, such as diameter, weight, and energetic content, are challenging to accurately measure because eggs degrade rapidly, and eggs are often preserved with formalin. Research is limited and has shown mixed results regarding effects of formalin preservation on egg diameter. No data exist on the influence of formalin preservation on oil droplet diameter. Egg and oil droplet diameters can be indicators of egg nutritional condition and subsequent larval survival and dynamics. We analyzed the diameter of Walleye Sander vitreus egg and oil droplets before and after formalin preservation from one Wisconsin and five Minnesota waterbodies in 2023. Preservation in 10% formalin altered egg and oil droplet diameters. The preservation effect differed depending on the initial egg or oil droplet diameter. Larger and smaller eggs decreased and increased in diameter following storage in formalin, respectively. Preserved eggs were more challenging to measure than fresh eggs due to changes in morphology, burst oil droplets, and increased opacity. Even though the preservation effects were small (5–12%), we recommend that studies involving precise egg measurements avoid formalin storage. The error introduced by formalin preservation was sufficient to prevent detection of small changes, particularly in the oil droplet.

Invasive bigheaded carps (Bighead Carp Hypophthalmichthys nobilis, Silver Carp Hypophthalmichthys molitrix, and their hybrids Hypophthalmichthys spp.) currently infest the Mississippi River Basin. Bigheaded carps can outcompete native species in invaded waters and can also transform the surrounding environment. Currently, resource managers seek to limit the population abundance of bigheaded carps and their range expansion into additional regions of the Upper Mississippi River (UMR) but lack a tool to evaluate different control strategies. Here, we present an application of a Silver Carp spatial population model in the UMR to fill this gap. We used the model to explore how simulated control strategies could affect Silver Carp metapopulation dynamics. More specifically, we assessed and compared the importance of movement deterrents, removal locations, and recruitment areas on Silver Carp population abundances across the UMR. Strategies that included a combination of removal efforts and deterrents resulted in the largest decreases in Silver Carp abundance in the upper pools of the UMR. Furthermore, scenarios that targeted source populations of Silver Carp rather than sink populations resulted in larger decreases in Silver Carp abundance at the invasion front. The effectiveness of these combined simulated strategies also depended on the location of Silver Carp recruitment. Our work suggests that an understanding of Silver Carp metapopulation dynamics may be important for control efforts and could help to inform the management of Silver Carp in the UMR.