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At least 343 records · Page 19Linked to original sources

USGS2010

Multiscale habitat use and selection in cooperatively breeding Micronesian kingfishers

Information about the interaction between behavior and landscape resources is key to directing conservation management for endangered species. We studied multi-scale occurrence, habitat use, and selection in a cooperatively breeding population of Micronesian kingfishers (Todiramphus cinnamominus) on the island of Pohnpei, Federated States of Micronesia. At the landscape level, point-transect surveys resulted in kingfisher detection frequencies that were higher than those reported in 1994, although they remained 15-40% lower than 1983 indices. Integration of spatially explicit vegetation information with survey results indicated that kingfisher detections were positively associated with the amount of wet forest and grass-urban vegetative cover, and they were negatively associated with agricultural forest, secondary vegetation, and upland forest cover types. We used radiotelemetry and remote sensing to evaluate habitat use by individual kingfishers at the home-range scale. A comparison of habitats in Micronesian kingfisher home ranges with those in randomly placed polygons illustrated that birds used more forested areas than were randomly available in the immediate surrounding area. Further, members of cooperatively breeding groups included more forest in their home ranges than birds in pair-breeding territories, and forested portions of study areas appeared to be saturated with territories. Together, these results suggested that forest habitats were limited for Micronesian kingfishers. Thus, protecting and managing forests is important for the restoration of Micronesian kingfishers to the island of Guam (United States Territory), where they are currently extirpated, as well as to maintaining kingfisher populations on the islands of Pohnpei and Palau. Results further indicated that limited forest resources may restrict dispersal opportunities and, therefore, play a role in delayed dispersal and cooperative behaviors in Micronesian kingfishers.

Journal of Wildlife Management↗

USGS2013

Molecular techniques to distinguish morphologically similar Hydrilla verticillata , Egeria densa , Elodea nuttallii , and Elodea canadensis

The four submerged aquatic species, hydrilla (Hydrilla verticillata [monoecious and dioecious]), Brazilian waterweed (Egeria densa), Canadian waterweed (Elodea canadensis), and western waterweed (Elodea nuttallii), are difficult to positively identify because of their morphological similarity to each other, resulting in possible misidentification. This limits our ability to understand their past and present distribution, which is important in aquatic plant management. We investigated a molecular technique to identify these species, which are problematic because of their invasive nature on multiple continents. Approximately 100 samples of these species, ranging in age from 40-yr-old herbarium samples to recently collected plants, were collected from regions across the United States. The distribution and range of the samples collected in this research were compared to those reported in the literature. We confirmed information on the current wide distribution of both hydrilla biotypes in the United States and discovered that hydrilla had actually invaded the waterways near Washington, DC 6 yr earlier than originally reported. In addition, we found evidence of the confusion, dating back to the 1980s, between Canadian waterweed and western waterweed in the mid-Atlantic region of the United States. Canadian waterweed was previously reported as common and western waterweed as rare; however, our samples indicate the opposite is true. This information indicates there is a need for investigators to anticipate the spread of hydrilla populations to northern U.S. waterways, where it will compete with existing plant species, including Canadian and western waterweeds. Our ability to confirm distribution and pace of spread of invasive and noninvasive species will improve with increased application of molecular techniques.

Journal of Aquatic Plant Management↗

USGS2025

Assessing the topographic distribution of legacy soil phosphorus in agricultural fields of the Delmarva Peninsula, Mid-Atlantic Coastal Plain, USA

Phosphorus (P) management remains a challenge in agricultural watersheds. The Choptank River Conservation Effects Assessment Project watershed, located in Maryland and Delaware and draining to the Chesapeake Bay, contains legacy soil P from historical dairy and poultry manure applications. These practices elevated soil P beyond crop needs, contributing to persistent P export to aquatic ecosystems. We assessed spatial P distribution and analyzed GIS (Geographic Information Systems)-derived landscape features driving legacy P movement on a farm (47 ha). We hypothesized that P accumulates in drained lowlands and depressional areas due to gravity-driven processes that accelerate P-enriched water to receiving waters via overland flow. In collaboration with the US Department of Agriculture Legacy P project, we collected 105 soil samples (0- to 5-cm and 5- to 15-cm depths) and 14 ditch sediment samples across five topographic openness classes from a farm with >100 years of dairy manure application. Average Mehlich-III P concentrations were 218 and 179 mg kg −1 at 0- to 5-cm and 5- to 15-cm depths, respectively, with legacy areas defined by P content > 100 mg kg −1 . Soil P and clay particle size were positively correlated ( r = 0.42, p < 0.05), increased as landscape openness decreased, and were negatively correlated with topographic openness (ranging from −0.2 to −0.4, p < 0.05), indicating accumulation of P and clay in low-lying areas. These patterns suggest that historical field-level managements have primarily shaped P distribution, while hydrologic and landscape properties further influence its redistribution via transport pathways and drainage. These findings support the development of landscape models to map critical source areas in low-relief watersheds and guide targeted mitigation in high-risk P export zones.

Maryland↗

USGS2021

Age-0 Silver Carp otolith microchemistry and microstructure reveal multiple early life environments and protracted spawning in the upper Mississippi River

Silver Carp Hypophthalmichthys molitrix are highly mobile and fecund planktivorous cyprinids that have invaded much of the Mississippi River and are known to alter food webs and compete with native planktivores. In 2016, for the first time, an abundance of age-0 Silver Carp ( n = 12,208; 16–231 mm) were captured at many ( n = 11) sites upstream of Lock and Dam 19 on the upper Mississippi River. Previous reports were of a few individuals at a few locations; however, effort to capture juveniles of this size was likely less in previous years. Determining the origin, frequency, and timing of the reproductive events that led to this large year-class is important for determining control strategies. We used otolith microstructure and microchemistry from age-0 Silver Carp to estimate timing and frequency of spawning and early life environments of these fish. Hatch dates were determined from the lapillus otoliths of 190 age-0 Silver Carp (16–231 mm), and early life environments were identified from otolith microchemistry for 124 of these fish (64–231 mm). Age-0 Silver Carp were collected from Pools 18 and 19 during July–October 2016 by using a variety of sampling gears. We identified 10 cohorts with hatch dates ranging from May to August 2016 and with main-stem Mississippi River (75%) and tributary (23%) early life signatures. Tributary otolith chemistry signatures were present in all cohorts between May and July ( n = 8) but were absent from the August cohorts ( n = 2). Our results indicate that tributaries and small tributary streams, in addition to the main-stem river, play an important role in Silver Carp recruitment in areas near the reproductive front, where management actions (e.g., contract removal and deterrents) are often targeted.

Illinois, Iowa, Missouri↗

USGS2010

A simple solar radiation index for wildlife habitat studies

Solar radiation is a potentially important covariate in many wildlife habitat studies, but it is typically addressed only indirectly, using problematic surrogates like aspect or hillshade. We devised a simple solar radiation index (SRI) that combines readily available information about aspect, slope, and latitude. Our SRI is proportional to the amount of extraterrestrial solar radiation theoretically striking an arbitrarily oriented surface during the hour surrounding solar noon on the equinox. Because it derives from first geometric principles and is linearly distributed, SRI offers clear advantages over aspect-based surrogates. The SRI also is superior to hillshade, which we found to be sometimes imprecise and ill-behaved. To illustrate application of our SRI, we assessed niche separation among 3 ungulate species along a single environmental axis, solar radiation, on the northern Yellowstone winter range. We detected no difference between the niches occupied by bighorn sheep ( Ovis canadensis ) and elk ( Cervus elaphus; P = 0.104), but found that mule deer ( Odocoileus hemionus ) tended to use areas receiving more solar radiation than either of the other species ( P < 0.001). Overall, our SRI provides a useful metric that can reduce noise, improve interpretability, and increase parsimony in wildlife habitat models containing a solar radiation component.

Wyoming↗

USGS2017

No flood effect on recruitment of a small Louisiana black bear population

A flood event in 2011 had minor impacts on apparent survival and movement probabilities of a small, isolated population of Louisiana black bears ( Ursus americanus luteolus ) in the Upper Atchafalaya River Basin, Louisiana, USA. However, the potential effects of the flood on recruitment of juveniles into the population, then listed as threatened under the United States Endangered Species Act, were not evaluated. We used hair trapping data collected from 2007 to 2015 and Pradel temporal symmetry models in a robust‐design framework to investigate changes in per capita recruitment that could have resulted from the flood. We detected 91 bears (37 M:54 F) within the flooded area during our study period, ranging from 21 to 44 individuals/year. Models that tested for reduced recruitment resulting from the flood were not supported more than models with constant recruitment, and the population growth rate did not decline. Although we documented marginally lower recruitment following the 2011 flood, lag effects and detectability biases complicated our analysis. We suggest that wildlife managers continue monitoring recruitment and survival in this recently delisted black bear population given the potential for heightened flood frequency and severity in the future.

Journal of Wildlife Management↗

USGS2016

Effectiveness of vegetation buffers surrounding playa wetlands at contaminant and sediment amelioration

Playa wetlands, the dominant hydrological feature of the semi-arid U.S. High Plains providing critical ecosystem services, are being lost and degraded due to anthropogenic alterations of the short-grass prairie landscape. The primary process contributing to the loss of playas is filling of the wetland through accumulation of soil eroded and transported by precipitation from surrounding cultivated watersheds. We evaluated effectiveness of vegetative buffers surrounding playas in removing metals, nutrients, and dissolved/suspended sediments from precipitation runoff. Storm water runoff was collected at 10-m intervals in three buffer types (native grass, fallow cropland, and Conservation Reserve Program). Buffer type differed in plant composition, but not in maximum percent removal of contaminants. Within the initial 60 m from a cultivated field, vegetation buffers of all types removed >50% of all measured contaminants, including 83% of total suspended solids (TSS) and 58% of total dissolved solids (TDS). Buffers removed an average of 70% of P and 78% of N to reduce nutrients entering the playa. Mean maximum percent removal for metals ranged from 56% of Na to 87% of Cr. Maximum removal was typically at 50 m of buffer width. Measures of TSS were correlated with all measures of metals and nutrients except for N, which was correlated with TDS. Any buffer type with >80% vegetation cover and 30–60 m in width would maximize contaminant removal from precipitation runoff while ensuring that playas would continue to function hydrologically to provide ecosystem services. Watershed management to minimize erosion and creations of vegetation buffers could be economical and effective conservation tools for playa wetlands.

Journal of Environmental Management↗

USGS2018

The flathead catfish invasion of the Great Lakes

A detailed review of historical literature and museum data revealed that flathead catfish were not historically native in the Great Lakes Basin , with the possible exception of a relict population in Lake Erie. The species has invaded Lake Erie, Lake St. Clair, Lake Huron, nearly all drainages in Michigan, and the Fox/Wolf and Milwaukee drainages in Wisconsin. They have not been collected from Lake Superior yet, and the temperature suitability of that lake is questionable. Flathead catfish have been stocked sparingly in the Great Lakes and is not the mechanism responsible for their spread. A stocking in 1968 in Ohio may be one exception to this. Dispersal resulted from both natural range expansions and unauthorized introductions. The invasion is ongoing, with the species invading both from the east and the west to meet in northern Lake Michigan. Much of this invasion has likely taken place since the 1990s. This species has been documented to have significant impacts on native fishes in other areas where it has been introduced; therefore, educating the public not to release them into new waters is important. Frequent monitoring of rivers and lakes for the presence of this species would detect new populations early so that management actions could be utilized on new populations if desired.

Great Lakes↗

USGS2000

Monitoring hydrilla using two RAPD procedures and the nonindigenous aquatic species database

Hydrilla (Hydrilla verticillata (L.f.) Royle), an invasive aquatic weed, continues to spread to new regions in the United States. Two biotypes, one a female dioecious and the other monoecious have been identified. Management of the spread of hydrilla requires understanding the mechanisms of introduction and transport, an ability to map and make available information on distribution, and tools to distinguish the known U.S. biotypes as well as potential new introductions. Review of the literature and discussions with aquatic scientists and resource managers point to the aquarium and water garden plant trades as the primary past mechanism for the regional dispersal of hydrilla while local dispersal is primarily carried out by other mechanisms such as boat traffic, intentional introductions, and waterfowl. The Nonindigenous Aquatic Species (NAS) database is presented as a tool for assembling, geo-referencing, and making available information on the distribution of hydrilla. A map of the current range of dioecious and monoecious hydrilla by drainage is presented. Four hydrilla samples, taken from three discrete, non-contiguous regions (Pennsylvania, Connecticut, and Washington State) were examined using two RAPD assays. The first, generated using primer Operon G17, and capable of distinguishing the dioecious and monoecious U.S. biotypes, indicated all four samples were of the monoecious biotype. Results of the second assay using the Stoffel fragment and 5 primers, produced 111 markers, indicated that these samples do not represent new foreign introductions. The differences in the monoecious and dioecious growth habits and management are discussed.

Connecticut, Pennsylvania, Washington↗

USGS2019

The influence of layout on Appalachian Trail soil loss, widening, and muddiness: Implications for sustainable trail design and management

This research investigates the influence of layout and design on the severity of trail degradation. Previous trail studies have been restricted by relatively small study areas which provide a limited range of environmental conditions and therefore produce findings with limited applicability; this research improves on this limitation by analyzing a representative sample of the Appalachian Trail with significant topographical, ecological, use-related, and managerial diversity. Many trail science studies have also focused on a singular form of trail degradation, whereas this study investigates all three core types of trail impact: trail soil loss, widening and muddiness. Relational analyses with all three indicators provide a more cohesive understanding of trail impact and reveal interrelationships between trail degradation processes. ANOVA testing of the mean values for these trail impact indicators across categories of influential independent factors confirms and refines the relevance of core trail design principles, specifically the sustainability advantages of trails with low grades and side-hill alignments. Findings also reveal and clarify the importance of landform grade in determining the susceptibility of trails to degradation and the influence of routing decisions; these relationships have received relatively little attention in the literature. The results also reveal several methodological considerations for trail alignment metrics and trail impact indicators

Connecticut, Georgia, Maine, Massachusetts, Maryla↗

USGS2017

Estimated seepage rates from selected ditches, ponds, and lakes at the Camas National Wildlife Refuge, eastern Idaho

The Camas National Wildlife Refuge (Refuge) in eastern Idaho, established in 1937, contains wetlands, ponds, and wet meadows that are essential resting and feeding habitat for migratory birds and nesting habitat for waterfowl. Initially, natural sources of water supported these habitats. However, during the past few decades, changes in climate and surrounding land use have altered and reduced natural groundwater and surface-water inflows, resulting in a 5-meter decline in the water table and an earlier, and more frequent, occurrence of no flow in Camas Creek at the Refuge. Due to these changes in water availability, water management that includes extensive groundwater pumping is now necessary to maintain the wetlands, ponds, and wet meadows. These water management activities have proven to be inefficient and expensive, and the Refuge is seeking alternative water-management options that are more efficient and less expensive. More efficient water management at the Refuge may be possible through knowledge of the seepage rates from ditches, ponds, and lakes at the Refuge. With this knowledge, water-management efficiency may be improved by natural means through selective use of water bodies with the smallest seepage rates or through engineering efforts to minimize seepage losses from water bodies with the largest seepage rates. The U.S. Geological Survey performed field studies in 2015 and 2016 to estimate seepage rates for selected ditches, ponds, and lakes at the Refuge. Estimated seepage rates from ponds and lakes ranged over an order of magnitude, from 3.4 ± 0.2 to 103.0 ± 0.5 mm/d, with larger seepage rates calculated for Big Pond and Redhead Pond, intermediate seepage rates calculated for Two-way Pond, and smaller seepages rates calculated for the south arm of Sandhole Lake. Estimated seepage losses from two reaches of Main Diversion Ditch were 21 ± 2 and 17 ± 2 percent/km. These losses represent seepage rates of about 890 and 860 mm/d, which are one- to two-orders-of-magnitude larger than seepage rates from the ponds and lake. The depth-integrated vertical hydraulic conductivity ( K v ) for sediment underlying the ponds and lake was the primary control of seepage rates. The K v 's were 30 and 34 m/d for Big Pond, 14 and 18 m/d for Toomey Pond, 8 and 10 m/d for Two-way Pond, and 47 m/d for the north arm of Sandhole Lake.

Idaho↗

USGS2006

Growth and sustainability of black bears at White River National Wildlife Refuge, Arkansas

The black bear ( Ursus americanus ) population at White River National Wildlife Refuge is isolated and genetically distinct, but hunting occurs adjacent to refuge boundaries and females with cubs are removed annually for a reintroduction project. We trapped and radiotracked bears to determine level of exploitation and compare methods for estimating population growth and sustainability. We captured 260 bears (113 M:147 F), 414 times, from 1998 through 2003. Survival estimates based on radiotracking and mark–recapture indicated that hunting and translocations were significant sources of loss. Based on mark–recapture data (Pradel estimator), the annual population growth rate (λ) averaged 1.066 (SE = 0.077) when translocation removals occurred and averaged 0.961 (SE = 0.155) when both harvest and translocations occurred. Estimates of λ based on a population simulation model (program RISKMAN) averaged 1.061 (SD = 0.104) and 1.100 (SD = 0.111) when no removals occurred, 1.003 (SD = 0.097) and 1.046 (SD = 0.102) when translocations occurred, and 0.973 (SD = 0.096) and 1.006 (SD = 0.099) when both harvest and translocations occurred, depending on the survival rate estimates we used. The probability of population decline by >25% over a 10-year period ranged from 13.8 to 68.8%, given our estimated removal rates. We conclude that hunting and translocation losses are at or exceed the maximum the population is capable of sustaining. Although extinction risks of this important bear population are low over the near term, it should continue to be closely monitored by state and federal agencies. The mark–recapture method we used to estimate λ proved to be a reliable alternative to more costly population modeling methods.

Arkansas↗

USGS2016

Management decision making for fisher populations informed by occupancy modeling

Harvest data are often used by wildlife managers when setting harvest regulations for species because the data are regularly collected and do not require implementation of logistically and financially challenging studies to obtain the data. However, when harvest data are not available because an area had not previously supported a harvest season, alternative approaches are required to help inform management decision making. When distribution or density data are required across large areas, occupancy modeling is a useful approach, and under certain conditions, can be used as a surrogate for density. We collaborated with the New York State Department of Environmental Conservation (NYSDEC) to conduct a camera trapping study across a 70,096-km 2 region of southern New York in areas that were currently open to fisher ( Pekania [ Martes ] pennanti ) harvest and those that had been closed to harvest for approximately 65 years. We used detection–nondetection data at 826 sites to model occupancy as a function of site-level landscape characteristics while accounting for sampling variation. Fisher occupancy was influenced positively by the proportion of conifer and mixed-wood forest within a 15-km 2 grid cell and negatively associated with road density and the proportion of agriculture. Model-averaged predictions indicated high occupancy probabilities (>0.90) when road densities were low (<1 km/km 2 ) and coniferous and mixed forest proportions were high (>0.50). Predicted occupancy ranged 0.41–0.67 in wildlife management units (WMUs) currently open to trapping, which could be used to guide a minimum occupancy threshold for opening new areas to trapping seasons. There were 5 WMUs that had been closed to trapping but had an average predicted occupancy of 0.52 (0.07 SE), and above the threshold of 0.41. These areas are currently under consideration by NYSDEC for opening a conservative harvest season. We demonstrate the use of occupancy modeling as an aid to management decision making when harvest-related data are unavailable and when budgetary constraints do not allow for capture–recapture studies to directly estimate density.

Journal of Wildlife Management↗

USGS2022

Movement of white‐tailed deer in contrasting landscapes influences management of chronic wasting disease

Chronic wasting disease (CWD) continues to expand in distribution and prevalence across North America. Upon detection, either for the first time in a novel area or in a region with an existing outbreak, wildlife management agencies are tasked with responding to mitigate the disease. This response often entails creation or modification of a management zone with modified rules and regulations that support an agency's disease management plan. To guide the process of creating an appropriately sized CWD management zone, assuming that wild deer movements are a major risk factor for disease spread, we used data from global positioning system (GPS)-collared white-tailed deer ( Odocoileus virginianus ) in southeastern Minnesota and southcentral Pennsylvania, USA, between 2018 and 2021 to estimate long-distance movements associated with dispersal and migratory behaviors. These contrasting study areas with active CWD outbreaks permitted an evaluation of deer movement dynamics in different parts of their range. We quantified the proportion, distribution, timing, and orientation of dispersing and migratory deer. We observed 21% of female and 58% of male yearlings disperse from their apparent natal home range in Minnesota, while in Pennsylvania 4% of female and 68% of male yearlings dispersed. We also documented 20% of females and 6% of males migrated between seasonal home ranges in Minnesota, while in Pennsylvania no females and 5% of males migrated. The average distance deer dispersed or migrated in Minnesota was 20 km and 11 km, respectively, while in Pennsylvania male deer dispersed only about 4 km. Both sexes in Minnesota tended to disperse in a consistent, westerly direction; however, there was no directional preference observed for migratory deer or for dispersing deer in Pennsylvania. We found differences between natal and adult home range size for both sexes in Minnesota but not for males in Pennsylvania. Our results identify the considerable variability in dispersal and migration dynamics of white-tailed deer in disparate landscapes, which is important to agencies managing CWD. We summarize the distribution of these movements and suggest agencies use this information to help make decisions about optimal management zone size. We suggest the development of formalized assessments of the tradeoffs associated with optimizing decisions about creation of CWD management zones across white-tailed deer populations that exhibit variation in dispersal behavior and suggest careful evaluation to avoid using an arbitrary size or shape to create disease management zones.

Minnesota, Pennsylvania↗

USGS2008

Dispersal of Culex quinquefasciatus (Diptera: Culicidae) in a Hawaiian rain forest

Introduced mosquito-borne pathogens avian malaria (Plasmodium relictum Grassi and Feletti) and avian pox virus (Avipoxvirus) have been implicated in the past extinctions and declines of Hawaiian avifauna and remain significant obstacles to the recovery and restoration of endemic Hawaiian birds. Effective management of avian disease will require extensive mosquito control efforts that are guided by the local ecology of the vector Culex quinquefasciatus Say (Diptera: Culicidae). During October and November 1997 and September through November 1998 five mark-release-recapture experiments with laboratory-reared Cx. quinquefasciatus were conducted in a native rain forest on Hawaii Island. Of the overall 66,047 fluorescent dye-marked and released females, 1,192 (1.8%) were recaptured in 43-52 CO2-baited traps operated for 10-12-d trapping periods. Recaptured mosquitoes were trapped in all directions and at distances up to 3 km from the release site. The cumulative mean distance traveled (MDTs) over the trapping period ranged from a high of 1.89 km after 11 d (September 1998) to a low of 0.81 km after 11 d (November 1998). Released mosquitoes moved predominately in a downwind direction and they seemed to use forestry roads as dispersal corridors. Applying an estimated MDT of 1.6 km to a geographical information system-generated map of the Hakalau Forest National Wildlife Refuge clearly demonstrated that the effective refuge area could be reduced 60% by mosquitoes infiltrating into managed refuge lands. These findings should have significant implications for the design of future refuges and development of effective mosquito-borne avian disease control strategies.

Journal of Medical Entomology↗

USGS1992

Annual survival rates of adult and immature eastern population tundra swans

Tundra swans ( Cygnus columbianus) of the eastern population were neckbanded in Maryland, North Carolina, and Alaska from 1966 through 1990. These swans were resighted and recaptured during autumn, winter, and spring, 1966-1990. Although the original motivation for this study involved swan movements, we wanted to use the resulting data to test hypotheses about sources of variation in swan survival rates. Recaptures of legbanded and neckbanded swans permitted us to estimate neckband loss rates, which were found to vary with age and sex of swans, and number of years since initial application. Estimates of annual neckband retention rate ranged from about 0.50 for adult male swans ≥ 2 years after initial neckbanding to > 0.96 for immature swans and adult females the first year following neckbanding. This variation in neckband loss rates prevented the simple correction of survival estimates to account for such loss. Consequently, we developed a series of multinomial models parameterized with survival, sighting, and neckband retention probabilities for use with the recapture and resighting data.

Alaska, Maryland, North Carolina↗

USGS2022

Do unpublished data help to redraw distributions? The case of the spectacled bear in Peru

Data availability remains a principal factor limiting the use of species distribution models (SDMs) as tools for wildlife conservation and management of rare species. Although data collected in systematic and rigorous fashion are preferable, available data for most species of conservation interest are usually low in both quality and number. Here we show that combining records published in peer-reviewed journals and gray literature sources (e.g., theses, government, and NGO reports) with unpublished records obtained by personal communications from relevant stakeholders affect the predicted distribution of spectacled bears ( Tremarctos ornatus ) in Peru. We built SDMs using generalized linear models, random forest, and Maxent, first using a dataset that only included published records, and second with a dataset using both published and unpublished records. All models were replicated ten times with random subsets with controlled sample size. Models that combined published and unpublished spectacled bear records had a better performance, irrespective of with SDM method used, increasing the connectivity of the species’ range, and increasing the overall predicted distribution area than models that only included published records. This was because unpublished records added key new localities, reducing spatial sampling biases. Our study shows that the inclusion of commonly disregarded data such as opportunistic records, reports from natural park rangers, student theses, and data-deficient small studies can make an important contribution to the overall ecological knowledge of rare and difficult-to-study species such as the spectacled bear.

Mammal Research↗

USGS2025

Silver Carp passage at three locks and dams on the Tennessee and Cumberland rivers from 2016–2019

Bigheaded carps (i.e., Silver Carp Hypophthalmichthys molitrix and Bighead Carp H. nobilis ) are non-native species that continue to expand their ranges throughout North American river systems, including the Tennessee and Cumberland river systems in the southeastern United States. These species are known to have deleterious effects on native fishes. Management efforts have focused on reducing upstream passage at dams coupled with intensive removal of individuals occupying upstream reaches. Understanding mechanisms affecting the success of upstream fish passage through lock chambers is critical to determining immigration rates into upstream habitats, the likelihood of success for upstream removal efforts, and potential effects of upstream passage reduction using deterrents. We used acoustic telemetry to examine the timing of Silver Carp upstream and downstream dam passages, patterns of fish movement throughout the river systems, and the relationship between fish size and upstream passage through the lock chamber. During 2016–2019, 465 Silver Carp were surgically implanted with transmitters within the two river systems. We documented 37 upstream passages and 57 downstream passages of Barkley, Kentucky, and Pickwick dams. During the two years in which dam passages were observed, most upstream dam passages (89%) occurred during April–August when water temperature ranged from 12–31°C. Most downstream passages (89%) occurred from late-February through July. The relatively small portion of Silver Carp tagged in Pickwick Lake (11% of total tagged), the uppermost reach of the study area, accounted for nearly two-thirds of all dam passages. Our findings may help managers model Silver Carp populations and inform decisions regarding fish deterrent placement and operation.

Alabama, Arkansas, Illinois, Kentucky, Mississippi↗