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At least 433 records · Page 24Linked to original sources
USGS2021

American Woodcock singing-ground survey: Comparison of four models for trend in population size

Wildlife biologists monitor the status and trends of American woodcock Scolopax minor populations in the eastern and central United States and Canada via a singing-ground survey, conducted just after sunset along roadsides in spring. Annual analyses of the survey produce estimates of trend and annual indexes of abundance for 25 states and provinces, management regions, and survey-wide. In recent years, researchers have used a log-linear hierarchical model that defines year effects as random effects in the context of a slope parameter (the S model) to model population change. Recently, researchers have proposed alternative models suitable for analysis of singing-ground survey data. Analysis of a similar roadside survey, the North American Breeding Bird Survey, has indicated that alternative models are preferable for almost all species analyzed in the Breeding Bird Survey. Here, we use leave-one-out cross-validation to compare model fit for the present singing-ground survey model to fits of three alternative models, including a model that describes population change as the difference in expected counts between successive years (the D model) and two models that include t -distributed extra-Poisson overdispersion effects (H models) as opposed to normally distributed extra-Poisson overdispersion. Leave-one-out cross-validation results indicate that the Bayesian predictive information criterion favored the D model, but a pairwise t -test indicated that the D model was not significantly better-fitting to singing-ground survey data than the S model. The H models are not preferable to the alternatives with normally distributed overdispersion. All models provided generally similar estimates of trend and annual indexes suggesting that, within this model set, choice of model will not lead to alternative conclusions regarding population change. However, as in Breeding Bird Survey analyses, we note a tendency for S model results to provide slightly more extreme estimates of trend relative to D models. We recommend use of the D model for future singing-ground survey analyses.

Eastern and Central United States and Canada↗
USGS2022

Nonlethal tools to identify mass ovarian follicular atresia in Burbot

Skipped spawning, or variation in spawning periodicity, occurs in many annual spawning fish species and is an important consideration for population management. We assessed plasma sex steroid concentrations and measured gonad size and ovarian follicle diameter as metrics to nonlethally identify mass ovarian follicular atresia, which may contribute to skipped spawning in Burbot Lota lota . We maintained wild fish in captivity and exposed them to increasing water temperatures during a 3-wk period before the spawning season to induce mass ovarian follicular atresia. We collected ovarian follicles, blood plasma, and gonadal sonograms from fish weekly between January 28, 2018, and March 25, 2018. We histologically analyzed ovarian follicles to confirm stage of maturity. We measured concentrations of plasma sex steroids testosterone (T) and estradiol-17β (E2) by radioimmunoassay. We measured gonad diameter and circumference by ultrasonography and ovarian follicle diameter by image analysis. Mean plasma T concentration decreased from 8.94 ng/mL during late vitellogenesis to 1.83 ng/mL during atresia, suggesting that plasma T concentrations may be used to identify mass ovarian follicular atresia. We do not recommend using plasma E2 concentrations to identify mass ovarian follicular atresia because E2 concentrations rapidly decreased during the completion of vitellogenesis and the initiation of atresia in Burbot; therefore, plasma E2 may not accurately identify mass ovarian follicular atresia. Mean gonad diameter measured by ultrasonography decreased from 4.05 cm during late vitellogenesis to 3.65 cm during atresia. Mean diameter of ovarian follicles decreased during the final week of the study, suggesting that ovarian follicle diameter may be used to identify advanced mass ovarian follicular atresia. The nonlethal tools assessed—plasma sex steroid concentrations, ultrasonography, and ovarian follicle diameter—enable fisheries biologists to determine the occurrence and frequency of mass ovarian follicular atresia among Burbot in Lake Roosevelt and may be applied to other Burbot populations.

Journal of Fish and Wildlife Management↗
USGS2024

Prioritizing imperiled native aquatic species for conservation propagation

Native aquatic species are in decline, and hatcheries can play an important role in stemming these losses until larger ecological issues are addressed. However, as more federal and state agencies face budget uncertainty and the number of imperiled species increases, it is necessary to develop a tool to prioritize species for conservation propagation. Our objective was to create prioritized lists of aquatic species that may benefit from conservation propagation for five states in the United States. Biologists developed an influence diagram and provided information for multiple attributes affecting prevalence of species. The influence diagram and information for each species was used in a Bayesian belief network to generate a score to prioritize propagation of a species and the feasibility of propagation. When all taxa were ranked together within a state, mussels, amphibians, and a crustacean were included among fishes in the top species that may benefit from propagation. We recognize that propagation is one tool for conservation of imperiled species and that additional factors will need to be addressed to ensure species persistence. Nevertheless, we contend our quantitative approach provides a useful framework for prioritizing conservation propagation.

Colorado, Kansas, North Dakota, South Dakota, Utah↗
USGS2024

Visual interpretation of high-resolution aerial imagery: A tool for land managers

Remotely sensed imagery from various collection platforms (e.g., satellites, crewed and uncrewed aircraft) are used by biologists and other conservation personnel to support management activities ranging from monitoring invasive species to assessing land cover and vegetation characteristics. Although remote sensing–based vegetation indices and models have been developed and used for some management applications, straightforward visual interpretation of imagery by on-the-ground personnel may be a pragmatic approach for obtaining time-sensitive and spatially relevant information to support and guide local management activities. Our primary objective was to qualitatively assess our ability to identify patches of target invasive plant species based on simple visual interpretation of high-resolution aerial imagery. We also sought to compare the high-resolution imagery to widely available imagery (e.g., National Agriculture Imagery Program) to determine the efficacy of each for assessing vegetation communities and land-cover features in support of management activities. To accomplish these objectives, we obtained high-resolution imagery and visually scanned and assessed the imagery by using standard geographic information system software. We were able to differentiate patches of crownvetch Securigera varia (L.) Lassen and wild parsnip Pastinaca sativa L., but not spotted knapweed Centaurea stoebe L. or leafy spurge Euphorbia esula L. The relative success in identifying these species had a relationship to plant characteristics (e.g., flower color and morphology, height), time of year (phenology), patch size and density, and potentially site characteristics such density of the underlying vegetation (e.g., grasses), substrate color characteristics (i.e., color contrast with flowers), and physical disturbance. Our straightforward, qualitative assessment suggests that visual interpretation of high-resolution imagery, but not some lower-resolution imagery, may be an efficient and effective tool for supporting local invasive species management through activities such as monitoring known patches, identifying undetected infestations, assessing management actions, guiding field work, or prioritizing on-the-ground monitoring activities.

Journal of Fish and Wildlife Management↗
USGS2003

Mapping the seabed and habitats in National Marine Sanctuaries - Examples from the East, Gulf and West Coasts

The National Marine Sanctuary System requires seabed and habitat maps to serve as a basis for managing sanctuary resources and for conducting research. NOAA, the agency that manages the sanctuaries, and the USGS have conducted mapping projects in three sanctuaries (Stellwagen Bank NMS, Flower Garden Banks NMS, and Channel Islands NMS) with an emphasis on collaboration of geologists and biologists from the two agencies and from academic institutions. Mapping of seabed habitats is a developing field that requires the integration of geologic and biologic studies and the use of swath imaging techniques such as multibeam and sidescan sonar. Major products of swath mapping are shaded-relief topographic imagery which shows seabed features in great detail, and backscatter imagery which provides an indication of the types of materials that constitute the seabed. Sea floor images provide an excellent basis for conducting the groundtruthing studies (using video, photo, and sampling techniques) that are required to collect the data necessary for making meaningful interpretative maps of the seabed. The compilation of interpretive maps showing seabed environments and habitats also requires the development of a sea floor classification system that will be a basis for comparing, managing, and researching characteristic areas of the seabed. Seabed maps of the sanctuaries are proving useful for management and research decisions that address commercial and recreational fishing, habitat disturbance, engineering projects, tourism, and cultural resources.

Marine Technology Society Journal↗
USGS2012

Telemetry techniques: A user guide for fisheries research

Telemetry provides a powerful and flexible tool for studying fish and other aquatic animals, and its use has become increasingly commonplace. However, telemetry is gear intensive and typically requires more specialized knowledge and training than many other field techniques. As with other scientific methods, collecting good data is dependent on an understanding of the underlying principles behind the approach, knowing how to use the equipment and techniques properly, and recognizing what to do with the data collected. This book provides a road map for using telemetry to study aquatic animals, and provides the basic information needed to plan, implement, and conduct a telemetry study under field conditions. Topics include acoustic or radio telemetry study design, tag implantation techniques, radio and acoustic telemetry principles and case studies, and data management and analysis. Chapters are written by biologists, technicians, and engineers from the private, academic, and government sectors, with decades of experience using these technologies.

Book↗
USGS2024

Statistical analysis

Effective monitoring of populations is critical for assessing the efficacy of conservation and management activities, determining the conservation status of a species, and examining trends over time. However, far too often, monitoring efforts fall short of adequately describing the population. Poorly defined problems and objectives, a lack of standard operating procedures, a poor selection of attributes to monitor (We define attributes as characteristics such as presence-absence, relative abundance, size structure, body condition, and age structure data), inadequate survey designs (e.g., low survey effort or statistical power), a lack of consistency due to budget shortages or staffing turnover, and a lack of rigorous analyses of the data focused on improving monitoring methods are the causes of ineffective monitoring (Lindenmayer and Likens 2010; Reynolds 2012). Many of these issues can be addressed prior to implementing a monitoring program by defining clear objectives, developing a formal protocol with specific instructions on how to conduct the survey, analyzing historical data to estimate the required sample size, exploring collaborations between biologists and statisticians, and instituting a formal goal to regularly analyze the data collected to improve the monitoring process (Lindenmayer and Likens 2010). The goal of this chapter is to provide an overview of defining the sampling frame, site selection from the sampling frame, sample size estimation, data summarization and analysis techniques, parameter estimation, and hypothesis testing, as well as recognizing when a monitoring program is unlikely to produce the desired results.

Book chapter↗
USGS2024

Standard data management practices

Accomplishing data management in a standardized and practical way begins with an understanding of what data management is. The Data Management Association defines data management as “the development, execution, and supervision of plans, policies, programs, and practices that deliver, control, protect, and enhance the value of data and information assets throughout their lifecycles” (Earley 2017). In this chapter, we present the tenets of data management in the context of fisheries for our target audience: fisheries biologists who may have limited formal training in data science. Experienced data managers may also benefit from the contents of this chapter, but the authors’ goal is to enhance and improve those activities that produce data, from project planning to acquiring data through field sampling, to cataloging and analyzing data, to sharing and archiving data.

Book chapter↗
USGS2021

Oases: Finding hidden biodiversity gems in the southern Sonoran Desert

In the arid southern Sonoran Desert, the rugged canyons of the Sierra El Aguaje contain numerous freshwater oases. These habitats are supported by small springs which are usually located along geologic faults in volcanic and granitic bedrock. Genetic evidence from freshwater-obligate species (e.g., fish and frogs) suggests these or similar spring-fed habitats have persisted for thousands to millions of years. Though biologists are just beginning to study these habitats, at least 210 species of aquatic invertebrates have been documented, along with several species of fishes, amphibians, and semi-aquatic reptiles. Additionally, euryhaline fishes occasionally colonize freshwater habitats when hurricane-induced floods connect oases with the sea. At least six new, potentially endemic, species of aquatic invertebrates have been found in recent years, but much work remains to be done to fully document the biota of these oases. Groundwater pumping, introductions of nonnative species, and unmanaged human recreation all threaten the biodiversity of these desert oases. We hope this chapter will draw attention to these beautiful habitats and promote conservation of their unique biota

Sonora↗
USGS2023

Evaluating baits with lufenuron and nitenpyram for flea control on prairie dogs (Cynomys spp.) to mitigate plague

Plague, caused by Yersinia pestis , is a widespread threat to endangered black-footed ferrets ( Mustela nigripes ) and their primary prey, prairie dogs ( Cynomys spp.). Wildlife biologists most commonly manage plague using insecticides to control fleas, the primary vectors of Y. pestis . We tested edible baits containing the insecticides lufenuron and/or nitenpyram in prairie dogs. During a laboratory study, we treated 26 white-tailed prairie dogs ( Cynomys leucurus ) with lufenuron at 300 mg/kg body mass. All animals remained clinically healthy over the 9 wk monitoring period. Although serum lufenuron concentrations were >130 ppb in two treatment groups at week 1, concentrations declined to ≤60 ppb after 3 wk in non-torpid prairie dogs and after 7 wk in torpid prairie dogs. In a field experiment, we tested baits containing a combination of 75 mg lufenuron and 6 mg nitenpyram, respectively, in black-tailed prairie dogs ( Cynomys ludovicianus ). We uniformly distributed baits at 125 baits/ha on two plots (treated once) and 250 baits/ha on two plots (each treated twice 4.4 wk apart). Following treatments, flea abundance increased on prairie dogs and remained stable in burrows. Our findings indicate that baits containing lufenuron and nitenpyram, at the reported treatment rates, are ineffective tools for flea control on prairie dogs. Future experiments might evaluate efficacy of higher doses of lufenuron and nitenpyram, and repetitive treatments at differing intervals over time to evaluate potentially therapeutic treatments.

Journal of Wildlife Diseases↗
USGS2024

Little brown bats (Myotis lucifugus) are resistant to SARS-CoV-2 infection

It has been proposed that the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus that spread through human populations as a pandemic originated in Asian bats. There is concern that infected humans could transmit the virus to native North American bats; therefore, the susceptibility of several North American bat species to the pandemic virus has been experimentally assessed. Big brown bats ( Eptesicus fuscus ) were shown to be resistant to infection by SARS-CoV-2, whereas Mexican free-tailed bats ( Tadarida brasiliensis ) became infected and orally excreted moderate amounts of virus for up to 18 d postinoculation. Little brown bats ( Myotis lucifugus ) frequently contact humans, and their populations are threatened over much of their range due to white-nose syndrome, a fungal disease that is continuing to spread across North America. We experimentally challenged little brown bats with SARS-CoV-2 to determine their susceptibility and host potential and whether the virus presents an additional risk to this species. We found that this species was resistant to infection by SARS-CoV-2. These findings provide reassurance to wildlife rehabilitators, biologists, conservation scientists, and the public at large who are concerned with possible transmission of this virus to threatened bat populations.

Journal of Wildlife Diseases↗
USGS2026

Fipronil baits as emerging tools for flea control and plague mitigation: Experiments with cricetid mice on prairie dog colonies

Plague is a zoonotic disease of mammalian hosts and flea vectors. Wildlife biologists most commonly mitigate plague by controlling flea populations. We evaluated the efficacy of edible baits for systemic flea control with two cricetid species on colonies of black-tailed prairie dogs ( Cynomys ludovicianus ): the western deer mouse ( Peromyscus sonoriensis ) and the northern grasshopper mouse ( Onychomys leucogaster ). We tested grain bait with 0.005% fipronil by weight and “FipBit” pellets with 0.46–1.52 mg of fipronil/pellet. Flea prevalence was assessed via combing of live-trapped mice. In one experiment with fipronil grain bait and FipBits ( n =564 combings), flea prevalence declined from 74% (grain) and 45% (FipBits) before treatments to 0% for both treatments from 30–44 d and from 324–413 d after treatments. During a second experiment with FipBits ( n =299 combings), flea prevalence declined from 13% to 32% before treatments to 0% from 11–15 d after treatments, but increased to 29–56% from 349–378 d after treatments. Results herein suggest annual fipronil bait treatments may be most effective for flea control.

Journal of Wildlife Diseases↗
USGS2025

Environmental conditions influencing the abundance of the salmonid ectoparasite Salmincola californiensis across upper Willamette River Reservoirs, Oregon

The freshwater copepod Salmincola californiensis is an ectoparasite of Pacific salmon and trout ( Oncorhynchus spp.). High levels of infection by this parasite can significantly damage gills and result in blood loss, affecting the fitness and survival of hosts, and it may hinder recovery efforts of threatened and endangered salmonids. Juvenile salmonids that rear in reservoirs have been reported to experience higher rates of infection than their stream-dwelling counterparts. To date, the relationship between reservoir environmental conditions and infection rates remains poorly understood. Here, we evaluated sampling methods designed to capture S. californiensis copepodids, the free-swimming infectious life stage of this parasitic copepod, and develop predictive models of parasite abundance in reservoirs . We used light traps to collect 675 zooplankton samples from various sites and depths in Cougar, Lookout Point, and Fall Creek reservoirs, Oregon, USA during five months in 2020. We tested several predictive models of parasite abundance using environmental covariates obtained concurrently during plankton surveys ( e.g. , temperature, ambient light and water clarity, reservoir plankton profiles, and water flow). Our models showed a strong influence of water temperature on abundance of copepodids, with maximum initial abundance occurring at the mean water temperature 15.2 °C. At that temperature, August abundance was estimated to be 58.6 copepodids per site in Cougar Reservoir, 43.8 copepodids per site in Fall Creek Reservoir, and 3.5 copepodids per site in Lookout Point Reservoir. Water temperature and reservoir outflow both affected population growth of copepodids: increased water temperature was associated with an increase in population growth rate while an increased reservoir outflow was associated with a decrease in population growth rate. The efficacy of our sampling method was influenced by percent of moon fullness, whether the sample site was above or below the thermocline, water temperature, and number of juvenile sculpin fishes ( Cottus spp.) captured in the trap. The mean probability of detecting a single copepodid if one was present was 0.042, but detection probability increased to 0.29 under ideal trap set conditions of warmer water, location above the thermocline, and a full moon. Biologists and managers could use these methods to assess the presence and abundance of S. californiensis in other locations, or to inform reservoir operations to reduce potential salmonid infections.

Oregon↗
USGS2000

Field surveys of Midwestern and Northeastern Fish and Wildlife Service lands for the presence of abnormal frogs and toads

The national distribution of information on the discovery of malformations in Minnesota frogs in 1995 stimulated collection and examination of newly metamorphosed frogs during 1996. By late summer and early fall of 1996, malformed frogs and toads were reported on U.S. Fish and Wildlife Service (USFWS) lands in Vermont (Northeast, Region 5) and Minnesota (Midwest, Region 3). In response to these reports, biologists in USFWS Regions 3 and 5 conducted a survey, during the summer of 1997 to determine the distribution and type of malformations in frogs and toads on selected federal lands. Region 3 personnel surveyed 38 field stations at National Wildlife Refuges (NWR's) and Wetland Management Districts. Malformed frogs and toads were collected at 23 (61%) of the Region 3 sites. External malformations were detected in 110 of 6632 individuals representing seven of 13 frog species and one of three toad species examined for an overall of 1.7% affected (percentages for affected species ranged from 0.4-5.2%). In Region 5, 17 NWR's and one National Park were surveyed. Malformed frogs were collected at 10 (56%) of the Region 5 sites. External malformations were detected in 58 of 2267 individuals representing six of 11 frog species and one of two toad species examined for an overall total of 2.6% affected (percentages for affected species ranged from 1.8-15.6%). The majority of malformations observed in frogs and toads collected in Regions 3 and 5 were partially or completely missing hind limbs and digits (50%)or malformed hind limbs and digits (14%). A few individuals had an extra limb or toe, missing or malformed front limb, missing eye, or malformation of the mandible. Despite small sample sizes at some sites, malformations were confirmed to be present in eight species of frogs and two species of toads on Federal lands in USFWS Regions 3 and 5. Further study is needed to determine the extent and distribution of amphibian malformations in these Regions. Data from this study were provided to the national database on distribution of malformed amphibians.

Iowa, Illinois, Michigan, Minnesnowta, Missouri, O↗
USGS2002

Avian vacuolar myelinopathy: a newly recognized fatal neurologic disease of eagles, waterfowl, and other birds

Wildlife biologists and health specialists have been frustrated by a long list of negative findings in their AVM investigations, however studies continue to provide pieces of information to aid the determination of the cause and its source. Available data indicated that AVM may have been present since at least 1990, occurs in at least five states, has been documented during October through April at sites of wintering populations of birds where the exposure apparently occurs, and has killed at least 90 bald eagles. Birds with AVM have difficulty or inability to fly, swim, walk, or perch, but there has been resolution of clinical signs in some affected coots. The list of affected species continues to grow, but remains confined to wild avians, including bald eagle, American coot, great horned owl, killdeer, Canada goose, mallard, ring-necked duck and bufflehead. The effects of the AVM agent on mammals, including human beings, are unknown. A neurotoxicant of manmade or natural origin is the suspected cause of AVM because no infectious disease agents, such as viruses, bacteria, parasites and prions, have been found, and the lesion and epizootiology of AVM resemble those of toxicoses. Additionally it is documented, experimentally, that exposure to raptors can occur through ingestion of infected coots. Collaborative studies will continue in the effort to identify the cause of AVM, its geographic distribution, and the range of species susceptibility. Hopefully, this information can be used to identify measures that might be taken to reduce the impact of AVM on the wildlife resource. Multiple agencies, institutions, and individuals must rely on each other's expertise in the multidisciplinary approach to this problem, persevere in their efforts and take advantage of serendipity that presents itself during investigations of this newly recognized cause of wild bird mortality.

Arkansas, Georgia, North Carolina, South Carolina↗
USGS2003

Satellite telemetry and wildlife studies in India: Advantages, options and challenges

Greater spatial coverage, accuracy and non-invasiveness of satellite technology make it one of the best tools to track long-distance migrants, which is otherwise difficult using conventional radio telemetry. In this article, we review the evolution of satellite telemetry and its application. We provide examples of three recent studies in India that have demonstrated and created a widespread appreciation of the use and benefits of satellite telemetry among biologists and managers. We also discuss the future prospects of this technology vis-a-vis benefits and challenges in the Indian subcontinent.

Current Science↗
USGS1993

A model of the productivity of the northern pintail

We adapted a stochastic computer model to simulate productivity of the northern pintail (Anas acuta). Researchers at the Northern Prairie Wildlife Research Center of the U.S. Fish and Wildlife Service originally developed the model to simulate productivity of the mallard (A. platyrhynchos). We obtained data and descriptive information on the breeding biology of pintails from a literature review and from discussions with waterfowl biologists. All biological parameters in the productivity component of the mallard model (e.g, initial body weights, weight loss during laying and incubation, incubation time, clutch size, nest site selection characteristics) were compared with data on pintails and adjusted accordingly. The function in the mallard model that predicts nest initiation in response to pond conditions adequately mimicked pintail behavior and did not require adjustment.Recruitment rate was most sensitive to variations in parameters that control nest success, seasonal duckling survival rate, and yearling and adult body weight. We simulated upland and wetland habitat conditions in central North Dakota and compared simulation results with observed data. Simulated numbers were not significantly different from observed numbers of successful nests during wet, average, and dry wetland conditions. The simulated effect of predator barrier fencing in a study area in central North Dakota increased recruitment rate by an average of 18.4%. This modeling synthesized existing knowledge on the breeding biology of the northern pintail, identified necessary research, and furnished a useful tool for the examination and comparison of various management options.

Biological Report↗
USGS1977

Some Bayesian statistical techniques useful in estimating frequency and density

This paper presents some elementary applications of Bayesian statistics to problems faced by wildlife biologists. Bayesian confidence limits for frequency of occurrence are shown to be generally superior to classical confidence limits. Population density can be estimated from frequency data if the species is sparsely distributed relative to the size of the sample plot. For other situations, limits are developed based on the normal distribution and prior knowledge that the density is non-negative, which insures that the lower confidence limit is non-negative. Conditions are described under which Bayesian confidence limits are superior to those calculated with classical methods; examples are also given on how prior knowledge of the density can be used to sharpen inferences drawn from a new sample.

Special Scientific Report - Wildlife↗