Search USGS⌕ Search

SEARCH · Search USGS

Results for “Wildlife Biology”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 901 records · Page 50Linked to original sources
USGS2001

Negative binomial models for abundance estimation of multiple closed populations

Counts of uniquely identified individuals in a population offer opportunities to estimate abundance. However, for various reasons such counts may be burdened by heterogeneity in the probability of being detected. Theoretical arguments and empirical evidence demonstrate that the negative binomial distribution (NBD) is a useful characterization for counts from biological populations with heterogeneity. We propose a method that focuses on estimating multiple populations by simultaneously using a suite of models derived from the NBD. We used this approach to estimate the number of female grizzly bears (Ursus arctos) with cubs-of-the-year in the Yellowstone ecosystem, for each year, 1986-1998. Akaike's Information Criteria (AIC) indicated that a negative binomial model with a constant level of heterogeneity across all years was best for characterizing the sighting frequencies of female grizzly bears. A lack-of-fit test indicated the model adequately described the collected data. Bootstrap techniques were used to estimate standard errors and 95% confidence intervals. We provide a Monte Carlo technique, which confirms that the Yellowstone ecosystem grizzly bear population increased during the period 1986-1998.

Idaho, Montana, Wyoming↗
USGS1988

Nutritional values of waterfowl foods

wetland habitats throughout their annual cycles. Survival, reproduction, and growth are dependent on the availability of foods that meet nutritional requirements for recurring biological events. These requirements occur among a wide variety of environmental conditions that also influence nutritional demands. Recent work on nesting waterfowl has identified the female’s general nutrient needs for egg laying and incubation. Far less is known about nutritional requirements for molt and other portions of the life cycle, particularly those during the nonbreeding season. Although information on specific requirements for amino acids and micronutrients of wild birds is meager, the available information on waterfowl requirements can be used to develop waterfowl management strategies. For example, nutrient content of foods, nutritional requirements of waterfowl, and the cues waterfowl use in locating and selecting foods are all kinds of information that managers need to encourage use of habitats by feeding waterfowl. Waterfowl nutritional needs during the annual cycle and the nutritional values of natural foods and crops will be discussed below.

Fish and Wildlife Leaflet↗
USGS2000

Survival and reproductive biology of the Bachman's Sparrow

We estimated breeding season survival rates and nest success for Bachman's Sparrows at the Savannah River Site, South Carolina, using radio telemetry. The 1995 breeding season (2 May-9 Aug) survival rate was 0.905 (95% C. I. 0.779-1.03) with 2 mortalities out of 20 individuals. The 1996 breeding season (10 May-25 Jul) survival rate was 0.882 (95% C. I. 0.729-1.04) with 2 mortalities out of 18 individuals. No significant differences in survival rates were detected between years, sexes, or habitat types. The overall breeding season survival rate was 0.893 (95%, C. I. 0.794-0.992). Daily nest survival rate in 1995 was 0.952 (0.013 SE N=26) and 0.889 (0.027 SE N=15) in 1996. Daily nest survival was significantly greater during 1995, with only 1 of 15 nests fledging a single individual in 1996. Nests attempts initiated before 15 June (0.975 [0.012], N=15) had higher survival rates than later nest attempts (0.914 [0.029] N=11, C2=3.77, 1 df, P=0.05).

Proceedings of the Annual Conference of the Southe↗
USGS2019

Surrogate rearing a keystone species to enhance population and ecosystem restoration

Translocation and rehabilitation programs are critical tools for wildlife conservation. These methods achieve greater impact when integrated in a combined strategy for enhancing population or ecosystem restoration. From 2002-2016, we reared 37 orphaned southern sea otter (Enhydra lutris nereis) pups, using captive sea otters as surrogate mothers, then released them into a degraded coastal estuary. As a keystone species, observed increases in the local sea otter population unsurprisingly brought many ecosystem benefits. The role that surrogate-reared otters played in this success story, however, remained uncertain. To resolve this question, we developed an individual-based model (IBM) of the local population using surveyed individual fates (survival and reproduction) of surrogate-reared and wild-captured otters, and modeled estimates of immigration. Estimates derived from a decade of population monitoring indicated that surrogate-reared and wild sea otters experienced similar reproductive and survival rates. This was true for males and females, across all ages (1-13 years) and locations evaluated. The IBM simulations indicated that reconstructed counts of the wild population are best explained by surrogate-reared otters combined with low levels of unassisted immigration. In addition, the model shows that 55% of observed population growth over this period is attributable to surrogate-reared otters and their wild progeny. Together, our results indicate that the integration of surrogacy methods and reintroduction of juvenile sea otters helped establish a biologically successful population and restore a once-impaired ecosystem.

California↗
USGS2025

Mercury trophic transfer to a freshwater biosentinel: Quantifying controlled bioaccumulation in larval dragonflies

Mercury bioavailability and biomagnification in freshwater systems can be highly variable; thus, tissue data from biosentinel taxa can be useful to assess risk. Dragonfly larvae have emerged as biological indicators of mercury impairment, yet their mercury biodynamics over time and across exposure levels are not well understood. Evaluating these attributes using controlled experimental approaches is an important step to validate larval dragonflies as biosentinels for spatial and temporal trends in mercury risk. We conducted an experimental series quantifying methylmercury trophic transfer from dosed prey to predatory dragonfly larvae at environmentally relevant concentrations. Dragonfly total mercury concentrations increased proportionally by factors of 2.7 to 4.2 with each doubling of prey methylmercury concentration, responding to dietary treatments in 7–28 days and reaching equilibrium in as little as 40 days, supporting their utility to indicate changing mercury exposure regimes. Dosed dragonflies biomagnified methylmercury by factors of 1.0 ± 0.1 to 3.4 ± 0.2 relative to their prey, and biomagnification efficiency decreased by over 40% for each doubling of prey methylmercury concentration. Dragonfly development had dose-dependent effects on bioaccumulation: mercury concentrations increased with growth and decreased with age in higher exposure treatments, whereas they decreased with growth and increased with age in lower exposure treatments. Bioaccumulation also varied taxonomically; within treatments, mean mercury concentrations for each genus varied up to 10% from family-level means. Dragonfly sex, size, and body condition did not significantly affect mercury concentrations. These results help validate and expand the utility of dragonfly larvae as biosentinels to monitor mercury risk and better protect wildlife and human health.

Oregon↗
USGS2018

Annotated bibliography of scientific research on greater sage-grouse published since January 2015

The greater sage-grouse ( Centrocercus urophasianus ; hereafter GRSG) has been a focus of scientific investigation and management action for the past two decades. The 2015 U.S. Fish and Wildlife Service listing determination of “not warranted” was in part due to a large-scale collaborative effort to develop strategies to conserve GRSG populations and their habitat and to reduce threats to both. New scientific information augments existing knowledge and can help inform updates or modifications to existing plans for managing GRSG and sagebrush ecosystems. However, the sheer number of scientific publications can be a challenge for managers tasked with evaluating and determining the need for potential updates to existing planning documents. To assist in this process, the U.S. Geological Survey (USGS) has reviewed and summarized the scientific literature published since January 1, 2015. To identify articles and reports published about GRSG, we first conducted a structured search of three reference databases (Web of Science, Scopus, and Google Scholar) using the search term “greater sage-grouse.” We refined the initial list of products by (1) removing duplicates, (2) excluding products that were not published as research or scientific review articles in peer-reviewed journals or as formal government technical reports, and (3) retaining only those products for which GRSG or their habitat was a research focus. We summarized the contents of each product by using a consistent structure (background, objectives, methods, location, findings, and implications) and assessed the content of each product relevant to a list of 31 management topics. These topics include GRSG biology and habitat characteristics along with potential management actions, land uses, and environmental factors related to GRSG management and conservation. We also noted which articles/reports created new geospatial data. The final search was conducted on January 6, 2018, and application of our criteria resulted in the inclusion of 169 published products (2 of these products were published corrections to journal articles). The management topics most commonly addressed were GRSG behavior or demographics and GRSG habitat selection or habitat characteristics at broad or site scales. Few products addressed captive breeding, recreation, wild horses and burros, and range management structures (including fences). We include in this annotated bibliography the full citation, product summary, and management topics addressed by each product. The online version of this bibliography ( https://apps.usgs.gov/gsgbib/index.php ) is searchable by topic and location and includes links to the original publications. A substantial body of literature has been compiled based on research explicitly related to the conservation, management, monitoring, and assessment of GRSG. These studies may inform planning and management actions that seek to balance conservation, economic, and social objectives and manage diverse resource uses and values across the western United States. The review process for this product included requesting input on each summary from one or more authors of the original peer-reviewed article or report and a formal review of the entire document by three independent reviewers and, subsequently, the USGS Bureau Approving Official. This process is consistent with USGS Fundamental Science Practices.

Open-File Report↗
USGS1996

Relation between selected water-quality variables and lake level in Upper Klamath and Agency Lakes, Oregon

Upper Klamath Lake is a large (140 square-mile), shallow (mean depth about 8 ft) lake in south-central Oregon that the historical record indicates has been eutrophic since its discovery by non-Native Americans. In recent decades, however, the lake has had annual occurrences of near- monoculture blooms of the blue-green alga Aphanizomenon flos-aquae. In 1988 two sucker species endemic to the lake, the Lost River sucker (Deltistes luxatus) and the shortnose sucker (Chasmistes brevirostris), were listed as endangered by the U.S. Fish and Wildlife Service, and it has been proposed that the poor water quality conditions associated with extremely long and productive blooms are contributing to the decline of those species. It has also been proposed that the low lake levels made possible by the construction of a dam at the outlet from the lake in 1921 have contributed to worsening water quality through a variety of possible mechanisms (Jacob Kann, Klamath Tribes, written commun., 1995). One such mechanism would be an increase in internal phosphorus loading from resuspended sediments (Jacoby and others, 1982), resulting from an increase in bottom shear stresses at lower lake levels (Laenen and LeTourneau, 1996), leading in turn to more intense algal blooms. Another possible mechanism is an earlier triggering of algal blooms. When early spring lake levels are low, greater light intensity at the sediment surface might speed recruitment of algal cells from the sediments. Sediment recruitment has been shown to be an important contributor to water column biomass increases in A. flos aquae (Barbiero and Kann, 1994) and Gloeotrichia echinulata (Barbiero, 1993). An earlier bloom could result in poor water quality conditions occurring earlier in the year, when young-of-the-year fish may be more susceptible to those conditions. Lake level can also influence water quality directly. An increased frequency of sediment resuspension at lower lake levels could increase chemical and biological oxygen demand, resulting in decreased dissolved oxygen concentrations. Sediment oxygen demand also may be enhanced at lower lake levels because it is concentrated over a smaller volume of water. Some compensation for increased oxygen demand at lower lake levels might be provided by increased reaeration, if the water column mixes from top to bottom more frequently. Based on the analysis of data that they have been collecting for several years, the Klamath Tribes recently recommended that the Bureau of Reclamation (Reclamation) modify the operating plan for the dam to make the minimum lake levels for the June-August period more closely resemble pre-dam conditions (Jacob Kann, written commun., 1995). The U.S. Geological Survey (USGS) was asked to analyze the available data for the lake and to assess whether the evidence exists to conclude that year-to-year differences in certain lake water-quality variables are related to year-to-year differences in lake level. The results of the analysis will be used as scientific input in the process of developing an operating plan for the Link River Dam.

Oregon↗
USGS2013

Water quality, sediment characteristics, aquatic habitat, geomorphology, and mussel population status of the Clinch River, Virginia and Tennessee, 2009-2011

Chemical, physical, and biological data were collected during 2009-2011 as part of a study of the Clinch River in Virginia and Tennessee. The data from this study, data-collection methods, and laboratory analytical methods used in the study are documented in this report. The study was conducted to describe the conditions of the Clinch River and to determine if there are measurable differences in chemical, physical, or biological characteristics in a segment of the river where freshwater mussel populations are in decline, have low density, richness, little to no recruitment, and lack endangered species (low-quality reach) compared to a segment of the river where mussel assemblages have relatively high density, richness, evidence of recruitment, and support endangered species (high-quality reach). Five continuous water-quality monitors were installed and operated on the mainstem of the Clinch River and two tributaries. Discrete water-quality sample sets were collected during base-flow and stormflow conditions two sites on the Clinch River and on the Guest River, a tributary to the Clinch River predominantly in the Appalachian Plateaus Physiographic Province. Base-flow water-quality samples were collected in July and August 2011 at 15 sites along the mainstem of the Clinch River. Other analyses included longitudinal sampling along the mainstem of the Clinch River at 10 sites to evaluate bed-sediment chemistry, habitat condition, and mollusk community status. In situ freshwater mussel growth and mortality experiments were conducted with hatchery propogated Villosa iris (rainbow mussels). Tissue from the V. iris as well as tissue from 16 Actinonaias pectorosa mussels were analyzed for trace metals, and V. iris mussel tissue was analyzed for organic compounds. Data collected during this investigation were analyzed by various U.S. Geological Survey or U.S. Fish and Wildlife Service laboratories.

Tennessee, Virginia↗
USGS2019

Activity center selection by northern spotted owls

The federally threatened northern spotted owl ( Strix occidentalis caurina ) has been intensively studied across its range, and habitat needs for the species have influenced forest management in northwestern North America for decades. Dense forest canopies are often reported in the scientific literature and agency management plans as an important habitat attribute for spotted owls, though the means of measuring forest canopy and interpreting species requirements vary across studies and more importantly, among management plans. We used light detection and ranging (lidar) measurements of canopy cover, canopy surface heterogeneity, and upper canopy surface connectivity, and an index of the presence of a competitive invasive species, the barred owl ( S. varia ), in multinomial discrete choice models using a Bayesian framework to evaluate selection of forest cover types by spotted owls in Oregon, USA, 2008–2015. We designated yearly activity centers based on the most biologically significant observation during the nesting season (Mar–Aug), generally centered on the nest tree. Spotted owls selected activity centers with more canopy cover and higher heterogeneity of the canopy surface within 100 m than was available within their territories. The average proportion of canopy cover within 100 m of a spotted owl activity center was 0.79 ± 0.12 (SD; range = 0.34–0.99). The presence of barred owls did not explain variability in selection of spotted owl activity centers, but barred owls might not affect third‐order habitat selection within territories, or our index was too spatially coarse to detect these effects on spotted owl resource selection. We demonstrate that lidar provides researchers and managers with a tool that can accurately measure forest canopies over large areas, and assist in mapping spotted owl habitat.

Oregon↗
USGS2004

Water quality in Big Cypress National Preserve and Everglades National Park — Trends and spatial characteristics of selected constituents

Seasonal changes in water levels and flows in Big Cypress National Preserve (BICY) and Everglades National Park (EVER) affect water quality. As water levels and flows decline during the dry season, physical, geochemical and biological processes increase the breakdown of organic materials and the build-up of organic waste, nutrients, and other constituents in the remaining surface water. For example, concentrations of total phosphorus in the marsh are less than 0.01 milligram per liter (mg/L) during much of the year. Concentrations can rise briefly above this value during the dry season and occasionally exceed 0.1 mg/L under drought conditions. Long-term changes in water levels, flows, water management, and upstream land use also affect water quality in BICY and EVER, based on analysis of available data (1959-2000). During the 1980's and early 1990's, specific conductance and concentrations of chloride increased in the Taylor Slough and Shark River Slough. Chloride concentrations more than doubled from 1960 to 1990, primarily due to greater canal transport of high dissolved solids into the sloughs. Some apparent long-term trends in sulfate and total phosphorus were likely attributable, at least in part, to high percentages of less-than and zero values and to changes in reporting levels over the period of record. High values in nutrient concentrations were evident during dry periods of the 1980's and were attributable either to increased canal inflows of nutrient-rich water, increased nutrient releases from breakdown of organic bottom sediment, or increased build-up of nutrient waste from concentrations of aquatic biota and wildlife in remaining ponds. Long-term changes in water quality over the period of record are less pronounced in the western Everglades and the Big Cypress Swamp; however, short-term seasonal and drought-related changes are evident. Water quality varies spatially across the region because of natural variations in geology, hydrology, and vegetation and because of differences in water management and land use. Nutrient concentrations are relatively low in BICY and EVER compared with concentrations in parts of the northern Everglades that are near agricultural and urban lands. Concentrations of total phosphorus generally are higher in BICY (median values, 1991-2000, were mostly greater than 0.015 mg/L) than in EVER (median values, 1991-2000, less than 0.01 mg/L), probably because of higher phosphorus in natural sources such as shallow soils, rocks, and ground water in the Big Cypress region than in the Everglades region. Conversely, concentrations of chloride and sulfate are higher in EVER (median values in Shark River Slough, 1991-2000, mostly greater than 2 mg/L sulfate and 50 mg/L chloride) than in BICY (median values, 1991-2000, less than 1 mg/L sulfate and at most sites less than 20 mg/L chloride), probably because of the canal transport system, which conveys more water from an agricultural source into EVER than into BICY. Trace elements and contaminants such as pesticides and other toxic organic compounds are in relatively low concentrations in BICY and EVER compared with concentrations in parts of the northern Everglades near agricultural and urban sources. Concentrations rarely exceeded aquatic life criteria in BICY and EVER. Atrazine was the only pesticide found in water that exceeded the criteria (in 2 out of 304 samples). The pesticides heptachlor expoxide, lindane, and p,p?-DDE exceeded criteria in canal bed sediments in 1, 2, and 16 percent of the samples, respectively.

Florida↗
USGS2006

Land-Cover Trends of the Central Basin and Range Ecoregion

The U.S. Geological Survey (USGS) Land Cover Trends research project is focused on understanding the amounts, rates, trends, causes, and implications of contemporary land-use and land-cover (LU/LC) change in the United States. This project is supported by the USGS Geographic Analysis and Monitoring Program in collaboration with the U.S. Environmental Protection Agency (EPA) and the National Aeronautics and Space Administration (NASA). LU/LC change is a pervasive process that modifies landscape characteristics and affects a broad range of socioeconomic, biologic, and hydrologic systems. Understanding the impacts and feedbacks of LU/LC change on environmental systems requires an understanding of the rates, patterns, and driving forces of past, present, and future LU/LC change. The objectives of the Land Cover Trends project are to (1) determine and describe the amount, rates, and trends of contemporary LU/LC change by ecoregion for the period 1973-2000 for the conterminous United States, (2) document the causes, driving forces, and implications of change, and (3) synthesize individual ecoregion results into a national assessment of LU/LC change. The Land Cover Trends research team includes staff from the USGS National Center for Earth Resources Observation and Science (EROS), Rocky Mountain Geographic Science Center, Eastern Geographic Science Center, Mid-Continent Geographic Science Center, and the Western Geographic Science Center. Other partners include researchers at South Dakota State University, University of Southern Mississippi, and State University of New York College of Environmental Science and Forestry. This report presents an assessment of LU/LC change in the Central Basin and Range ecoregion for the period 1973-2000. The Central Basin and Range ecoregion is one of 84 Level-III ecoregions as defined by the Environmental Protection Agency. Ecoregions have served as a spatial framework for environmental resource management and to denote areas that contain a geographically distinct assemblage of biotic and abiotic phenomena including geology, physiography, vegetation, climate, soils, land use, wildlife, and hydrology. The established Land Cover Trends methodology generates estimates of LU/LC change using a probability sampling approach and change-detection analysis of thematic land-cover images derived from Landsat satellite imagery.

Scientific Investigations Report↗
USGS1974

Feeding Ecology of Breeding Blue-Winged Teals

A 5-year investigation of factors influencing the selection of foods consumed by blue-winged teals ( Anas discors ) during the breeding season in the glaciated prairie region of south-central North Dakota showed that birds first arriving on the breeding grounds consumed a diet consisting of 45 percent invertebrates. The proportion of animal foods in the diet increased to 95 percent at the onset of the nesting season. The quality and quantity of foods selected at any given time were influenced by the biological demands and morphological adaptations of the bird, the behavior and ecology of the invertebrates selected as foods, and the general nature of the aquatic ecosystems as determined by the hydrology and geology of the area and modified by land use and weather. Feeding activities changed significantly when food availability within the aquatic ecosystem changed. During the spring and early summer, temporary and seasonal wetlands, if not severely disturbed, were of paramount importance to breeding blue-winged teals since they provided abundant and readily available, high protein, animal foods. Later in the summer when seasonal wetlands began to dry up, insects began to emerge in the semipermanent ponds and lakes, and feeding intensity shifted to these more permanent waters. This trend, however, was often reversed temporarily during the early summer following heavy precipitation that refilled shallow water areas and again stimulated invertebrate development.

North Dakota↗
USGS1997

Kauai's endangered solitaires: Update on population status and distribution 1996

The puaioihi ( Myadestes palmeri ) and the kamao ( M. myadestinus ) are endangered solitaires endemic to Kauai in the Hawaiian Islands and now restricted to the Alakai Swamp. The puaiohi has been rare historically with population estimates declining since the first population surveys 1968-73. Puaiohi were believed to be on the verge of extinction with population estimates less than 35 birds since 1981. In 1995 intensive studies of the breeding biology and population status of the puaiohi began using mist netting, color banding, spot mapping, and surveys. Fifty active nests were discovered and 63-75 birds monitored at the Koaie study site. Seven survey expeditions in 1996 detected 55-70 more puaiohi from 6 of 8 main river drainages of four survey areas explored. Although still rare and vulnerable to extinction (145±19 individuals known), puaiohi are more widely distributed within the Alakai Swamp than previously believed. Our data from 1996 suggest previous surveys methods have underestimated the population size or that the population has increased since 1981. The kamao has not been confirmed since 1985, but unconfirmed reports were made from 1989-1996. We have not sighted kamao to date despite intensive search efforts. We infer from detection probabilities that the species in highly likely to be extinct.

Hawaii↗
USGS2012

Developing accurate survey methods for estimating population sizes and trends of the critically endangered Nihoa Millerbird and Nihoa Finch.

This report describes the results of a comparative study of bird survey methods undertaken for the purpose of improving assessments of the conservation status for the two endemic passerines on the Island of Nihoa—Nihoa Millerbird (Sylviidae: Acrocephalus familiaris kingi ) and Nihoa Finch (Fringilidae: Telespiza ultima ; also referred herein as millerbird and finch)—both listed as endangered under the Federal Endangered Species Act (ESA) and Hawai`i Revised Statutes 195D. The current survey protocol, implemented since 1967, has produced a highly variable range of counts for both the millerbird and finch, making difficult assessments of population size and trend. This report details the analyses of bird survey data collected in 2010 and 2011 in which three survey methods were compared―strip-transect, line-transect, and point-transect sampling―and provides recommendations for improved survey methods and protocols. Funding for this research was provided through a Science Support Partnership grant sponsored jointly by the U.S. Geological Survey (USGS) and the U.S. Fish and Wildlife Service (USFWS). Point-transect surveys indicated that millerbirds were more abundant than shown by the striptransect method, and were estimated at 802 birds in 2010 (95%CI = 652 – 964) and 704 birds in 2011 (95%CI = 579 – 837). Point-transect surveys yielded population estimates with improved precision which will permit trends to be detected in shorter time periods and with greater statistical power than is available from strip-transect survey methods. Mean finch population estimates and associated uncertainty were not markedly different among the three survey methods, but the performance of models used to estimate density and population size are expected to improve as the data from additional surveys are incorporated. Using the pointtransect survey, the mean finch population size was estimated at 2,917 birds in 2010 (95%CI = 2,037 – 3,965) and 2,461 birds in 2011 (95%CI = 1,682 – 3,348). Preliminary testing of the line-transect method in 2011 showed that it would not generate sufficient detections to effectively model bird density, and consequently, relatively precise population size estimates. Both species were fairly evenly distributed across Nihoa and appear to occur in all or nearly all available habitat. The time expended and area traversed by observers was similar among survey methods; however, point-transect surveys do not require that observers walk a straight transect line, thereby allowing them to avoid culturally or biologically sensitive areas and minimize the adverse effects of recurrent travel to any particular area. In general, pointtransect surveys detect more birds than strip-survey methods, thereby improving precision and resulting population size and trend estimation. The method is also better suited for the steep and uneven terrain of Nihoa

Hawaii↗
USGS2000

Effects of neck collars and radiotransmitters on survival and reproduction of emperor geese

Neck collars have been used widely for studies of goose population biology. Despite concerns about their negative impacts, few studies have employed designs capable of clearly demonstrating these effects. During a 1993-98 study of emperor geese ( Chen canagica ), we contrasted survival and reproduction of geese marked with tarsal bands to those marked with either small neck collars, large neck collars, or small neck collars with attached radiotransmitters. Annual survival of adult females marked with tarsal bands varied among years and averaged 0.807 ?? 0.140 (v?? ?? SE). Survival of geese with other types of markers also varied among years but was lower (0.640 ?? 0.198). Collars with radiotransmitters lowered breeding propensity, as indexed by resighting rates. Although clutch sizes of tarsal banded birds were similar to those for unmarked birds, other markers reduced clutch sizes by about 1 egg. Egg mass and hatch date were not affected by marker type. Future studies of goose demographics should seriously consider use of alternative markers.

Alaska↗
USGS2024

Monitoring animal populations with cameras using open, multistate, N-mixture models

Remote cameras have become a mainstream tool for studying wildlife populations. For species whose developmental stages or states are identifiable in photographs, there are opportunities for tracking population changes and estimating demographic rates. Recent developments in hierarchical models allow for the estimation of ecological states and rates over time for unmarked animals whose states are known. However, this powerful class of models has been underutilized because they are computationally intensive, and model outputs can be difficult to interpret. Here, we use simulation to show how camera data can be analyzed with multistate, Dail-Madsen (hereafter multistate DM) models to estimate abundance, survival, and recruitment. We evaluated four commonly encountered scenarios arising from camera trap data (low and high abundance and 25% and 50% missing data) each with 18 different sample size combinations (camera sites = 40, 250; surveys = 4, 8, and 12; and years = 2, 5, 10) and evaluated the bias and precision of abundance, survival, and recruitment estimates. We also analyzed our empirical camera data on moose ( Alces alces ) with multistate DM models and compared inference with telemetry studies from the same time and region to assess the accuracy of camera studies to track moose populations. Most scenarios recovered the known parameters from our simulated data with higher accuracy and increased precision for scenarios with more sites, surveys, and/or years. Large amounts of missing data and fewer camera sites, especially at higher abundances, reduced accuracy, and precision of survival and recruitment. Our empirical analysis provided biologically realistic estimates of moose survival and recruitment and recovered the pattern of moose abundance across the region. Multistate DM models can be used for estimating demographic parameters from camera data when developmental states are clearly identifiable. We discuss several avenues for future research and caveats for using multistate DM models for large-scale population monitoring.

New Hampshire, Vermont↗
USGS2023

Dynamic population models with temporal preferential sampling to infer phenology

To study population dynamics, ecologists and wildlife biologists typically use relative abundance data, which may be subject to temporal preferential sampling. Temporal preferential sampling occurs when the times at which observations are made and the latent process of interest are conditionally dependent. To account for preferential sampling, we specify a Bayesian hierarchical abundance model that considers the dependence between observation times and the ecological process of interest. The proposed model improves relative abundance estimates during periods of infrequent observation and accounts for temporal preferential sampling in discrete time. Additionally, our model facilitates posterior inference for population growth rates and mechanistic phenometrics. We apply our model to analyze both simulated data and mosquito count data collected by the National Ecological Observatory Network. In the second case study, we characterize the population growth rate and relative abundance of several mosquito species in the Aedes genus. Supplementary materials accompanying this paper appear on-line.

Journal of Agricultural, Biological, and Environme↗
USGS2014

The role of protected area wetlands in waterfowl habitat conservation: implications for protected area network design

The principal goal of protected area networks is biodiversity preservation, but efficacy of such networks is directly linked to animal movement within and outside area boundaries. We examined wetland selection patterns of mallards (Anas platyrhynchos) during non-breeding periods from 2010 to 2012 to evaluate the utility of protected areas to migratory waterfowl in North America. We tracked 33 adult females using global positioning system (GPS) satellite transmitters and implemented a use-availability resource selection design to examine mallard use of wetlands under varying degrees of protection. Specifically, we examined effects of proximities to National Wildlife Refuges, private land, state wildlife management areas, Wetland Reserve Program easements (WRP), and waterfowl sanctuaries on mallard wetland selection. In addition, we included landscape-level variables that measured areas of sanctuary and WRP within the surrounding landscape of each used and available wetland. We developed 8 wetland selection models according to season (autumn migration, winter, spring migration), hunting season (present, absent), and time period (diurnal, nocturnal). Model averaged parameter estimates indicated wetland selection patterns varied across seasons and time periods, but ducks consistently selected wetlands with greater areas of sanctuary and WRP in the surrounding landscape. Consequently, WRP has the potential to supplement protected area networks in the midcontinent region. Additionally, seasonal variation in wetland selection patterns indicated considering the effects of habitat management and anthropogenic disturbances on migratory waterfowl during the non-breeding period is essential in designing protected area networks.

Biological Conservation↗