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At least 1,081 records · Page 60Linked to original sources
USGS2011

Lead exposure and poisoning of songbirds using the Coeur d'Alene River Basin, Idaho, USA

Previous studies have found widespread Pb poisoning of waterfowl in the Coeur d'Alene River Basin in northern Idaho, USA, which has been contaminated by mining and smelting activities. We studied the exposure of ground-feeding songbirds to Pb, sampling 204 American robins ( Turdus migratorius ), song sparrows ( Melospiza melodia ), and Swainson's thrushes ( Catharus ustulatus ) throughout the basin. These songbirds had mean blood Pb concentrations (mg/kg, dry weight) of less than 0.19 at a reference area (25 mg Pb/kg soil), 1.09 at moderately contaminated sites (170 to 1300 mg Pb/kg soil), and 2.06 at highly contaminated sites (2000 to 5000 mg Pb/kg soil). Based on guidelines for evaluating blood Pb in birds, 6% of robins from the highly contaminated sites had background concentrations, 24% were subclinically poisoned, 52% were clinically poisoned, and 18% were severely clinically poisoned with Pb. Blood Pb concentrations were lower in song sparrows than in robins and lowest in Swainson's thrushes. More than half of the robins and song sparrows from all contaminated sites and more than half of the Swainson's thrushes from highly contaminated sites showed at least 50% inhibition of the activity of the enzyme δ-aminolevulinic acid dehydratase (ALAD), commonly used as a measure of exposure to Pb. The highest hepatic Pb concentration of 61 mg/kg (dry weight) was detected in a song sparrow. Using Al as a marker for soil in songbird ingesta, we estimated average soil ingestion rates as 20% in robins, 17% in song sparrows, and 0.7% in Swainson's thrushes. Soil Pb in ingesta accounted for almost all of the songbirds' exposure to Pb. Based on these results, it is recommended that ecological risk assessments of ground-feeding songbirds at contaminated sites include soil ingestion as a pathway of exposure to Pb.

Idaho↗
USGS2016

Survey for West Nile virus antibodies in wild ducks, 2004-06, USA

Detection of West Nile virus (WNV) in ducks has been reported in North America in isolated cases of mortality in wild waterbirds and following outbreaks in farmed ducks. Although the virus has been noted as an apparent incidental finding in several species of ducks, little is known about the prevalence of exposure or the outcome of infection with WNV in wild ducks in North America. From 2004–06, we collected sera from 1,406 wild-caught American Wigeon ( Anas americana ), Mallard ( Anas platyrhynchos ), and Northern Pintail ( Anas acuta ) ducks at national wildlife refuges (NWRs) in North Dakota and Wood Ducks ( Aix sponsa ) at NWRs in South Carolina and Tennessee. We measured the prevalence of previous exposure to WNV in these ducks by measuring WNV antibodies and evaluated variation in exposure among species, age, and year. Additionally, we evaluated the performance of a commercial antibody to wild bird immunoglobulin in duck species that varied in their phylogenetic relatedness to the bird species the antibody was directed against. As determined by a screening immunoassay and a confirmatory plaque reduction neutralization assay, the prevalence of WNV antibody was 10%. In light of experimental studies that show ducks to be relatively resistant to mortality caused by WNV, the antibody prevalence we detected suggests that wild ducks may be less-frequently exposed to WNV than expected for birds inhabiting wetlands where they may acquire infection from mosquitoes.

North Dakota, South Carolina, Tennessee↗
USGS2006

Home range characteristics of great gray owls in Yosemite National Park, California

We studied home range and habitat use of radio-tagged Great Gray Owls ( Strix nebulosa ) in Yosemite, California. From 1986–90 we made 5338 relocations on nine adult and three juvenile owls. Home-range size was not correlated with number of locations and was significantly different between breeding and nonbreeding periods. Breeding female summer home range averaged 61.47 ha and during the winter 2457.27 ha, while males average 19.89 and 2112.87 ha, respectively. Juveniles and nonbreeding birds had home-range sizes intermediate between seasonal values of breeding owls. Home ranges for California Great Gray Owls were larger than has been recorded for all studies in North America, but smaller than in Europe. All owls were found to have intensive high-use activity centers ( x − = 17.56 ha) in summer, with use patterns influenced primarily by meadows. Over 60% of all relocations occurred within 100 m of a meadow. Great Gray Owls habitat usage during summer was concentrated in fir ( Abies spp.) and lodgepole ( Pinus contorta ) habitat types, while during the winter, birds moved to lower elevations into Sierra mixed conifer habitats. This post-breeding movement was the cause of the large nonbreeding home ranges. During winter, paired birds did not remain together, even though all birds moved to lower elevation habitats below deep snow-pack levels. We suggest that Great Gray Owls in California have responded to the relatively hot and southern habitat with unique adaptations that have allowed several local populations to persist within the upper montane Sierra Nevada forest zone. The protection of meadow foraging habitat, as well as nesting locations, will be important for the continued preservation of this southernmost North American population of Great Gray Owls in Yosemite National Park.

California↗
USGS2018

A full annual-cycle conservation strategy for Sprague’s Pipit, Chestnut-collared and McCown’s Longspurs, and Baird’s Sparrow

Sprague’s Pipit ( Anthus spragueii ), Chestnut-collared Longspur ( Calcarius ornatus ), McCown’s Longspur ( Rhynchophanes mccownii ), and Baird’s Sparrow ( Centronyx bairdii ) [hereafter, “the Species”] are North American grassland-obligate songbirds whose populations have experienced significant annual population declines and are the focus of increasing conservation concern. The purpose of this strategy is to summarize current knowledge of the Species and identify priority research, monitoring and conservation actions required to improve their population status. Grasslands are among the most threatened ecosystems in the world with historic losses of 61-70% converted to other land uses, primarily cropland agriculture. Losses continue, with current conversion in the northern Great Plains occurring several times faster than grasslands can be protected. The Partners in Flight North American Landbird Conservation Plan (PIF NALCP) estimates current global populations of 900,000, 3,000,000, 600,000, and 2,000,000 for Sprague’s Pipit, Chestnut-collared Longspur, McCown’s Longspur, and Baird’s Sparrow, respectively. Over the period of 1967-2015, these populations have declined at -3.1, -4.2, -5.9 and -2.2% annually for estimated total losses of 78, 87, 94 and 65%, respectively. Habitat associations of breeding birds, especially at the local scale, represent the majority of the existing scientific literature on the Species’ biology. Landscape-scale associations are more poorly understood, and few studies have linked habitat, at any scale, to population vital rates. Increasing effort is focused on nonbreeding season and very little is known about migration. Current knowledge identifies three primary threats: 1) loss of native grasslands, 2) degradation and fragmentation of remaining native grasslands, and 3) disturbance inconsistent with needs of the Species. Top priorities for future research include: identification of population limiting factors, links between breeding habitat and demographics, identification of migratory habitat requirements, and identification of conditions promoting winter survival. Implementation strategies must focus on the protection, restoration, and enhancement (i.e., management) of grassland communities. Most imperative is the protection of remaining native grasslands from conversion to other uses. Actions supporting grass-based agriculture on privately-owned, native grasslands are paramount. These include incentive-based tools to support livestock grazing that benefits both priority birds and healthy ranching communities, which in turn prevent the conversion of native grasslands to cropland. Where cropland conversion has already taken place, conservation partners should work to continue and improve programs such as the Conservation Reserve Program (CRP) to restore and maintain permanent native cover. This strategy adopts the PIF NALCP objective, which is to reduce the rate of the Species’ decline in the first 10 years, then stabilize and ultimately increase the 2016 population by 5-15% over the subsequent 20 years. Ongoing monitoring programs such as the Breeding Bird Survey, Integrated Monitoring of Bird Conservation Regions, and eBird are critical for informing broadscale demographic and geographic trends for the Species. However, to achieve PIF NALCP goals, there is additional need for monitoring that links habitat conservation accomplishments to population performance within a strategic habitat conservation framework.

Report↗
USGS2013

Assessing movement and sources of mortality of juvenile catostomids using passive integrated transponder tags, Upper Klamath Lake, Oregon - Summary of 2012 effort

Executive Summary Survival of juvenile endangered Lost River and shortnose suckers is thought to limit recruitment into the adult populations and ultimately limit the recovery of these species in Upper Klamath Lake, Oregon. Although many hypotheses exist about the sources of mortality, the contribution of each speculated source of mortality has not been examined. To examine causes of mortality, validate estimated age to maturity, and examine movement patterns for juvenile suckers in Upper Klamath Lake, passive integrated transponder (PIT) tags and remote tag detection systems were used. Age-1 suckers were opportunistically tagged in 2009 and 2010 during another study on juvenile sucker distribution. After the distribution study concluded in 2010, USGS redirected sampling efforts to target age-1 suckers for tagging. Tags were redetected using an existing infrastructure of remote PIT tag readers and tag scanning surveys at American white pelican ( Pelecanus erythrorhynchos ), double-crested cormorant ( Phalacrocorax auritus ), and Forster’s tern ( Sterna forsteri ) breeding and loafing areas. Individual fish histories are used to describe the distance, direction, and timing of juvenile sucker movement. Sucker PIT tag detections in the Sprague and Williamson Rivers in mid-summer and in autumn indicate tagged juvenile suckers use these tributaries outside of the known spring spawning season. PIT tags detected in bird habitats indicate predation by birds was a cause of mortality.

Oregon↗
USGS1984

Disseminated visceral coccidiosis in sandhill cranes

Disseminated visceral coccidiosis (DVC) caused by Eimeria spp was first recognized as a disease entity in captive sandhill cranes (Grus canadensis) and whooping cranes (G americana) at the Patuxent Wildlife Research Center. Because cranes produced at the Center are reintroduced to the wild to augment wild populations, studies involving both experimentally induced and natural infections were initiated to determine the potential or actual occurrence of DVC in wild Gruidae. Nine sandhill cranes dosed orally with eimerian oocysts of wild origin developed lesions characteristic of DVC. Extraintestinal granulomas associated with developing schizonts were found in 6 birds. Similar lesions were observed in wild sandhill cranes throughout parts of midwestern United States, Alaska, and Saskatchewan. These studies revealed the wide geographic distribution and the high frequency of occurrence of DVC in wild cranes.

Journal of the American Veterinary Medical Associa↗
USGS2024

Nerodia clarkii (Saltmarsh Watersnake). Predation

Predators of Nerodia clarkii are suspected to include larger species of crabs, fish, wading birds, snakes, alligators, and crocodiles. To our knowledge, there have only been two published observations of predation on N. clarkii, including a predation attempt from a Callinectes sapidus (Blue Crab) in Mississippi, USA and a successful predation by a Grus americana (Whooping Crane) in Texas, USA. Herein we report on predation of N. clarkii and a suspected Nerodia clarkii x fasciata pictiventris (Saltmarsh Watersnake and Florida Banded Watersnake) hybrid by Crocodylus acutus (American Crocodile) in South Florida, USA.

Herpetological Review↗
USGS2023

Assessing contaminants of emerging concern in the Great Lakes Ecosystem: A decade of method development and practical application

Assessing the ecological risk of contaminants in the field typically involves consideration of a complex mixture of compounds which may or may not be detected via instrumental analyses. Further, there are insufficient data to predict the potential biological effects of many detected compounds, leading to their being characterized as contaminants of emerging concern (CECs). Over the past several years, advances in chemistry, toxicology, and bioinformatics have resulted in a variety of concepts and tools that can enhance the pragmatic assessment of the ecological risk of CECs. The present Focus article describes a 10+- year multiagency effort supported through the U.S. Great Lakes Restoration Initiative to assess the occurrence and implications of CECs in the North American Great Lakes. State-of-the-science methods and models were used to evaluate more than 700 sites in about approximately 200 tributaries across lakes Ontario, Erie, Huron, Michigan, and Superior, sometimes on multiple occasions. Studies featured measurement of up to 500 different target analytes in different environmental matrices, coupled with evaluation of biological effects in resident species, animals from in situ and laboratory exposures, and in vitro systems. Experimental taxa included birds, fish, and a variety of invertebrates, and measured endpoints ranged from molecular to apical responses. Data were integrated and evaluated using a diversity of curated knowledgebases and models with the goal of producing actionable insights for risk assessors and managers charged with evaluating and mitigating the effects of CECs in the Great Lakes. This overview is based on research and data captured in approximately about 90 peer-reviewed journal articles and reports, including approximately about 30 appearing in a virtual issue comprised of highlighted papers published in Environmental Toxicology and Chemistry or Integrated Environmental Assessment and Management . Environ Toxicol Chem 2023;42:2506–2518. © 2023 SETAC. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.

Environmental Toxicology and Chemistry↗
USGS1977

The status and distribution of woodcock in Oklahoma

The seasonal and spatial distributions of the American woodcock (Philohela minor) in Oklahoma were determined through field surveys and the collection of all known reports of woodcock sightings. Woodcock were reported in Oklahoma in all seasons and were most Jrequently sighted from 11 October to 10 January. The peak in fall migration occurred between 11 November and 10 December. Woodcock were found in 5 major areas across the eastern two-thirds of the state but 57 percent of the birds reported during the study were in the eastern one-third. A total of 148 displaying males were encountered on 25 sites in 15 of 29 counties included roadside singing ground surveys in 1975 and 1976. The peak number of displaying birds (58) was observed during the second IO-day period in February; displays occurred from January through late March. Personal observations plus data reported via volunteer survey cards, indicated that the typical site used for diurnal cover by woodcock in Oklahoma is a brushy bottomland with moist loamy soils, vegetated by oaks (Quercus spp.), elms (Ulmus spp,), bluestem grasses (Andropogon spp.), dogwoods (Cornus spp.) and green briars (Smilax spp.).

Conference Paper↗
USGS1988

Guild structure of a riparian avifauna relative to seasonal cattle grazing

The avifauna within the willow ( Salix spp.) community on the Arapaho National Wildlife Refuge (NWR) was dominated (96% of all observations each year) by 11 species of passerine birds during the summers of 1980-81. Using 28 vegetation variables measured or calculated for randomly selected points and points where birds were sighted, we assigned the species to 3 distinct response guilds relative to historical patterns of seasonal grazing. A eurytopic response guild (habitat generalists) included yellow warblers ( Dendroica petechia ) (YEWA), savannah sparrows ( Passerculus sandwichensis ) (SASP), and song sparrows ( Melospiza melodia ) (SOSP). A stenotopic response guild (habitat specialists) included willow flycatchers ( Empidonax traillii ) (WIFL). Lincoln's sparrows ( Melospiza lincolnii ) (LISP), and white-crowned sparrows ( Zonotrichia leucophrys ) (WCSP). The intermediate, mesotopic response guild included American robins ( Turdus migratorius ) (AMRO), red-winged blackbirds ( Agelaius phoeniceus ) (RWBL), and brown-headed cowbirds ( Molothrus ater ) (BHCO). Population densities of the eurytopic response guild differed little between healthy (historically winter-grazed) and decadent (historically summer-grazed) willow communities within a year. Densities of species in the mesotopic response guild differed more dramatically, and stenotopic response-guild species were absent or accidental in decadent willows. Information on habitat use patterns of the individual species between years supported the definition of response guilds; vegetation structure was most variable in habitats of eurytopic species and least variable in habitats of stenotopic species. Comparisons between used and available vegetation features indicated that species in the stenotopic response guild used locations that differed from random on the basis of bush spacing. We hypothesize that the response-guild structure primarily reflects the impact of cattle upon the horizontal patterning of the vegetative community.

Colorado↗
USGS1993

Distribution and abundance of predators that affect duck production--prairie pothole region

During 1983-88, the relative abundance of 18 species and species-groups of mammalian and avian predators affecting duck production in the prairie pothole region was determined in 33 widely scattered study areas ranging in size from 23-26 km2. Accounts of each studied species and species-group include habitat and history, population structure and reported densities, and information on distribution and abundance from the present study. Index values of undetected, scarce, uncommon, common, or numerous were used to rate abundance of nearly all species in each study area. Principal survey methods were livetrapping of striped skunks (Mephitis mephitis) and Franklin's ground squirrels (Spermophilus franklinii), systematic searches for carnivore tracks in quarter sections (0.65 km2), daily records of sightings of individual predator species, and systematic searches for occupied nests of tree-nesting avian predators. Abundances of predators in individual areas were studied 1-3 years.The distribution and abundance of predator species throughout the prairie pothole region have undergone continual change since settlement of the region by Europeans in the late 1800's. Predator populations in areas we studied differed markedly from those of pristine times. The changes occurred from habitat alterations, human-inflicted mortality of predators, and interspecific relations among predator species. Indices from surveys of tracks revealed a decline in the abundance of red foxes (Vulpes vulpes) and an albeit less consistent decline in the abundance of raccoons (Procyon lotor) with an increase in the abundance of coyotes (Canis latrans). Records of locations of occupied nests revealed great horned owls (Bubo virginianus) and red-tailed hawks (Buteo jamaicensis) tended to nest 0.5 km apart, and American crows (Corvus brachyrhynchos) tended to avoid nesting 0.5 km of nests of red-tailed hawks. Excluding large gulls, for which no measurements of abundance were obtained, the number of predator species averaged 12.2 (SD = 1.60) per study area; common or numerous predator species averaged 6.0 (SD = 1.54) per study area (minimal because the abundance of weasels [Mustela erminea; M. frenata] in all areas and of minks [Mustela vison] and raptors in some areas was not rated). Major changes in relative abundance of individual predator species studied >1 year were few. Predator species most restricted to the aspen parkland were the Franklin's ground squirrel, black-billed magpie (Pica pica), American crow (Corvus brachyrlus), and red-tailed hawk; species most restricted to the prairie were the badger (Taxidea taxus), Swainson's hawk (Buteo swainsoni), and ferruginous hawk (B. regalis). The coyote, black-billed magpie, and American crow were most numerous in Canada, whereas the red fox, raccoon, mink, ferruginous hawk, and great horned owl were most numerous in the United States. The number of common or numerous egg-eating predator species (excludes large gulls and weasels, which were not rated) averaged 4.6 (SD = 0.90) per study area. The average numbers of common or numerous egg-eating species per study area did not differ among provinces and states, but birds gradually replaced mammals from southeast to northwest across the region. Investigators are urged to assess composition of predator populations and relative abundance of predator species for evaluations of waterfowl recruitment.

Resource Publication↗
USGS2025

Landscape changes and declines in Aquila chrysaetos (Golden Eagle) territory occupancy in southwestern Idaho

Rapid loss of native shrubs and expansion of invasive annual plants like cheatgrass ( Bromus tectorum ) have altered North American shrub-steppe systems across extensive areas. Predators, like Aquila chrysaetos (Golden Eagle) that forage on shrub-reliant prey, may abandon historically occupied territories or increase their territory size to cope with degraded habitat. We used a multiseason Bayesian occupancy model that accounted for imperfect detection to investigate the associations between landscape cover, fire history, conspecific neighbor density, and occupancy of 36 A. chrysaetos territories in southwestern Idaho and the Morley Nelson Snake River Birds of Prey National Conservation Area, USA from 1986 to 2022. The probability of A. chrysaetos occupancy at historically occupied territories decreased 25% from 1986 to 2022 (0.83–0.58). Once territories became vacant for 5 yr, they tended to remain vacant, suggesting that they were no longer suitable for eagles, or that no new eagles were recruiting into the population. Territory occupancy was positively associated with shrub cover ( β : 0.90, 95% CrI: 0.12 to 1.71) and negatively (albeit weakly) associated with annual herbaceous cover ( β : –0.63, 95% CrI: –1.32 to 0.05). Territories closer to other occupied territories had a lower probability of occupancy than territories with distant neighbors ( β : –3.89, 95% CrI: –4.61 to –3.14), likely because eagles compensated for degraded habitat by expanding their territories. Years since the territory last burned had a slightly positive effect on occupancy with high uncertainty and a credible interval that overlapped 0 ( β : 0.28, 95% CrI: –0.26 to 0.87). The probability of detecting eagles in an occupied territory was high (0.90) and improved in surveys conducted earlier in the day and later in the breeding season. Shrub conversion to invasive grasslands has negative bottom-up consequences on A. chrysaetos territory occupancy, which may decrease the local carrying capacity for eagles in this area.

Idaho↗
USGS2002

Supplemental planting of early successional tree species during bottomland hardwood afforestation

Reforestation of former bottom land hardwood forests that have been cleared for agriculture (i.e., afforestation) has historically emphasized planting heavy-seeded oaks (Quercus spp.) and pecans (Carya spp.). These species are slow to develop vertical forest structure. However, vertical forest structure is key to colonization of afforested sites by forest birds. Although early-successional tree species often enhance vertical structure, few of these species invade afforested sites that are distant from seed sources. Furthermore, many land mangers are reluctant to establish and maintain stands of fast-growing plantation trees. Therefore, on 40 afforested bottomland sites, we supplemented heavy-seeded seedlings with 8 patches of fast-growing trees: 4 patches of 12 eastern cottonwood (Populus deltoides) stem cuttings and 4 patches of 12 American sycamore (Platanus occidentalis) seedlings. To enhance survival and growth, tree patches were subjected to 4 weed control treatments: (1) physical weed barriers, (2) chemical herbicide, (3) both physical and chemical weed control, or (4) no weed control. Overall, first-year survival of cottonwood and sycamore was 25 percent and 47 percent, respectively. Second-year survival of extant trees was 52 percent for cottonwood and 77 percent for sycamore. Physical weed barriers increased survival of cottonwoods to 30 percent versus 18 percent survival with no weed control. Similarly, sycamore survival was increased from 49 percent without weed control to 64 percent with physical weed barriers. Chemical weed control adversely impacted sycamore and reduced survival to 35 percent. Tree heights did not differ between species or among weed control treatments. Girdling of trees by deer often destroyed saplings. Thus, little increase in vertical structure was detected between growing seasons. Application of fertilizer and protection via tree shelters did not improve survival or vertical development of sycamore or cottonwood.

Book chapter↗
USGS2026

American kestrel population trends and vital rates at the continental scale

The American kestrel ( Falco sparverius , hereafter referred to as kestrel) has declined across much of its North American range since at least the mid-1960s. Kestrel population dynamics have been explored through a multitude of local studies and two broad reviews of available data. Across large geographic extents, however, the demographic cause(s) of kestrel population declines remain(s) largely unknown. As part of a collaborative effort to elucidate the drivers of kestrel population declines, we developed a continental-scale integrated population model using band-recovery data, productivity data, and Breeding Bird Survey indices from 1986 to 2019 to estimate indices of annual population sizes, survival, and productivity rates across the continental United States. We detected a decline in population size of ~1%–2% per year. Overall estimates of population growth from 1986 to 2019 suggest a 29% decline in population size (95% CI = −34% to −23%). There was little evidence of a trend in brood size. However, survival of juvenile birds (mean = −0.015, SD = 0.008 and mean = −0.024, SD = 0.010 for females and males, respectively) and adult males (mean = −0.016, SD = 0.010) in the summer declined, suggesting that these vital rates could be contributing to declines in populations over time. Winter adult survival rates (mean = −0.004, SD = 0.009 and mean = −0.009, SD = 0.010 for females and males, respectively) also declined but to a lesser extent than summer survival. For juvenile birds, winter survival increased (mean = 0.006, SD = 0.008 and mean = 0.002, SD = 0.009 for females and males, respectively); however, this was not enough to offset declines in summer survival and annual survival rates declined over the time series. Annual adult survival was also low relative to previous research on kestrel survival rates. Given the importance of survival to population trends, our findings provide support for several previously proposed broad classes of factors potentially contributing to observed population declines: declines in arthropod prey, second-generation rodenticides, neonicotinoid insecticides, and predation.

Ecosphere↗
USGS2009

Stochastic variation in avian survival rates: Life-history predictions, population consequences, and the potential responses to human perturbations and climate change

Stochastic variation in survival rates is expected to decrease long-term population growth rates. This expectation influences both life-history theory and the conservation of species. From this expectation, Pfister ( 1998 ) developed the important life-history prediction that natural selection will have minimized variability in those elements of the annual life cycle (such as adult survival rate) with high sensitivity. This prediction has not been rigorously evaluated for bird populations, in part due to statistical difficulties related to variance estimation. I here overcome these difficulties, and in an analysis of 62 populations, I confirm her prediction by showing a negative relationship between the proportional sensitivity (elasticity) of adult survival and the proportional variance (CV) of adult survival. However, several species deviated significantly from this expectation, with more process variance in survival than predicted. For instance, projecting the magnitude of process variance in annual survival for American redstarts ( Setophaga ruticilla ) for 25 years resulted in a 44% decline in abundance without assuming any change in mean survival rate. For most of these species with high process variance, recent changes in harvest, habitats, or changes in climate patterns are the likely sources of environmental variability causing this variability in survival. Because of climate change, environmental variability is increasing on regional and global scales, which is expected to increase stochasticity in vital rates of species. Increased stochasticity in survival will depress population growth rates, and this result will magnify the conservation challenges we face.

Book chapter↗
USGS2015

Assessment and Mmanagement of North American horseshoe crab populations, with emphasis on a multispecies framework for Delaware Bay, U.S.A. populations: Chapter 24

The horseshoe crab fishery on the US Atlantic coast represents a compelling fishery management story for many reasons, including ecological complexity, health and human safety ramifications, and socio-economic conflicts. Knowledge of stock status and assessment and monitoring capabilities for the species have increased greatly in the last 15 years and permitted managers to make more informed harvest recommendations. Incorporating the bioenergetics needs of migratory shorebirds, which feed on horseshoe crab eggs, into the management framework for horseshoe crabs was identified as a goal, particularly in the Delaware Bay region where the birds and horseshoe crabs exhibit an important ecological interaction. In response, significant effort was invested in studying the population dynamics, migration ecology, and the ecologic relationship of a key migratory shorebird, the Red Knot, to horseshoe crabs. A suite of models was developed that linked Red Knot populations to horseshoe crab populations through a mass gain function where female spawning crab abundance determined what proportion of the migrating Red Knot population reached a critical body mass threshold. These models were incorporated in an adaptive management framework wherein optimal harvest decisions for horseshoe crab are recommended based on several resource-based and value-based variables and thresholds. The current adaptive framework represents a true multispecies management effort where additional data over time are employed to improve the predictive models and reduce parametric uncertainty. The possibility of increasing phenologic asynchrony between the two taxa in response to climate change presents a potential challenge to their ecologic interaction in Delaware Bay.

Book chapter↗
USGS2010

Using a distribution and conservation status weighted hotspot approach to identify areas in need of conservation action to benefit Idaho bird species

Identification of biodiversity hotspots (hereafter, hotspots) has become a common strategy to delineate important areas for wildlife conservation. However, the use of hotspots has not often incorporated important habitat types, ecosystem services, anthropogenic activity, or consistency in identifying important conservation areas. The purpose of this study was to identify hotspots to improve avian conservation efforts for Species of Greatest Conservation Need (SGCN) in the state of Idaho, United States. We evaluated multiple approaches to define hotspots and used a unique approach based on weighting species by their distribution size and conservation status to identify hotspot areas. All hotspot approaches identified bodies of water (Bear Lake, Grays Lake, and American Falls Reservoir) as important hotspots for Idaho avian SGCN, but we found that the weighted approach produced more congruent hotspot areas when compared to other hotspot approaches. To incorporate anthropogenic activity into hotspot analysis, we grouped species based on their sensitivity to specific human threats (i.e., urban development, agriculture, fire suppression, grazing, roads, and logging) and identified ecological sections within Idaho that may require specific conservation actions to address these human threats using the weighted approach. The Snake River Basalts and Overthrust Mountains ecological sections were important areas for potential implementation of conservation actions to conserve biodiversity. Our approach to identifying hotspots may be useful as part of a larger conservation strategy to aid land managers or local governments in applying conservation actions on the ground.

Idaho↗
USGS2016

Avian predation on juvenile Salmonids: Spatial and temporal analysis based on acoustic and passive integrated transponder tags

We evaluated the impact of predation on juvenile steelhead Oncorhynchus mykiss and yearling and subyearling Chinook Salmon O. tshawytscha by piscivorous waterbirds from 11 different breeding colonies in the Columbia River basin during 2012 and 2014. Fish were tagged with both acoustic tags and PIT tags and were tracked via a network of hydrophone arrays to estimate total smolt mortality (1 – survival) at various spatial and temporal scales during out‐migration. Recoveries of PIT tags on bird colonies, coupled with the last known detections of live fish passing hydrophone arrays, were used to estimate the impact of avian predation relative to total smolt mortality. Results indicated that avian predation was a substantial source of steelhead mortality, with predation probability (proportion of available fish consumed by birds) ranging from 0.06 to 0.28 for fish traveling through the lower Snake River and the lower and middle Columbia River. Predation probability estimates ranged from 0.03 to 0.09 for available tagged yearling Chinook Salmon and from 0.01 to 0.05 for subyearlings. Smolt predation by gulls Larus spp. was concentrated near hydroelectric dams, while predation by Caspian terns Hydroprogne caspia was concentrated within reservoirs. No concentrated areas of predation were identified for double‐crested cormorants Phalacrocorax auritus or American white pelicans Pelecanus erythrorhynchos . Comparisons of total smolt mortality relative to mortality from colonial waterbirds indicated that avian predation was one of the greatest sources of mortality for steelhead and yearling Chinook Salmon during out‐migration. In contrast, avian predation on subyearling Chinook Salmon was generally low and constituted a minor component of total mortality. Our results demonstrate that acoustic and PIT tag technologies can be combined to quantify where and when smolt mortality occurs and the fraction of mortality that is due to colonial waterbird predation relative to non‐avian mortality sources.

Transactions of the American Fisheries Society↗