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At least 325 records · Page 18Linked to original sources

USGS2025

Land cover, elevation, and precipitation predict distribution and hotspots of three bird species of concern in boreal Alaska

The boreal forest biome is an important breeding area for migratory birds and is undergoing rapid changes, including drying of wetlands, changes to vegetation composition, and human development. Many boreal bird populations are declining, but information is often lacking on how these species associate with habitat characteristics and thus how they may respond to changing conditions. We used a large point-count dataset to describe habitat associations and hotspots for three boreal species of concern in Alaska, USA: Tringa flavipes (Lesser Yellowlegs), Contopus cooperi (Olive-sided Flycatcher), and Euphagus carolinus (Rusty Blackbird). We used an N-mixture model to evaluate covariates of abundance and two components of detection (availability and perceptibility). We then used the estimated relationships with covariates to predict density of each species across the Northwestern Interior Forest (Bird Conservation Region 4) in Alaska, including identifying hotspots where density was predicted to be in the top 10% of all locations. T. flavipes and E. carolinus were associated with wetlands and mean values of June precipitation; T. flavipes were also associated with low elevation and recent fire; and C. cooperi was associated with needleleaf forest and moderate elevation. Hotspots for T. flavipes and E. carolinus usually overlapped, while hotspots for C. cooperi almost never overlapped with those of the other two species. Following ground-truthing, these predicted distributions could be used to indicate areas of high importance for species of conservation concern and thus inform management decisions and mitigation measures. Our results could also help identify areas that are likely to be important for these species in the future, given the rapid changes now occurring across the boreal biome in response to climate warming and drying.

Alaska↗

USGS2022

Detection of Splendidofilaria sp. (Onchocercidae:Splendidofilariinae) Microfilaria within Alaskan ground-dwelling birds in the grouse subfamily tetraoninae using taqman probe-based real-time PCR

Grouse and ptarmigan (Galliformes) harbor fairly diverse helminth faunas that can impact the host's health, including filarial nematodes in the genus Splendidofilaria . As host and parasite distributions are predicted to shift in response to recent climate change, novel parasites may be introduced into a region and impose additional stressors on bird populations. Limited information is available on the prevalence of filariasis in Alaska galliforms. To date, no molecular surveys have been completed. Past studies relied on examining blood smears or total body necropsies, which are time-consuming and may not detect filarial parasites with low prevalence in hosts. Therefore, we developed a TaqMan probe-based real-time PCR assay targeting the cytochrome c oxidase 1 gene ( COI ) of Splendidofilaria to decrease processing times and increase sensitivity as well as provide baseline data on the diversity of filariid infections in galliform species in Alaska. We screened a combined total of 708 galliform samples (678 unique individual birds) from different tissues (blood, muscle, and lung) for the presence of filarial DNA across the state of Alaska. Real-time PCR screening revealed an overall prevalence of filarial infection of 9.5% across species: Bonasa umbellus (0%, n = 23), Dendragapus fuliginosus (0%, n = 8), Falcipennis canadensis (26.8%, n = 198), Lagopus lagopus (2.6%, n = 274), Lagopus leucura (0%, n = 23), Lagopus muta (3%, n = 166), and Tympanuchus phasianellus (12.5%, n = 16). We observed microfilarial infections throughout most of Alaska except in Arctic regions and the Aleutian Islands where viable vectors may not be present.

Journal of Parasitology↗

USGS1985

Problems in estimating age-specific survival rates from recovery data of birds ringed as young

(1) The life table model is frequently employed in the analysis of ringer samples of young in bird populations. The basic model is biologically unrealistic and of little use in making inferences concerning age-specific survival probabilities. (2) This model rests on a number of restrictive assumptions, the failure of which causes serious biases. Several important assumptions are not met with real data and the estimators of age-specific survival are not robust enough to these failures. (3) Five major problems in the use of the life table method are reviewed. Examples are provided to illustrate several of the problems involved in using this method in making inferences about survival rates and its age-specific nature. (4) We conclude that this is an invalid procedure and it should not be used. Furthermore, ringing studies involving only young birds are pointless as regards survival estimation because no valid method exists for estimating age-specific or time-specific survival rates from such data. (5) In our view, inferences about age-specific survival rates are possible only if both young and adult (or young, subadult and adult) age classes are ringed each year for k years ( k ≥ 2).

Journal of Animal Ecology↗

USGS2012

Chesapeake Bay Watershed - Protecting the Chesapeake Bay and its rivers through science, restoration, and partnership

The Chesapeake Bay, the Nation's largest estuary, has been degraded due to the impact of human-population increase, which has doubled since 1950, resulting in degraded water quality, loss of habitat, and declines in populations of biological communities. Since the mid-1980s, the Chesapeake Bay Program (CBP), a multi-agency partnership which includes the Department of Interior (DOI), has worked to restore the Bay ecosystem. The U.S. Geological Survey (USGS) has the critical role of providing unbiased scientific information that is utilized to document and understand ecosystem change to help assess the effectiveness of restoration strategies in the Bay and its watershed. The USGS revised its Chesapeake Bay science plan for 2006-2011 to address the collective needs of the CBP, DOI, and USGS with a mission to provide integrated science for improved understanding and management of the Bay ecosystem. The USGS science themes for this mission are: Causes and consequences of land-use change; Impact of climate change and associated hazards; Factors affecting water quality and quantity; Ability of habitat to support fish and bird populations; and Synthesis and forecasting to improve ecosystem assessment, conservation, and restoration.

Delaware, Maryland, New York, Pennsylvania, Virgin↗

USGS2014

Land use and climate affect Black Tern, Northern Harrier, and Marsh Wren abundance in the Prairie Pothole Region of the United States

Bird populations are influenced by many environmental factors at both large and small scales. Our study evaluated the influences of regional climate and land-use variables on the Northern Harrier (Circus cyaneus), Black Tern (Childonias niger), and Marsh Wren (Cistothorus palustris) in the prairie potholes of the upper Midwest of the United States. These species were chosen because their diverse habitat preference represent the spectrum of habitat conditions present in the Prairie Potholes, ranging from open prairies to dense cattail marshes. We evaluated land-use covariates at three logarithmic spatial scales (1,000 ha, 10,000 ha, and 100,000 ha) and constructed models a priori using information from published habitat associations and climatic influences. The strongest influences on the abundance of each of the three species were the percentage of wetland area across all three spatial scales and precipitation in the year preceding that when bird surveys were conducted. Even among scales ranging over three orders of magnitude the influence of spatial scale was small, as models with the same variables expressed at different scales were often in the best model subset. Examination of the effects of large-scale environmental variables on wetland birds elucidated relationships overlooked in many smaller-scale studies, such as the influences of climate and habitat variables at landscape scales. Given the spatial variation in the abundance of our focal species within the prairie potholes, our model predictions are especially useful for targeting locations, such as northeastern South Dakota and central North Dakota, where management and conservation efforts would be optimally beneficial. This modeling approach can also be applied to other species and geographic areas to focus landscape conservation efforts and subsequent small-scale studies, especially in constrained economic climates.

Iowa;Minnesota;Montana;Nebraska;North Dakota;South↗

USGS2026

Improved estimates of relative occurrence and abundance using opportunistic surveys and presence-only observations: A zero-inflated integrated species distribution model

Modeling tools for estimating and forecasting shifts in species distributions are becoming increasingly valuable for conservation planning and response. This is especially true for wild bird populations, which have been declining across habitats and regions. Species distribution models (SDM) represent a diverse set of tools with options for addressing various sources of bias. Complex spatial processes associated with rare or clustered species can be accounted for using zero-inflated SDMs, whereas biased survey data can be integrated with additional data sources to improve estimates. Each option addresses an important and common source of bias, but the two SDM frameworks have not been implemented together previously. We present a novel zero-inflated extension of an integrated SDM framework for a Poisson regression (ZI-iSDM), allowing for the estimation of independent occurrence and abundance processes by integrating opportunistic survey and presence-only data. We validated performance of this ZI-iSDM using simulated datasets under different degrees of species rarity and density on the landscape as well as sampling bias in opportunistic datasets. We additionally applied this model to real survey data for multiple wild bird species using publicly available observation data combined with open-access environmental information to describe habitat associations. We found that integrating presence-only data, such as banding or harvest events, can compensate for potential deficiencies in opportunistic surveys by expanding sampling to be more representative of available and used habitat. Additionally, models that first differentiated occurrence and abundance using a ZI term were better suited for approximating distributions of spatially clustered species.

Ecological Modeling↗

USGS2019

Community-based conservation and recovery of native species on Monuriki Island, Fiji

The small uninhabited island of Monuriki (40.4 ha) in western Fiji is of national and international conservation concern for its several protected species. Exotic invasive species and a Category 5 cyclone have exacerbated conservation challenges. The cooperation of local, national, and international stakeholders continues to be crucial in restoration of the island’s native flora and fauna. This summary presents a timeline of restoration efforts and current status of the recovery programme for Monuriki. The critically endangered dry forest habitat of Fiji is only found in a few isolated patches on disparate islands. The Fijian crested iguana (Brachylophus cf. vitiensis) is a critically endangered species restricted to a few small islands in this dry forest zone of western Fiji. The population of crested iguanas on Monuriki Island is the third largest remaining population. Even before iguanas were first documented on the island in the early 1980s, individuals had been removed by local resorts for display purposes, a practice that was previously unregulated. In the late 1990s, the first efforts to conserve and restore Monuriki Island were discussed, but conservation initiatives were not implemented until the development of the Crested Iguana Recovery Plan in 2008. In 2011, domestic goats (Capra hircus) and non-native rats (Rattus exulans) were removed from the island, and 10 pairs of iguanas were brought into captive breeding facilities within Fiji. In 2015, the first 32 captive-bred crested iguanas were released back on Monuriki Island. More than half of these iguanas (N=26) were radio-tracked for 56 days post-release in order to assess survivorship and help provide insights into their short-term movement patterns. Of the 26 iguanas that were tracked, nearly 70% (N=18) were found after 56 days indicating excellent short-term survival. In February 2016, Tropical Cyclone Winston, a Category 5 storm passed through Fiji and devastated some of the tropical dry forest habitat on Monuriki. With sustained winds of up to 230 km/ hr nearly all of the canopy leaves from trees on Monuriki Island were removed and large amounts of debris covered the forest floor. Following the cyclone, a brief wildlife survey revealed Monuriki’s iguana and bird populations were still present. In 2017, the crested iguana captive breeding programme was brought to an end when 16 of the original 20 iguana founders, and an additional 32 captive bred off spring, were reintroduced onto Monuriki. This was accomplished, in part, due to successful breeding and reestablishment of the remaining wild iguanas on the island. Despite a major storm event, reestablishment likely resulted from reduced egg and hatchling predation by the rats, and excellent habitat recovery after goat removal. Overall these invasive species eradications have proven highly successful for the recovery of the iguanas, wedge-tailed shearwaters (Puffi nus pacifi cus), and several other non-target species including the banded rail (Gallirallus philippensis) and endangered Fijian peregrine falcon (Falco peregrinus). Furthermore, eradication of non-native species has also helped the recovery of the highly threatened tropical dry forest ecosystem in which these species exist.

Monuriki island↗

USGS2017

Population trends of birds wintering in the Central Valley of California

Since the 1970s, the Central Valley of California has seen a large investment in preservation and restoration of wetlands and riparian areas. At the same time, grasslands have been lost to vineyards, orchards, and residential development at an accelerating rate. We analyzed data from 17 Christmas Bird Count circles that were surveyed regularly between winter 1978–79 and winter 2013–14 to document population trends for birds wintering in this region. We selected 112 taxa (species or species groups) that were relatively abundant and widespread in the Central Valley during winter and used a hierarchical model to estimate annual rates of population change from the count data while accounting for varying survey effort. A much larger proportion of taxa showed positive (46%) than negative (18%) trends; about a third (36%) showed no detectable change. Central Valley habitats that showed the highest proportion of taxa with increasing vs. decreasing trends were riparian (59% vs. 9%; n = 32), wetlands (49% vs. 11%; n = 47), and open water (44% vs. 0%; n = 9), likely reflecting the conservation efforts in these habitats in recent decades. In contrast, a greater proportion of the taxa associated with grasslands and other open habitats (n = 25) showed decreases (48%) than increases (28%). As expected, species that adapt well to areas of human habitation showed stable or increasing trends. Examples of such species with strong positive trends include Anna's Hummingbird ( Calypte anna ), Black Phoebe ( Sayornis nigricans ) and recent Central Valley arrivals, Eurasian Collared-Dove ( Streptopelia decaocto ) and Great-tailed Grackle ( Quiscalus mexicanus ). Scavenging, opportunistic species such as Turkey Vulture ( Cathartes aura ) and Common Raven ( Corvus corax ) also showed strong positive trends. Trends in wintering populations were largely concordant with estimated trends available from breeding areas in California and western North America. Overall, these abundance data suggest that recent efforts to preserve and restore wetland and riparian habitats may be benefiting birds. However, a similar focus on conservation of the Central Valley's remaining grasslands may be needed to maintain populations of grassland-associated birds.

Book chapter↗

USGS2019

Increased nesting success of Hawaii Elepaio in response to the removal of invasive black rats

In Hawaii and other oceanic islands with few native land mammals, black rats (Rattus rattus) are among the most damaging invasive vertebrate species to native forest bird populations and habitats, due to their arboreal behavior and generalist foraging habits and habitat use. We evaluated the nesting response of Hawaii Elepaio (Chasiempis sandwichensis; Monarchidae), a generalist insectivore, to the removal of black rats using rodenticide in a before-after-control-impact study in high- and low-elevation mesic montane habitat recovering from long-term damage from introduced ungulates and weeds. We monitored nesting success and rat abundance during 2015–2016 before applying rodenticide bait in 2017 to remove rats from two 700 × 700 m treatment plots that were paired with 2 nontreatment plots of the same size. Rat abundance was reduced by 90% during treatment, with combined variables treatment and elevation best explaining the change using GLM methods and AIC model selection. The daily survival rate (DSR) of nests (n = 191) was greater on treated plots after rodenticide application (mean ± SE = 0.980 ± 0.004 treatment; 0.964 ± 0.004 nontreatment), modeled nest success increased from 29% to 50%, and apparent nest success (number of successful nests per total nests) increased from 37% to 52%. The most informative model for predicting DSR included the effect of treatment. Predation by rats was documented at 3 of 16 nests using video surveillance, and we observed additional evidence of rat predation during in-person nest monitoring. Rats targeted adults on the nest and sometimes removed intact eggs, leaving little trace of their activity. Our results demonstrate that reducing rat predation can immediately improve the nesting success of even a common bird species in habitat with a long history of forest restoration. Sustained predator control may be critical to accelerating the recovery of native forest bird communities.

Hawaii↗

USGS2011

Nest success of grassland sparrows on reclaimed surface mines

Grasslands resulting from surface mine reclamation support grassland songbird populations in several midwestern and eastern states in the United States, especially where reclaimed mines are large (>1,000ha). However, most reclaimed surface mines in Pennsylvania are small (<200ha), and nest success is unknown. We evaluated nest success of grasshopper (Ammodramus savannarum), Henslow's (A. henslowii), and Savannah sparrows (Passerculus sandwichensis) on 4 reclaimed surface mines (50-180ha) in western Pennsylvania, USA from 2006 to 2007. Overall nest success based on mean covariate values was 0.435 (95% CI = 0.376-0.504) for grasshopper sparrows, 0.396 (95% CI = 0.295-0.533) for Henslow's sparrows, and 0.158 (95% CI = 0.063-0.392) for Savannah sparrows. These estimates of nest success are comparable to those on larger reclaimed mines and other habitats. Grasshopper and Henslow's sparrow nests that were well concealed were less likely to fail than highly visible nests (??visible = -0.028, CI = -0.051 to -0.005 for grasshopper sparrows; ??visible = -0.063, CI = -0.112 to -0.014 for Henslow's sparrows), and nests in areas with surrounding deep litter were more likely to fail than nests in areas with shallow litter (??litterD = -0.145, CI = -0.335 to 0.045 for grasshopper sparrows; ??litterD = -0.676, CI = -1.187 to -0.116 for Henslow's sparrows). Savannah sparrow nests in areas with high visual obstruction by vegetation were less likely to fail than nests in areas with sparse and short vegetation (??VisOb = 0.048, CI = 0.006-0.091). Daily probability of survival for grasshopper sparrow nests was greatest early and late in the breeding season, and Savannah sparrow nest survival followed a decreasing linear trend. Nest survival of Henslow's sparrows was greater on warm days (??temp = 0.197, CI = 0.014-0.379), whereas for Savannah sparrows nest survival decreased on warm days and on days with rain, but for Savannah sparrows confidence intervals of weather effects included zero (??temp = -0.098, CI = -0.246 to 0.050; ??rain = 3.13, CI = -14.19 to 20.45). We suggest that small reclaimed surface mine grasslands can provide valuable nesting habitat and could be important to the conservation of grassland bird populations. Because nest success can increase in the latter part of the nesting season, agricultural disturbances or management activities in mid- to late summer could adversely affect reproductive success. ?? 2011 The Wildlife Society.

Journal of Wildlife Management↗

USGS1987

Latent population responses of summer birds to a catastrophic, climatological event

Catastrophic events can create ecological crunches for avian populations. Ornithologists generally assume that such events elicit immediate, dramatic declines in populations followed by rapid recolonization of a site with habitat recovery. Despite total inundation of habitats within the South Platte floodplain of eastern Colorado during the 1983 breeding season, populations of Brown Thrashers (Toxostoma rufum) and Rufoussided Towhees (Pipilo erythrophthalmus) did not decline significantly from 1982 densities. However, populations of both species declined significantly in 1984 and towhee populations remained low in 1985. These observations support speculations from recent studies of shrubsteppe bird populations that site tenacity may play a stronger role in determining annual densities of breeding birds than previously realized.

The Condor↗

USGS2023

Movement dynamics influence population monitoring and adaptive harvest management strategies in migratory birds

Informed population monitoring efforts are essential for sound management of harvested species, and adaptive strategies that provide detailed information to monitoring efforts often require data inputs from complimentary sources. Movement ecology information is seldom directly incorporated into population monitoring or adaptive harvest management strategies, yet can provide valuable information on species distributions, emigration and immigration rates, and aid in determining optimal population monitoring timing. The Rocky Mountain Population (RMP) of Sandhill Cranes is a harvested population subject to a stringent adaptive harvest management framework and an annual aerial survey to estimate population abundance, but movements of Sandhill Cranes during survey windows, and subsequent changes to harvest quotas based on their movement and distribution have not been investigated. We used seven years of GPS tracking data to estimate state-specific emigration and immigration rates, using a Bayesian multi-state capture-recapture model, among states within the RMP distribution to understand how seasonal crane movements may influence optimal aerial survey timing. We then leveraged these transition probabilities in conjunction with aerial survey count data to model how changes in aerial survey timing and movement-informed crane distribution would influence the current RMP Sandhill Crane adaptive harvest management model resulting in estimated changes to harvest allocation among states based on Sandhill Crane movement. We found that Sandhill Crane emigration from northern states began to increase the week of the aerial survey in late September, and continued to increase as autumn migration progressed into October. As expected, immigration to southern states began as emigration from northern states increased. Importantly, little movement among states occurred prior to the current aerial survey design timing. Overall, we found that current survey timing and shortly thereafter (∼1 week) did not greatly influence estimates of Sandhill Crane distribution, and did not greatly influence the harvest reallocation to each state until mid to late October (range of −42–+52 tag allocation change), much later than the current survey design would allow. Using GPS locations, we found that optimal population monitoring efforts could be improved to account for both detection and seasonal movements, while minimally influencing current adaptive harvest management strategies to stakeholders. Linking movement ecology with population monitoring efforts and subsequently adaptive harvest management strategies yields insightful information that can be beneficial for conservation planning, decision-making, and optimal species management of a migratory bird.

Colorado, Idaho, Montaha, Utah, Wyoming↗

USGS2020

A multispecies approach to manage effects of land cover and weather on upland game birds

Loss and degradation of grasslands in the Great Plains region have resulted in major declines in abundance of grassland bird species. To ensure future viability of grassland bird populations, it is crucial to evaluate specific effects of environmental factors among species to determine drivers of population decline and develop effective conservation strategies. We used threshold models to quantify the effects of land cover and weather changes in "lesser prairie-chicken" and "greater prairie-chicken" ( Tympanuchus pallidicinctus and T. cupido , respectively), northern bobwhites ( Colinus virginianus ), and ring-necked pheasants ( Phasianus colchicus ). We demonstrated a novel approach for estimating landscape conditions needed to optimize abundance across multiple species at a variety of spatial scales. Abundance of all four species was highest following wet summers and dry winters. Prairie chicken and ring-necked pheasant abundance was highest following cool winters, while northern bobwhite abundance was highest following warm winters. Greater prairie chicken and northern bobwhite abundance was also highest following cooler summers. Optimal abundance of each species occurred in landscapes that represented a grassland and cropland mosaic, though prairie chicken abundance was optimized in landscapes with more grassland and less edge habitat than northern bobwhites and ring-necked pheasants. Because these effects differed among species, managing for an optimal landscape for multiple species may not be the optimal scenario for any one species.

Kansas↗

USGS2015

An empirical evaluation of landscape energetic models: Mallard and American black duck space use during the non-breeding period

Bird conservation Joint Ventures are collaborative partnerships between public agencies and private organizations that facilitate habitat management to support waterfowl and other bird populations. A subset of Joint Ventures has developed energetic carrying capacity models (ECCs) to translate regional waterfowl population goals into habitat objectives during the non-breeding period. Energetic carrying capacity models consider food biomass, metabolism, and available habitat to estimate waterfowl carrying capacity within an area. To evaluate Joint Venture ECCs in the context of waterfowl space use, we monitored 33 female mallards ( Anas platyrhynchos ) and 55 female American black ducks ( A. rubripes ) using global positioning system satellite telemetry in the central and eastern United States. To quantify space use, we measured first-passage time (FPT: time required for an individual to transit across a circle of a given radius) at biologically relevant spatial scales for mallards (3.46 km) and American black ducks (2.30 km) during the non-breeding period, which included autumn migration, winter, and spring migration. We developed a series of models to predict FPT using Joint Venture ECCs and compared them to a biological null model that quantified habitat composition and a statistical null model, which included intercept and random terms. Energetic carrying capacity models predicted mallard space use more efficiently during autumn and spring migrations, but the statistical null was the top model for winter. For American black ducks, ECCs did not improve predictions of space use; the biological null was top ranked for winter and the statistical null was top ranked for spring migration. Thus, ECCs provided limited insight into predicting waterfowl space use during the non-breeding season. Refined estimates of spatial and temporal variation in food abundance, habitat conditions, and anthropogenic disturbance will likely improve ECCs and benefit conservation planners in linking non-breeding waterfowl habitat objectives with distribution and population parameters. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.

Arkansas, Delaware, Louisiana, Michigan, New Jerse↗

USGS2011

Ducks and passerines nesting in northern mixed-grass prairie treated with fire

Prescribed fire is an important, ecology-driven tool for restoration of grassland systems. However, prescribed fire remains controversial for some grassland managers because of reported reductions in bird use of recently burned grasslands. Few studies have evaluated effects of fire on grassland bird populations in the northern mixed-grass prairie region. Fewer studies yet have examined the influence of fire on nest density or survival. In our review, we found no studies that simultaneously examined effects of fire on duck and passerine nesting. During 1998—2003, we examined effects of prescribed fire on the density of upland-nesting ducks and passerines nesting in north-central North Dakota, USA. Apparent nest densities of gadwall ( Anas strepera ), mallard ( A. platyrhynchos ), and all duck species combined, were influenced by fire history of study units, although the degree of influence was not compelling. Fire history was not related to nest densities of blue-winged teal ( A. discors ), northern shoveler ( A. clypeata ), or northern pintail ( A. acuta ); however, apparent nest densities in relation to the number of postfire growing seasons exhibited a strikingly similar pattern among all duck species. When compared to ducks, fire history strongly influenced apparent nest densities of clay-colored sparrow ( Spizella pallida ), Savannah sparrow ( Passerculus sandwichensis ), and bobolink ( Dolichonyx oryzivorus ). For most species examined, apparent nest densities were lowest in recently burned units, increased during the second postfire growing season, and stabilized or, in some cases, decreased thereafter. Prescribed fire is critical for restoring the ecology of northern mixed-grass prairies and our findings indicate that reductions in nest densities are limited mostly to the first growing season after fire. Our results support the premise that upland-nesting ducks and several grassland passerine species are adapted to periodic fires occurring at a frequency similar to that of pre-Euro-American settlement of the region.

North Dakota↗

USGS2018

Evaluating autonomous acoustic surveying techniques for rails in tidal marshes

There is a growing interest toward the use of autonomous recording units (ARUs) for acoustic surveying of secretive marsh bird populations. However, there is little information on how ARUs compare to human surveyors or how best to use ARU data that can be collected continuously throughout the day. We used ARUs to conduct 2 acoustic surveys for king ( Rallus elegans ) and clapper rails ( R. crepitans ) within a tidal marsh complex along the Pamunkey River, Virginia, USA, during May–July 2015. To determine the effectiveness of an ARU in replacing human personnel, we compared results of callback point‐count surveys with concurrent acoustic recordings and calculated estimates of detection probability for both rail species combined. The success of ARUs at detecting rails that human observers recorded decreased with distance ( P ≤ 0.001), such that at <25 m, 90.3% of human‐recorded rails also were detected by the ARU, but at >75 m, only 34.0% of human‐detected rails were detected by the ARU. To determine a subsampling scheme for continuous ARU data that allows for effective surveying of presence and call rates of rails, we used ARUs to conduct 15 continuous 48‐hr passive surveys, generating 720 hr of recordings. We established 5 subsampling periods of 5, 10, 15, 30, and 45 min to evaluate ARU‐based presence and vocalization detections of rails compared with each of the full 60‐min sampling of ARU‐based detection of rails. All subsampling periods resulted in different ( P ≤ 0.001) detection rates and unstandardized vocalization rates compared with the hourly sampling period. However, standardized vocalization counts from the 30‐min subsampling period were not different from vocalization counts of the full hourly sampling period. When surveying rail species in estuarine environments, species‐, habitat‐, and ARU‐specific limitations to ARU sampling should be considered when making inferences about abundances and distributions from ARU data.

Wildlife Society Bulletin↗

USGS2011

Swallows as a sentinel species for contaminant exposure and effect studies

Tree swallows are an important model species to study the effects of contaminants in wild bird populations and have been used extensively in studies across North America. The advantages of swallows compared to other avian species are detailed. Three case histories are provided where swallows have been successfully used in Natural Resource Damage and Ecological Risk Assessments. The final two sections of this chapter are for individuals who want more in-depth information and include a summary of the chemical classes for which there are swallow data, including effect levels when known. Information provided in this section can be used to put exposure to most classes of contaminants into context with other sites across North America. Finally, commonly used endpoints, ranging from population-level down to cellular and genetic endpoints, are discussed including considerations and pitfalls, and when further work is needed to more fully understand the role of environmental and biological variation in interpreting these endpoints.

Book chapter↗

USGS2002

Paleoecological insights on fixed tree island development in the Florida Everglades: I. environmental controls

Palynological and geochemical analyses of sediment cores collected on two tree islands in the Florida Everglades indicate long-term hydrologic and chemical differences between tree islands and surrounding marshes and sloughs. Gumbo Limbo and Nuthouse tree islands are elongate, teardrop-shaped islands in Water Conservation Area 3B. Prior to tree island formation at both sites, pollen records indicate that sites on modern tree island heads were covered with sawgrass marshes with abundant weedy annuals. Such vegetation is characteristic of moderate water depths and hydroperiods with frequent droughts or disturbances. Contemporaneously deposited sediments on tree island tails indicate progressively deeper water conditions with increasing distance from the head; wetlands surrounding tree islands were covered by sloughs with deep water and long hydroperiods. Tree island formation occurred at about 1200 BC on Gumbo Limbo Island, with mature tree island vegetation established by about 800 AD. On Nuthouse Island, tree island formation occurred around 300 AD, shifting to mature tree island vegetation around 1400 AD. Thus, tree island formation began on these islands between 3.2 Ka and 1.7 Ka. Maturation of tree islands took between 1,000 and 2,000 years, and vegetation on these tree islands has been relatively stable for the last 600–1,200 years. Phosphorus levels on tree island heads have been extremely high (approximately six times greater than baseline levels in marshes) throughout the history of the sites, and phosphorus content in tree island tails began increasing when tree island formation occurred. Elevated phosphorus content may reflect the long-term presence of wading birds at these sites and provide a proxy for reconstructing the historic distribution of wading bird populations.

Florida↗