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At least 361 records · Page 20Linked to original sources
USGS2015

Species richness and distributions of boreal waterbirds in relation to nesting and brood-rearing habitats

Identification of ecological factors that drive animal distributions allows us to understand why distributions vary temporally and spatially, and to develop models to predict future changes to populations–vital tools for effective wildlife management and conservation. For waterbird broods in the boreal forest, distributions are likely driven by factors affecting quality of nesting and brood-rearing habitats, and the influence of these factors may extend beyond singles species, affecting the entire waterbird community. We used occupancy models to assess factors influencing species richness of waterbird broods on 72 boreal lakes, along with brood distributions of 3 species of conservation concern: lesser scaup ( Aythya affinis ), white-winged scoters ( Melanitta fusca ), and horned grebe ( Podiceps auritus ). Factors examined included abundance of invertebrate foods (Amphipoda, Diptera, Gastropoda, Hemiptera, Odonata), physical lake attributes (lake area, emergent vegetation), water chemistry (nitrogen, phosphorus, chlorophyll a concentrations), and nesting habitats (water edge, non-forest cover). Of the 5 invertebrates, only amphipod density was related to richness and occupancy, consistently having a large and positive relationship. Despite this importance to waterbirds, amphipods were the most patchily distributed invertebrate, with 17% of the study lakes containing 70% of collected amphipods. Lake area was the only other covariate that strongly and positively influenced species richness and occupancy of scaup, scoters, and grebes. All 3 water chemistry covariates, which provided alternative measures of lake productivity, were positively related to species richness but had little effect on scaup, scoter, and grebe occupancy. Conversely, emergent vegetation was negatively related to richness, reflecting avoidance of overgrown lakes by broods. Finally, nesting habitats had no influence on richness and occupancy, indicating that, at a broad spatial scale, brood distributions are largely driven by the presence of quality brood-rearing lakes, not nesting habitats. Our findings are relevant to generating conservation plans or management goals; specifically, boreal lakes with abundant amphipods and surface areas >25 ha are important habitat for waterbird broods and merit conservation, especially given the patchy distribution of amphipods. Moreover, these high quality brood-rearing lakes are much rarer, and thus more constraining, than are quality nesting habitats, which are likely abundant in the boreal.

Alaska↗
USGS2015

Spatially explicit modeling of blackbird abundance in the Prairie Pothole Region

Knowledge of factors influencing animal abundance is important to wildlife biologists developing management plans. This is especially true for economically important species such as blackbirds (Icteridae), which cause more than $100 million in crop damages annually in the United States. Using data from the North American Breeding Bird Survey, the National Land Cover Dataset, and the National Climatic Data Center, we modeled effects of regional environmental variables on relative abundance of 3 blackbird species (red-winged blackbird, Agelaius phoeniceus ; yellow-headed blackbird, Xanthocephalus xanthocephalus ; common grackle, Quiscalus quiscula ) in the Prairie Pothole Region of the central United States. We evaluated landscape covariates at 3 logarithmically related spatial scales (1,000 ha, 10,000 ha, and 100,000 ha) and modeled weather variables at the 100,000-ha scale. We constructed models a priori using information from published habitat associations. We fit models with WinBUGS using Markov chain Monte Carlo techniques. Both landscape and weather variables contributed strongly to predicting blackbird relative abundance (95% credibility interval did not overlap 0). Variables with the strongest associations with blackbird relative abundance were the percentage of wetland area and precipitation amount from the year before bird surveys were conducted. The influence of spatial scale appeared small—models with the same variables expressed at different scales were often in the best model subset. This large-scale study elucidated regional effects of weather and landscape variables, suggesting that management strategies aimed at reducing damages caused by these species should consider the broader landscape, including weather effects, because such factors may outweigh the influence of localized conditions or site-specific management actions. The regional species distributional models we developed for blackbirds provide a tool for understanding these broader landscape effects and guiding wildlife management practices to areas that are optimally beneficial. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.

Iowa, Minnesotta, Montana, Nebraska, North Dakota↗
USGS2011

Effects of flow dynamics on the aquatic-terrestrial transition zone (ATTZ) of lower Missouri river sandbars with implications for selected biota

Sandbars are an important aquatic terrestrial transition zone (ATTZ) in the active channel of rivers that provide a variety of habitat conditions for riverine biota. Channelization and flow regulation in many large rivers have diminished sandbar habitats and their rehabilitation is a priority. We developed sandbar-specific models of discharge-area relationships to determine how changes in flow regime affect the area of different habitat types within the submerged sandbar ATTZ (depth) and exposed sandbar ATTZ (elevation) for a representative sample of Lower Missouri River sandbars. We defined six different structural habitat types within the sandbar ATTZ based on depth or exposed elevation ranges that are important to different biota during at least part of their annual cycle for either survival or reproduction. Scenarios included the modelled natural flow regime, current managed flow regime and two environmental flow options, all modelled within the contemporary river active channel. Thirteen point and wing-dike sandbars were evaluated under four different flow scenarios to explore the effects of flow regime on seasonal habitat availability for foraging of migratory shorebirds and wading birds, nesting of softshell turtles and nursery of riverine fishes. Managed flows provided more foraging habitat for shorebirds and wading birds and more nursery habitat for riverine fishes within the channelized reach sandbar ATTZ than the natural flow regime or modelled environmental flows. Reduced summer flows occurring under natural and environmental flow alternatives increased exposed sandbar nesting habitat for softshell turtle hatchling emergence. Results reveal how management of channelized and flow regulated large rivers could benefit from a modelling framework that couples hydrologic and geomorphic characteristics to predict habitat conditions for a variety of biota.

River Research and Applications↗
USGS2022

Population connectivity of aquatic insects in a dam-regulated, desert river

Humans have exaggerated natural habitat fragmentation, negatively impacting species dispersal and reducing population connectivity. Habitat fragmentation can be especially detrimental in freshwater populations, whose dispersal is already constrained by the river network structure. Aquatic insects, for instance, are generally limited to two primary modes of dispersal: downstream drift in the aquatic juvenile life stages and flight during the terrestrial winged adult stage. Yet the impacts of large hydropower dams can make rivers uninhabitable for incoming (drifting) juvenile insects, with remaining refugia found only in tributaries. The ability of adult aquatic insects to traverse such river stretches in search of suitable tributary habitat likely depends on factors such as species-specific dispersal ability and distance between tributaries. To explore the intersection of natural and human-induced habitat fragmentation on aquatic insect dispersal ability, we quantified population genetics of three taxa with varying dispersal abilities, a caddisfly (Hydropsychidae, Hydropsyche oslari ), a mayfly (Baetidae: Fallceon quilleri ), and a water strider (Veliidae: Rhagovelia distincta ), throughout tributaries of the Colorado River in the Grand Canyon, Arizona, USA. Using 2bRAD reduced genome sequencing and landscape genetics analyses, we revealed a strong pattern of isolation by distance among mayfly populations. This contrasts with caddisfly and water strider populations, which were largely panmictic. Analysis of thousands of informative single nucleotide polymorphisms showed that realized dispersal ability may not be accurately predicted by species traits for these widespread species. Principal components analysis revealed a strong division between caddisfly populations upstream and downstream of Havasu Creek (279 km through the 390 km study reach), suggesting that the geography of the Grand Canyon imposes a dispersal barrier for this species. Our use of genetic tools in the Grand Canyon to understand population structure has enabled us to elucidate dispersal barriers for aquatic insects. Ultimately, these data may be useful in informing effective conservation management plans for understudied organisms of conservation interest.

River Research and Applications↗
USGS2026

Population trends of dabbling ducks wintering in the alluvial valleys of Arkansas and Mississippi

Population abundances, distributions, and compositions across a diversity of taxa are changing, partly as a consequence of human-induced global modifications. Although linking population fluctuations to anthropogenic-induced alterations can be challenging, it is increasingly clear that long-term monitoring is critical to understanding changing populations. For waterfowl, concerns over recent declines in breeding populations or possible redistribution from using traditional wintering grounds for some species support continued monitoring of regional populations. To further understand population trends on traditional wintering grounds, we examined abundance trends over time within the Mississippi and Arkansas portions of the Mississippi Alluvial Valley, using two sources of data: systematic aerial surveys and citizen science data. We found great annual variability in rates of population change ( r ranging from −1.04 to 0.71) in five species of dabbling ducks. Despite this annual variation, green-winged teal Anas carolinensis , mallards Anas platyrhynchos , northern pintail Anas acuta , and northern shoveler Spatula clypeata showed no significant trends in population size over approximately 15 years in Mississippi and Arkansas, but gadwall Mareca strepera showed a 4% annual increase in the citizen science data for Mississippi. Despite substantial variation in annual abundance, the timing of peak abundance was remarkably consistent from year to year, with peaks typically occurring in January. Our results demonstrate that autumn–winter population numbers of dabbling ducks can be quite variable interannually, but they lack a consistent trend in the Mississippi Alluvial Valley during the past two decades. Going forward, investigation into how citizen science data could be leveraged to increase the precision of trends within this landscape might be of benefit, and sampling efforts could perhaps be added towards the latter portion of the wintering period. As populations continue to adjust in a changing world, maintaining monitoring surveys in regions important to waterfowl is an effective and important means of evaluating trends.

Arkansas, Illinois, Kentucky, Louisiana, Mississip↗
USGS2019

Using morphological measurements to predict subspecies of Midcontinent sandhill cranes

The Midcontinent population of sandhill cranes ( Antigone canadensis ) has historically been classified into 3 putative subspecies, but genetic analyses have identified only 2 genetically distinct subspecies. Previous studies have successfully used morphometrics in combination with an individual's sex to differentiate subspecies of sandhill cranes that had been inferred based on breeding area, but no study has used a sample of genetically determined subspecies to discriminate and develop predictive models. Using measurements from 843 adult sandhill cranes captured throughout their range and annual cycle (in 4 States and 1 Canadian province during 1998–2007), we used linear discriminant analysis to classify genetically identified A. c. canadensis (lesser) and A. c. tabida (greater) sandhill crane subspecies, and developed a field‐ready tool to predict subspecies using common morphometric measurements without determination of an individual's sex. Our top‐ranked model was 89.5% accurate overall, and used flattened wing chord, total culmen, and tarsometatarsus lengths to correctly identify 93.1% of A. c. canadensis and 82.8% of A. c. tabida subspecies. Additionally, we identified measurement thresholds based on posterior probabilities of correct classification to aid in subspecies determination when the linear discriminant procedure provided equivocal results. We also investigated whether sex determination could increase accuracy of our top‐ranked model, and found that accuracy increased <1% when including this information. We suggest collection of the morphometric measurements used in our top‐ranked model to determine subspecies of adult Midcontinent sandhill cranes. Our method does not require determining sex of the individual to correctly classify subspecies, allows for accurate and rapid subspecies determination, and can largely avoid additional costs and time associated with genetic analyses to determine subspecies. © 2019 The Wildlife Society.

Wildlife Society Bulletin↗
USGS2020

Reliability of external characteristics to age Barrow’s goldeneye

Accurate assignment of age class is critical for understanding most demographic processes. For waterfowl, most techniques for determining age class require birds in hand, reducing utility for quickly and efficiently sampling a large portion of the population. As an alternative, we sought to establish an observation‐based methodology, achievable in the field with standard optics, for determining age class of Barrow's goldeneyes ( Bucephala islandica ). We photographed heads, wings, and bellies of 232 Barrow's goldeneyes captured during late winter (February–April) of 2007–2015 along the north Pacific Coast. From these photographs, we focused on 5 external characteristics for both males and females, with binary states that putatively corresponded to 2 age classes—first‐year birds (<1 yr) and adults (>1 yr). For males, all 5 external traits (belly color, head color, eye color, facial crescent, median secondary coverts color) had binary states that were reliably distinguishable by observers. Moreover, all 5 external traits were highly predictive of age class (≥96% concordance between external vs. bursal‐derived ages), and novice observers, after receiving training, were able to accurately age 96% of first‐year and 99% of adult males. In contrast, patterns were weaker for females; putative external characteristics of female age class (belly color, bill radiance, bill blackness, eye color, median secondary coverts color) had 77–91% concordance with bursal‐derived age, compared with 96–100% for males, and observers misidentified age classes of 15% of females, compared with only 2% of males. Overall, age classes of male Barrow's goldeneyes were accurately and reliably distinguishable during winter based on several external characteristics, whereas those of females were not. Our technique may be used to estimate age composition of male Barrow's goldeneyes during winter, providing a useful metric for monitoring annual changes in adult‐to‐juvenile ratios and other important demographic parameters.

Alaska, British Columbia↗
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&mdash;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↗
USGS2017

Attaching transmitters to waterbirds using one versus two subcutaneous anchors: Retention and survival trade-offs

A major challenge of wildlife telemetry is choosing an attachment technique that maximizes transmitter retention while minimizing negative side effects. For waterbirds, attachment of transmitters with subcutaneous anchors has been an effective and well-established technique, having been used on >40 species. This method was recently modified to include a second subcutaneous anchor, presumably increasing transmitter retention beyond that of single-anchor attachments. This putative benefit may be offset, however, by increased health risks related to additional incisions and subcutaneous protrusions. To test this potential trade-off, we attached radiotransmitters to molting and wintering surf ( Melanitta perspicillata ) and white-winged scoters ( M. fusca ) during 2008 and 2009 in Washington State and southeast Alaska, USA, using single- (121 scoters) and double-anchor (128 scoters) attachment techniques. We estimated daily probabilities of survival and radio retention for each group, this being apparent retention for wintering scoters because we could not differentiate shed transmitters from flighted emigration. For scoters during the flightless remigial molt, we found that addition of a second anchor increased cumulative retention probability (±SE) over a 49-day period from 0.69 ± 0.11 for single-anchor to 0.88 ± 0.07 for double-anchor attachments, while having no effect on survival. However, during winter, scoters with double-anchor attachments experienced no improvement in apparent retention, while having significantly lower survival during their first 14 days following transmitter attachment; of 15 mortalities during this period, 11 had 2 subcutaneous anchors. From day 15 onward, winter survival rates were nearly identical for single- versus double-anchor attachments, indicating that adverse effects of subcutaneous anchors were mainly limited to the 14-day postattachment period. Overall, given that the survival cost of adding a second subcutaneous anchor was substantial for wintering scoters—decreasing 14-day survival by 12% for adults and 23% for juveniles—we recommend that researchers opt for single-anchor attachments under most circumstances, especially during winter when birds may be energetically challenged.

Wildlife Society Bulletin↗
USGS2018

An historical overview and update of wolf-moose interactions in northeastern Minnesota

Wolf (Canis lupus) and moose (Alces americanus) populations in northeastern Minnesota, USA, have fluctuated for decades and, based on helicopter counts, moose numbers declined to a new low from 2006 to about 2012. Other steep declines were found in 1991 and 1998 during periods when moose counts were done with ®xed-wing aircraft; these declines also appeared to be real. Winter wolf numbers, monitored in part of the moose range, had been increasing since about 2002 to the highest population in decades in 2009. However, from 2009 to 2016, wolves decreased precipitously, and the moose-population decline leveled off from 2012 to 2017. Calf:population ratios from 1985 to 1997 and from 2005 to 2016 were inversely related to wolf numbers in the wolf-study area the previous winter both as wolves increased and decreased in abundance. Similarly, log annual growth rates of moose numbers were negatively correlated with counts of wolves in the prior year. Other factors such as nutrition and parasites, and possibly climate change, likely have been involved in the recent moose decline. However, wolves, as in other areas, appear to have contributed to the decline in the northeastern Minnesota moose population at least in part through predation on calves, supporting earlier reports. Published 2018. This article is a U.S. Government work and is in the public domain in the USA.

Minnesota↗
USGS2013

Photography applications

Photographic imaging is the oldest form of remote sensing used in coral reef studies. This chapter briefly explores the history of photography from the 1850s to the present, and delves into its application for coral reef research. The investigation focuses on both photographs collected from low-altitude fixed-wing and rotary aircraft, and those collected from space by astronauts. Different types of classification and analysis techniques are discussed, and several case studies are presented as examples of the broad use of photographs as a tool in coral reef research.

Book chapter↗
USGS1988

Radarclinometry: Bootstrapping the radar reflectance function from the image pixel-signal frequency distribution and an altimetry profile

A method is derived for determining the dependence of radar backscatter on incidence angle that is applicable to the region corresponding to a particular radar image. The method is based on enforcing mathematical consistency between the frequency distribution of the image's pixel signals (histogram of DN values with suitable normalizations) and a one-dimensional frequency distribution of slope component, as might be obtained from a radar or laser altimetry profile in or near the area imaged. In order to achieve a unique solution, the auxiliary assumption is made that the two-dimensional frequency distribution of slope is isotropic. The backscatter is not derived in absolute units. The method is developed in such a way as to separate the reflectance function from the pixel-signal transfer characteristic. However, these two sources of variation are distinguishable only on the basis of a weak dependence on the azimuthal component of slope; therefore such an approach can be expected to be ill-conditioned unless the revision of the transfer characteristic is limited to the determination of an additive instrumental background level. The altimetry profile does not have to be registered in the image, and the statistical nature of the approach minimizes pixel noise effects and the effects of a disparity between the resolutions of the image and the altimetry profile, except in the wings of the distribution where low-number statistics preclude accuracy anyway. The problem of dealing with unknown slope components perpendicular to the profiling traverse, which besets the one-to-one comparison between individual slope components and pixel-signal values, disappears in the present approach. In order to test the resulting algorithm, an artificial radar image was generated from the digitized topographic map of the Lake Champlain West quadrangle in the Adirondack Mountains, U.S.A., using an arbitrarily selected reflectance function. From the same map, a one-dimensional frequency distribution of slope component was extracted. The algorithm recaptured the original reflectance function to the degree that, for the central 90% of the data, the discrepancy translates to a RMS slope error of 0.1 ???. For the central 99% of the data, the maximum error translates to 1 ???; at the absolute extremes of the data the error grows to 6 ???. ?? 1988 Kluwer Academic Publishers.

Earth, Moon and Planets↗
USGS1996

Lipid and water depletion in migrating passerines following passage over the Gulf of Mexico

Lipid depletion is currently believed to be the primary factor limiting flight duration of migrating birds in North America, while the influence of water loss is thought to be small. Three migrating species of passerines, wood thrush ( Hylocichla mustelina ), Swainson's thrush ( Catharus ustulatus ), and summer tanager ( Piranga rubra ) were captured during the 1993 spring migration just after crossing the Gulf of Mexico and examined for lipid and water depletion. The redwinged blackbird ( Agelaius phoeniceus ), a winter resident, was examined for comparison. Although some migrants had low levels of fat, most were not seriously fat-depleted and had much higher lipid levels than red-winged blackbirds. Migrants appeared dehydrated, usually having less than 60% body water and significantly less water than the blackbirds. Recaptured wood thrushes had significantly higher mass than when initially captured. Many of these birds were replenishing significant amounts of water, while the acquisition of lipid mass was dependent on the amount of time the birds spent on the study site. Migrants were significantly fatter but had significantly less water mass when captured during unfavorable weather than under favorable conditions. It appears that both dehydration and lipid depletion are major physiological constraints on migrating passerines.

Louisiana↗
USGS1989

Monitoring contaminant exposure: Relative concentrations of organochlorines in three tissues of American black ducks

Comparison of organochlorine residues in wildlife must often be made to regulatory standards or to values of known biological significance; this is difficult when dissimilar tissues are analyzed and results are expressed on different bases. To relate levels in the different tissues used for regulatory and monitoring purposes and for biological assessments, we exposed American black ducks to mixtures of three organochlorines. Differences in residue burdens among tissues were not statistically significant when levels were expressed on a lipid weight basis. Levels of heptachlor and Aroclor 1254 in one tissue can be accurately predicted from those in another; such predictions for endrin are less reliable. Lipid weight based residue concentrations in wings may be used to predict whether levels in fat exceed residue standards set for human health or approach those associated with effects on populations of species sampled.

Environmental Monitoring and Assessment↗
USGS1990

Acid precipitation and food quality: Inhibition of growth and survival in black ducks and mallards by dietary aluminum, calcium and phosphorus

In areas impacted by acid precipitation, water chemistry of acidic ponds and streams often changes, resulting in increased mobilization of aluminum and decreased concentration of calcium carbonate. Aluminum binds with phosphorus and inhibits its uptake by organisms. Thus, invertebrate food organisms used by waterfowl may have inadequate Ca and P or elevated Al for normal growth and development. Acid rain and its effects may be one of the factors negatively impacting American black ducks ( Anas rubripes ) in eastern North America. One-day old mallards ( A. platyrhynchos ) and black ducks were placed on one of three Ca:P regimens: low:low (LL), normal:normal (NN), and low:high (LH) with each regimen divided further into three or four Al levels for 10 weeks. Forty-five % of the black ducks died on nine different diets whereas only 28% of the mallards died on three different diets. Mortality was significantly related to diet in both species. Growth rates for body weight, culmens, wings, and tarsi of both species on control diets exceeded those on many treatment diets but the differences were less apparent for mallards than for black ducks. Differences among treatments were due to both Ca:P and A1 levels.

Archives of Environmental Contamination and Toxico↗
USGS1988

Selenium teratogenesis in natural populations of aquatic birds in central California

The frequency and types of malformations are described that were encountered during the spring of 1983 in a natural population of aquatic birds exposed to agricultural drainwater ponds and food items containing high concentrations of selenium in central California. A total of 347 nests of aquatic birds containing 1,681 eggs was selected for study at Kesterson Reservoir located in the Kesterson National Wildlife Refuge (NWR), Merced County, California. Embryos collected during incubation or from eggs that failed to hatch were examined to determine the age at death and presence of malformations. Embryonic death was generally high; approximately 17–60% of the nests of different species contained at least one dead embryo. The incidence of malformed embryos was also high; approximately 22–65% of the nests where at least two embryos were examined contained abnormal embryos. American coots ( Fulica americana ) and black-necked stilts ( Himantopus mexicanus ) experienced the highest incidence of malformed embryos. For all species, the average percentage of eggs containing dead or live abnormal embryos was 16.1 whereas the average percentage containing live abnormal embryos was 10.7. Multiple gross malformations of the eyes, brain, and feet were often present. Brain defects included hydrocephaly and exencephaly. Eye defects included both unilateral and bilateral anophthalmia and microphthalmia. Eye and foot defects with ectrodactyly and swollen joints were the most common in coots. Beak defects also occurred frequently and most often included incomplete development of the lower beak of ducks ( Anas spp.) and stilts. Wing and leg defects were most prevalent in stilts and ducks, with ectromelia and amelia most prevalent in stilts. Other malformations occurring at lower frequencies included enlarged hearts with thin ventricular walls, liver hypopiasia, and gastroschisis. Based upon simultaneous examination of a control population of aquatic birds of the same species and published studies, the incidences of embryonic mortality and deformities were 9–30 times greater than expected. The role of the form of selenium responsible for teratogenesis in laboratory studies is discussed.

California↗
USGS1985

Metals in riparian wildlife of the lead mining district of southeastern Missouri

Five species of riparian vertebrates (425 individuals) primarily representing upper trophic levels were collected from the Big River and Black River drainages in two lead mining districts of southeastern Missouri, 1981–82. Big River is subject to metal pollution via erosion and seepage from large tailings piles from inactive lead mines. Black River drains part of a currently mined area. Bullfrogs ( Rana catesbeiana ), muskrats ( Ondatra zibethicus ), and green-backed herons ( Butorides striatus ) collected downstream from the source of metal contamination to Big River had significantly (ANOVA, P<0.05) higher lead and cadmium levels than specimens collected at either an uncontaminated upstream site or on Black River. Northern water snakes ( Nerodia sipedon ) had elevated lead levels below the tailings source, but did not seem to accumulate cadmium. Levels of lead, cadmium, or zinc in northern rough-winged swallows ( Stelgidopteryx serripennis ) were not related to collecting locality. Carcasses of ten bank swallows ( Riparia riparia ) collected from a colony nesting in a tailings pile along the Big River had lead concentrations of 2.0–39 ppm wet weight. Differences between zinc concentrations in vertebrates collected from contaminated and uncontaminated sites were less apparent than differences in lead and cadmium. There was little relationship between metal concentrations in the animals studied and their trophic levels. Bullfrogs are the most promising species examined for monitoring environmental levels of lead, cadmium, and zinc. Downstream from the source of tailings, bullfrogs had markedly higher levels of these metals in most of their tissues. The species is also widely distributed in North America, easily caught, and relatively sedentary.

Missouri↗
USGS1983

The acute oral toxicity, repellency, and hazard potential of 998 chemicals to one or more species of wild and domestic birds

The acute oral toxicity, repellency, and hazard potential of 998 chemicals to one or more of 68 species of wild and domestic birds was determined by standardized testing procedures. Red winged blackbirds were the most sensitive of the bird species tested on a large number of chemicals, and an index based on redwing toxicity and repellency may provide an appropriate indication of the probability of acute avian poisoning episodes. Avian repellency and toxicity were not positively correlated ( i.e. toxicity varied independently with repellency).

Archives of Environmental Contamination and Toxico↗