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USGS2025

Summary of selenium in the lower Gunnison River Basin, Colorado—Information and data gaps

The Cretaceous Mancos Shale is a geologic source of selenium in the lower Gunnison River Basin. Natural weathering processes and human activity mobilize selenium from the Mancos Shale and derived materials, and surface water, groundwater, and sediment all affect the transport of selenium from source areas to receiving streams and biota. Selenium accumulates through the aquatic food chain, and its toxic effects can result in invertebrate mortality and mortality, decreased reproduction, and deformities to fish and birds. The Bureau of Reclamation, in cooperation with the State of Colorado and Gunnison River Basin water users, is implementing a Selenium Management Program to reduce selenium concentrations in the lower Gunnison River Basin of Colorado. Goals of the Selenium Management Program are to (1) achieve compliance with the State of Colorado chronic aquatic-life standard for dissolved selenium (4.6 micrograms per liter) in the Gunnison River near Grand Junction, Colorado; (2) sufficiently improve water-quality conditions to assist in the recovery of endangered species in the Gunnison and Colorado Rivers by reducing selenium concentrations; and (3) support continued water uses in the basin. Many previous studies have contributed to the understanding of selenium in the environment; however, monitoring and research data gaps exist in the lower Gunnison River Basin. The purpose of this report is to summarize information regarding selenium in the lower Gunnison River Basin and describe strategies for scientific research and monitoring to potentially improve understanding of selenium sources; processes affecting the mobilization, transport, and fate of selenium; and the effects of selenium-mitigation projects in the lower Gunnison River Basin. Monitoring and research data gaps discussed in this report include geologic mapping and geochemical source characterization, long-term and ongoing monitoring of the surface-water and groundwater networks, developing and refining statistical models, characterizing selenium on suspended sediment, modeling selenium in the food web, evaluating best management practices, and more.

Colorado↗

USGS1986

Cholinesterase activity in black-crowned night-herons exposed to fenthion-treated water

Fenthion, ( 0,0 -Dimethyl 0 -[3-methyl-4-(methylthio)phenyl] phosphorothioate), a widely used mosquito control agent, has caused wildlife mortality. To simulate a shallow wetland environment, an exposure chamber was used containing water treated with fenthion at 1 and 10 times the field application rate of 112 g active ingredient (AI)/ ha. This system permitted an evaluation of exposure routes and the effects of fenthion in a representative species of wading bird, the black-crowned night-heron ( Nycticorax nycticorax ). The results suggested that herons received only a dermal exposure, and that their brain acetylcholinesterase activity was not significantly inhibited. In contrast, however, plasma butyrylcholinesterase activity was inhibited, suggesting the herons were exposed to the insecticide. The application rates and types of exposures were not life-threatening in this species.

Archives of Environmental Contamination and Toxico↗

USGS1999

Poisoning of raptors with organophosphorus and carbamate pesticides with emphasis on Canada, U.S. and U.K.

We reviewed cases of raptor mortality resulting from cholinesterase-inhibiting pesticides. We compiled records from the U.S., U.K. and Canada for the period 1985-95 (520 incidents) and surveyed the relevant literature to identify the main routes of exposure and those products that led to the greatest number of poisoning cases. A high proportion of cases in the U.K. resulted from abusive uses of pesticides (willful poisoning). The proportion was smaller in North America where problems with labeled uses of pesticides were as frequent as abuse cases. Poisoning resulting from labeled use was possible with a large number of granular pesticides and some seed treatments through secondary poisoning or through the ingestion of contaminated invertebrates, notably earthworms. With the more toxic products, residue levels in freshly-sprayed insects were high enough to cause mortality. The use of organophosphorus products as avicides and for the topical treatment of livestock appeared to be common routes of intoxication. The use of insecticides in dormant oils also gave rise to exposure that can be lethal or which can debilitate birds and increase their vulnerability. A few pesticides of high toxicity were responsible for the bulk of poisoning cases. Based on limited information, raptors appeared to be more sensitive than other bird species to organophosphorus and carbamate pesticides. Some of the more significant risk factors that resulted in raptor poisonings were: insectivory and vermivory; opportunistic taking of debilitated prey; scavenging, especially if the gastrointestinal tracts are consumed; presence in agricultural areas; perceived status as pest species; and flocking or other gregarious behavior at some part of their life cycle. Lethal or sublethal poisoning should always be considered in the diagnosis of dead or debilitated raptors even when another diagnosis (e.g., electrocution, car or building strike) is apparent. Many cases of poisoning are not currently diagnosed as such and, even when diagnosed, the information is often not made available to regulatory authorities. The importance of pesticide intoxications relative to other sources of mortality is highly variable in time and place; on a regional level, the increased mortality of raptors resulting from cholinesterase-inhibiting pesticides can be significant, especially in the case of rare species.

Journal of Raptor Research↗

USGS2016

First steps for mitigating bycatch of Pink-footed Shearwaters Ardenna creatopus: Identifying overlap of foraging areas and fisheries in Chile

The Pink-footed Shearwater, Ardenna creatopus, is listed as in danger of extinction by Chile and under Annex 1 of ACAP, with an estimated global population of approximately 56,000 individuals. Incidental bycatch of this species in fisheries is thought to be an important cause in population decline (i.e. annual estimated mortality of >1000 adults). This species is an endemic breeder in Chile, nesting only on the Juan Fernandez Archipelago (JFI; 30% of global population), and Isla Mocha (70% of global population). Using miniature GPS and satellite transmitters, we determined foraging areas of Pink-footed Shearwaters during the chick-rearing period in 2002 (JFI) and 2015-2016 (Isla Mocha). We overlaid shearwater tracking data with data from the Instituto de Fomento Pesquero (IFOP) on fishing effort in Chile (type of fishery, number sets per day, location of sets, and target species) to identify fisheries and fishing zones with the greatest potential for Pink-footed Shearwater bycatch. During the 2002-2006 (N = 28 birds total) and 2015 (N = 18 birds) breeding periods, foraging areas were associated with the continental shelf and shelf-break, generally less than 30 km offshore. All foraging trips occurred between 31.5 and 40.0 degrees south, and birds remained in Chile territorial waters 100% of the time. We identified two primary foraging hotspots, one offshore near Talcahuano, Chile (approximately 36-37.5° south), and one offshore north of Valdivia, Chile (approximately 39-39.5° south). Birds tracked from the Juan Fernández Archipelago foraged in the Talcahuano hotspot but did not visit the southerly hotspot near Valdivia. Birds tracked from Isla Mocha used both areas, with a greater proportion of birds using the Valdivia hotspot than the Talcahuano hotspot. Other major areas of use were around the respective breeding colonies from which the birds were tracked. Overlay of these data with fisheries data is currently in progress. Preliminary results indicate extensive overlap of Pink-footed Shearwater foraging grounds with industrial and artisanal purse-seine fisheries within Chile, representing a significant risk of bycatch. Further work could be initiated to track Pink-footed Shearwaters during other life-stages (i.e. pre-breeding and incubation), and would enhance collaborative efforts with fisheries managers and fishers concerned with mitigating bycatch.

Conference Paper↗

USGS2007

Coupling contaminants with demography: Effects of lead and selenium in Pacific common eiders

We coupled intensive population monitoring with collection of blood samples from 383 nesting Pacific common eiders ( Somateria mollisima v-nigrum ) at two locations in Alaska (USA) from 2002 to 2004. We investigated annual, geographic, and within-season variation in blood concentrations of lead and selenium; compared exposure patterns with sympatrically nesting spectacled eiders ( Somateria fischeri ); and examined relationships with clutch size, egg viability, probability of hatching, and apparent survival of adult females. Lead concentrations were elevated in 3.6% of females, and all individuals exhibited elevated selenium, most (81%) at concentrations associated with death in captive waterfowl. Blood lead and selenium concentrations varied both within and among site-years and were lower than those of spectacled eiders. During incubation, blood lead concentrations in females increased significantly (possibly via re-release of stored lead from bone), whereas selenium concentrations decreased (likely because of natural excretion). Probability of a nest containing at least one nonviable egg was positively related to blood selenium in hens, but adverse effects in other life-history variables were not supported. Although reproduction appeared to be sensitive to selenium toxicity, our data suggest that high rates of nonviability are unlikely in this population and that selenium-related reductions to clutch size would be inconsequential at the scale of overall population dynamics. We conclude that Pacific common eiders and other wild marine birds likely have higher selenium tolerances than freshwater species and that interspecific differences in exposure levels may reflect differences in reproductive strategies.

Environmental Toxicology and Chemistry↗

USGS2024

Seasonal resource selection of a grassland bird in a dynamic landscape: Importance of a heterogeneous landscape

Habitat loss and fragmentation are a growing threat to wildlife, and a better understanding of these landscape processes is needed to mitigate their effects on species populations. Grassland biomes are among the most imperiled ecosystems in the world, and grassland birds are experiencing significant population declines in North America. Understanding how species respond to differences in resource availabilities across spatiotemporal extents is critical to determining animals' distributions. Here, we investigated the relationship of landscape attributes to spatiotemporal distribution of a grassland bird, the ring-necked pheasant ( Phasianus colchicus ), which has experienced population declines in the Midwest, USA. Pheasant declines have been attributed to two anthropogenic stressors, land use change and climate change. In this study, we evaluated the effect of landscape attributes (composition and configuration) on the home-range size and resource selection of pheasants. We used a 95% fixed kernel estimator to estimate home-range size and identified scales at which landscape features influenced home-range sizes. We quantified landscape features within radii of 250, 500, and 1000 m (i.e., local to broader spatial scales) from the home-range center. We also used resource selection functions to predict the home-range placement (second order) and resource selection within home ranges (third order) of pheasants during winter, pre-nesting, and nesting seasons. We developed multi-scale predictions of pheasant resource selection and identified wetlands, grasslands, Conservation Reserve Program (CRP) grasslands, and small grains as land cover types used by pheasants to fulfill their life requirements. Our results indicated home ranges were more likely to be in a landscape with more CRP, wetlands, and grasslands; more connected grasslands; and a greater number of grassland patches. Pheasants also selected heterogeneous landscape and avoided row crops at both orders of selection. Maintaining habitat heterogeneity, by managing landscapes composed of a high proportion of grasslands and CRP surrounded by small grains and wetlands, could enhance the benefits of local management practices for pheasants. Collectively, insights obtained from our study can advance habitat conservation efforts for similar grassland birds and consequently are of broad utility to biologists and wildlife managers.

South Dakota↗

USGS2026

Carryover effects across juvenile periods vary by species, cause-specific mortality, and stage-specific behavior

Conditions during one life-stage can carry over to influence fitness outcomes in later stages. How carryover effects manifest, however, may vary depending on the type and magnitude of risks that animals face in subsequent life-stages. The influence of carryover effects on cause-specific mortality remains largely unclear, particularly during vulnerable life-stages, including juvenile periods. We proposed and investigated the Cause-specific carryover hypothesis, that the relative influence of traits developed during a previous stage on mortality during the next vary by cause of mortality, using juvenile sagebrush songbirds (Brewer’s sparrow, Spizella breweri ; sagebrush sparrow, Artemisiospiza nevadensis ; sage thrasher, Oreoscoptes montanus ) as a focal system. We tracked birds during the post-fledging period (a juvenile period following the nestling period), identified the rates and causes of mortality, and tested the relative influence of different nestling traits (wing length, tarsus length, feather development, and body condition) on post-fledging mortality risk. Carryover effects varied across co-occurring species and differed by cause of mortality, and tarsus length had an unexpected and outsized impact on predation risk in the two sparrows. Although wing morphology typically is considered the most important trait for mobility in birds, most mortalities occurred during the first 5 days of the post-fledging period when altricial fledglings were incapable of flight and likely relied on running or scrambling ability to escape predators. Therefore, carryover effects were driven by stage-specific behavior during the period of highest risk. Developing animals may face investment trade-offs between morphological traits that influence different types of risk during different subsequent stages.

Wyoming↗

USGS2019

Variation in selective regimes drives intraspecific variation in life-history traits and migratory behaviour along an elevational gradient

Comparative studies, across and within taxa, have made important contributions to our understanding of the evolutionary processes that promote phenotypic diversity. Trait variation along geographic gradients provides a convenient heuristic for understanding what drives and maintains diversity. Intraspecific trait variation along latitudinal gradients is well-known, but elevational variation in the same traits is rarely documented. Trait variation along continuous elevational gradients, however, provides compelling evidence that individuals within a breeding population may experience different selective pressures. Our objectives were to quantify variation in a suite of traits along a continuous elevational gradient, evaluate whether individuals in the population experience different selective pressures along that gradient and quantify variation in migratory tendency along that gradient. We examined variation in a suite of 14 life-history, morphological and behavioural traits, including migratory tendency, of yellow-eyed juncos along a continuous 1000-m elevational gradient in the Santa Catalina Mountains of Arizona. Many traits we examined varied along the elevational gradient. Nest survival and nestling growth rates increased, while breeding season length, renesting propensity and adult survival declined, with increasing elevation. We documented the migratory phenotype of juncos (partial altitudinal migrants) and show that individual migratory tendency is higher among females than males and increases with breeding elevation. Our data support the paradigm that variation in breeding season length is a major selective pressure driving life-history variation along elevational gradients and that individuals breeding at high elevation pursue strategies that favour offspring quality over offspring quantity. Furthermore, a negative association between adult survival and breeding elevation and a positive association between nest survival and breeding elevation help explain both the downslope and reciprocal upslope seasonal migratory movements that characterize altitudinal migration in many birds. Our results demonstrate how detailed studies of intraspecific variation in suites of traits along environmental gradients can lend new insights into the evolutionary processes that promote diversification and speciation, the causes of migratory behaviour, and how animal populations will likely respond to climate change.

Journal of Animal Ecology↗

USGS1995

Age-class separation of blue-winged ducks

Accurate determination of age is of fundamental importance to population and life history studies of waterfowl and their management. Therefore, we developed quantitative methods that separate adult and immature blue-winged teal ( Anas discors ), cinnamon teal ( A. cyanoptera ), and northern shovelers ( A. clypeata ) during spring and summer. To assess suitability of discriminant models using 9 remigial measurements, we compared model performance (% agreement between predicted age and age assigned to birds on the basis of definitive cloacal or rectral feather characteristics) in different flyways (Mississippi and Pacific) and between years (1990-91 and 1991-92). We also applied age-classification models to wings obtained from U.S. Fish and Wildlife Service harvest surveys in the Mississippi and Central-Pacific flyways (wing-bees) for which age had been determined using qualitative characteristics (i.e., remigial markings, shape, or wear). Except for male northern shovelers, models correctly aged lt 90% (range 70-86%) of blue-winged ducks. Model performance varied among species and differed between sexes and years. Proportions of individuals that were correctly aged were greater for males (range 63-86%) than females (range 39-69%). Models for northern shovelers performed better in flyway comparisons within year (1991-92, La. model applied to Calif. birds, and Calif. model applied to La. birds: 90 and 94% for M, and 89 and 76% for F, respectively) than in annual comparisons within the Mississippi Flyway (1991-92 model applied to 1990-91 data: 79% for M, 50% for F). Exclusion of measurements that varied by flyway or year did not improve model performance. Quantitative methods appear to be of limited value for age separation of female blue-winged ducks. Close agreement between predicted age and age assigned to wings from the wing-bees suggests that qualitative and quantitative methods may be equally accurate for age separation of male blue-winged ducks. We interpret annual and flyway differences in remigial measurements and reduced performance of age classification models as evidence of high variability in size of blue-winged ducks' remiges. Variability in remigial size of these and other small-bodied waterfowl may be related to nutrition during molt.

Louisiana↗

USGS2013

Toxic exposure of songbirds to lead in the Southeast Missouri Lead Mining District

Mining and smelting in the Southeast Missouri Lead Mining District has caused widespread contamination of soils with lead (Pb) and other metals. Soils from three study sites sampled in the district contained from approximately 1,000–3,200 mg Pb/kg. Analyses of earthworms [33–4,600 mg Pb/kg dry weight (dw)] collected in the district showed likely high Pb exposure of songbirds preying on soil organisms. Mean tissue Pb concentrations in songbirds collected from the contaminated sites were greater (p < 0.05) than those in songbirds from reference sites by factors of 8 in blood, 13 in liver, and 23 in kidney. Ranges of Pb concentrations in livers (mg Pb/kg dw) were as follows: northern cardinal (Cardinalis cardinalis) = 0.11–3.0 (reference) and 1.3–30 (contaminated) and American robin (Turdus migratorius) = 0.43–8.5 (reference) and 7.6–72 (contaminated). Of 34 adult and juvenile songbirds collected from contaminated sites, 11 (32 %) had hepatic Pb concentrations that were consistent with adverse physiological effects, 3 (9 %) with systemic toxic effects, and 4 (12 %) with life-threatening toxic effects. Acid-fast renal intranuclear inclusion bodies, which are indicative of Pb poisoning, were detected in kidneys of two robins that had the greatest renal Pb concentrations (952 and 1,030 mg/kg dw). Mean activity of the enzyme delta-aminolevulinic acid dehydratase (ALAD) in red blood cells, a well-established bioindicator of Pb poisoning in birds, was decreased by 58–82 % in songbirds from the mining sites. We conclude that habitats within the mining district with soil Pb concentrations of ≥1,000 mg Pb/kg are contaminated to the extent that they are exposing ground-feeding songbirds to toxic concentrations of Pb.

Missouri↗

USGS2003

[Book Review] Biology of marine birds

A text devoted to the biology and ecology of marine birds has not been published in the last 15 years. Although a number of more taxa-specific texts have been produced during that period, there has not been a single publication that attempted to review our knowledge of all the major seabird orders since the works of Nelson (1979), Croxall (1987), and Furness and Monaghan (1987). Following the publication of those works, a large and impressive body of literature has been produced. Given the rapid expansion of the field in the last two decades, the time was ripe for production of an extensive compendium on the biology, ecology, and conservation of the world's seabirds. E. A. Schreiber and J. Burger are editors of this CRC publication, Biology of Marine Birds . The book consists of 19 chapters that vary in length from 15 to 51 pages. There are also two extensive appendices: (1) a list of seabird species (restricted to the orders Sphenisciformes, Procellariiformes, Pelecaniformes, and Charadriiformes, the latter limited to Stercorariidae, Laridae, Rhynchopidae, and Alcidae) and their IUCN status, and (2) a very useful table of species-specific life-history traits. The 19 chapters were prepared by 26 authors, among them some of the most respected and published seabird scientists in the world. A brief preface introduces the book, its objective (to provide an examination and summary of the research on seabirds), its audience (researchers, conservationists, managers, and policy-makers), and the taxa covered. The editors coauthored the introductory chapter, Seabirds in the Marine Environment. The authors describe distinctive characteristics of seabird life-histories in comparison to other taxa, hypotheses for why those lifestyles evolved and the potential role of energy limitation in the evolution of seabird life-histories. Along with a discussion of other common seabird traits, such as a propensity for colonial breeding, the authors also suggest directions for future research in seabird ecology.

The Auk↗

USGS2007

Selenium and Mercury Concentrations in Fish, Wolford Mountain Reservoir, Colorado, 2005

A reconnaissance investigation of selenium and total mercury in fish in Wolford Mountain Reservoir, Colorado, was conducted by the U.S. Geological Survey in June 2005, in cooperation with the Colorado River Water Conservation District. A total of 32 game and nongame fish were collected from three sites in the reservoir for analysis of selenium and total mercury. Five species of fish were sampled: white sucker (Catostomus commersonii, n=17), brown trout (Salmo trutta, n=5), rainbow trout (Oncorhynchus mykiss, n=5), cutthroat trout (Oncorhynchus clarkii, n=3), and splake (Salvelinus fontinalis x Salvelinus namaycush, n=2). Selenium concentrations ranged from 1.05 to 11.7 micrograms per gram (equivalent to parts per million or ppm) dry weight, whole body. Almost 22 percent (7 of 32) of fish samples had selenium concentrations greater than 7.91 micrograms per gram dry weight, the U.S. Environmental Protection Agency 2004 draft freshwater chronic criterion for selenium in whole-body fish tissue. Total mercury concentrations in muscle plug samples ranged from 0.012 to 0.320 microgram per gram wet weight. Concentrations of mercury in muscle plug samples are comparable to concentrations in fillet samples, and only one fish sample, a nongame white sucker, had a total mercury concentration greater than the U.S. Environmental Protection Agency water-quality criterion for the protection of human health of 0.3 microgram per gram wet weight in fillets. Converting muscle plug or fillet concentrations of mercury to whole-body concentrations, four fish samples (12.5 percent) had estimated whole-body total mercury concentrations greater than 0.1 microgram per gram wet weight concentration in whole-body fish tissue, the U.S. Fish and Wildlife Service criterion for protection of fish-eating birds and wildlife. Water-quality data for dissolved selenium and total mercury in two tributaries and three reservoir sites were compiled and compared. Dissolved concentrations of selenium in one tributary and one reservoir site (prior to 1998) were greater than 4.6 micrograms per liter, the State of Colorado chronic water-quality standard for dissolved selenium for protection of aquatic life. Total mercury concentrations in most water samples from two tributaries and three reservoir sites were less than or equal to 0.01 microgram per liter, the State of Colorado chronic water-quality standard for total mercury for protection of aquatic life. Selenium and mercury in fish in Wolford Mountain Reservoir most likely are not directly related to selenium and mercury concentrations in reservoir water, as most selenium and mercury in fish tissue results from the presence of selenium and mercury in the diet rather than through gill uptake from water. Results of this reconnaissance investigation of selenium and total mercury in fish in Wolford Mountain Reservoir indicate that concentrations of selenium were elevated in some fish. Most total mercury concentrations in fish were less than criteria levels.

Scientific Investigations Report↗

USGS2014

Assessment of sediments in the riverine impoundments of national wildlife refuges in the Souris River Basin, North Dakota

Accelerated sedimentation of reservoirs and riverine impoundments is a major concern throughout the United States. Sediments not only fill impoundments and reduce their effective life span, but they can reduce water quality by increasing turbidity and introducing harmful chemical constituents such as heavy metals, toxic elements, and nutrients. U.S. Fish and Wildlife Service national wildlife refuges in the north-central part of the United States have documented high amounts of sediment accretion in some wetlands that could negatively affect important aquatic habitats for migratory birds and other wetland-dependent wildlife. Therefore, information pertaining to sediment accumulation in refuge impoundments potentially is important to guide conservation planning, including future management actions of individual impoundments. Lands comprising Des Lacs, Upper Souris, and J. Clark Salyer National Wildlife Refuges, collectively known as the Souris River Basin refuges, encompass reaches of the Des Lacs and Souris Rivers of northwestern North Dakota. The riverine impoundments of the Souris River Basin refuges are vulnerable to sedimentation because of the construction of in-stream dams that interrupt and slow river flows and because of post-European settlement land-use changes that have increased the potential for soil erosion and transport to rivers. Information regarding sediments does not exist for these refuges, and U.S. Fish and Wildlife Service personnel have expressed interest in assessing refuge impoundments to support refuge management decisions. Sediment cores and surface sediment samples were collected from impoundments within Des Lacs, Upper Souris, and J. Clark Salyer National Wildlife Refuges during 2004–05. Cores were used to estimate sediment accretion rates using radioisotope (cesium-137 [ 137 Cs], lead-210 [ 210 Pb]) dating techniques. Sediment cores and surface samples were analyzed for a suite of elements and agrichemicals, respectively. Examination of core characteristics along the depth profile suggests that there has been regular sediment mixing and removal, as well as non-uniform sediment deposition with time. Estimated mean accretion rates based on the three methods of determination (two time markers for 137 Cs, 210 Pb) ranged from 0.22–0.35 centimeters per year, and approximately 70 percent of cores had less 137 Cs than expected. Concentrations of sediment-associated elements generally were within reported reference ranges, and all agrichemicals analyzed were below detection limits. Results suggest that there does not appear to be widespread sediment accumulation in impoundments of the Souris River Basin refuges. In addition, there were no identifiable patterns among sedimentation rates from the upstream (Des Lacs, Upper Souris) to the downstream (J. Clark Salyer) refuges. There were, however, apparent upstream to downstream patterns of increased concentrations of some elements (for example, aluminum, boron, and vanadium) that may warrant further exploration. Future related monitoring and research efforts should focus on areas with high potential for sediment accumulation, such as upstream areas adjacent to dams, to identify potential sediment problems before they become too severe. Further, assessments of suspended sediments transported in the Des Lacs and Souris Rivers would augment interpretation of sedimentation data by identifying potential sediment sources and areas with the greatest potential for accumulation.

North Dakota↗

USGS2014

Factors affecting fat content in mottled ducks on the Upper Texas Gulf Coast

Body condition, or an individual's ability to address metabolic needs, is an important measure of organism health. For waterfowl, body condition, usually some measure of fat, provides a useful proxy for assessing energy budgets during different life history periods and potentially is a measure of response to ecosystem changes. The mottled duck (Anas fulvigula) is relatively poorly studied in respect to these dynamics and presents a unique case because its non-migratory life-history strategy releases it from metabolic costs experienced by many related migratory waterfowl species. Additionally, as a species in decline and of conservation concern in many parts of its range, traditional methods of fat content estimation that involve destructive sampling are less viable. The goal of this study was to produce an equation for estimating fat content in mottled ducks using birds (n = 24) donated at hunter-check stations or collected by law enforcement efforts on the Texas Chenier Plain National Wildlife Refuge Complex from 2005 - 2007. Morphometric measurements were taken, and ether extraction and fat removal was used to estimate percent body fat content and abdominal fat mass, respectively. A hierarchical simple linear regression modeling approach was used to determine external morphometrics that best predicted abdominal fat content. A ratio model based on body mass and a length metric (keel and wing chord length possessed equal model support) provided the best relationship with abdominal fat in sampled individuals. We then applied the regression equation to historical check station data to examine fluctuations in fat content over time; fat content or condition varied relatively little with the exception of years characterized by major disturbances. The mottled duck condition model created here can be used to better monitor population status and health without destructively sampling individuals.

Journal of the Southeastern Association of Fish an↗

USGS2024

A review of the ecology and conservation biology of Sali (Micronesian Starling, Aplonis opaca guami) on Guam

The accidental introduction of the Brown Treesnake (BTS, Boiga irregularis ) to Guam following World War II led to the extinction, extirpation, or severe decline of most of Guam’s native avifauna. One forest bird species that managed to persist is the cavity-nesting Såli (Micronesian Starling, Aplonis opaca guami ), a once-ubiquitous native omnivore whose current Guam distribution is restricted primarily to urbanized areas in the northern half of the island, with a second much smaller population on Cocos Island off southern Guam. Såli on Guam breed year-round and are habitat generalists with large home ranges. Besides arthropods and small vertebrates, they consume fruit from a wide range of native and introduced plant species and are key seed dispersers within the local ecosystem. Såli on Guam suffer extremely high post-fledging mortality due to predation by BTS and cats, leading to a population age structure strongly skewed towards adult birds. Other threats include habitat loss and degradation, extreme weather events, and sea level rise. Key management activities aimed at restoring this species include predator control, while non-native ungulate removal and vegetation management may be undertaken to support broader ecological recovery. This species account on Såli provides a review of the literature on this species, synthesizing information on habitat use, life history, and demographics to provide a biological foundation for future recovery efforts.

Micronesica↗

USGS2020

Factors influencing Cinnamon Teal nest attendance patterns

Patterns of nest attendance in birds result from complex behaviours and influence the success of reproductive events. Incubation behaviours vary based on individual body condition, energy requirements and environmental factors. We assessed nest attendance patterns in Cinnamon Teal Spatula cyanoptera breeding in the San Luis Valley of Colorado in 2016–2017 using trail and video cameras to observe behaviours throughout incubation. We evaluated the effect of temporal, life-history and environmental covariates on the frequency and duration of incubation recesses as well as the incubation constancy. There was considerable model uncertainty among the models used to evaluate recess frequency. Recess duration varied according to the interaction between nest age and a quadratic effect of time of day, with hens on older nests taking longer recesses in the afternoon and hens on nests earlier in incubation taking longer recesses in the morning and evening. Incubation constancy decreased with higher ambient temperatures in the study area. This study provides evidence that Cinnamon Teal modify their behaviour during incubation according to the age of the nest and the time of day. These results improve our knowledge of Cinnamon Teal breeding ecology and shed light on the behaviours that fast-lived species may use to cope with environmental factors during nesting.

Colorado↗

USGS1981

Pharmocokinetics of cephalothin and cephalexin in selected avian species

Plasma concentrations and the biological half-lives of cephalothin and cephalexin in avian species of a variety of body sizes and metabolic rates were studied. The species chosen were eastern bobwhite quail (Colinus v virginianus), pigeons (Columba livia), hybrid rosybill ducks (Netta sp), greater sandhill cranes (Grus canadensis tabida), and emus (Dromiceius novaehollandiae). In the 1st phase of the study, cephalothin sodium was given IM in a dose of 100 mg/kg of body weight. Plasma concentrations reached peak (av 18 micrograms/ml) at 0.5 hour and were measurable 2.5 to 5.5 hours after drug administration. The biological half-life of cephalothin was 16 to 54 minutes; the half-life varied directly with increased species body weight, with the exception of the ducks studied. In the 2nd phase, cephalexin monohydrate was given orally in doses of 25, 35, and 50 mg/kg of body weight. Plasma concentrations reached peak (av 20 micrograms/ml) at 0.5 to 1 hour and were measurable 2.5 to 5.5 hours after drug administration. The biological half-life of cephalexin was 36 to 126 minutes. In the 3rd phase, differences in plasma concentrations and the half-lives of cephalexin between fed quail and fasted quail were insignificant. Dosage regimens for cephalothin of 100 mg/kg 4 times a day and for cephalexin of 35 to 50 mg/kg 4 times a day would be expected to establish and maintain therapeutic plasma concentrations in large birds (pigeons, cranes, and emus). These same doses, administered every 2 to 3 hours, would be expected to establish and maintain therapeutic plasma concentrations in smaller birds (quail, ducks).

American Journal of Veterinary Research↗

USGS2022

Pink-footed Shearwater Ardenna creatopus

The Pink-footed Shearwater’s life history is tied to the Humboldt and California upwelling currents in the Eastern Pacific Ocean. It is larger than other shearwaters in its range, other than Flesh-footed Shearwater Ardenna carneipes. It is also distinct in appearance with pinkish bill and feet, pale underparts, and brown to grayish upperparts. It is known to breed on the Juan Fernández Islands and Isla Mocha, off central Chile. Birds spend the non-breeding period in waters off Peru and northward to waters off the west coast of North America. Breeding occurs in colonies, where pairs nest in burrows and the female lays a single egg. Breeding colonies generally are located on steep slopes in both open and forested habitats. During the breeding period, the species forages mainly in waters over the relatively narrow continental shelf as well as over deep offshore waters, depending on breeding colony. During the non-breeding period, individuals concentrate near the continental shelf-break and slope, and in more pelagic waters while making migratory movements. The Pink-footed Shearwater preys on fish and squid by seizing them at the surface or by making shallow dives. Foraging is often in association with albacore, dolphins, other seabirds, and fishing vessels. Pink-footed Shearwater is listed as Vulnerable by the IUCN and Endangered by Chile and Canada. Principal conservation threats are mortality from fisheries bycatch (especially in South American fisheries), and predation and habitat degradation from introduced mammals on breeding islands.

Birds of the World↗