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At least 721 records · Page 40Linked to original sources
USGS2022

A critical review of bioaccumulation and biotransformation of organic chemicals in birds

A literature review of bioaccumulation and biotransformation of organic chemicals in birds was undertaken, aiming to support scoping and prioritization of future research. The objectives were to characterize available bioaccumulation/biotransformation data, identify knowledge gaps, determine how extant data can be used, and explore the strategy and steps forward. An intermediate approach balanced between expediency and rigor was taken given the vastness of the literature. Following a critical review of > 500 peer-reviewed studies, > 25,000 data entries and 2 million information bytes were compiled on > 700 organic compounds for ~ 320 wild species and 60 domestic breeds of birds. These data were organized into themed databases on bioaccumulation and biotransformation , field survey , microsomal enzyme activity , metabolic pathway , and bird taxonomy and diet . Significant data gaps were identified in all databases at multiple levels. Biotransformation characterization was largely fragmented over metabolite/pathway identification and characterization of enzyme activity or biotransformation kinetics. Limited biotransformation kinetic data constrained development of an avian biotransformation model. A substantial shortage of in vivo biotransformation kinetics has been observed as most reported rate constants were derived in vitro. No metric comprehensively captured all key contaminant classes or chemical groups to support broad-scope modeling of bioaccumulation or biotransformation. However, metrics such as biota-feed accumulation factor, maximum transfer factor, and total elimination rate constant were more readily usable for modeling or benchmarking than other reviewed parameters. Analysis demonstrated the lack of bioaccumulation/biotransformation characterization of shorebirds, seabirds, and raptors. In the study of bioaccumulation and biotransformation of organic chemicals in birds, this review revealed the need for greater chemical and avian species diversity, chemical measurements in environmental media, basic biometrics and exposure conditions, multiple tissues/matrices sampling, and further exploration on biotransformation. Limitations of classical bioaccumulation metrics and current research strategies used in bird studies were also discussed. Forward-looking research strategies were proposed: adopting a chemical roadmap for future investigations, integrating existing biomonitoring data, gap-filling with non-testing approaches, improving data reporting practices, expanding field sampling scopes, bridging existing models and theories, exploring biotransformation via avian genomics, and establishing an online data repository.

Reviews of Environmental Contamination and Toxicol↗
USGS2014

An integrated modeling approach to estimating Gunnison Sage-Grouse population dynamics: Combining index and demographic data

Evaluation of population dynamics for rare and declining species is often limited to data that are sparse and/or of poor quality. Frequently, the best data available for rare bird species are based on large‐scale, population count data. These data are commonly based on sampling methods that lack consistent sampling effort, do not account for detectability, and are complicated by observer bias. For some species, short‐term studies of demographic rates have been conducted as well, but the data from such studies are typically analyzed separately. To utilize the strengths and minimize the weaknesses of these two data types, we developed a novel Bayesian integrated model that links population count data and population demographic data through population growth rate ( λ ) for Gunnison sage‐grouse ( Centrocercus minimus ). The long‐term population index data available for Gunnison sage‐grouse are annual (years 1953–2012) male lek counts. An intensive demographic study was also conducted from years 2005 to 2010. We were able to reduce the variability in expected population growth rates across time, while correcting for potential small sample size bias in the demographic data. We found the population of Gunnison sage‐grouse to be variable and slightly declining over the past 16 years.

Colorado, Utah↗
USGS2003

Population increase in Kirtland's warbler and summer range expansion to Wisconsin and Michigan's Upper Peninsula, USA

The threatened Kirtland's warbler Dendroica kirtlandii breeds in stands of young jack pine Pinus banksiana growing on well-drained soils in Michigan, USA. We summarize information documenting the range expansion of Kirtland's warbler due to increased habitat management in the core breeding range in the Lower Peninsula of Michigan during 1990–2000. We collected records and conducted searches for the species in Michigan's Upper Peninsula and Wisconsin over 1978–2000. During that time 25 males were found in Wisconsin and 90 males in the Upper Peninsula. We documented colonization of Michigan's Upper Peninsula by six ringed males from the Lower Peninsula of Michigan. Four ringed birds also moved back to the core breeding range, including two males that made two-way movements between the core breeding range and the Upper Peninsula. Thirty-seven females were observed with males from 1995 to 2000, all in Michigan. Nesting activities were noted for 25 pairs and at least nine nests fledged young. One male ringed as a fledgling returned to breed in two subsequent years. After a 19-year period of population stability, the Kirtland's warbler population increased four-fold during 1990–2000, most likely in response to a tripling in habitat area. This increase in sightings and documented breeding may be related to habitat availability in Michigan's Upper Peninsula and to saturation of habitat in the main breeding range. The increase in extra-limital records during 1995–1999 corresponds to the time when the population went from the minimum to the maximum projected population densities, and a decline in natural wildfire habitat was just offset by new managed habitat for the Kirtland's warbler.

Michigan, Wisconsin↗
USGS2012

Effects of sea ice on winter site fidelity of Pacific common eiders ( Somateria mollissima v-nigrum )

In northern marine habitats, the presence or absence of sea ice results in variability in the distribution of many species and the quality and availability of pelagic winter habitat. To understand the effects of ice on intra- and inter-annual winter site fidelity and movements in a northern sea-duck species, we marked 25 adult Pacific Common Eiders ( Somateria mollissima v-nigrum ) on their nesting area at Cape Espenberg, Alaska, with satellite transmitters and monitored their movements to their wintering areas in the northern Bering Sea for a 2-year period. We examined changes in winter fidelity in relation to home-range characteristics and ice. Characteristics of polynyas (areas with persistent open water during winter) varied substantially and likely had an effect on the size of winter ranges and movements within polynyas. Movements within polynyas were correlated with changes in weather that affected ice conditions. Ninety-five percent of individuals were found within their 95% utilization distribution (UD) of the previous year, and 90% were found within their 50% UD. Spatial distributions of winter locations between years changed for 32% of the individuals; however, we do not consider these subtle movements biologically significant. Although ice conditions varied between polynyas within and between years, the Common Eiders monitored in our study showed a high degree of fidelity to their winter areas. This observation is counterintuitive, given the requirement that resources are predictable for site fidelity to occur; however, ice may not have been severe enough to restrict access to other resources and, subsequently, force birds to move.

Alaska↗
USGS2012

Extreme weather and experience influence reproduction in an endangered bird

Extreme weather events, such as droughts and heat waves, are expected to become more severe and more frequent in the coming years, and understanding their impacts on demographic rates is of increasing interest to both evolutionary ecologists and conservation practitioners. An individual's breeding probability can be a sensitive indicator of the decision to initiate reproductive behavior under varying environmental conditions, has strong fitness consequences, and can be considered the first step in a life history trade-off between allocating resources for breeding activities or self-survival. Using a 14-year time series spanning large variation in climatic conditions and the entirety of a population's breeding range, we estimated the effects of extreme weather conditions (drought) on the state-specific probabilities of breeding and survival of an endangered bird, the Florida Snail Kite ( Rostrhamus sociabilis plumbeus ). Our analysis accounted for uncertainty in breeding status assignment, a common source of uncertainty that is often ignored when states are based on field observations. Breeding probabilities in adult kites (>1 year of age) decreased during droughts, whereas the probability of breeding in young kites (1 year of age) tended to increase. Individuals attempting to breed showed no evidence of reduced future survival. Although population viability analyses of this species and other species often implicitly assume that all adults will attempt to breed, we find that breeding probabilities were significantly <1 for all 13 estimable years considered. Our results suggest that experience is an important factor determining whether or not individuals attempt to breed during harsh environmental conditions and that reproductive effort may be constrained by an individual's quality and/or despotic behavior among individuals attempting to breed.

Florida↗
USGS2019

A Methodology to Assess the National and Regional Impacts of U.S. Wind Energy Development on Birds and Bats

This scientific investigations report describes an effort by the U.S. Geological Survey (USGS) that used research, monitoring data, and modeling to develop a methodology to assess both the current and future population-level consequences of wind energy development on species of birds and bats that are present in the United States during any part of their life cycle. The methodology is currently applicable to birds and bats, focuses primarily on the effects of collisions with turbines, and can be applied to any species that breeds in, migrates through, or otherwise uses any part of the United States. The methodology assesses species at the national and regional scales and identifies those species potentially in need of more detailed study, as well as those species that are likely at low risk from wind energy development. This approach is fundamentally different from existing methods focusing on impacts at individual facilities. This report supersedes USGS Scientific Investigations Report 2015–5066 by the same authors, which described a preliminary version of the methodology. Following reviews of the preliminary methodology by a panel of external experts, public comments, and additional internal review, the methodology was revised and finalized. The three components of the refined methodology described in this new report rely on publicly available fatality information, population estimates, species range maps, turbine location data, biological characteristics of species, and population models. First, three metrics are combined to determine direct and indirect relative effects from wind energy facilities to generate a list of species scores. Second, a generic population model estimates the expected change in population trend caused by the additive mortality from collisions with wind turbines. Third, the methodology combines an estimate of observed fatalities and an estimate of potential biological removal to assess the possibility of a decrease in population size. The latter two components are quantitative. In a test case, the methodology was used to analyze data for six bird species and three bat species. Components of the methodology are based on simplifying assumptions and require information that, for many species, may be sparse or unreliable or may require further study. These assumptions should be carefully considered when using outputs from the methodology. Increases in the quality of data for fatalities from collisions with wind turbines, species distributions, abundance, and demography will likely improve results for uses of the methodology. The methodology’s design identifies and prioritizes a subset of the bird and bat species that may experience population-level impacts from collisions with wind turbines, both currently and from future wind energy development in the United States. Results of an assessment using this methodology could focus future research to improve our understanding of those impacts and to guide avoidance and minimization strategies. In addition, this methodology can be used to identify species for more intensive demographic modeling or to highlight those species that may not require any additional research because effects of wind energy development on their populations are projected to be small. The effects of wind energy facilities on nine unidentified species used in the test case described in this report have not been assessed. Their data were simply used to show the application of the methodology to real-world data and the types of outputs it would produce.

Scientific Investigations Report↗
USGS1949

Wildlife effects of DDT dust used for tick control on a Texas prairie

The effect of DDT dust on wildlife was studied at Camp Bullis, Bexar County, Texas, in the summer of 1947. Studies were made on a 206.6 acre plot that was treated with DDT for experimental control of the Lone Star tick ( Amblyomma americanum ). A dust consisting of one part of DDT to nine parts of pyrophyllite was applied at an average rate of 4.4 pounds of DDT per acre. The limits of DDT concentration that affected wildlife cannot be stated exactly because of a heavy rain that fell near the end of the dusting, and because of irregularity in DDT deposition. Since absolute uniformity of dusting could not be expected in any large scale DDT application, the effects observed in these trials were probably fairly representative. However, continued dry weather would have permitted longer exposure to DDT, possibly with more severe effects than those found in this study. The vegetation of the experimental area was roughly 70 percent ungrazed tall-grass prairie and 30 percent trees and shrubs. Ground and bush feeding birds were severely affected. Cardinals, lark sparrows, field sparrows, Bewick's wrens, Carolina wrens, Kentucky warblers, yellow-breasted chats, blue grosbeaks, and painted buntings were nearly or entirely eliminated from the treated area. Birds affected, but less drastically reduced in numbers, were yellow-billed cuckoo, black and white warbler, yellow-throated vireo, and white-eyed vireo. Birds found dead in the DDT area were 9 cardinals, 2 painted buntings, 2 lark sparrows, 1 yellow-breasted chat, and 1 white-eyed vireo. Bird mortality had begun by the day after dusting and was largely over by the end of the fifth day. Census of deer in DDT and check areas before and after treatment showed no reduction in deer numbers and no diminution in use of the DDT area. No deer or fawns were found dead or affected. Box-trapping of raccoons in DDT and check areas before and after treatment showed no effects that could be attributed to DDT. Limited observations on armadillos, striped skunks, and rabbits gave no indication of pronounced damage to these forms. No mammals of any kind were found dead or affected in or near the DDT area. Four rough green snakes and one Texan spiny lizard were found dead in the DDT area. Mortality was probably high among insectivorous reptiles.

Texas↗
USGS1960

Lake Erie walleyes--again on the upswing?

SUMMARY The effect of DDT dust on wildlife was studied at Camp Bullis, Bexar County, Texas, in the summer of 1947. Studies were made on a 206.6 acre plot that was treated with DDT for experimental control of the Lone Star tick (Amblyomrna americanum). A dust consisting of one part of DDT to nine parts of pyrophyllite was applied at an average rate of 4.4 pounds of DDT per acre. The limits of DDT concentration that affected wildlife cannot be stated exactly because of a heavy rain that fell near the end of the dusting, and because of irregularity in DDT deposition. Since absolute uniformity of dusting could not be expected in any large scale DDT application, the effects observed in these trials were probably fairly representative. However, continued dry weather would have permitted longer exposure to DDT, possibly with more severe effects than those found in this study. The vegetation of the experimental area was roughly 70 percent ungrazed tall-grass prairie and 30 percent trees and shrubs. Ground and bush feeding birds were severely affected. Cardinals, lark sparrows, field sparrows, Bewick's wrens, Carolina wrens, Kentucky warblers, yellow-breasted chats, blue grosbeaks, and painted buntings were nearly or entirely eliminated from the treated area. Birds affected, but less drastically reduced in numbers, were yellow-billed cuckoo, black and white warbler, yellow-throated vireo, and white-eyed vireo. Birds found dead in the DDT area were 9 cardinals, 2 painted buntings, 2 lark sparrows, 1 yellow-breasted chat, and 1 white-eyed vireo. Bird mortality had begun by the day after dusting and was largely over by the end of the fifth day. Census of deer in DDT and check areas before and after treatment showed no reduction in deer numbers and no diminution in use of the DDT area. No deer or fawns were found dead or affected. Box-trapping of raccoons in DDT and check areas before and after treatment showed no effects that could be attributed to DDT. Limited observations on armadillos, striped skunks, and rabbits gave no indication of pronounced damage to these forms. No mammals of any kind were found dead or affected in or near the DDT area. Four rough green snakes and one Texan spiny lizard were found dead in the DDT area. Mortality was probably high among insectivorous reptiles.

Ohio Conservation Bulletin↗
USGS2011

Teratogenic efects of injected methylmercury on avian embryos

Controlled laboratory studies with game farm mallards ( Anas platyrhynchos ) and chickens ( Gallus gallus ) have demonstrated that methylmercury can cause teratogenic effects in birds, but studies with wild species of birds are lacking. To address this need, doses of methylmercury chloride were injected into the eggs of 25 species of birds, and the dead embryos and hatched chicks were examined for external deformities. When data for controls were summed across all 25 species tested and across all types of deformities, 24 individuals out of a total of 1,533 (a rate of 1.57%) exhibited at least one deformity. In contrast, when data for all of the mercury treatments and all 25 species were summed, 188 deformed individuals out of a total of 2,292 (8.20%) were found. Some deformities, such as lordosis and scoliosis (twisting of the spine), misshapen heads, shortening or twisting of the neck, and deformities of the wings, were seldom observed in controls but occurred in much greater frequency in Hg-treated individuals. Only 0.59% of individual control dead embryos and hatchlings exhibited multiple deformities versus 3.18% for Hg-dosed dead embryos and hatchlings. Methylmercury seems to have a widespread teratogenic potential across many species of birds.

Environmental Toxicology and Chemistry↗
USGS2024

Forest bird populations at the Big Island National Wildlife Refuge Complex, Hawai'i

E ndemic Hawaiian forest birds have experienced dramatic population declines. The Big Island National Wildlife Refuge Complex (Refuge Complex) was established for the conservation of endangered forest birds and their habitats. Surveys have been conducted at two units of the Refuge Complex to monitor forest bird populations and their response to management actions. We analyzed survey data from 1987 to 2019 at the Hakalau Forest Unit (HFU) and from 1995 to 2019 at the Kona Forest Unit (KFU). We analyzed three strata at HFU: open-forest, closed-forest, and afforested-pasture, and two strata at KFU: upper (>1,524 m elevation) and lower (<1,524 m). In all years, ‘i‘iwi Vestiaria coccinea , ‘apapane Himatione sanguinea , and Hawai'i ‘amakihi Chlorodrepanis virens virens were the most abundant species at HFU. Three endangered forest bird species, Hawai'i ‘ākepa Loxops coccineus , ‘alawī Loxops mana (also known as Hawai'i creeper) and ‘akiapōlā‘au Hemignathus wilsoni , had much lower densities. The most abundant species at KFU was ‘apapane, followed by Hawai'i ‘amakihi at much lower densities. We found a continuation of several trends observed in previous analyses at HFU up to 2012, with most species’ trends upward in afforested-pasture stratum, stable in the open-forest stratum, and downward in the closed-forest stratum. However, more species were showing downward trends in all three strata during the most recent decade. Results were mixed at KFU, with most species’ trends downward in the upper stratum and upward in the lower stratum. Populations of endangered species were either locally extirpated at KFU or in numbers too low to reliably estimate population abundance. The Refuge Complex is important for conservation of forest birds on Hawai'i Island. Our results show that HFU supports the majority of three endangered forest bird species. Threats to forest birds at the Refuge Complex appear to be having a negative impact. These threats include habitat loss, disease, feral ungulates, and nonnative predators. Continuing and enhancing management actions, such as forest restoration and removal of invasive species, could help mitigate these impacts and allow the Refuge Complex to remain a key site for forest bird conservation in Hawai'i.

Hawaii↗
USGS1975

Death feigning by ducks in response to predation by red foxes (Vulpes fulva)

Predation by captive red foxes ( Vulpes fulva ) on approximately 50 ducks comprised of five species was observed in tests conducted at the Northern Prairie Wildlife Research Center, Jamestown, North Dakota. Most ducks were attacked from a rear or lateral position and seized in the cervical or thoracic region. All birds became immobile (death-feigned) immediately when seized and with few exceptions remained motionless during prey-handling and for varying lengths of time thereafter. Initial death feints lasted from 20 sec to 14 min. Recovery was delayed by tactile, visual and, possibly, auditory cues from the foxes. Death-feigning birds appeared alert and often took advantage of escape opportunities. Twenty-nine birds survived initial capture and handling by the foxes. Naive foxes were wary of ducks during initial confrontations, but experienced foxes showed little hesitation in attacking them. After capture, most ducks were taken alive to lay-down sites where they were mouthed and often killed. Then the ducks were usually cached or taken to dens or pups. Several birds were cached alive. Red foxes appear to have adapted to the escape of death-feigning ducks by learning to kill some birds soon after capture and by the evolution of an appendage-severing behavior. Death feigning appears to be a highly developed antipredator behavior of ducks that facilitates the escape of some birds after capture by red foxes.

American Midland Naturalist↗
USGS2000

Pathogenicity of avian malaria in experimentally-infected Hawaii Amakihi

The introduction of avian malaria (Plasmodium relictum) and mosquitoes (Culex quinquefasciatus) to the Hawaiian Islands (USA) is believed to have played a major role in the decline and extinction of native Hawaiian honeycreepers (Drepanidinae). This introduced disease is thought to be one of the primary factors limiting recovery of honeycreepers at elevations below 1,200 m where native forest habitats are still relatively intact. One of the few remaining species of honeycreepers with a wide elevational distribution is the Hawaii Amakihi (Hernignathus virens). We measured morbidity and mortality in experimentally-infected Hawaii Amakihi that were captured in a high elevation, xeric habitat that is above the current range of the mosquito vector. Mortality among amakihi exposed to a single infective mosquito bite was 65% (13/20). All infected birds had significant declines in food consumption and a corresponding loss in body weight over the 60 day course of the experiment. Gross and microscopic lesions in birds that succumbed to malaria included enlargement and discoloration of the spleen and liver and parasitemias as high as 50% of circulating erythrocytes. Mortality in experimentally-infected amakihi was similar to that observed in Apapane (Himnatione sanguinea) and lower than that observed in Iiwi (Vestiaria coccinea) infected under similar conditions with the same parasite isolate. We conclude that the current elevational and geographic distribution of Hawaiian honeycreepers is determined by relative susceptibility to avian malaria.

Hawaii↗
USGS2010

Beak deformities in Northwestern Crows: Evidence of a multispecies epizootic

Beak abnormalities are rare among adult birds and, typically, are not widespread in a given population, within a region, or across multiple species. A high concentration of beak deformities was recently documented in Black-capped Chickadees ( Poecile atricapillus ) and other resident avian species in Alaska. We describe a parallel condition in Northwestern Crows ( Corvus caurinus ) that signals the emergence of a multispecies epizootic. On the basis of 186 Northwestern Crows captured at six sites in Alaska during 2007 and 2008, we estimated the prevalence of beak deformities in adults to be 16.9 ± 5.3%, the highest rate of gross deformities ever recorded in a wild bird population. Prevalence varied among sites and was as high as 36% on the Kenai Peninsula, which suggests possible epizootic clusters. We also documented beak abnormalities in an additional 148 Northwestern Crows in south-central and southeastern Alaska and in 64 crows near Vancouver, British Columbia, and Puget Sound, Washington, a region where both Northwestern Crows and American Crows ( C. brachyrhynchos ) occur. The increase in frequency and distribution of crows observed with abnormal beaks throughout the Pacific Northwest since the late 1990s indicates a geographic expansion of this problem. Affected crows exhibited elongated and often crossed beaks that were morphologically similar to deformities documented in Black-capped Chickadees and other species in Alaska over approximately the same period. Additional research is needed to determine the etiology and potential adverse effects on bird populations affected by this disorder.

Alaska, British Columbia, Washington↗
USGS2018

Acquisition and dissemination of cephalosporin-resistant E. coli in migratory birds sampled at an Alaska landfill as inferred through genomic analysis

Antimicrobial resistance (AMR) in bacterial pathogens threatens global health, though the spread of AMR bacteria and AMR genes between humans, animals, and the environment is still largely unknown. Here, we investigated the role of wild birds in the epidemiology of AMR Escherichia coli. Using next-generation sequencing, we characterized cephalosporin-resistant E. coli cultured from sympatric gulls and bald eagles inhabiting a landfill habitat in Alaska to identify genetic determinants conferring AMR, explore potential transmission pathways of AMR bacteria and genes at this site, and investigate how their genetic diversity compares to isolates reported in other taxa. We found genetically diverse E. coli isolates with sequence types previously associated with human infections and resistance genes of clinical importance, including blaCTX-M and blaCMY. Identical resistance profiles were observed in genetically unrelated E. coli isolates from both gulls and bald eagles. Conversely, isolates with indistinguishable core-genomes were found to have different resistance profiles. Our findings support complex epidemiological interactions including bacterial strain sharing between gulls and bald eagles and horizontal gene transfer among E. coli harboured by birds. Results suggest that landfills may serve as a source for AMR acquisition and/or maintenance, including bacterial sequence types and AMR genes relevant to human health.

Alaska↗
USGS2021

The North American Breeding Bird Survey in Mexico, 2008 to 2018—A status report

Collection of avian population data has repeatedly been identified as a high priority for bird conservation in Mexico. To meet this need, in 2008 the North American Breeding Bird Survey (BBS), a volunteer-based survey, was expanded to include northern Mexico. The BBS in Mexico (Mexican BBS) is managed by the North American Bird Conservation Initiative (NABCI), Mexico’s National Coordination Office inside the Comisión Nacional para el Conocimiento y Uso de la Biodiversidad (CONABIO). During 2008–18, 252 surveys were conducted along 68 routes in Mexico, with geographic coverage varying from year to year. Of these 68 routes, 36 were surveyed three or more times. Thirty-one observers conducted the surveys, and 21 of these observers conducted two or more surveys. Just two observers conducted more than one-third of the 252 surveys, and both observers were paid to conduct the surveys. The low availability of local observers who are qualified, willing, and able to volunteer their services to conduct BBS surveys may prove to be the biggest obstacle to the success of the Mexican BBS program, especially in the context of Mexico’s ongoing safety and security concerns. Apart from the amount of data collected, many surveys did not adhere to pre-established quality-control requirements, and this would result in the exclusion of a large percentage of the data from potential trend analyses. Only 31 percent of the surveys met all the quality-control criteria. Additional observer training may help resolve this issue. Of greater concern is the selection of region-specific sampling date windows during which the surveys are conducted. Observers consistently conducted surveys outside the preliminarily prescribed sampling date window, reflecting the need to re-evaluate the regional appropriateness of this date window. Regardless of the quality of the data, the quantity of data available from 2008 to 2018 is insufficient for trend analysis using methods typically employed by U.S. Geological Survey BBS analysts. Reaching minimum sample size thresholds for statistical analysis will require a substantial increase in effort. During 2008–18, no strata (defined as the intersection of State and Bird Conservation Region boundaries) reached the suggested minimum of 14 sampled routes, and most routes were not run consistently. This report provides information needed for an evaluation of the merits of continuing to invest in the Mexican BBS program in its current form. Such an evaluation should consider the likelihood of achieving the primary project goal of producing reliable long-term population trend estimates, a projected timeline for meeting this goal, and include an assessment of the potential value of any additional data products.

Baja California, Baja California Sur, Chihuahua, C↗
USGS1972

Biological data on PCBs in animals other than man

SUMMARY: Polychlorinated biphenyls have become ubiquitous in the world ecosystem in quantities similar to those of DDE. Experimental studies have shown that PCBs have a toxicity to mallards, pheasants, bobwhite quail, coturnix quail, red-winged blackbirds, starlings, cowbirds, and grackles that is of the same order as the toxicity of DDE to these species. Overt signs of poisoning also are similar to those caused by compounds of the DDT group. Toxic effects of DDE and Aroclor 1254 to coturnix chicks were additive, but not synergistic. PCBs containing higher percentages of chlorine are more toxic to birds than those containing lower percentages. PCBs of foreign manufacture contained contaminants to an extent that greatly increased their toxicity. Residues of PCBs in the brains of birds killed by these compounds measure in the hundreds of parts per million. PCBs may have contributed to mortality of some birds in the field. Toxicity to insects of PCBs of different degrees of chlorination is the reverse of the pattern in birds: the lower chlorinations are more toxic to insects. PCBs enhanced the toxicity of dieldrin and DDT to insects. Shrimp are very sensitive to PCBs and most will die as a result of 20-day exposure to a concentration of 5 ppb. PCBs also inhibit shell growth of oysters. Crabs are less sensitive; all accumulate residues to many times the concentrations in the water, and a test with crabs showed that they lost the residues very slowly. Growth of certain species of marine diatoms was experimentally inhibited by PCBs, but algae were not affected. The small marine crustacean, Gammarus, is sensitive to PCBs in concentrations of thousandths to tenths of a part per billion. Exposure to 5 ppb of Aroclor 1254 caused mortality of two species of fish in 14-45 days. Onset of death was delayed and was accompanied by fungus-like lesions. Rainbow trout were quickly killed by terphenyls at 10 ppb under normal oxygen conditions and at 2 ppb with reduced oxygen. Metabolic changes of PCBs have been suggested by environmental observations of different isomeric patterns in animals of different trophic levels. Quantitative differences also are pronounced, with magnifications of hundreds to thousands of times. Laboratory studies have shown no metabolic changes of PCBs by crabs and shrimps, minimal changes by fish, and pronounced changes by birds. PCBs induce microsomal enzyme activity in birds. Exposure to PCBs increased the susceptibility of mallard ducklings to duck hepatitis virus. Offspring of pheasants whose parents received high dosages of PCBs made poor choices in visual cliff tests. Egg production and hatching after pipping also were affected. Migratory restlessness was increased in English robins exposed to PCBs. Long-term studies of the reproductive effects of Aroclor 1254 on mallards and bobwhite quail and of Aroclor 1254 plus DDE on quail showed no significant differences from controls. In studies of chickens, however, egg production and hatchability were impaired by high doses of Aroclor 1254 and by low doses of Aroclor 1242. Statistical evaluations of the role that different chemicals may play in thinning eggshells of brown pelicans showed that DDE residues correlate better with shell thinning than do residues of dieldrin or PCBs, confirming observations with cormorants and white pelicans.

Book chapter↗
USGS2018

Evaluation of social attraction measures to establish Forster’s tern (Sterna forsteri) nesting colonies for the South Bay Salt Pond Restoration Project, San Francisco Bay, California—2017 Annual Report

Forster’s terns ( Sterna forsteri ), historically one of the most numerous colonial-breeding waterbirds in South San Francisco Bay, California, have had recent decreases in the number of nesting colonies and overall breeding population size. The South Bay Salt Pond (SBSP) Restoration Project aims to restore 50–90 percent of former salt evaporation ponds to tidal marsh habitat in South San Francisco Bay. This restoration will remove much of the historical island nesting habitat used by Forster’s terns, American avocets ( Recurvirostra americana ), and other waterbirds. To address this issue, the SBSP Restoration Project organized the construction of new nesting islands in managed ponds that will not be restored to tidal marsh, thereby providing enduring island nesting habitat for waterbirds. In 2012, 16 new islands were constructed in Pond A16 in the Alviso complex of the Don Edwards San Francisco Bay National Wildlife Refuge, increasing the number of islands in this pond from 4 to 20. However, despite a history of nesting on the four historical islands in Pond A16 before 2012, no Forster’s terns have nested in Pond A16 since the new islands were constructed. In 2017, we used social attraction measures (decoys and electronic call systems) to attract Forster’s terns to islands within Pond A16 to re-establish nesting colonies. We maintained these systems from March through August 2017. To evaluate the effect of these social attraction measures, we also completed waterbird surveys between April and August, where we recorded the number and location of all Forster’s terns and other waterbirds using Pond A16, and monitored waterbird nests. We compared bird survey and nest monitoring data collected in 2017 to data collected in 2015 and 2016, prior to the implementation of social attraction measures, allowing for direct evaluation of social attraction efforts on Forster’s terns. To increase the visibility and stakeholder involvement of this project, we engaged in multiple outreach activities, including the development of a project web site ( https://apps.usgs.gov/shorebirds/ ) and educational video ( https://www.youtube.com/watch?v=-IaZD0YlAvM&feature=youtu.be ); publication of a popular article ( http://www.sfestuary.org/estuary-news-caspian-push-and-pull/ ); and public presentations to relay findings to managers, stakeholders, and the general public. The relative number of Forster’s terns using Pond A16, after adjusting for the overall South San Francisco Bay breeding population each year, was higher during the nesting period in 2017 (after social attraction was used) than in 2015 and 2016 (before social attraction was used). Furthermore, in 2017, more Forster’s terns were observed in the areas of Pond A16 where decoys and call systems were deployed during the pre-nesting and nesting periods. Although no Forster’s tern nests were recorded in Pond A16 before (2015, 2016) or after (2017) implementation of social attraction measures, bird survey results indicate that Forster’s terns were attracted to areas within Pond A16 where decoys and call systems were deployed, suggesting that terns may have been prospecting for future breeding sites. As social attraction efforts often benefit from multiple years of decoy and call system deployment, these first-year results suggest that continued implementation of social attraction measures could help to re-establish Forster’s tern breeding colonies in Pond A16 and other areas of South San Francisco Bay.

California↗
USGS2021

Augmentation of natural prey reduces cattle predation by puma (Puma concolor) and jaguar (Panthera onca) on a ranch in Sonora, Mexico

Retaliatory killing of large carnivores due to livestock predation is one of the major threats for the conservation of many declining populations of predators. According to empirical observations, there is a higher incidence of livestock predation when native prey abundance is low. In this study, we applied a treatment consisting of augmentation of prey abundance by translocation of peccaries ( Pecari tajacu ) and placement of four feed stations for white-tailed deer ( Odocoileus virginianus ) on a cattle ranch in Sonora, Mexico, with verified calf predation by puma ( Puma concolor ) and jaguar ( Panthera onca ). We quantified and compared consumed prey over two periods—phase I (8 months before the augmentation of prey) and phase II (8 months after the augmentation of prey)—through investigation of kill sites from Global Positioning System–collared jaguar and puma, prey identification from analyzed scat using molecular DNA techniques, and opportunistic discoveries of recently killed animal remains by either predator. We calculated the relative abundance of species (17 mammals [one species with two distinct age classes] and 1 bird species) through camera traps and for the most relevant prey species for this study (deer, calf, and peccary), we also estimated prey use by the predator, based on their availability during each period (prey preference). In the prey composition analyses of scat, we observed a significant reduction in the consumption of bovids and a significant increase in the consumption of peccaries during phase II. In the analyses of prey use, during phase I, predators consumed peccaries and calves at a higher proportion in relation to their availability. During phase II, consumption of calves declined from being preferred, to being consumed at the same proportion as their availability. Application of these results can contribute to the decrease of livestock predation and therefore conservation of pumas and jaguars.

Sonora↗