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At least 559 records · Page 31Linked to original sources
USGS2023

Modeled distribution shifts of North American birds over four decades based on suitable climate alone do not predict observed shifts

As climate change alters the global environment, it is critical to understand the relationship between shifting climate suitability and species distributions. Key questions include whether observed changes in population abundance are aligned with the velocity and direction of shifts predicted by climate suitability models and if the responses are consistent among species with similar ecological traits. We examined the direction and velocity of the observed abundance-based distribution centroids compared with the model-predicted bioclimatic distribution centroids of 250 bird species across the United States from 1969 to 2011. We hypothesized that there is a significant positive correlation in both direction and velocity between the observed and the modeled shifts. We then tested five additional hypotheses that predicted differential shifting velocity based on ecological adaptability and climate change exposure. Contrary to our hypotheses, we found large differences between the observed and modeled shifts among all studied bird species and within specific ecological guilds. However, temperate migrants and habitat generalist species tended to have higher velocity of observed shifts than other species. Neotropical migratory and wetland birds also had significantly different observed velocities than their counterparts, which may be due to their climate change exposure. The velocity based on modeled bioclimatic suitability did not exhibit significant differences among most guilds. Boreal forest birds were the only guild with significantly faster modeled-shifts than the other groups, suggesting an elevated conservation risk for high latitude and altitude species. The highly idiosyncratic species responses to climate and the mismatch between shifts in modeled and observed distribution centroids highlight the challenge of predicting species distribution change based solely on climate suitability and the importance of non-climatic factors traits in shaping species distributions.

Science of the Total Environment↗
USGS2008

Fecal indicator bacteria and Salmonella in ponds managed as bird habitat, San Francisco Bay, California, USA

Throughout the world, coastal resource managers are encouraging the restoration of previously modified coastal habitats back into wetlands and managed ponds for their ecosystem value. Because many coastal wetlands are adjacent to urban centers and waters used for human recreation, it is important to understand how wildlife can affect water quality. We measured fecal indicator bacteria (FIB) concentrations, presence/absence of Salmonella, bird abundance, and physico-chemical parameters in two coastal, managed ponds and adjacent sloughs for 4 weeks during the summer and winter in 2006. We characterized the microbial water quality in these waters relative to state water-quality standards and examined the relationship between FIB, bird abundance, and physico-chemical parameters. A box model approach was utilized to determine the net source or sink of FIB in the ponds during the study periods. FIB concentrations often exceeded state standards, particularly in the summer, and microbial water quality in the sloughs was generally lower than in ponds during both seasons. Specifically, the inflow of water from the sloughs to the ponds during the summer, more so than waterfowl use, appeared to increase the FIB concentrations in the ponds. The box model results suggested that the ponds served as net wetland sources and sinks for FIB, and high bird abundances in the winter likely contributed to net winter source terms for two of the three FIB in both ponds. Eight serovars of the human pathogen Salmonella were isolated from slough and pond waters, although the source of the pathogen to these wetlands was not identified. Thus, it appeared that factors other than bird abundance were most important in modulating FIB concentrations in these ponds.

Water Research↗
USGS2002

Selenium toxicity: cause and effects in aquatic birds

There are several manners in which selenium may express its toxicity: (1) an important mechanism appears to involve the formation of CH3Se- which either enters a redox cycle and generates superoxide and oxidative stress, or forms free radicals that bind to and inhibit important enzymes and proteins. (2) Excess selenium as selenocysteine results in inhibition of selenium methylation metabolism. As a consequence, concentrations of hydrogen selenide, an intermediate metabolite, accumulate in animals and are hepatotoxic, possibly causing other selenium-related adverse effects. (3) It is also possible that the presence of excess selenium analogs of sulfur-containing enzymes and structural proteins play a role in avian teratogenesis. l-selenomethionine is the most likely major dietary form of selenium encountered by aquatic birds, with lesser amounts of l-selenocysteine ingested from aquatic animal foods. The literature is suggestive that l-selenomethionine is not any more toxic to adult birds than other animals. l-Selenomethionine accumulates in tissue protein of adult birds and in the protein of egg white as would be expected to occur in animals. There is no suggestion from the literature that the levels of l-selenomethionine that would be expected to accumulate in eggs in the absence of environmental concentration of selenium pose harm to the developing embryo. For several species of aquatic birds, levels of Se as selenomethionine in the egg above 3 ppm on a wet weight basis result in reduced hatchability and deformed embryos. The toxicity of l-selenomethionine injected directly into eggs is greater than that found from the entry of l-selenomethionine into the egg from the normal adult diet. This suggests that there is unusual if not abnormal metabolism of l-selenomethionine in the embryo not seen when l-selenomethionine is present in egg white protein where it likely serves as a source of selenium for glutathione peroxidase synthesis in the developing aquatic chick.

Aquatic Toxicology↗
USGS2003

Heavy metals and metalloids in egg contents and eggshells of passerine birds from Arizona

Concentrations of inorganic elements were determined in eggs of passerine birds including the endangered southwestern willow flycatcher ( Empidonax traillii extimus ) from four regions in Arizona. The main aim of the study was to determine the distribution of metals in egg contents and eggshells, with emphasis on the deposition of Sr in eggshells. Seventy eggs of 11 passerine species were collected at four nesting locations during 2000. Aluminum, Ba, Cr, Cu, Mn, Se, Sr, and Zn, were detected primarily in egg contents of all bird species. Arsenic, Ni, Pb, and V were detected primarily in eggshells. A proportion of most inorganic elements accumulated in the eggshell. Concentrations of Ba, Cu, Mn, Se, Sr, and Zn in egg contents and As, Ba, Cu, and V in eggshells of yellow-breasted chats ( Icteria virens ) were similar among locations. However, concentrations of Mn, Ni, Sr, and Zn in eggshells were significant different among locations. Except for Cu, Mn, Se, and Zn, concentrations of inorganic elements were 2–35 times greater in eggshells than in eggs. Most concentrations of metals and metalloids in eggs and eggshells of all the bird species were below levels known to affect reproduction or that have other deleterious effects. However, I found somewhat elevated concentrations of Sr in eggshells (highest mean=1505 μg/g dw, n =3) of yellow-breasted chats and willow flycatchers, and in egg contents of yellow warblers ( Dendroica petechia) and song sparrows ( Melospiza melodia ). Whether current observed concentrations of Sr in eggshells are affecting nesting birds in Arizona remains to be determined. Strontium and other metals could be associated with lower hatching success in some areas. This study shows that a proportion of many inorganic elements accumulates in the eggshell and that the potential effects on the proper structure and functioning of the eggshell should not be ignored.

Environmental Pollution↗
USGS2003

Establishing appropriate measures for monitoring aging in birds: comparing short and long lived species

In order to reveal patterns of reproductive aging in birds we focus on a short lived species, the Japanese quail and the American kestrel, which has a life span of medium length. Quail have been studied extensively in the laboratory as models for understanding avian endocrinology and behavior, and as a subject for toxicological research and testing. In the lab, Japanese quail show age-related deterioration in endocrine, behavioral, and sensory system responses; the American kestrel is relatively long lived and shows moderate evidence of senescence in the oldest birds. Using data collected from captive kestrels at the Patuxent Wildlife Research Center, a database was designed to document selected parameters over the life cycle of the kestrels. Life table data collated from many species indicate that longer lived species of birds show senescence in survival ability but this pattern has not been established for reproductive function. We suggest that useful comparisons among species can be made by identifying stages in reproductive life history, organized on a relative time scale. Preliminary data from quail and kestrels, admittedly only two species, do not yet indicate a pattern of greater reproductive senescence in longer-lived birds.

Experimental Gerontology↗
USGS1999

Poisoning of wild birds from exposure to anticholinesterase compounds and lead: diagnostic methods and selected cases

Organophosphorus and carbamate compounds have largely replaced chlorinated hydrocarbons for pesticidal use in the United States, and many cases of poisoning resulting from exposure to these anticholinesterase agents have occurred in free-living birds. Although lead shot has been prohibited for waterfowl hunting throughout the United States since 1991, lead poisoning from the ingestion of spent lead shot is still occasionally seen in wild birds, and lead poisoning from the ingestion of fishing sinkers is an emerging issue of concern. A thorough history, a complete necropsy evaluation, and appropriate laboratory analysis of tissues are required to diagnose toxicoses in wild birds, including those caused by anticholinesterase compounds and lead. The interpretation of brain cholinesterase (ChE) activity results depends on the methods of analysis and comparison with expected normal enzyme activities in brain tissue from the same species. Although lead residues in tissues vary among species, many lead poisoned birds have tissue residues that are much higher than the lower threshold commonly accepted for a diagnosis of lead poisoning. We review histories, necropsy findings, and analytical methodologies and results for selected anticholinesterase and lead poisoning cases diagnosed in wild raptors, waterfowl, and loons.

Seminars in Avian and Exotic Pet Medicine↗
USGS2019

Synthesis of maternal transfer of mercury in birds: Implications for altered toxicity risk

Maternal transfer is the predominant route of methylmercury (MeHg) exposure to offspring. We reviewed and synthesized published and unpublished data on maternal transfer of MeHg in birds. Using paired samples of females’ blood (n=564) and their eggs (n=1814) from 26 bird species in 6 taxonomic orders, we conducted a meta-analysis to evaluate whether maternal transfer of MeHg to eggs differed among species and caused differential toxicity risk to embryos. Total mercury (THg) concentrations in eggs increased with maternal blood THg concentrations; however, the proportion of THg transferred from females to their eggs differed among bird taxa and with maternal THg exposure. Specifically, a smaller proportion of maternal THg was transferred to eggs with increasing female THg concentrations. Additionally, the proportion of THg that was transferred to eggs at the same maternal blood THg concentration differed among taxonomic orders, with waterfowl (Anseriformes) transferring up to 382% more THg into their eggs than songbirds (Passeriformes). We provide equations to predict THg concentrations in eggs using female blood THg concentrations, and vice versa, which may help translate toxicity benchmarks across tissues and life stages. Our results indicate that toxicity risk of MeHg can vary among bird taxa due to differences in the maternal transfer of MeHg to offspring.

Environmental Science & Technology↗
USGS1997

A citywide breeding bird survey for Washington, D.C.

`DC Birdscape' was initiated in 1993 to systematically count the birds occurring throughout Washington D.C. during the breeding season. It involved a coordinated planning effort and partnership between the Audubon Naturalist Society, the National Park Service, and the National Biological Survey, and engaged the participation of more than 100 volunteers. A method for rapidly assessing the status of bird populations over a large area was developed and incorporated into a Geographic Information System to allow a multidimensional analysis of species presence and abundance across a variety of urban land use areas. A total of 91 species were observed, with an estimated total number of 115, making Washington D.C. almost as `bird rich' as nearby suburban counties. Data from the study clearly indicate that avian species are not randomly distributed throughout the Washington D.C. metropolitan area, and show affinity, at least in part, to some of the most broadly recognized land use patterns that are commonly used to zone and classify urban areas under development schemes. This study represents a prototype that will allow efficient and economical monitoring of urban bird populations.

Washington, D.C.↗
USGS2001

Forest area and distribution in the Mississippi alluvial valley: Implications for breeding bird conservation

Knowing the current forest distribution and patch size characteristics is integral to the development of geographically defined, habitat-based conservation objectives for breeding birds. Towards this end, we classified 2.6 million ha of forest cover within the Mississippi Alluvial Valley using 1992 thematic mapper satellite imagery. Although historically this area, from southern Illinois to southern Louisiana, was dominated by forested wetlands, forest cover remains on less than 25% of the floodplain. Remaining forest cover is comprised of > 38,000 discrete forest patches > 2 ha. Mean patch area (64.1±5.2 ha; x̄ ±SE) was highly skewed towards small fragment size. Larger patches had a higher proportion of more hydric forest cover classes than did smaller patches which had a higher proportion of less hydric forest cover classes. Public lands accounted for 16% of remaining forested wetlands. Fewer than 100 forest patches exceeded our hypothesized habitat objective (4000 ha minimum contiguous forest area) intended to support self-sustaining populations of forest breeding birds. To increase the number of forest patches exceeding 4000 ha contiguous area, and thereby increase the likelihood of successful forest bird conservation, we recommend afforestation adjoining existing forest fragments ≥1012 ha and focused within designated Forest Bird Conservation Regions.

Journal of Biogeography↗
USGS2009

Oxychlordane, HCS-3260, and nonachlor in birds: Lethal residues and loss rates

Oxychlordane reached lethal levels in birds given dietary dosages of HCS-3260 (70.75% cis-chlordane and 23.51% trans-chlordane) at 6 levels from 50 to 500 ppm. Oxychlordane ranged from 9.4 to 22.1 ppm in brains of cowbirds (Molothrus ater ) grackles (Quiscalus quiscula , and red-winged blackbirds (Agelaius phoeniceus ) that died on dosage and from 1.3 to 4.8 ppm in sacrificed birds, providing a clear diagnostic separation. Among starlings (Sturnus vulgaris ) however, oxychlordane ranged from 5.0 to 19.1 ppm in brains of birds that died, significantly lower than in the other species, and from 1.4 to 10.5 ppm in sacrificed birds, overlapping the levels in those that died. Lethal levels, therefore, begin near 5.0 ppm, as in a previous study in which oxychlordane itself was fed, but the data from starlings emphasizes the need for confirmatory necropsy findings in diagnosis of poisoning.

Journal of Toxicology and Environmental Health↗
USGS1988

Selenium toxicosis in wild aquatic birds

Severe gross and microscopic lesions and other changes were found in adult aquatic birds and in embryos from Kesterson Reservoir (a portion of Kesterson National Wildlife Refuge), Merced County, Calif., during 1984. Adult birds from that area were emaciated, had subacute to extensive chronic hepatic lesions, and had excess fluid and fibrin in the peritoneal cavity. Biochemical changes in their livers included elevated glycogen and non-protein-bound sulfhydryl concentrations and glutathione peroxidase activity but lowered protein, total sulfhydryl, and protein-bound sulfhydryl concentrations. Congenital malformations observed grossly in embryos were often multiple and included anophthalmia, microphthalmia, abnormal beaks, amelia, micromelia, ectrodactyly, and hydrocephaly. Mean concentrations of selenium in livers (94.4 ppm, dry weight) and kidneys (96.6 ppm) of birds collected at the Kesterson ponds were about 10 times those found at a nearby control area (8.3 and 12.2 ppm). We conclude that selenium present in the agricultural drainage water supplied to the Kesterson ponds accumulated in the food chain of aquatic birds to toxic concentrations and caused the lesion and other changes observed.

California↗
USGS2025

Population trends of native and non-native forest birds on the island of Molokai, Hawaii

Hawaiʻi’s avifauna has undergone profound changes over the past 1,000 years, with many endemic bird species driven to extinction and non-native introductions reshaping forest ecosystems. On the island of Molokaʻi, habitat degradation and the introduction of mosquito-borne disease, mainly avian malaria ( Plasmodium relictum ), have caused extinctions and severe declines in native forest bird populations. To assess these changes, point-transect distance sampling surveys were initiated in 1979 and 1980 and repeated six times, most recently in 2021, covering a 3,527 ha area. This study analyzes species composition, population densities, abundances, and long-term trends for species with sufficient detections using log-linear regression. Since 1979–1980, a total of 17 non-native and 3 native species were detected across all six surveys. The non-native Warbling White-eye ( Zosterops japonicus ) had the highest density and abundance in every survey, while abundance of Red-billed Leiothrix ( Leiothrix lutea ) significantly trended upward. The Japanese Bush Warbler ( Horornis diphone ) irrupted in the survey area, increasing in abundance by more than 99% since 1979–1980. Among native species, ʻApapane ( Himatione sanguinea ) populations increased by 33%, while Hawaiʻi ʻAmakihi ( Chlorodrepanis virens ) declined by 78% from their peak in 1995. Federally threatened ʻIʻiwi ( Drepanis coccinea ), highly susceptible to avian malaria, have not been recorded on Molokaʻi since 2010, and the endemic Olomaʻo ( Myadestes lanaiensis ) has not been detected since 1980 and is possibly extinct. Our results underscore the ongoing conservation crisis for Molokaʻi’s forest birds and the continued vulnerability of native birds to disease and habitat loss.

Hawaii↗
USGS1990

Survival rates of birds of tropical and temperate forests: Will the dogma survive?

Survival rates of tropical forest birds are widely assumed to be high relative to the survival rates of temperate forest birds. Much life-history theory is based on this assumption despite the lack of empirical data to support it. We provide the first detailed comparison of survival rates of tropical and temperate forest birds based on extensive data bases and modern capture-recapture models. We find no support for the conventional wisdom. Because clutch size is only one component of reproductive rate, the frequently assumed, simple association between clutch size and adult survival rates should not necessarily be expected. Our results emphasize the need to consider components of fecundity in addition to clutch size when comparing the life histories of tropical and temperate birds and suggest similar considerations in the development of vertebrate life-history theory.

American Naturalist↗
USGS2003

Detection of West Nile virus infection in birds in the United States by blocking ELISA and immunohistochemistry

A blocking ELISA targeting an immunodominant West Nile epitope on the West Nile Virus NS1 protein was assessed for the detection of West Nile–specific antibodies in blood samples collected from 584 sentinel chickens and 238 wild birds collected in New Jersey from May–December 2000. Ten mallard ducks ( Anas platyrhynchos ) experimentally infected with West Nile virus and six uninfected controls were also tested. The ELISA proved specific in detecting WNV antibodies in 9/10 chickens and 4/4 wild birds previously confirmed as positive by Plaque Reduction Neutralization test (PRNT) at the Center for Disease Control, Division of Vector Borne Diseases, Fort Collins, CO, USA (CDC). Nine out of the ten experimentally infected mallard ducks also tested positive for WN antibodies in the blocking ELISA, while 6/6 uninfected controls did not. Additionally, 1705 wild birds, collected in New Jersey from December 2000–November 2001 and Long Island, New York between November 1999 and August 2001 were also tested for WN antibodies by the blocking ELISA. These tests identified 30 positive specimens, 12 of which had formalin-fixed tissues available to allow detection of WN specific viral antigen in various tissues by WNV-specific immunohistochemistry. Our results indicate that rapid and specific detection of antibodies to WN virus in sera from a range of avian species by blocking ELISA is an effective strategy for WN Virus surveillance in avian hosts. In combination with detection of WN-specific antigens in tissues by immunohistochemistry (IHC) the blocking ELISA will also be useful for confirming WN infection in diseased birds.

Colorado, New Jersey, New York↗
USGS2012

Cross-seasonal patterns of avian influenza virus in breeding and wintering migratory birds: a flyway perspective

The spread of avian influenza viruses (AIV) in nature is intrinsically linked with the movements of wild birds. Wild birds are the reservoirs for the virus and their migration may facilitate the circulation of AIV between breeding and wintering areas. This cycle of dispersal has become widely accepted; however, there are few AIV studies that present cross-seasonal information. A flyway perspective is critical for understanding how wild birds contribute to the persistence of AIV over large spatial and temporal scales, with implications for how to focus surveillance efforts and identify risks to public health. This study characterized spatio-temporal infection patterns in 10,389 waterfowl at two important locations within the Pacific Flyway--breeding sites in Interior Alaska and wintering sites in California's Central Valley during 2007-2009. Among the dabbling ducks sampled, the northern shoveler (Anas clypeata) had the highest prevalence of AIV at both breeding (32.2%) and wintering (5.2%) locations. This is in contrast to surveillance studies conducted in other flyways that have identified the mallard (Anas platyrhynchos) and northern pintail (Anas acuta) as hosts with the highest prevalence. A higher diversity of AIV subtypes was apparent at wintering (n=42) compared with breeding sites (n=17), with evidence of mixed infections at both locations. Our study suggests that wintering sites may act as an important mixing bowl for transmission among waterfowl in a flyway, creating opportunities for the reassortment of the virus. Our findings shed light on how the dynamics of AIV infection of wild bird populations can vary between the two ends of a migratory flyway.

Vector-Borne and Zoonotic Diseases↗
USGS2003

Agricultural landscapes: Can they support healthy bird populations as well as farm products?

At the beginning of the twentieth century, prospects for bird populations occupying farmlands were promising. Agricultural expansion and the resulting deforestation produced wholesale changes to the landscape of eastern North America (Trautman 1977, Zeranski and Baptist 1990, Nicholson 1997). Regional avifaunas were transformed as Horned Larks ( Eremophila alpestris ), Dickcissels (Spiza americana), and other farmland birds undertook range expansions (Hurley and Franks 1976, Askins 1999). Those farmland birds became conspicuous, frequently in numbers that are hard to imagine today (Trautman 1940). One hundred years later, many of those once plentiful species experienced dramatic population declines (Askins 1993, Peterjohn and Sauer 1999). Those trends were evident for many decades, although pre-1965 trends were largely based on anecdotal accounts and were frequently attributed to changing regional landscapes due to urban expansion, farm abandonment resulting in increased forest cover, and the more intensive use of remaining agricultural fields (Trautman 1940, Herkert 1991, Askins 2000). However, numerous specific factors were implicated in local declines of individual species (Kantrud 1981, Bollinger et al. 1990, Lymn and Temple 1991, Bowen and Kruse 1993, Herkert 1994, Houston and Schmutz 1999, Blackwell and Dolbeer 2001). Understanding factors responsible for population changes can be approached at various geographic scales. Local studies identify specific factors influencing small populations, but the applicability of those results across broad geographic areas is often uncertain. Studies conducted at large geographic scales identify broad patterns of change, but those patterns frequently involve interrelated factors that may be only loosely related to the actual causes of population change. However, correlations between broad patterns of changes in bird populations and land-use characteristics provide a basis for directing future studies conducted at smaller geographic scales.

The Auk↗
USGS2002

Temporal variation in bird counts within a Hawaiian rainforest

We studied monthly and annual variation in density estimates of nine forest bird species along an elevational gradient in an east Maui rainforest. We conducted monthly variable circular-plot counts for 36 consecutive months along transects running downhill from timberline. Density estimates were compared by month, year, and station for all resident bird species with sizeable populations, including four native nectarivores, two native insectivores, a non-native insectivore, and two non-native generalists. We compared densities among three elevational strata and between breeding and nonbreeding seasons. All species showed significant differences in density estimates among months and years. Three native nectarivores had higher density estimates within their breeding season (December-May) and showed decreases during periods of low nectar production following the breeding season. All insectivore and generalist species except one had higher density estimates within their March-August breeding season. Density estimates also varied with elevation for all species, and for four species a seasonal shift in population was indicated. Our data show that the best time to conduct counts for native forest birds on Maui is January-February, when birds are breeding or preparing to breed, counts are typically high, variability in density estimates is low, and the likelihood for fair weather is best. Temporal variations in density estimates documented in our study site emphasize the need for consistent, well-researched survey regimens and for caution when drawing conclusions from, or basing management decisions on, survey data.

Hawaii↗
USGS2020

Monocrotophos and dicrotophos residues in birds as a result of misuse of organophosphates in Matagorda county Texas USA

About 1100 birds of 12 spp. [Red-winged blackbird ( Agelaius phoeniceus ), great-tailed grackle ( Quiscalus mexicanus ), brown-headed cowbird ( Molothrus ater ), mourning dove ( Zenaida macrours ), Eastern meadowlark ( Sturnella magna ), vesper sparrow ( Pooecetes gramineus ), common snipe ( Gallinago gallinago ), blue-winged teal ( Anas discors ), mottled duck ( Anas fulvigula ), common moorhen ( Gallinula chloropus ), redhead ( Aythya americana ) and ruddy turnstone ( Arenaria interpres )] died from organophosphate poisoning in Matagorda County on the Texas Gulf Coast in March and May 1982. Birds died from feeding on rice seed that was illegally treated with dicrotophos or monocrotophos and placed near rice fields as bait to attract and kill birds. Brain acetylcholinesterase inhibition of affected birds averaged 87% (range 82-89%), and contents of gastrointestinal tracts contained residues of dicrotophos (5.6-14 ppm) or monocrotophos (2.1-13 ppm). Rice seed collected at mortality sites contained 210 ppm dicrotophos or 950 ppm monocrotophos. Mortality from dicrotophos poisoning continued for almost 3 wk. The practice of illegally treating rice seed with either of the 2 organophosphates appears to be infrequent but widespread at present.

Texas↗