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At least 19 recordsLinked to original sources
USGS2011

Migration And wintering areas Of Glaucous-winged Gulls From south-central Alaska

We used satellite telemetry to investigate the migration patterns and wintering areas of Glaucous-winged Gulls (Larus glaucescens) from Middleton Island, Alaska, where this species' population increased tenfold from the 1970s to the 1990s. Fall migration spanned 11 weeks, including numerous stopovers en route, apparently for feeding. Spring migration from wintering sites to Middleton Island was shorter (4 weeks) and more direct. One juvenile spent several months in southern Prince William Sound. An adult spent several months near Craig, southeast Alaska, while three others overwintered in southern British Columbia. For all four wintering adults use of refuse-disposal sites was evident or strongly suggested. Commensalism with humans may have contributed to the increase on Middleton, but a strong case can also be made for a competing explanation-regional recruitment of gulls to high-quality nesting habitat in Alaska created after the earthquake of 1964. An analysis of band returns reveals broad overlap in the wintering grounds of gulls from different Alaska colonies and of gulls banded on the west coast from British Columbia to California. The seasonal movement of many gulls from Alaska is decidedly migratory, whereas gulls from British Columbia, Washington, and Oregon disperse locally in winter.

Alaska↗
USGS2006

Effectiveness of spinning-wing decoys varies among dabbling duck species and locations

Spinning-wing decoys are strong attractants to ducks and inc rease kill rates over traditional decoying methods. However, it is unknown whether all duck species are attracted similarly to spinning-wing decoys and whether the effectiveness of these decoys changes with latitude. We examined the effectiveness of spinning-wing decoys for 9 species of dabbling ducks during 545 experimental hunts in California (1999-2000), Minnesota (2002), Manitoba (2001-2002), Nebraska (2000-2002), Missouri (2000-2001), and Arkansas (2001-2003). During each experimental hunt, we systematically alternated between 2 paired decoy treatments every 15-30 min (depending on study site): traditional decoys only and traditional decoys with a spinning-wing decoy. Overall, 70.2% (n=1,925) of dabbling ducks were harvested (shot and retrieved) when spinning-wing decoys were turned on, ranging from 63.6% (n=187) in Missouri to 76.4% (n=356) in Minnesota. Effectiveness of spinning-wing decoys increased with latitude of study sites. Proportions of ducks shot when spinning-wing decoys were turned on differed among species, from a low of 50.0% (n=8) for cinnamon teal (Anas cyanoptera) to a high of 79.0% (n=119) for American wigeon (A. americana). The probability of being shot when spinning-wing decoys were turned on increased with annual survival rates among species; for example, spinning-wing decoys were more effective for American wigeon and mallard (A. platyrhynchos) than they were for cinnamon teal and American green-winged teal (A. crecca). Effectiveness of spinning-wing decoys did not differ consistently by age or sex of harvested ducks. Our results indicate that the effectiveness of spinning-wing decoys differs among duck species and changes with latitude; thus, consideration of these effects may be warranted when setting harvest regulations and methods of take.

Journal of Wildlife Management↗
USGS2017

Refined conservation strategies for Golden-winged Warblers in the West Virginia highlands with implications for the broader avian community

Golden-winged Warbler ( Vermivora chrysoptera ) populations in the Appalachian Mountains region of North America are imperiled, warranting species-specific conservation. However, management for Golden-winged Warblers can affect both early-successional and forest species, many of which are also declining in the region. We conducted point counts in sites representing a range of successional stages within the Golden-winged Warbler's breeding range in West Virginia, USA, during 2008–2015. We identified plausible models of Golden-winged Warbler density using covariates at 4 spatial scales representing annual dispersal (5-km radius), extraterritorial movement (1.5-km radius), intraterritorial movement (100-m radius), and local resource utilization (11.3-m radius). Golden-winged Warbler density peaked at an intermediate elevation at the 1.5-km radius scale, but was negatively associated with 100-m radius minimum elevation. Density was positively associated with 100-m radius shrubland cover. Southerly latitudes were associated with higher densities when modeled alone, but there was no association when controlling for other covariates. We then examined the relationship between covariates from these plausible models and avian community structure using canonical correspondence analysis to assess the value of Golden-winged Warbler conservation for the broader avian community. We identified 5 species likely to benefit from management for Golden-winged Warblers and 21 species likely to be affected positively or negatively to varying degrees depending on their affinity for early-successional vegetation communities. Golden-winged Warblers were plotted higher along the 100-m shrubland cover gradient than any other bird species, suggesting that they may be the most shrubland area–sensitive songbird in our study area. However, the species also requires heavily forested landscapes. Therefore, a species-specific conservation strategy that balances shrubland (patches of 9–13 ha in size, comprising 15% of the landscape) and contiguous forest area (≥75% of the landscape) could concurrently meet the needs of Golden-winged Warblers and the 26 other species identified.

West Virginia↗
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↗
USGS1973

Organochlorine residues in woodcock wings, 11 states--1970-71

A survey of organochlorine residues in woodcock wings was undertaken to determine whether these wings are suitable for showing regional differences in residues and to obtain a baseline in 1970-71 for later comparisons. Woodcock wings were obtained from the annual hunter's wing survey. Samples came from eight States (Louisiana, Maine, Michigan, New Hampshire, New Jersey, New York, Pennsylvania, and Wisconsin) and one tri-State area (North Carolina, South Carolina, and Georgia). Wings from the tri-State area contained significantly higher (P<0.01) concentrations of DDT (including DDT, DDD, and DDE) than those from other States. Concentrations of polychlorinated biphenyls (PCB's) also were significantly higher (P<0.05) in samples from these three States. Wings from Louisiana and the tri-State area had significantly higher (P<0.01) concentrations of dieldrin than wings from the other States, and those from Louisiana had significantly higher (P < 0.01) concentrations of mirex than those from other States. (Residues are on lipid base) The compounds detected and the ranges of residue means for all sampling areas were as follows: Total DDT (5.89--65.15 ppm); DDT (0.34 m--14.93 ppm); DDE (4.66--47.47 ppm); DDD (0.11--3.44 ppm); mirex (0.76--16.93 ppm); dieldrin (0.09--3.06 ppm); and PCB's (4.27--8.63 ppm). Woodcock wings appear to be suitable for determining regional differences in organochlorine residues in this species.

Pesticides Monitoring Journal↗
USGS2015

Feather isotope analysis reveals differential patterns of habitat and resource use in populations of white-winged doves

The white-winged dove ( Zenaida asiatica ) serves an important ecological role as a diurnal pollinator of the saguaro cactus in the Sonoran desert and an economic role as a highly sought after game bird in North America. White-winged doves are intimately linked to anthropogenic changes on the landscape and because of this, have experienced dramatic population fluctuations over the last 75 years in response, both positively and negatively, to anthropogenic changes on the landscape. To understand the factors driving population growth and decline of migratory species like the white-winged dove, it is imperative we study resource use on both their breeding and wintering grounds. To understand how populations are distributed on the wintering grounds, we tested an alternative to band recovery approaches by using stable isotope analysis. Before we could use isotope analysis to link breeding and wintering locations for this species, we first needed to determine if hydrogen (&delta; 2 H) and carbon (&delta; 13 C) stable isotopes in feather tissue (&delta; 2 H f and &delta; 13 C f , respectively) could differentiate among populations of white-winged doves across their breeding range in Texas, New Mexico, and Arizona. &delta; 2 H f and &delta; 13 C f not only differentiated between populations of white-winged doves that breed in the United States, but &delta; 2 H f also provided further differentiation in white-winged doves that breed in native Sonoran Desert and agricultural habitats in the western portion of their range. Ecological processes associated with desert resources and anthropogenic influences, specifically saguaro cacti and irrigated crops, largely determined &delta; 2 H f in some white-winged doves in Arizona whereas &delta; 2 H of precipitation (&delta; 2 H p ) largely determined &delta; 2 H f of doves in New Mexico and Texas. This study highlights the usefulness of stable isotope analysis to differentiate populations of animals across the landscape and the insight isotopes can provide into habitat and resource use. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.

Arizona, California, New Mexico, Texas↗
USGS2016

Evidence for the exchange of blood parasites between North America and the Neotropics in blue-winged teal ( Anas discors )

Blue-winged teal ( Anas discors ) are abundant, small-bodied dabbling ducks that breed throughout the prairies of the northcentral USA and central Canada and that winter in the southern USA and northern Neotropics. Given the migratory tendencies of this species, it is plausible that blue-winged teal may disperse avian pathogens, such as parasites causing avian malaria, between spatially distant areas. To test the hypothesis that blue-winged teal play a role in the exchange of blood parasites between North America and areas further south, we collected information on migratory tendencies of this species and sampled birds at spatially distant areas during breeding and non-breeding periods to diagnose and genetically characterize parasitic infections. Using a combination of band recovery data, satellite telemetry, molecular diagnostics, and genetic analyses, we found evidence for (1) migratory connectivity of blue-winged teal between our sampling locations in the Canadian prairies and along the US Gulf Coast with areas throughout the northern Neotropics, (2) parasite acquisition at both breeding and non-breeding areas, (3) infection of blue-winged teal sampled in Canada and the USA with Plasmodium parasite lineages associated with the Neotropics, and (4) infection of blue-winged teal with parasites that were genetically related to those previously reported in waterfowl in both North America and South America. Collectively, our results suggest that blue-winged teal likely play a role in the dispersal of blood parasites between the Neotropics and North America, and therefore, the targeting of this species in surveillance programs for the early detection of Neotropical-origin avian pathogens in the USA may be informative.

Parasitology Research↗
USGS2017

Body mass, wing length, and condition of wintering ducks relative to hematozoa infection

Waterfowl managers lack information regarding factors that may be reducing the positive response of waterfowl body condition to habitat improvements. Protozoan blood parasites (i.e., hematozoa) are commonly found in birds and have been related to reduced body mass, wing length, and body condition. We studied relationships between 12 measures of hematozoa infection and body mass, wing length, and body mass divided by wing length (i.e., body condition index [BCI]) of the five most common duck species (northern pintail [ Anas acuta ], mallard [ A. platyrhynchos ], green-winged teal [ A. crecca ], American wigeon [ A. Americana ], northern shoveler [ A. clypeata ]) wintering in the Central Valley of California during October 2006-January 2007. After accounting for variation due to species, age-sex cohort, Central Valley region, and month; wing length, body mass, and BCI were found to be negatively related to infection by Leucocytozoon and by "any hematozoa" but not related to infection by only Plasmodium or Haemoproteus , or coinfections of greater than one genera or parasite haplotype (albeit, few ducks had Plasmodium or Haemoproteus infection or coinfections). Evidence of a negative relationship with infection was stronger for body mass and BCI than for wing length and indicated that the relationships varied among species, age-sex cohorts, regions, and months. Compared to uninfected ducks, hematozoa-infected duck body mass, wing length, and BCI was -1.63% (85% CI = -2.79%- -0.47%), -0.12% (-0.41%- +0.17%), and -1.38% (-2.49%- -0.26%), respectively. Although, seemingly small, the -1.63% difference in body mass represents a large percentage (e.g., 38% for northern pintail) of the observed increase in wintering duck body mass associated with Central Valley habitat improvements. Because infection prevalence and relationship to body condition might change over time due to climate or other factors, tracking hematozoa infection prevalence might be important to inform and accurately assess the effect of conservation programs designed to improve waterfowl body condition.

California↗
USGS1978

Organochlorine insecticide and polychlorinated biphenyl residues in woodcock wings, 1971-72

Pesticide residues in wings of adult woodcock (Philohela minor) were used to monitor regional differences in a 1970-71 survey of DDT, DDE, TDE, dieldrin, mirex, and PCBs in Maine, New Hampshire, New York, New Jersey, Pennsylvania, North Carolina, South Carolina, Georgia, Lousiana, Michigan, and Wisconsin. In 1971-72, wings were sampled again to compare levels of organochlorine insecticide residues with those of the previous survey and to delineate differences in residue values between adult and immature woodcock. Three additional states, Massachusetts, Minnesota, and Vermont, and one additional organochlorine insecticide, heptachlor epoxide, were included in the second survey. Residue levels in the 1971-72 wings showed the same pattern as that observed in 1970-71: organochlorine insecticide residues were highest in wings collected in the southern states and in New Jersey; residues were lowest in samplings taken in the northern and midwestern states. Residues of DDT, TDE, and dieldrin in the 1971-72 wings were slightly lower than those found in 1970-71. DDE, PCB, and mirex residues were significantly lower (P<0.05, P<0.01, and P<0.01, respectively) in 1971-72. Wings of immature woodcock in Louisiana had significantly lower (P <0.05) mirex residues than did adult wings.

Pesticides Monitoring Journal↗
USGS2016

Space and habitat use by breeding Golden-winged Warblers in the central Appalachian Mountains

Spot-mapping, or recording locations of observed use by territorial songbirds, is often used to delineate core breeding territories. However, a recent radiotelemetry study in Minnesota found that male Golden-winged Warblers ( Vermivora chrysoptera ) occurring in high-density populations used resources outside their spot-mapped territories. We compared differences in space use and quantified vegetation characteristics in territories and home ranges of individual male Golden-winged Warblers that we monitored using both spot-mapping and radiotelemetry. Our study sites in Pennsylvania and West Virginia had lower population density than in Minnesota. We recorded 524 telemetry locations among 12 male Golden-winged Warblers in Pennsylvania and 488 telemetry locations among seven males in West Virginia. Telemetry-delineated home ranges (100% and 50% minimum convex polygons [MCPs]) were two to four times larger than spot-mapped territories. Spot-mapped territories had minimal overlap among individual males, but home ranges had extensive space-use overlap in both the number and amount of MCP overlap among several males. Forty percent of telemetry locations were outside of spot-mapped territories. Sapling abundance was greater in home ranges (mean 22.5 saplings ± 2.1 SE) than spot-mapped territories in Pennsylvania (11.8 ± 1.9). In managed pastures of West Virginia, tree abundance was greater in home ranges (7.3 trees ± 0.8) than spot-mapped territories (1.9 ± 0.6). More telemetry locations than spot-mapped locations occurred in forest in both states, and telemetry locations were closer to intact forested edges of shrublands than spot-mapped locations in West Virginia. On several occasions, we observed radiomarked individuals >200 m (maximum of 1.5 km) from their MCP spot-mapped territory boundaries. Why Golden-winged Warblers leave their spot-mapped territories is unknown, but our observations suggest foraging, forays for extra-pair mating, and reconnaissance for postbreeding movements as possible motives. Our results from areas with low Golden-winged Warbler territory densities are similar to patterns reported for a high-density population in Minnesota. Ultimately, spot-mapping alone does not accurately reflect space use of Golden-winged Warblers during the breeding season, nor does it characterize all cover types used even in areas with relatively low territory densities. Current conservation plans for Golden-winged Warblers that are based on habitat characteristics measured within spot-mapped territories or at the landscape scale may not adequately incorporate space use at intermediate spatial scales of clusters of territories or home ranges.

Studies in Avian Biology↗
USGS1986

Organochlorine residues in adult mallard and black duck wings, 1981-1982

Ten organochlorine compounds were identified in pools of black duck ( Anas rubripes ) and mallard ( A. platyrhynchos ) wings from the 1981–82 hunting season. Most organochlorine compounds occurred very infrequently. Among those compounds positively identified by mass spectrometry, DDE and, secondarily, PCB had the highest frequencies of occurrence. Other compounds, positively identified and occurring less frequently, included DDT, DDD, DDMU, dieldrin, heptachlor epoxide, trans -nonachlor, cis -chlordane and mirex. Compounds looked for but not positively identified include oxychlordane, cis -nonachlor, endrin, hexachlorobenzene and toxaphene. PCB levels in black duck wings declined between the 1979–80 and 1981–82 collections. PCB levels in black duck wings from the northern region of the Atlantic Flyway were higher than those in wings from the southern region. Mean DDE residues in mallard wings declined between collections and differed among flyways and regions. PCB levels in mallard wings differed only among flyways and regions.

Environmental Monitoring and Assessment↗
USGS2002

Timing and magnitude of Broad-winged Hawk migration at Montclair Hawk Lookout, New Jersey, and Hawk Mountain Sanctuary, Pennsylvania

The Broad-winged Hawk ( Buteo platypterus ) breeds in eastern and central Canada and the United States, and winters in Central America and northern and central South America. Birders and ornithologists count migrating Broad-winged Hawks at dozens of traditional watch sites throughout the northeastern United States. We modeled counts of migrating Broad-winged Hawks from two raptor migration watch sites: Montclair Hawk Lookout, New Jersey, and Hawk Mountain Sanctuary, Pennsylvania, to determine whether annual abundance and trend estimates from individual sites within the mid-Atlantic states are representative of the region as a whole. We restricted ourselves to counts made between 10:00 and 16:00 EST during September to standardize count effort between sites. We created one model set for annual counts and another model set for daily counts. When modeling daily counts we incorporated weather and identity of individual observers. Akaike’s Information Criteria were used to select the best model from an initial set of competing models. Annual counts declined at both sites during 1979–1998. Broad-winged Hawk migration began, peaked, and ended later at Montclair than at Hawk Mountain, even though Hawk Mountain is 155 km west-southwest of Montclair. Mean annual counts of hawks at Montclair were more than twice those at Hawk Mountain, but were not correlated. Broad-winged Hawks counted at Montclair may not be the same birds as those counted at Hawk Mountain. Rather, the two sites may be monitoring different regional subpopulations. Broad-winged Hawks counted at the two sites may use different migration tactics, with those counted at Hawk Mountain being more likely to slope soar, and those at Montclair more likely to use thermal soaring. A system of multiple watch sites is needed to monitor various breeding populations of this widely dispersed migrant.

New Jersey, Pennsylvania↗
USGS2014

Nonlethal screening of bat-wing skin with the use of ultraviolet fluorescence to detect lesions indicative of white-nose syndrome

Definitive diagnosis of the bat disease white-nose syndrome (WNS) requires histologic analysis to identify the cutaneous erosions caused by the fungal pathogen Pseudogymnoascus [formerly Geomyces] destructans (Pd). Gross visual inspection does not distinguish bats with or without WNS, and no nonlethal, on-site, preliminary screening methods are available for WNS in bats. We demonstrate that long-wave ultraviolet (UV) light (wavelength 368&ndash;385 nm) elicits a distinct orange&ndash;yellow fluorescence in bat-wing membranes (skin) that corresponds directly with the fungal cupping erosions in histologic sections of skin that are the current gold standard for diagnosis of WNS. Between March 2009 and April 2012, wing membranes from 168 North American bat carcasses submitted to the U.S. Geological Survey National Wildlife Health Center were examined with the use of both UV light and histology. Comparison of these techniques showed that 98.8% of the bats with foci of orange&ndash;yellow wing fluorescence (n = 80) were WNS-positive based on histologic diagnosis; bat wings that did not fluoresce under UV light (n = 88) were all histologically negative for WNS lesions. Punch biopsy samples as small as 3 mm taken from areas of wing with UV fluorescence were effective for identifying lesions diagnostic for WNS by histopathology. In a nonlethal biopsy-based study of 62 bats sampled (4-mm diameter) in hibernacula of the Czech Republic during 2012, 95.5% of fluorescent (n = 22) and 100% of nonfluorescent (n = 40) wing samples were confirmed by histopathology to be WNS positive and negative, respectively. This evidence supports use of long-wave UV light as a nonlethal and field-applicable method to screen bats for lesions indicative of WNS. Further, UV fluorescence can be used to guide targeted, nonlethal biopsy sampling for follow-up molecular testing, fungal culture analysis, and histologic confirmation of WNS.

Journal of Wildlife Diseases↗
USGS1990

Weights of wild mallard Anas platyrhynchos, gadwall A. strepera, and blue-winged teal A. discors during the breeding season

During 1976-81 we weighed several thousands of wild Mallard, Gadwall, and Blue-winged Teal in central North Dakota to examine duckling growth patterns, adult weights, and the factors influencing them. One-day-old Mallard and Gadwall averaged 32.4 and 30.4 g, respectively, a reduction of 34% and 29% from fresh egg weights. In all three species, the logistic growth curve provided a good fit for duckling growth patterns. Except for the asymptote, there was no difference in growth curves between males and females of a species. Mallard and Gadwall ducklings were heavier in years when wetland area was extensive or had increased from the previous year. Weights of after-second-year females were greater than yearlings for Mallard but not for Gadwall or Blue-winged Teal. Adult Mallard females lost weight continuously from late March to early July. Gadwall and Blue-winged Teal females, which nest later than Mallard, gained weight after spring arrival, lost weight from the onset of nesting until early July, and then regained some weight. Females of all species captured on nests were lighter than those captured off nests at the same time. Male Mallard weights decreased from spring arrival until late May. Male Gadwall and Blue-winged Teal weights increased after spring arrival, then declined until early June. Males of all three species then gained weight until the end of June. Among adults, female Gadwall and male Mallard and Blue-winged Teal were heavier in years when wetland area had increased from the previous year; female Blue-winged Teal were heavier in years with more wetland area.

Wildfowl↗
USGS2012

Spot-mapping underestimates song-territory size and use of mature forest by breeding golden-winged warblers in Minnesota, USA

Studies of songbird breeding habitat often compare habitat characteristics of used and unused areas. Although there is usually meticulous effort to precisely and consistently measure habitat characteristics, accuracy of methods for estimating which areas are used versus which are unused by birds remains generally untested. To examine accuracy of spot-mapping to identify singing territories of golden-winged warblers ( Vermivora chrysoptera ), which are considered an early successional forest specialists, we used spot-mapping and radiotelemetry to record song perches and delineate song territories for breeding male golden-winged warblers in northwestern Minnesota, USA. We also used radiotelemetry to record locations (song and nonsong perches) of a subsample ( n &thinsp;=&thinsp;12) of males throughout the day to delineate home ranges. We found that telemetry-based estimates of song territories were 3 times larger and included more mature forest than those estimated from spot-mapping. In addition, home ranges estimated using radiotelemetry included more mature forest than spot-mapping- and telemetry-based song territories, with 75% of afternoon perches located in mature forest. Our results suggest that mature forest comprises a larger component of golden-winged warbler song territories and home ranges than is indicated based on spot-mapping in Minnesota. Because it appears that standard observational methods can underestimate territory size and misidentify cover-type associations for golden-winged warblers, we caution that management and conservation plans may be misinformed, and that similar studies are needed for golden-winged warblers across their range and for other songbird species.

Minnesota↗
USGS1984

Changes in levels of organochlorines in woodcock wings from 1971 to 1975

Wings from woodcock ( Philohela minor ) were first monitored for organochlorine pesticides and polychlorinated biphenyls (PCBs) in the eastern U.S. in 1971. Regional differences in these compounds were clearly demonstrated and baseline residue levels were obtained for later comparisons. An expanded sampling of wings in 1972 revealed that residues in wings of adult woodcock may differ significantly from those in immatures, and that residues of several important agricultural insecticides and PCBs had declined significantly. More extensive sampling was undertaken in 1975 to determine if changes in residue levels had taken place in the intervening years. PCBs, mirex, and heptachlor epoxide increased significantly between 1972 and 1975 in adult woodcock wings. In immature woodcock wings mirex, dieldrin, and PCBs increased significantly between 1972 and 1975, but DDT residues decreased significantly.

Environmental Monitoring and Assessment↗
USGS2016

Mercury concentrations in eggs of red-winged blackbirds and tree swallows breeding in Voyageurs National Park, Minnesota

Most investigations of the environmental effects of mercury (Hg) have focused on aquatic food webs that include piscivorous fish or wildlife. However, recent investigations have shown that other species, including passerine songbirds, may also be at risk from exposure to methylmercury (MeHg). We quantified Hg concentrations in eggs of two species of songbirds, red-winged blackbirds ( Agelaius phoeniceus ) and tree swallows ( Tachycineta bicolor ), nesting in Voyageurs National Park, Minnesota, USA. Geometric mean concentrations of total Hg (THg) were lower in red-winged blackbird eggs [218 and 107 ng/g dry weight (dw) for 2012 and 2013, respectively] than in tree swallow eggs (228 and 300 ng/g dw for 2012 and 2013, respectively), presumably reflecting differences in the trophic positions of these two species. Concentrations of MeHg averaged 98.4 % of THg in red-winged blackbird eggs. Levels of THg observed in this study were well below critical toxicological benchmarks commonly applied to eggs of avian species, suggesting these breeding populations were not adversely affected by exposure to MeHg. In red-winged blackbirds, concentrations of THg in eggs collected in 2012 were twice those in eggs collected in 2013. Hg levels in eggs of both species increased with date of clutch initiation. In red-winged blackbirds, for example, temporal patterns showed that a 3-week delay in clutch initiation increased egg THg by 60 %. These observations indicate that in ovo exposure of wetland birds to MeHg can vary significantly within nesting season as well as between years.

Minnesota↗
USGS2018

Annual cycle of White-winged Scoters (Melanitta fusca) in eastern North America: Migratory phenology, population delineation, and connectivity

Understanding full annual cycle movements of long-distance migrants is essential for delineating populations, assessing connectivity, evaluating crossover effects between life stages, and informing management strategies for vulnerable or declining species. We used implanted satellite transmitters to track up to 2 years of annual cycle movements of 52 adult female White-winged Scoters ( Melanitta fusca (Linnaeus, 1758)) captured in the eastern United States and Canada. We used these data to document annual cycle phenology; delineate migration routes; identify primary areas used during winter, stopover, breeding, and molt; and assess the strength of migratory connectivity and spatial population structure. Most White-winged Scoters wintered along the Atlantic coast from Nova Scotia to southern New England, with some on Lake Ontario. White-winged Scoters followed four migration routes to breeding areas from Quebec to the Northwest Territories. Principal postbreeding molting areas were in James Bay and the St. Lawrence River estuary. Migration phenology was synchronous regardless of winter or breeding origin. Cluster analyses delineated two primary breeding areas: one molting area and one wintering area. White-winged Scoters demonstrated overall weak to moderate connectivity among life stages, with molting to wintering connectivity the strongest. Thus, White-winged Scoters that winter in eastern North America appear to constitute a single continuous population.

Canadian Journal of Zoology↗