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Productivity of functional guilds of fishes in managed wetlands in coastal South Carolina

In coastal South Carolina, many wetlands are impounded and managed as migratory waterfowl habitat. Impoundment effects on fish production and habitat quality largely are unknown. We used the size-frequency method to estimate summer production of fish guilds in three impoundments along the Combahee River, South Carolina. We predicted that guild-specific production would vary with impoundment salinity, which ranged from 3 to 21 practical salinity units. We expected that marine species that use the estuary as nursery habitat would have greatest production in the impoundment with the highest salinity regime, and that species that inhabit the upper reaches of the estuary would have greatest production in the impoundment with the lowest salinity regime. Finally, we expected that estuarine species would be highly productive in all study impoundments, because these species can reproduce within these structures. We found that guild-specific productivity varied both among years and among impoundments, generally following salinity gradients, though to a lesser extent than expected. Our guild-specific estimates of fish productivity fell on the low end of the range of previously published estuarine fish production estimates. Additionally, we observed large mortality events in the study impoundments each summer. The results of our study indicate that during the summer, the study impoundments provided poor-quality fish habitat to all guilds.

South Carolina↗

Variation in age ratio of midcontinent greater white-fronted geese during fall migration

Annual productivity is an important parameter for the management of waterfowl populations. Fall age ratio (juveniles:total birds) is an index of productivity of the preceding breeding season. However, differences in the timing of migration between family groups and nonbreeding birds may bias age-ratio estimates. We examined temporal variation in age ratios of midcontinent greater white-fronted geese Anser albifrons frontalis from interior and northwestern Alaska at a northern autumn staging area near Delta Junction, Alaska. Photographic sampling conducted near Delta Junction resulted in an annual age ratio of 0.388 ± 0.004 (mean ± SE) in 2010 and 0.390 ± 0.001 in 2011. Our study demonstrated temporal variation in age ratios over the duration of the migration period during August and September. We recommend that sampling be conducted for 3-d periods at the beginning, middle, and end of the migration period to account for temporal variation in migration of family groups.

Journal of Fish and Wildlife Management↗

Waterbird habitat in California's Central Valley basins under climate, urbanization, and water management scenarios

California's Central Valley provides critical, but threatened habitat and food resources for migrating and wintering waterfowl, shorebirds, and other waterbirds. The Central Valley is comprised of nine basins that were defined by the Central Valley Joint Venture (CVJV) to assist in conservation planning. Basins vary in composition and extent of habitats, which primarily include croplands and wetlands that rely on water supplies shared with other competing human and environmental uses. Changes in climate, urban development, and water supply management are uncertain and could reduce future availability of water supplies supporting waterbird habitats and limit effectiveness of wetland restoration planned by the CVJV to support wintering waterbirds. We modeled 17 plausible scenarios including combinations of three climate projections, three urbanization rates, and five water supply management options to promote agricultural and urban water uses, with and without wetland restoration. Our research examines the reduction in quantity and quality of habitats during the fall migration-wintering period by basin under each scenario, and the efficacy of planned wetland restoration to compensate reductions in flooded areas of wetland habitats. Scenario combinations of projected climate, urbanization, and water supply management options reduced availability of flooded cropland and wetland habitats during fall-winter and degraded the quality of seasonal wetlands (i.e., summer-irrigation for improved forage production), though the extent and frequency of impacts varied by basin. Planned wetland restoration may substantially compensate for scenario-related effects on wetland habitats in each basin. However, results indicate that Colusa, Butte, Sutter, San Joaquin, and Tulare Basins may require additional conservation to support summer-irrigation of seasonal wetlands and winter-flooding of cropland habitats. Still further conservation may be required to provide sufficient areas of flooded seasonal and semi-permanent wetlands in San Joaquin and Tulare Basins during fall-winter. The main objective of this research is to provide decision-support for achieving waterbird conservation goals in the valley and to inform CVJV's regional conservation planning.

California↗

Limited land base and competing land uses force societal tradeoffs when siting energy development

As human populations grow, decisions regarding use of the world's finite land base become increasingly complex. We adopted a land use–conflict scenario involving renewable energy to illustrate one potential cause of these conflicts and resulting tradeoff decisions. Renewable energy industries wishing to expand operations in the United States are limited by multijurisdictional regulations in finding developable land. Interest groups entreat industries to avoid land for various reasons, including avoidance of prime wildlife habitat in accordance with an “avoidance-first” mitigation strategy. By applying a uniform set of rules for renewable energy facilities to the Prairie Pothole Region and portions of the Northern Great Plains, we evaluated the effects of regulations and avoidance of prime wildlife habitat on the amount of land available for development. In our scenario, existing regulations excluded 39% of the project area from potential development, with human infrastructure accounting for 30% (10–66% among states), whereas federally protected species accounted for < 1% at project area and state levels. Unregulated lands accounted for 61% of the project area, with conservation areas predicted as high-quality sites for breeding grassland birds and waterfowl and for migrating whooping cranes Grus americana accounting for 19% within the project area (6–27% among states). This model demonstrated a limited land base available for new development when accounting for regulations and concerns of a subset of societal interest groups. Additional interest groups likely will have different and competing concerns, further emphasizing the complexity of future land-use decisions as the available land base for development diminishes.

Journal of Fish and Wildlife Management↗

Structured decision making to rank North American Wetland Conservation Act proposals within joint venture regions

The North American Wetlands Conservation Act (16 U.S.C. 4401-4412) provided funding and administration for wetland management and conservation projects. The North American Wetland Conservation Fund, enabled in 1989 with the Act, provides financial resources. Resource allocation decisions are based, in part, on regional experts, particularly migratory bird Joint Ventures (JVs) (i.e., partnerships for cooperative planning and coordinated management of the continent’s waterfowl populations and habitats). The JVs evaluate funding proposals submitted with their respective regions each year and make funding recommendations to decision makers. Proposal evaluation procedures differ among JVs, however, it could be helpful to consider a transparent, repeatable, and data-driven framework for prioritization within regions. We used structured decision making and linear additive value models for ranking proposals within JV regions. We used two JVs as case studies and constructed two different value models using JV-specific objectives and weights. The framework was developed through a collaborative process with JV staff and stakeholders. Models were written in Microsoft Excel. To test these models, we used six NAWCA proposals submitted to the Upper Mississippi / Great Lakes Joint Venture in 2016 and seven proposals submitted to the Gulf Coast Joint Venture in 2017. We compared proposal ranks assigned by the value model to ranks assigned by each JV’s management board. Ranks assigned by the value model differed from ranks assigned by the board for the Upper Mississippi / Great Lakes Joint Venture, but not for the Gulf Coast Joint Venture. However, ranks from the value model could change markedly with different objective weights and value functions. The weighted linear value model was beneficial for ranking NAWCA proposals because it allows JVs to treat the ranking as a multiple objective problem and tailor the ranking to their specific regional concerns. We believe a structured decision making approach could be adapted by JV staff to facilitate a systematic and transparent process for proposal ranking by their management boards.

Journal of Fish and Wildlife Management↗

Habitat edges have weak effects on duck nest survival at local spatial scales

Edge effects on nesting success have been documented in breeding birds in a variety of contexts, but there is still uncertainty in how edge type and spatial scale determine the magnitude and detectability of edge effects. Habitat edges are often viewed as predator corridors that surround or penetrate core habitat and increase the risk of predation for nearby nests. We studied the effects of three different types of potential predator corridors (main perimeter roads, field boundaries, and ATV trails within fields) on waterfowl nest survival in California. We measured the distance from duck nests to the nearest edge of each type, and used distance as a covariate in a logistic exposure analysis of nest survival. We found only weak evidence for edge effects due to predation. The best supported model of nest survival included all three distance categories, and while all coefficient estimates were positive (indicating that survival increased with distance from edge), 85% coefficient confidence intervals approached or bounded zero indicating an overall weak effect of habitat edges on nest success. We suggest that given the configuration of edges at our site, there may be few areas far enough from hard edges to be considered &lsquo;core&rsquo; habitat, making edge effects on nest survival particularly difficult to detect.

Ardea↗

Winter carry-over effects on spring body condition driven by agricultural subsidies to Lesser Snow Geese (Anser caersulscens caerulescens)

Anthropogenic changes to landscapes associated with intensive agriculture often have deleterious effects on avian abundance. However, some species like the Lesser Snow Goose ( Anser caerulescens caerulescens ), can benefit from increases in agricultural crops on both wintering and migratory stopover sites. We investigated the influence of winter habitat use on spring body condition in Lesser Snow Goose, a species that has increased in population following expansion into agriculturally based winter habitats. We used stable isotope measurements of four elements (δ 2 H, δ 13 C, δ 15 N, and δ 34 S) to determine likely prior winter habitat use of snow geese collected during spring migration across Arkansas, Missouri, and Nebraska in 2016. We evaluated differences in body size, lipid, and protein reserves from individuals with isotope values that suggested winter habitat use in traditional coastal marsh and non-coastal /agriculture habitat. Inferred winter habitat influenced total body lipid levels in snow geese collected during spring migration. Adult and juvenile individuals inferred to have overwintered in coastal marsh (n = 60) had, on average, 33.4 g (95% Confidence Interval: 0.4 g, 66.4 g) less lipid than counterparts wintering in non-coastal / agricultural habitat (n = 77). Waterfowl foods found in marshes typically have low true metabolizable energy values as a consequence of their high fiber content, which likely increases daily consumption rates. Increased energy expenditure related to greater time spent foraging, paired with lower energetic rewards, may result in lower lipid reserves among geese using coastal marsh habitats compared to birds using agricultural landscapes. Consequently, carry-over effects based on winter habitat use could explain variation in lipid reserves among individuals during spring migration and may ultimately explain differential fitness rates or susceptibility to harvest. Our results have implications for the conservation and management of this species as historic wetland landscapes become more intensively converted and used for agricultural purposes.

Arkansas, Missouri, Nebraska↗

Contrasting migratory chronology and routes of Lesser Scaup: Implications of different migration strategies in a broadly distributed species

Migration allows birds to improve fitness by exploiting seasonal resource peaks and avoiding limitations. Migration strategies may differ among individuals within a species, but for all strategies, the benefit of increased fitness should outweigh the costs of migration. These costs can include increased mortality risk, time constraints in the annual cycle, and metabolic energy loss. We compared migratory chronology and routes of individuals from a broadly distributed species of waterfowl, the Lesser Scaup ( Aythya affinis ; hereafter Scaup), marked at the northern (66.51000° N, 145.98556° W) and southern (44.63778° N, 111.73694° W) extents of its breeding distribution in North America. Scaup breeding farther north in interior Alaska, USA migrated greater distances and had protracted migrations, especially in fall, compared to Scaup breeding farther south in southwest Montana, USA. During migration, Scaup breeding in Alaska used more staging and stopover areas compared to Scaup breeding in Montana. Scaup breeding in Alaska also spent less time at their breeding area and more time at their wintering areas compared to Scaup breeding in Montana. In addition, Scaup breeding in Alaska were largely absent from wintering areas in the Intermountain West that were used by Scaup breeding in Montana. These differences could have important effects on Scaup fitness and could contribute to differences in fecundity and recruitment observed across the Scaup’s broad latitudinal distribution. Understanding the fitness implications of intraspecific variation in migration strategies of broadly distributed species can assist resource managers by focusing conservation efforts on specific breeding populations, informing models of disease transmission, and improving projections of species’ responses to environmental change.

Journal of Field Ornithology↗

Case histories of wild birds killed intentionally with famphur in Georgia and West Virginia

Five incidences of bird mortality in Georgia and West Virginia (USA) involving migratory waterfowl, cranes, raptors, corvids and songbirds were investigated during the first 6 mo of 1988. Gross and histopathologic examinations revealed no evidence of infectious or other diseases. However, severe depression of cholinesterase activity was evident in brains of birds found dead, suggesting gross exposure to an organophosphorus (OP) or carbamate pesticide. All of the gastrointestinal tract contents chemically analyzed contained famphur, an OP insecticide used as a pour-on treatment against lice and grubs on livestock, ranging from 5 to 1,480 ppm (wet weight). Grain scattered at two of the mortality sites contained 4,240 and 8,500 ppm famphur. Gastrointestinal tracts of most of the dead birds contained mainly corn and some wheat. This is the first report to document the use of famphur as an intentional means of killing wildlife thought to be depredating crops.

Journal of Wildlife Diseases↗

Mortality in Laysan ducks (Anas laysanensis) by emaciation complicated by Echinuria uncinata on Laysan Island, Hawaii, 1993

In November 1993, unusual mortality occurred among endangered Laysan ducks on Laysan Island, one of the remote refugia of the Northwestern Hawaiian Islands National Wildlife Refuge (USA). Ten live ducks were emaciated, and blood samples documented anemia, heterophilia, and eosinophilia. Pathology in 13 duck carcasses revealed emaciation, marked thickening of the proventricular wall, abundant mucus, and nodules in the gastrointestinal tract. Histology revealed granulomata associated with nematodes in the proventriculus, small intestines, and body walls of nine of 10 ducks examined on histology. We suspect that low rainfall and low food abundance that year contributed to enhanced pathogenicity of parasite infection, either through increased exposure or decreased host resistance. Because the Laysan duck is found only on Laysan island and is critically endangered, translocation of this species to other islands is being considered. Given that we have not seen pathology associated with Echinuria spp. in native waterfowl on other Hawaiian Islands and given the parasite's potential to cause significant lesions in Laysan ducks, it will be important to prevent the translocation of Echinuria spp.

Hawai'i↗

Zinc toxicosis in a free-flying trumpeter swan (Cygnus buccinator)

A trumpeter swan (Cygnus buccinator) was observed near it mill pond in Picher, Oklahoma. USA. It became weakened and emaciated after about 1 mo, was captured with little resistance, and taken into captivity for medical care. Serum chemistry results were consistent with hepatic, renal, and muscular damage. Serum zinc concentration was elevated at 11.2 parts per million (ppm). The swan was treated for suspected heavy-metal poisoning, but died overnight. Gross postmortem findings were emaciation and pectoral muscle atrophy. Histopathologic lesions in the pancreas included mild diffuse disruption of acinar architecture, severe diffuse depletion or absence of zymogen granules, occasional apoptotic bodies ics in acinar epithelial cells, and mild interstitial and capsular fibrosis. Zinc concentration in pancreas was 3,200 ppm wet weight, and was similar to that reported in the pancreases of waterfowl known to be killed by zinc toxicity. Zinc concentrations in liver (154 ppm) and kidneys (145 ppm) also were elevated. Acute tubular necrosis of the collecting tubules of the kidneys was also possibly due to zinc toxicity. To the authors' knowledge, this is the first confirmed case of zinc poisoning in a trumpeter swan associated with mining wastes..

Journal of Wildlife Diseases↗

Avian cholera exposure and carriers in greater white-fronted geese breeding in Alaska, USA

We conducted a 3-yr study (2001–03) on greater white-fronted geese ( Anser albifrons frontalis ) breeding in Alaska, USA, to determine the exposure of this population to Pasteurella multocida and the potential role of these birds as disease carriers. We tested sera from nearly 600 adult geese for antibodies to P. multocida serotype 1. We found a low prevalence (<5%) of positive antibodies in adult geese, and based on the short duration of detectable antibodies, these findings indicate recent infection with P. multocida . Prevalence was similar to serologic results from both breeding and wintering lesser snow geese. We also collected oral ( n =1,035), nasal ( n =102), and cloacal ( n =90) swab samples to determine the presence of avian cholera carriers in this population. We were unable to isolate P. multocida serotype 1 from any of the birds sampled. Based on comparison with other waterfowl species, we concluded that these geese may be exposed to avian cholera during the winter or spring migration but are unlikely to play a significant role as carriers of the bacterium causing avian cholera.

Alaska↗

Persistence of Pasteurella multocida in wetlands following avian cholera outbreaks

Avian cholera, caused by Pasteurella multocida, affects waterbirds across North America and occurs worldwide among various avian species. Once an epizootic begins, contamination of the wetland environment likely facilitates the transmission of P. multocida to susceptible birds. To evaluate the ability of P. multocida serotype-1, the most common serotype associated with avian cholera in waterfowl in western and central North America, to persist in wetlands and to identify environmental factors associated with its persistence, we collected water and sediment samples from 23 wetlands during winters and springs of 1996a??99. These samples were collected during avian cholera outbreaks and for up to 13 wk following initial sampling. We recovered P. multocida from six wetlands that were sampled following the initial outbreaks, but no P. multocida was isolated later than 7 wk after the initial outbreak sampling. We found no significant relationship between the probability of recovery of P. multocida during resampling and the abundance of the bacterium recovered during initial sampling, the substrate from which isolates were collected, isolate virulence, or water quality conditions previously suggested to be related to the abundance or survival of P. multocida. Our results indicate that wetlands are unlikely to serve as a long-term reservoir for P. multocida because the bacterium does not persist in wetlands for long time periods following avian cholera outbreaks.

Journal of Wildlife Diseases↗

Using amplified fragment length polymorphism analysis to differentiate isolates of Pasteurella multocida serotype 1

Avian cholera, an infectious disease caused by the bacterium Pasteurella multocida , kills thousands of North American wild waterfowl annually. Pasteurella multocida serotype 1 isolates cultured during a laboratory challenge study of Mallards ( Anas platyrhynchos ) and collected from wild birds and environmental samples during avian cholera outbreaks were characterized using amplified fragment length polymorphism (AFLP) analysis, a whole-genome DNA fingerprinting technique. Comparison of the AFLP profiles of 53 isolates from the laboratory challenge demonstrated that P. multocida underwent genetic changes during a 3-mo period. Analysis of 120 P. multocida serotype 1 isolates collected from wild birds and environmental samples revealed that isolates were distinguishable from one another based on regional and temporal genetic characteristics. Thus, AFLP analysis had the ability to distinguish P. multocida isolates of the same serotype by detecting spatiotemporal genetic changes and provides a tool to advance the study of avian cholera epidemiology. Further application of AFLP technology to the examination of wild bird avian cholera outbreaks may facilitate more effective management of this disease by providing the potential to investigate correlations between virulence and P. multocida genotypes, to identify affiliations between bird species and bacterial genotypes, and to elucidate the role of specific bird species in disease transmission.

California, Iowa, Missouri, Nebraska, Utah, Wiscon↗

A blood survey of elements, viral antibodies, and hemoparasites in wintering Harlequin Ducks (Histrionicus histrionicus) and Barrow's Goldeneyes (Bucephala islandica)

Twenty-eight Harlequin Ducks (Histrionicus histrionicus) and 26 Barrow's Goldeneyes (Bucephala islandica) were captured in Prince William Sound, Alaska, between 1 and 15 March 2005. Blood was collected for quantification of element concentrations, prevalence of antibodies to several viruses, and hemoparasite prevalence and identification. Although we found selenium concentrations that have been associated with selenosis in some birds (???.0 ppm ww), our findings contribute to a growing literature describing relatively high selenium in apparently healthy birds in marine environments. Avian influenza virus antibodies were detected in the plasma of 28% of the ducks. No antibodies against adenovirus, reovirus, or paramyxovirus 1 were detected. Several hemoparasite species were identified in 7% of ducks. Our findings are similar to those in other free-living marine waterfowl and do not indicate unusual concerns for the health of these species in this area in late winter. ?? Wildlife Disease Association 2008.

Alaska↗

Avian botulism: a case study in translocated endangered Laysan ducks ( Anas laysanensis ) on Midway Atoll

Laysan Ducks are endemic to the Hawaiian archipelago and are one of the world&rsquo;s most endangered waterfowl. For 150 yr, Laysan Ducks were restricted to an estimated 4 km2 of land on Laysan Island in the northwestern Hawaiian Islands. In 2004 and 2005, 42 Laysan Ducks were translocated to Midway Atoll, and the population increased to approximately 200 by 2007. In August 2008, mortality due to botulism type C was identified, and 181 adult, fledgling, and duckling carcasses were collected from August to October. Diseased birds were found on two islands within Midway Atoll at multiple wetlands; however, one wetland contributed most carcasses. The epidemic was discovered approximately 14&ndash;21 days after the mortality started and lasted for 50 additional days. The details of this epidemic highlight the disease risk to birds restricted to small island populations and the challenges associated with managing newly translocated endangered species. Frequent population monitoring for early disease detection and comprehensive wetland monitoring and management will be needed to manage avian botulism in endangered Laysan Ducks. Vaccination may also be beneficial to reduce mortality in this small, geographically closed population.

Hawaii↗

Avian influenza virus antibodies in Pacific Coast Red Knots (Calidris canutus rufa)

Prevalence of avian influenza virus (AIV) antibodies in the western Atlantic subspecies of Red Knot ( Calidris canutus rufa ) is among the highest for any shorebird. To assess whether the frequency of detection of AIV antibodies is high for the species in general or restricted only to C. c. rufa , we sampled the northeastern Pacific Coast subspecies of Red Knot ( Calidris canutus roselaari ) breeding in northwestern Alaska. Antibodies were detected in 90% of adults and none of the chicks sampled. Viral shedding was not detected in adults or chicks. These results suggest a predisposition of Red Knots to AIV infection. High antibody titers to subtypes H3 and H4 were detected, whereas low to intermediate antibody levels were found for subtypes H10 and H11. These four subtypes have previously been detected in shorebirds at Delaware Bay (at the border of New Jersey and Delaware) and in waterfowl along the Pacific Coast of North America.

Alaska, Delaware, New Jersey↗

Elements in whole blood of Northwestern Crows ( Corvus caurinus ) in Alaska: No evidence for an association with beak deformities

A recent outbreak of beak deformities among resident birds in Alaska has raised concern about environmental contamination as a possible underlying factor. We measured whole blood concentrations of 30 essential and nonessential elements to determine whether any were associated with beak deformities in Northwestern Crows ( Corvus caurinus ). We tested for differences between 1) adults with versus those without beak deformities and 2) unaffected adults versus juveniles. Crows with beak deformities had slightly higher levels of barium, molybdenum, and vanadium (all P <0.05), but concentrations were generally low and within the range of values reported from other apparently healthy wild birds. Concentrations of several elements, including selenium, were higher in birds without versus birds with beak deformities (all P <0.05), a difference that may be explained in part by compromised foraging ability associated with the deformities. Adult crows had higher concentrations of cadmium, silicon, and zinc than juveniles (all P <0.05), although differences were relatively small and values were similar to those from other wild birds. Our results suggest that neither selenium nor other tested elements are likely to be causing beak deformities in Alaskan crows. We also provide the first data on elemental concentrations in Northwestern Crows. Levels of selenium far exceeded those typically found in passerine birds and were similar to those in marine-associated waterfowl, suggesting that background levels should be interpreted relative to a species's environment.

Alaska↗