American Black Ducks Anas Rubripes Research Articles

Blood Lead Declines in Wintering American Black Ducks in New Jersey Following the Lead Shot Ban

AbstractWaterfowl managers first recognized the problem of lead poisoning in ducks from the ingestion of spent lead shot (pellets) over 100 years ago. The phaseout of lead shot for waterfowl hunting began in the Atlantic Flyway in the 1970s. Lead shot was subsequently banned throughout the United States and Canada prior to 2000. We compared blood lead levels in American black ducks Anas rubripes wintering in coastal New Jersey in 1978, prior to the lead ban, and in 2017, about 39 years after lead shot was first banned for use in Atlantic coastal marshes and 27 years after it was banned for waterfowl hunting in New Jersey. The prevalence of blood lead >0.2 ppm, a level commonly used to indicate lead exposure, declined nearly fourfold from 1978 (79%) to 2017 (20%). We found no significant differences in the prevalence of birds with blood lead levels >0.2 ppm between sexes in either year or between age classes in 2017. The prevalence of ducks with blood lead levels >1.0 ppm, considered clinically evident toxicity, declined from 19% in 1978 to 1% in 2017. Our study provides further evidence that the ban on the use of lead shot over 20 years ago throughout North America has resulted in lower blood lead levels in waterfowl. Notwithstanding, we still found evidence of lead exposure in black ducks in 2017, which warrants further investigation.

Does Invasive Common Reed in Coastal Salt Marshes Affect Dabbling Duck Food Availability?

AbstractCommon reed, Phragmites australis, a nonnative perennial grass, is considered a nuisance species to land managers and wildlife biologists. Common reed thrives in areas with reduced soil salinities, increased nitrogen availability, and anthropogenic shoreline development. The expansion of nonnative common reed into tidal wetlands of North America detrimentally affects native wildlife by altering resource utilization, modifying trophic structures, and changing disturbance regimes. Thus, it also has the potential to drastically affect dabbling duck (Family Anatidae, SubFamily Anatinae, Tribe Anatini) energetic carrying capacity in salt marsh ecosystems. We assessed whether invaded monocultures of common reed in dabbling duck habitat could alter the availability of invertebrate and seed foods for the mallard Anas platyrhynchos, American black duck Anas rubripes, green-winged teal Anas crecca, northern shoveler Spatula clypeata, and northern pintail Anas acuta as compared with wetland type (mudflat, low marsh, high marsh, and impoundments). We compared food and energy availability in > 90% common reed monocultures with noncommon reed-invaded salt marshes in five study areas in Edwin B. Forsythe National Wildlife Refuge, New Jersey, 2015–2016. To estimate wetland-specific food energy supply, we collected sediment core samples, fixed them with formalin, and washed, dried, sorted, and weighed them for seeds and invertebrates. We multiplied biomass (g) by true metabolizable energy values to estimate species-specific dabbling duck food energy availability. We further estimated wetland-specific energetic carrying capacity (duck energy days) on the basis of known species-specific energetic demands. We determined that duck energy days/ha were greater for dabbling ducks in wetlands invaded with common reed because they contained more consumable seed energy and less consumable invertebrate energy. However, future research should explore how accessible these foods are when common reed grass is dense. To aid in restoration efforts once common reed is removed by control efforts, our results indicate that a robust seed bank exists in the soil strata, thus increasing salt-marsh seed biodiversity.

Food Resources for Wintering and Spring Staging American Black Ducks

Abstract Habitat restoration and enhancement objectives for wintering waterfowl are typically derived by a bioenergetics modeling approach. This approach has been developed as a planning tool to identify the amount of foraging habitat required to meet North American Waterfowl Management Plan population objectives. Our objective was to provide the energetic supply component of the bioenergetics model at an important wintering area for American black ducks Anas rubripes in the Atlantic Flyway, the Eastern Shore of Virginia. We estimated food availability among four main wetland cover types used by overwintering American black ducks: brackish water, freshwater, mudflat, and salt marsh. Mudflat (221 ± 50 kg/ha) and salt marsh (728 ± 175 kg/ha) had the highest amounts of available invertebrate food density, and freshwater (42 ± 9 kg/ha) had the highest amounts of available seed biomass. Our results suggest that seed density found in freshwater wetlands on the Eastern Shore of Virginia is considerably lower than densities found in inland freshwater cover types used by dabbling ducks. We also found that levels of invertebrate density found in Virginia mudflat and salt marsh are considerably lower than levels on Long Island, New York, and in southern New Jersey. Lower levels of food density compared with both more inland and northern wintering areas suggest that American black ducks wintering in Virginia are more likely to be limited by forage availability than American black ducks and other dabbling ducks wintering both inland and in the northern portion of the wintering range.

Disentangling density‐dependent dynamics using full annual cycle models and Bayesian model weight updating

Summary Density dependence regulates populations of many species across all taxonomic groups. Understanding density dependence is vital for predicting the effects of climate, habitat loss and/or management actions on wild populations. Migratory species likely experience seasonal changes in the relative influence of density dependence on population processes such as survival and recruitment throughout the annual cycle. These effects must be accounted for when characterizing migratory populations via population models. To evaluate effects of density on seasonal survival and recruitment of a migratory species, we used an existing full annual cycle model framework for American black ducks Anas rubripes, and tested different density effects (including no effects) on survival and recruitment. We then used a Bayesian model weight updating routine to determine which population model best fit observed breeding population survey data between 1990 and 2014. The models that best fit the survey data suggested that survival and recruitment were affected by density dependence and that density effects were stronger on adult survival during the breeding season than during the non‐breeding season. Analysis also suggests that regulation of survival and recruitment by density varied over time. Our results showed that different characterizations of density regulations changed every 8–12 years (three times in the 25‐year period) for our population. Synthesis and applications. Using a full annual cycle, modelling framework and model weighting routine will be helpful in evaluating density dependence for migratory species in both the short and long term. We used this method to disentangle the seasonal effects of density on the continental American black duck population which will allow managers to better evaluate the effects of habitat loss and potential habitat management actions throughout the annual cycle. The method here may allow researchers to hone in on the proper form and/or strength of density dependence for use in models for conservation recommendations.

Observed Herring Gull Kleptoparasitism of American Black Ducks

Abstract Herring gulls Larus argentatus were observed to kleptoparasitize American black ducks Anas rubripes feeding on fiddler crabs Uca pugnax in coastal New Jersey. Although widespread in Laridae, kleptoparasitism has never been described between these two species. Over two winters of intensive 24-hour behavioral observations, this interaction was observed on two occasions during similar tidal conditions. Although this appears to be a rare interaction with limited energetic consequences, we note that quantifying these uncommon interspecific interactions is a benefit of thorough behavior observations, which may refine estimates of daily energy expenditure.

Sjeldne fugler i Norge i 2006 - Rapport fra Norsk sjeldenhetskomité for fugl (NSKF)

This is the 31st annual report from the Norwegian Rarities Committee (NSKF). The majority of records treated here are from 2006, but some older records are also included. The Norwegian rarities committee follow advises given by the Taxonomic Advisory Committee (TAC) of the Association of European Record and Rarities Committees (AERC) on issues concerning taxonomy and nomenclature. The systematic list of accepted records is set out in the following system: (1) The bird’s Norwegian name, (2) scientific name, (3) the numbers in brackets, e.g. (2, 30/32, 1), refers respectively to the ( i ) total number of records/total number of individuals up to and including 1974, ( ii ) total number of records/total number of individuals from 1975 (the foundation year of NSKF), except ( iii ) records/individuals in 2006, (4) any breeding, (5) year, (6) county, (7) number of individuals, age (1K = first calendar year etc.), sex (if known) and sometimes circumstances («rm» means that the bird was ringed), (8) site and municipality, (9) date, (10) * indicates if the record was complemented by positive evidence, and type of the evidence (F = photo, V = video-recorded, L = tape-recorded, DNA = DNA-analysis, D = found dead), (11) observers’ names in brackets, main observer(s) is specified first and emphasized with *, (12) roughly gives the species’ distribution and (13) comments concerning the records. Species, subspecies and hybrids new to the Norwegian list: With 245 accepted records presented in this report, 2006 was another good year for rare birds in Norway. A total of 42 accepted records from previous years complete the status of rare birds on the Norwegian list. There are five records presented that have been shelved. Also presented are 26 records that for some reason have not been accepted. All previous records of Booted Warbler Hippolais caligata ssp. and Bonelli’s Warbler Phylloscopus bonelli ssp. have been reassessed following the recent split of these two species. The two formerly accepted records of Snow Bunting Plectrophenax nivalis of the subspecies vlasowae have also been reassessed based on new knowledge on the variation within the nominate subspecies. Three new species to the Norwegian category A list are presented in this report. This brings the official Norwegian list to 477 species. Included in this list are accepted records in category A-C. The new species in 2006 were Masked Shrike Lanius nubicus (Utsira, Rogaland 2nd to 15 th October) and Blackpoll Warbler Dendroica striata (Reve, Rogaland 2nd to 12th November). In addition the first two Sykes’s Warblers Hippolais rama (Forus, Rogaland 11th September 1983 and Monstermyr, Vest-Agder 20th September 1997) were accepted during the reassessment of older records. A Red-necked Grebe Podiceps grisegena collected at Traena, Nordland 28th January 1949 has been accepted as the first Norwegian record of the holboellii subspecies. Two records of hybrid Blue-winged Teal Anas discors x Northern Shoveler A. clypeata (Aheim, More og Romsdal 7th – 9th June 2003 and Lista fyr, Vest-Agder 31 st July – 5th August 2006) have also been accepted as the national first and second records. General trends: Record numbers for Norway was recorded for the following species during 2006: Great Bittern Botaurus stellaris (eight records), Black Kite Milvus migrans (nine records), Mediterranean Gull Larus melanocephalus (ten records), Citrine Wagtail Motacilla citreola (nine records) and Lesser Grey Shrike Lanius minor (three records). Also, 2006 saw the highest number (six records of eleven birds) for Corn Bunting in recent times, including the first successful breeding since 1939. Six records involving ten birds of Arctic Redpoll Carduelis hornemanni of the nominate subspecies was also an all time high. Also published here are the 4th & 5th Egyptian Goose Alopochen aegyptiaca for Norway, 4 th American Black Duck Anas rubripes , 3rd Piedbilled Grebe Podilymbus podiceps , 2nd Little Shearwater Puffinus [assimilis] baroli , 3rd Swinhoe’s Storm-petrel Oceanodroma monorhis , 5th Collared Pratincole Glareola pratincola , 4 th American Golden Plover Pluvialis dominica , 8th & 9th Bonaparte’s Gull Larus philadelphia , 4th, 8th & 9th Yellow-legged Gull Larus michahellis , 10th & 11th Caspian Gull Larus cachinnans , 7 th Gull-billed Tern Sterna nilotica , 4th Isabelline Wheatear Oenanthe isabellina , 2nd Eastern Orphean Warbler Sylvia crassirostris and 2 nd Black-faced Bunting Emberiza spodocephala (cat. D).

Effect of lake acidity and morphometry on the distribution of aquatic birds in southern Quebec

More than half the lakes in the deciduous and boreal forest regions of southern Quebec harbour at least one aquatic bird species during the nesting period. Although the number of nesting pairs per lake is generally small, those pairs are most commonly seen on lakes with a surface area of more than 15 ha, a winter pH lower than that of normal rain (i.e. < 5.6), an irregular shore configuration marked by abundant riparian vegetation, and islands.In a correspondence analysis, the first axis, representing lake acidity, explains 68% of the total variance. The common goldeneye Bucephala clangula, which is frequently seen on the most acidic lakes, and the American black duck Anas rubripes, which tends to avoid acidic lakes, show the largest contributions to that axis. The second axis describes an altitude/surface area gradient and brings the cumulative percentage of explained total variance to 94%; the great blue heron Ardea herodias and the common loon Gavia immer primarily use large, low‐altitude lakes, whereas the ringnecked duck Aythya collaris and the American black duck are often found on the smaller, higher‐altitude lakes. Those results are discussed as they relate to the feeding requirements of the various species of bird and the biology of their main prey. The ecological segregation of the three waterfowl species is attributed to interspecific competition.

THE EVOLUTIONARY SIGNIFICANCE OF WILD HYBRIDIZATION IN SOUTH AFRICAN HIGHVELD DUCKS

Summary Milstein, P. Le S. 1979. The evolutionary significance of wild hybridization in South African Highveld ducks. Ostrich Suppl. 13. Wild hybrid ducks of interspecific and intergeneric origin were unexpectedly captured at Barberspan, the major waterfowl-ringing station in Africa. In addition to a single record by Shewell (1957), 24 hybrids and back-crosses between Yellowbilled Ducks Anas undulata, Red-billed Teal A. erythrorhyncha and Southern Pochard Netta erythrophthalma were captured over a three-year period. These hybrids call for a revision of current theory concerning wild hybridization with respect to monomorphic and dimorphic ducks. Frequencies are apparently only exceeded in the literature by the controversial American Black Duck Anas rubripes x Mallard A. platyrhynchos incidence. A comparative description and statistical comparison of the different phenotypes is given. Hybrid syringes and tracheae are illustrated and compared with the parent species. The apparent evolution of a biological is...