Comparative toxicity of lead shot in black ducks (Anas rubripes) and mallards (Anas platyrhynchos)

In winter, pen-reared and wild black ducks (Anas rubripes), and game farm and wild mallards (Anas platyrhynchos), maintained on pelleted feed, were sham-dosed or given one number 4 lead shot. After 14 days, dosed birds were redosed with two or four additional lead shot. This dosing regimen also was repeated in summer using pen-reared black ducks and game farm mallards. Based upon mortality, overt intoxication, weight change, delta-aminolevulinic acid dehydratase activity and protoporphyrin concentration, black ducks and mallards were found to be equally tolerant to lead shot. However, captive wild ducks were more sensitive than their domesticated counterparts, as evidenced by greater mortality and weight loss following lead shot administration. This difference may be related to stress associated with captivity and unnatural diet.     

A comparison of two methods to establish the prevalence of lead shot ingestion in mallards (Anas platyrhynchos) from The Netherlands

Two collection methods for screening the mallard (Anas platyrhynchos) population in the Netherlands for the ingestion of spent lead shot were compared. One method consisted of examination of gizzards from mallards shot by hunters (n = 2,859) and the other method consisted of examination of gizzards from mallards caught in duck traps (n = 865). The 95% confidence interval of lead shot ingestion in the mallard population estimated by the first method was 1.7 to 2.9% and by the second method 1.1 to 3.1%. These values were not significantly different. From the numbers of lead pellets embedded in the gizzard wall in hunter-killed and trapped mallards it was estimated that at least 22 to 68% of the trapped ducks had been hit by lead shot previously, but survived. Furthermore, this study shows that it is reasonable to assume that a substantial part of the pellets which are identified (in this study and other studies) as ingested, may well have been shot into the gizzard lumen at some time before the birds were actually killed. To avoid lead poisoning in mallards and in raptors depredating waterfowl hit by lead shot, a change to steel shot is advocated.     

Effects of ingested lead on antibody production in mallards (Anas platyrhynchos)

We examined the effects of lead ingestion on in vitro and in vivo indices of immune function in mallards (Anas platyrhynchos). Twenty-four mallard drakes were randomly divided into three groups (I, II, III), then assigned to treatment or control subgroups (n = 4). On day 0, all treatment birds were dosed orally with one number 4 lead shot (mean = 0.2 g). We challenged all individuals in each group with washed sheep red blood cells (SRBC) injected intraperitoneally on days 0 (Group I), 7 (Group II) or 14 (Group III), and collected blood for analyses 7 and 8 days after SRBC challenge. We measured and compared blood lead concentrations, in vitro lymphocyte transformation responses to phytohemagglutinin A and lipopolysaccharide, and hemagglutination titers to SRBC. Mean blood lead concentrations were elevated (P less than or equal to 0.04) in treatment birds at each sampling period. Large individual variability in lymphocyte stimulation responses precluded further analysis of those data. Hemagglutination titers to SRBC were lower (P less than 0.0001) in lead-poisoned ducks than in controls, suggesting that ingested lead may have immunosuppressive effects on mallards.     

Acute toxicity of lead, steel, and an iron-tungsten-nickel shot to mallard ducks (Anas platyrhynchos)

Twenty mallards (Anas platyrhynchos) of both sexes were dosed by oral gavage with Heavi-Shot (H-S; Environ-Metal, Inc., Sweet Home, Oregon, USA) pellets, 20 with steel shot, and 10 with lead (Pb) pellets, all of equal size. All pellets were fired from a shotgun into an absorbent material, retrieved, and weighed prior to introduction into the ducks. Birds were fed whole kernel corn and grit and observed for signs of toxicity for 30 days following dosing. Hevi-Shot pellets lost an average of 6.2% of their mass and steel shot pellets lost 57% of their mass in the birds' gizzards. Almost all (90%) of the Pb shot dosed birds died before the end of the study, while no mortality was observed in the steel or H-S dosed groups. Even though total food consumption differed between the H-S and steel shot groups, mean bird weight change was not different. There were no significant morphologic or histopathologic abnormalities of the liver and kidney in the H-S and steel shot groups. Results indicated that mallards dosed orally with eight No. 4 H-S pellets were not adversely affected over a 30-day period, and that H-S provides another environmentally safe nontoxic shot for use in waterfowl hunting.     

Effects of lead shot ingestion on selected cells of the mallard immune system

The immunologic effects of lead were measured in game-farm mallards (Anas platyrhynchos) that ingested lead shot while foraging naturally, mallards intubated with lead shot, and unexposed controls. Circulating white blood cells (WBC) declined significantly in male mallards exposed to lead by either natural ingestion or intubation, but not females. Spleen plaque-forming cell (SPFC) counts were significantly lower in mallards intubated with lead pellets compared to controls. Declines in WBC and SPFC means with increasing tissue lead concentrations provide further evidence that lead exposure reduced immunologic cell numbers. Hormonal activity and diet may have influenced the immunologic effects of lead exposure in this study.     

The amino-acid sequence of Northern Mallard (Anas platyrhynchos platyrhynchos) hemoglobin

The complete amino-acid sequence of the major hemoglobin component (HbA) of the adult Northern Mallard (Anas platyrhynchos platyrhynchos) is presented. A minor component HbD was also detected but in low concentrations. The sequences of alpha A- and beta-chains were established by automatic Edman degradation on tryptic peptides and peptides obtained by specific chemical cleavages. The alignment of the peptides was performed by comparison with the alpha A- and beta-chains of Greylag Goose hemoglobin (Anser anser). Thereby an exchange of five positions in the alpha A-chains and three in the beta-chains was observed. No exchanges were found in the surroundings of the heme, in alpha 1 beta 2-contact points, or allosteric regulatory sites. In the alpha 1 beta 1-subunit interface one amino-acid residue in alpha A-chains and one in beta-chains are exchanged. By comparison with the amino-acid sequence derived from globin genes of Domestic Duck (Anas platyrhynchos), the alpha A-chains differ by two exchanges in the N-terminal region and the beta-chains by five exchanges the in C-terminal region. The comparison of the amino-acid sequence derived from alpha A-globin gene of the Moscovy Duck (Cairina moschata) and alpha A-chains of the Northern Mallard, shows only one replacement.     

Habitat selection and waterbody-complex use by wintering Gadwall and Shoveler in South West London: Implications for the designation and management of multi-site protected areas

The degree to which Special Protection Area (SPA) designation reflects ecological reality is of critical importance to wildlife conservation. We examined whether the designation of a large SPA designated to conserve wintering waterfowl (chiefly Gadwall Anas strepera and Northern Shoveler Anas clypeata), reflected the birds’ habitat preferences and their use of the SPA in the context of the broader geographic area. To do this, 67 discrete waterbodies in and around the South-West London Waterbodies Special Protection Area (SWL SPA) were surveyed regularly each winter from 2004/5 to 2006/7, and new analytical methods developed, to investigate habitat selection and multiple-site use by the birds. Significant pressure on these waterbodies for mineral extraction, development and recreation, together with a long history of human usage has resulted in a wide range of habitats and conditions for these wildfowl.We found that Gadwall and Shoveler were able to adjust their site preferences and patterns of site use in response to changes in food resources and other ecological variables both within and between winters. Akaike's Information Criterion (AIC) was used to model the distribution of wildfowl between sites using a large number of physical and ecological predictor variables. This showed that Gadwall and Shoveler differ in many of their habitat preferences, to the extent that managing a site for one will not necessarily directly benefit the other.At the time of this study the habitat preferences of Gadwall and Shoveler do not closely match the ecological condition of the SWL SPA waterbodies. Furthermore, an investigation into the use of multiple sites by Gadwall and Shoveler indicated that although there is evidence for populations of wintering birds using groups of waterbodies in the SW London area, their patterns of site use do not closely match the distribution of the seven separate SPA component waterbodies.We provide guidelines for managing habitats for Gadwall and Shoveler, and suggest that in addition to bird counts the SPA designation process for multi-site protected areas should consider the behaviour, habitat requirements and the influence of human disturbance on the species concerned. In this instance, the patterns of wildfowl site use present a reasoned argument for the inclusion of additional sites in the SW London Waterbodies SPA, or for dealing with the SPA in a different manner to a site with a more contiguous boundary.     

Lead shot ingestion by mourning doves on a disked field

Previous field studies of hunter-harvested mourning doves (Zenaida macroura) have reported the percentage of birds with ingested lead shot as 0.2–6.5%. To reduce the uncertainty concerning the number of doves that ingest shot, we conducted an experiment to test the proportion of mourning doves that ingested lead shot on the bare soil of a disked field (typical of a managed dove field) to simulate more natural feeding conditions. In each of 3 treatment groups of 80 birds, we exposed 35 birds to low-density lead shot (1.5 million shot/ha), and35 birds to high-density lead shot (29.5 million shot/ha), and 10 birds served as controls (no shot). We dosed 5 positive control birds with 2 lead shot each in trials 2 and 3. We scattered lead shot and mixed seed on the loosely packed soil of treatment cages and after 4 days of exposure, 2.9% of doves voluntarily ingested ≥1 lead shot. The proportion of birds that ingested shot when exposed to the high-density shot treatment (4.9%) was not different (P = 0.098) from that of the low-density shot treatment (1.0%). Lead concentrations in liver, kidneys, and blood reached maxima of 94.402 ppm, 346.033 ppm, and 13.883 ppm wet mass, respectively. Differences in delta-aminolevulinic acid dehydratase (ALAD) activity, packed cell volume, and heterophil:lymphocyte ratio (H:L) were greater posttreatment in doves that had ingested shot than in those that did not. The risk posed to mourning doves from lead shot ingestion can be reduced by banning lead shot on management areas or dove fields or disking fields after hunting season to reduce shot availability. © 2011 The Wildlife Society.     

Estimation of carcass fat and protein in northern pintails (Anas acuta) during spring migration

Foraging in stopover areas influences nutritional condition of birds during spring migration. Our purpose was to determine if body mass, percent carcass water, and serum biochemistry would predict energy reserves (carcass fat and protein) in northern pintails (Anas acuta) at a spring staging area, Lake St. Pierre in Québec, Canada (46 degrees 11 'N, 73 degrees 08 'W). Northern pintails were collected during spring 1997 (14 April-9 May). In this staging area, body mass and percent body water successfully estimated carcass protein and fat in male northern pintails, but only carcass protein in females. None of the seven blood parameters we used accurately estimated nutritional reserves in staging northern pintails. These findings suggest that investigators must use direct estimates of carcass reserves to examine nutrient reserve requirements for egg production, migration, or body maintenance during spring migration.     

The relation between the feeding activity of wintering shovelers (Anas clypeata) and the horizontal distribution of zooplankton in Lake Teganuma,Japan

We investigated seasonal changes in the number and feeding activity of Shovelers wintering in Lake Teganuma in connection with temporal and horizontal fluctuations of zooplankton, and analyzed esophageal contents of a captured Shoveler. Zooplankton community was dominated by rotifers followed by copepods during the study period. Horizontal distribution of both invertebrate taxa differed; rotifers most abundant in the western and eastern parts of the lake in February–March, and cyclopoid copepodids and nauplii more common in the northeast area of the eastern portion of the lake. The number and feeding activity of Shovelers increased from January to March in the northeast area of Lake Teganuma. A Shoveler captured in the area had mostly consumed cyclopoid copepodids despite the fact that rotifers dominated in the zooplankton community at that location. These results suggest that the horizontal distribution and feeding activity of the Shovelers were correlated with the distribution of the cyclopoid copepodids.     

Parasitic ulcerative ventriculitis in mallards (Anas platyrhynchos)

Natural infections of Streptocara crassicauda and Streptocara incognita were diagnosed in four mallards (Anas platyrhynchos) from Red Rock Lakes National Refuge, Beaverhead County, Montana. Lesions at the junctions of the gizzard and proventriculus were associated with the nematodes, and resulted in debilitation, emaciation and death.     

Phylogeography of the mallard Anas platyrhynchos from Eurasia inferred from sequencing of the mtDNA control region

Phylogenetic relationships, demographic history, and geographic distribution of the mtDNA haplotypes of the mallard Anas platyrhynchos were examined in three populations, Indian, Northern European, and Far Eastern. Two divergent halotype groups, A and B, were found in the Far Eastern population, while haplotypes identified in Northern European and Far Eastern populations were exclusively of the A group. The presence of B group haplotypes in the Far Eastern population can be explained either in terms of hybridization of the mallard with spot-billed duck Anas zonorhyncha at the south of the Russian Far East, or by the mtDNA paraphyly in mallards. In general, mallards from Eurasia were characterized by low genetic population differentiation along with slightly expressed phylogeographic structure. The most differentiated was the population from India (??_st = 0.076?0.077), while the difference between Northern European and Far Eastern populations was extremely low (??_st = 0.0029). Differentiation of Anas platyrhynchos Indian population was determined by the fact that a part of the population, inhabiting southern and eastern coasts of the Hindustan Peninsula, was resident.     

Moults and plumages and testicular regression of post-breeding male Blue-winged teal (Anas discors) and Northern shovelers (Anas clypeata)

Moults and plumages and testicular regression were compared in post-breeding male Northern shovelers ( Anus clypeala ) and Blue-winged teal ( A. discors ). Sequence of moults and plumages was similar between species, except that Northern shovelers became flightless before completion of pre-basic moult and initiated pre-alternate moult before complete regrowth of primaries. Testicular regression was similar in both species, occurring in a two-stage process of from four to six weeks. In all cases, both species had finished testes regression before the initiation of the flightless period. In both species, the lcft testis was larger in spring, regressed slower, and was larger after regression than the right testis.     

Filter-feeding dabbling ducks (Anas spp.) can actively select particles by size

The relationship between bill morphology, function and prey use among filter-feeding dabbling ducks (Anas spp.) is poorly understood. In particular, it is not clear if interspecific differences in morphology affect the retention of prey to allow prey partitioning. The size of particles retained by ducks may be determined entirely by the distance between adjacent mandibular lamellae (interlamellar distance), possibly allowing interspecific partitioning of prey by size. Alternatively, articulation of the maxilla and mandible allows ducks to increase the distance between the maxillary and mandibular lamellae (lamellar separation) so that it exceeds their interlamellar distance, possibly allowing them to selectively expel unwanted particles larger than their interlamellar distance. In contrast, if interlamellar distance alone determines the size of particles ingested, particles larger than the interlamellar distance will always be retained because lamellar spacing is fixed. When large, preferred millet and wheat seeds were mixed with small, less preferred poppy seeds, all three ducks in this investigation ingested a greater proportion of the millet and wheat seeds than the poppy seeds, even though all three seed types were larger than the ducks' interlamellar distance. The proportion of millet and poppy seeds ingested when seeds were mixed differed from the proportion expected from foraging rates on unmixed prey, indicating the ducks actively avoided poppy seeds. These results are consistent with the lamellar separation hypothesis and clearly reject the singular role of interlamellar distance in prey retention. Because lamellar separation and water filtration rate are both determined by movement of the maxilla and mandible, there may be a trade-off between particle size selection and prey ingestion rate that allows interspecific partitioning of prey by size.     

Comparative mechanics of filter feeding in Anas platyrhynchos,Anas clypeata and Aythya fuligula (Aves,Anseriformes)

Summary The straining of seeds ranging in size from 0.01 to 4.6 mm was investigated in the filtering mechanisms of three anseriform species, Anas platyrhynchos, Anas clypeata, and Aythya fuligala. The morphology of the filtering mechanisms was studied by dissection and from microsections. The kinematic work envelope of the beaks was measured by stereotactic manipulation. The actual beak kinematics were analyzed by calculating the changes of the mouth volume from computer simulations and comparing the results with the amounts of water expelled. The performances of the filter and the water pump were measured with special collection boxes. The influence of the lamellae was estimated by removing them in whole or in part and measuring the performances again. The results show that if the size of the strained seeds increases, the gapes and amplitudes also increase (cf. bill rotations). Beak rotation is elevated for small kernels, even more elevated for slightly larger ones, but depressed for large kernels. However, neither frequencies nor phase shifts change between different moving elements. Simulation of these data by stereotactic manipulation of fresh material and by measuring gape sizes and mesh widths shows that the beak kinematics during straining keep mesh widths and gapes carefully adjusted to the seed size. The pumping and the filtering mechanisms influence each other mutually in setting boundary conditions on mouth kinematics. Beyond a certain kernel size, the necessity for mesh-width control sets a boundary on the increase of the water flow. Conversely, phase shifts, frequency changes and change of lingual amplitudes were restricted by the pumping mechanism. Drastic shortening of either dorsal mandibular or maxillary lamellae in Anas platyrhynchos and Aythya fuligula does not effect either the filter performances, the pump performances, or the beak kinematics, but these modifications do change the performances in Anas clypeata. The usually accepted assumption concerning food sieving was thus verified for Anas clypeata and falsified for the other two anseriform species. Therefore, a vortex model in addition to the sieving model, was developed, based on the assumption that local vortices cause inertia of particles so that small kernels are filtered by centrifugation and translation out of the main water flow. Combined effects of sieving and centrifugation occur when larger kernels are filtered. The kinematics of the filtering mechanism are highly flexible; therefore, a wide tolerance for seed sizes exists. However, the morphology of the filtering mechanism differs in the three species. Testing whether the anseriform filter mechanism is so plastic that the mechanism in each species has developed in such a way that the staple food is gathered most economically has shown that filtering of the staple food does indeed occur at the most efficient levels of maxillary rotation.     

Comparisons of nine heavy metals in salt gland and liver of greater scaup (Aythya marila), black duck (Anas rubripes) and mallard (A. platyrhynchos)

Levels of nine heavy metals were measured in the livers and salt glands of greater scaup (Aythya marila), black duck (Anas rubripes) and mallard (A. platyrhynchos) from Raritan Bay, New Jersey to determine if the functioning avian salt gland concentrates heavy metals. Heavy metals examined were cadmium, cobalt, chromium, copper, lead, mercury, manganese, nickel and zinc. Heavy metal levels varied significantly by species and tissue for chromium, copper, lead, and manganese, and by tissue for cobalt, mercury, nickel and zinc. In comparing tissues cobalt was higher in the salt glands than in livers of all three species; chromium and nickel were higher in the salt gland than liver for mallard and black duck; and lead, manganese and zinc were higher in the liver than the salt gland in greater scaup. Generally metal levels were higher in the salt gland for mallard and black duck, and in the liver for greater scaup.     

Determination and analysis of complete mitochondrial genome sequence of mallard (Anas platyrhychos)

The complete mitochondrial genome (mtDNA) of mallard (Anas platyrhychos) was determined by long and accurate polymerase chain reaction and with primer walking sequence method. The entire genome was 16,606 bp in length. Similar to the typical mtDNA of vertebrates, it contained 37 genes (13 protein-coding genes, 2 rRNA genes, and 22 tRNA genes) and a non-coding region (D-loop). The characteristics of the mitochondrial genome were analyzed and discussed in detail.     

Sitting ducks: diet of wintering wildfowl in Lake Tonga,northeast Algeria

Dietary studies of five species of Anatidae (Gadwall Anas strepera, Shoveler Anas clypeata, Pochard Aythya ferina, Ferruginous Duck Aythya nyroca, and White-headed Duck Oxyura leucocephala) were carried out at Lake Tonga, northeast Algeria, from December 2011 to March 2012. Diet analysis of all five wintering species indicated a heavy reliance on seeds, which included a wide variety of aquatic plants, such as Myriophyllum spicatum, Ceratophyllum demersum, Sparganium erectum, Scirpus lacustris and Potamogeton pectinatus. Noteworthy is the paucity of ingested macroinvertebrates. Despite dietary overlap, the type, abundance and frequency of food consumed clearly indicated differences in resource use among the ducks. Incidentally, the study also highlighted the high vulnerability of threatened ducks to poaching (harvesting and disturbance) in a protected area. We discuss the implications of these findings for the management and conservation of wintering wildfowl and their North African habitats.