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Highly pathogenic avian influenza (HPAI) H5Nx viruses of the goose/Guangdong/96 lineage continue to cause outbreaks in poultry and wild birds globally. Shorebirds, known reservoirs of avian influenza viruses, migrate from Siberia to Australia along the East-Asian-Australasian Flyway. We examined whether migrating shorebirds spending nonbreeding seasons in Australia were exposed to HPAI H5 viruses. We compared those findings with those for a resident duck species. We screened >1,500 blood samples for nucleoprotein antibodies and tested positive samples for specific antibodies against 7 HPAI H5 virus antigens and 2 low pathogenicity avian influenza H5 virus antigens. We demonstrated the presence of hemagglutinin inhibitory antibodies against HPAI H5 virus clade 2.3.4.4 in the red-necked stint (Calidris ruficolis). We did not find hemagglutinin inhibitory antibodies in resident Pacific black ducks (Anas superciliosa). Our study highlights the potential role of long-distance migratory shorebirds in intercontinental spread of HPAI H5 viruses.

Understanding of avian nocturnal flight comes mainly from northern hemisphere species in seasonal temperate ecosystems where nocturnal flight is often precisely timed and entrained by annual photoperiod. Here we investigate patterns of nocturnal flight in waterbirds of Australian desert ecosystems that fly considerable distances to find temporary water bodies formed from rainfall which is highly unpredictable seasonally and spatially, and when there is sufficient water, they then breed. How they perform these feats of navigation and physiology remain poorly known. Using GPS tracking of 38 satellite tagged Pacific black ducks (Anas superciliosa) in two contrasting ecosystems, before and after heavy rainfall we revealed a key role for facultative nocturnal flight in the movement ecology of this species. After large rainfall events, birds rapidly increased nocturnal flight activity in the arid aseasonal ecosystem, but not in the mesic seasonal one. Nocturnal flights occurred throughout the night in both ecosystems. Long range flights (>50 km in 2 hours) occurred almost exclusively at night; at night the distance flown was higher than during the day, birds visited more locations, and the locations were more widely dispersed. Our work reveals that heavy rainfall triggers increased nocturnal flight activity in desert populations of waterbirds.

Numbers of four duck species present within a study area in a tidal embayment (Corner Inlet, south-eastern Australia) were obtained between 1977 and 2002. The species involved were Chestnut (Anas castanea) and Grey (A. gracilis) Teal, Pacific Black Duck (A. superciliosa) and Australian Shelduck (Tadorna tadornoides) and counts are compared with local and distant meteorological data. Chestnut and Grey Teal were most, and Australian Shelduck least, abundant. There was considerable monthly and annual variation; generally, teal and Pacific Black Duck were most numerous in summer and autumn, whereas Shelduck peaked somewhat earlier. Peak abundance corresponded to times of higher inter-annual variation and, apart from Shelduck, abundance had significant, usually weak, negative associations with rainfall though not beyond a one season lag. Pacific Black Duck numbers showed larger, more persistent and positive association with streamflows, particularly in south-eastern Australia, whereas associations for Chestnut Teal were negative and included lags of up to seven seasons. Grey Teal counts showed few significant correlations with streamflow, and Australian Shelduck numbers showed none. Abundance in some species was negatively related to the Southern Oscillation Index in the season of the count, but for Australian Shelduck there was a positive correlation for two seasons previously. Few significant relationships occurred between abundance in Corner Inlet and other Australian waterfowl abundance measures, although annual counts at Corner Inlet were positively correlated with Victorian Summer Waterfowl Counts and negatively with wetland area obtained during East Australia Counts. To an extent, results reflect current views on species' biologies, with birds moving into and out of a saline habitat determined by breeding conditions elsewhere. As found elsewhere, there were some relationships with meteorological variables, though strength and direction varied, perhaps reflecting species' plasticity in responses to rain events at local or distant scale and time.

Dabbling ducks are subject to many threatening processes. Hybridisation with introduced Mallards (Anas platyrhynchos) is a threat that is commonly overlooked. Mallards, both domestic and wild, have been introduced in Australia and New Zealand. While hybridisation with Mallards caused significant decline in the New Zealand populations of Pacific Black (Grey) Ducks (Anas superciliosa), the degree of hybridisation between Mallard and the Pacific Black Duck in Australia is currently unknown, largely because hybrid backcrosses are difficult to visually identify. We screened 27 cross-amplifying waterfowl microsatellite markers and developed a set of 9 markers that can be used for genotyping and assignment tests to identify cryptic hybrids. Assignment tests, performed with the program Structure 2.3.4, had a 99 % likelihood that specimens of a known species (Mallard or Pacific Black Duck) were assigned to the correct group. The system was applied used to confirm the hybrid status of two putative hybrids identified phenotypically. The successful application of this system demonstrates its potential use in determining the rate of hybridisation between introduced Mallards and Pacific Black Ducks throughout Australia.

This study investigated the activity budgets of eight species of waterfowl on a waste-stabilisation pond known to support a large waterfowl community. Most species examined were found to use the area extensively for feeding. Pink-eared Duck (Malacorhynchus membranaceus), Australasian Shoveler (Anas rhynchotis), Grey Teal (A. gibberifrons) and Chestnut Teal (A. castanea) fed most intensively at sunrise and sunset, and rested during the middle of the day. Hardhead (Aythya australis), a diving species, Australian Shelduck (Tadorna tadornoides) and Pacific Black Duck (Anas superciliosa) - large birds that were presumably able to reach the benthos from the water's surface - fed at relatively consistent levels throughout the day. Black Swans (Cygnus atratus) steadily increased the amount of time spent feeding from dawn to dusk. The diurnal activity budgets of these Australian species were similar to those observed for other species occupying similar ecological niches elsewhere. Imminent changes to sewage treatment operations may reduce the ability of this waste-stabilisation pond to support waterfowl populations. The monitoring of activity budgets after any such changes are implemented should be an effective means of detecting any effects, negative or positive. This study investigated the activity budgets of eight species of waterfowl on a waste-stabilisation pond known to support a large waterfowl community. Most species examined were found to use the area extensively for feeding. Pink-eared Duck (Malacorhynchus membranaceus), Australasian Shoveler (Anas rhynchotis), Grey Teal (A. gibberifrons) and Chestnut Teal (A. castanea) fed most intensively at sunrise and sunset, and rested during the middle of the day. Hardhead (Aythya australis), a diving species, Australian Shelduck (Tadorna tadornoides) and Pacific Black Duck (Anas superciliosa) - large birds that were presumably able to reach the benthos from the water's surface - fed at relatively consistent levels throughout the day. Black Swans (Cygnus atratus) steadily increased the amount of time spent feeding from dawn to dusk. The diurnal activity budgets of these Australian species were similar to those observed for other species occupying similar ecological niches elsewhere. Imminent changes to sewage treatment operations may reduce the ability of this waste-stabilisation pond to support waterfowl populations. The monitoring of activity budgets after any such changes are implemented should be an effective means of detecting any effects, negative or positive.

Migratory birds may introduce highly pathogenic H5N1 avian influenza from Southeast Asia into Australia via North Queensland, a key stopover along the East Asian-Australasian Flyway, with severe consequences for trade and human health. A 3-year repeated cross sectional study on the epidemiology of avian influenza in Australian nomadic wild aquatic birds was conducted in this potential biosecurity hotspot using molecular and serological techniques. Avian influenza virus subtypes H6 and H9 were commonly present in the studied population. It is likely that one of the H6 viruses was newly introduced through migratory birds confirming the perceived biosecurity risk. The matrix gene of another H6 virus was similar to the Australian H7 subtypes, which suggests the reassortment of a previously introduced H6 and local viruses. Similarly, a H9 subtype had a matrix gene similar to that found in Asian H9 viruses suggesting reassortment of viruses originated from Australia and Asia. Whilst H5N1 was not found, the serological study demonstrated a constant circulation of the H5 subtype in the sampled birds. The odds of being reactive for avian influenza viral antibodies were 13.1(95% CI: 5.9–28.9) for Pacific Black Ducks over Plumed Whistling Ducks, highlighting that some species of waterfowl pose a greater biosecurity risk. Antibody titres were slightly higher during warm wet compared with warm dry weather. Routine surveillance programmes should be established to monitor the introduction of avian influenza viruses from Asia and the interactions of the introduced viruses with resident viruses in order to better detect emerging pathogens in aquatic birds of North Queensland. Surveillance should be targeted towards highly susceptible species such as the Pacific Black Duck and carried out during favourable environmental conditions for viral transmission such as the wet season in northern Australia.

Waterbirds are currently facing various threats throughout the world. One threat that is often overlooked is hybridization with introduced species. This threatening process is especially significant for dabbling ducks (Genus Anas). The Mallard (Anas platyrhynchos) has been introduced to various parts of the world and now hybridizes and threatens numerous Anas species. In this paper, we review hybridization between Mallards and dabbling ducks with a specific emphasis on threats to the Pacific Black Duck (A. superciliosa). We then present an overview of the potential mechanisms of hybridization and discuss monitoring techniques. We conclude by proposing management strategies and speculating on the future of native dabbling duck species.

Toombullen was an intermittently flooded wetland near the Murrumbidgee River in southern inland New South Wales. In 1980 it was converted to an off-river storage. In the decade following impoundment, waterbirds at Tombullen showed a range of responses to permanent inundation. Abundances of Australia pelican, little pied cormorant, great cormorant, yellow-billed spoonbill, black swan, grey teal, maned duck, great crested grebe, Australasian grebe, freckled duck, Eurasian coot, great egret, little egret and intermediate egret decreased. Numbers of Pacific heron and straw-necked ibis increased, while Australia darter, little black comorant, Pacific black duck, Australian white ibis and royal spoonbill did not show consistent trends in abundance. The death of permanently inundated red gums coincided with cessation of egrets breeding and enhanced breeding of Pacific herons. Permanent impoundment of water in Tombullen disadvantaged most species, did not affect a few, had positive impacts on two species of waterbird and reduced species diversity.

Subspecies delineations may not reflect actual intraspecific diversity; an issue that becomes important when conservation of populations and/or subspecies that face severe declines is involved. The Grey Duck in New Zealand is considered a separate subspecies Anas superciliosa superciliosa from the Pacific Black Duck A. s. rogersi of Australia, even though poorly differentiated morphologically. Because the New Zealand and Australian populations of A. superciliosa are considered taxonomically distinct, the decline of New Zealand's Grey Duck and its hybridization with the introduced Mallard A. platyrhynchos has led to assignment of "endangered" conservation status. Taxonomic distinction and absence of periodic gene flow between the Australian and New Zealand populations are crucial for acceptance of this status. We used phylogeographic analysis of mitochondrial DNA control region sequences to determine whether haplotypes representing current subspecies are unique or are more consistent with populations in the two countries being considered the same subspecies. Two highly divergent genetic lineages of Grey Duck occur in New Zealand. One lineage (Group I) is found only in New Zealand primarily on North Island, while the other (Group II), occurs in populations throughout New Zealand and Australia. The split between Group I and II lineages is on the order of that found between some avian species. Even though subspecific designations of A. s. superciliosa and A. s. rogersi do not hold up based on molecular data, we identify a need for Grey Duck in New Zealand to be conserved to maintain the historical diversity within the species.

Niuafo'ou lies very isolated in the Pacific, is well forested and not densely populated by humans. These facts as well as the lack of larger rat species make it a refuge for birds rare elsewhere in the region. This paper covers all 17 breeding species and gives breeding data for 14 of them, collected from October 1991 to December 1992. Ten species had a well-defined breeding season of 2?7 months somewhere between September and April, which often differed from other adjacent islands: Audubon's Shearwater Puffinus Iherminieri, Pacific Black Duck Anas superciliosa, Banded Rail Rallus phillippensis, Spotless Crake Porzana tabuensis, Purple Swamphen Porphyrio porphyrio, Barn Owl Tyto alba, Red-vented Bulbul Pycnonotus cafer, Polynesian Starling Aplonis tabuensis nesiotes, and Jungle Myna Acridotheres fuscus. The Blue-crowned Lorikeet Vini australis nested in October, November and July. It did not only breed in tree hollows, but also inside a rotten log on the ground. Other observations suggest that it visits ground holes as well, either for nesting or resting. A breeding colony of Audubon's Shearwater is the first one confirmed for Tonga. Four species nested in the wet and dry season: White-tailed Tropicbird Phaethon lepturus, Pacific Reef-heron Egretta sacra, Pacific Pigeon Ducula pacifica and Polynesian Megapode Megapodius pritchardii. Since September to March is the main breeding season for birds on Niuafo'ou, it is proposed that hunting and egg collecting, both important parts of the local tradition, are restricted to the other months of the year. In case of the endangered Polynesian Megapode we suggest a restriction of egg collecting and propose a translocation programme to another island. Additionally, we suggest that the islets in the crater lake become protected as they are free of feral cats, and some birds occur in higher densities there. Niuafo'ou also deserves attention as resting place for six vagrant and migrant species; large numbers of Wedge-tailed Shearwaters Puffinus pacificus are hunted when they visit between October and June.

We examined the relationships between abundance of 16 species of waterbirds and the rainfall in eastern Australia, the rainfall west of this region, the annual Southern Oscillation index (SOI), the wetland area, and hunting in eastern Australia for the period 1983–92. Data were collected during aerial surveys of eastern Australia. For most explanatory variables, lags of up to five years before aerial surveys were also investigated during these analyses. The analyses covered all nine game species (plumed whistling-duck, Australian shelduck, Australian wood duck, pink-eared duck, grey teal, chestnut teal, Pacific black duck, Australasian shoveler, hardhead) and seven non-game species (Australian pelican, white-faced heron, yellow-billed spoonbill, freckled duck, black swan, black-winged stilt, red-necked avocet). Regression models were developed for all species apart from Australian pelicans. Rainfall and climate indices generally were most correlated with the species’ abundance. Bonferroni adjustments to significance levels meant that there were significant variables in regression models for seven of the 16 species. Abundance indices for plumed whistling-duck, chestnut teal, hardhead, black swan and black-winged stilt were related to the climate variables (rainfall, SOI) and wetland area, whereas abundance of pink-eared duck and red-necked avocets were negatively related. Abundance of chestnut teal was positively related to numbers of hunting licences sold. The results are equivocal about the role of hunting in determining waterfowl abundance, which is probably a reflection of few data points and numbers of variables included. In general, abundance indices of waterbirds appear to have decreased between 1983 and 1992, which may correspond to other factors not modelled

Duck hunters have been surveyed on the opening morning of duck seasons since 1972 at Lake Cowal and Barrenbox Swamp in southern inland New South Wales. Mean numbers of ducks shot per hunter on opening morning reflected the numbers of ducks at the sites two to three weeks previously. At Barrenbox Swamp, but not at Lake Cowal, mean bag sizes were inversely related to recent local rainfall. Mean bag sizes on opening morning at Lake Cowal and Barrenbox Swamp did not diminish following reduction of the opening-day bag limit from 20 to 10 ducks per day in 1988. Generally, numbers of ducks and mean bag sizes at Lake Cowal and Barrenbox Swamp have not declined or increased since 1972 (exceptions are increased numbers but decreased bag sizes of Pacific black duck at Barrenbox Swamp, and increased bag sizes of maned duck at Lake Cowal). At neither hunting site were numbers of ducks related to mean bag sizes in the previous year. In summary, hunting does not appear to be adversely affecting numbers of major species of game ducks at either Lake Cowal or Barrenbox Swamp.

The concentrations of lead in wing bones of Victorian waterfowl were determined from samples collected mainly during the opening weekend of the 1990 duck-hunting season. Of about 7000 wings collected, 1134 (of 12 species and from wetland collection sites throughout the State) were subsampled for analysis. Although lead concentrations in bone were low in some species (e.g. chestnut and grey teal, freckled duck), higher concentrations were found in some small samples of diving ducks and in Pacific black duck. Tissues of Pacific black duck from one major hunting area indicated exposure to lead. Of 194 gizzards inspected, 28 (14.4%) contained ingested and eroded lead shotgun pellets. Lead concentrations in the livers of some Pacific black duck were also elevated, with 4.6% having more than 2.0mg kg-1. Other studies have found that waterfowl may die after ingestion of lead shotgun pellets; since such pellets may present a similar threat to local waterfowl populations, the use of alternative non-toxic ammunition should be encouraged.

Aerial surveys between 1981 and 1984 were used to identify monthly trends in the abundance of wandering whistling-duck Dendrocygna arcuata, plumed whistling-duck D. eytoni, radjah shelduck Tadorna radjah, Pacific black duck Anas superciliosa, and grey teal A. gibberifrons on five floodplains of the Alligator Rivers region, 250 km east of Darwin in the monsoonal north of the Northern Territory. Ground surveys were conducted during the same period on one of the floodplains, the Magela plain, to provide more detailed information. The Magela floodplain was inhabited by few ducks during the wet season (November to March), but numbers then increased to dramatic peaks in the late dry season. The Nourlangie floodplain and Boggy Plain (a large backswamp of the South Alligator floodplain) showed similar patterns, but the numbers of ducks were usually fewer. Ducks were uncommon on the shallower East Alligator and Cooper floodplains except for relatively brief periods in the wet season. The ground surveys suggested that ducks sought out the persistent swamps that characterise the Magela floodplain in the dry season. Ground surveys also indicated that aerial surveys underestimated densities; on the basis of correction factors calculated from the ground surveys, peak numbers on the five floodplains were roughly estimated to be 400 000 wandering whistling-ducks, 70 000 plumed whistling-ducks, 20 000 radjah shelducks, 50 000 Pacific black ducks, and 50 000 grey teal. Pink-eared ducks Malacorhynchus membranaceus and hardhead Aythya australis were recorded sporadically in low numbers. The Alligator Rivers region acted as a dry season refuge for large concentrations of ducks because of the atypical persistence of freshwaters on the Magela and Nourlangie floodplains and some of the backswamps of the South Alligator, such as Boggy Plain. The large aggregations appear to be unique in Australia.

The activities of Pacific Black Ducks Anus superciliosa, Chestnut Teal A. castanea (adults and non-flying young) and Grey Teal A. gibberifrons in a fresh-water habitat and the use made of subdivisions within that habitat were studied by making hourly observations on every seventh day for ten weeks. In the study area most ducks spent the day loafing: Black Ducks fed more (28.6% of observations) than Chestnut Teal (18.3%) and Grey Teal spent little time (7.6%) feeding. Most ducks fed early and late in the day. All species shared all divisions of the habitat for feeding and loafing, the mam. activities considered, but Chestnut Teal used dead trees and logs more for loafing than the other specles, whch concentrated on isolated short grassland, Younger ducklings spent most time feedmg but older ones tended to resemble adults in time spent in various activities. Any competition for food that may occur between the three species could be reduced by nocturnal dispersal to different feeding areas, by selection of different foods or by the selection of Mering sues of the same food as a consequence of the different sizes of bid.

Details of changes in numbers of Chestnut Teal Anas castanea, Grey Teal A. gibberifrons and Pacific Black Duck A. superciliosa within a study area in Corner Inlet, Victoria are given. Whilst a few Black Duck were seen occasionally, Chestnut Teal showed a regular movement into the area in October or November and maximum numbers were seen from April to June. It is suggested that they move into the area following breeding and disperse from it to breed. Peak counts of Grey Teal were more variable, but both species left the area, following heavy local rain, and were either absent or scarce between July and October. Activities of the three species were governed by the tide. Though few Pacific Black Duck were seen feeding in the study area, Chestnut and Grey Teal fed on mud flats there as they became available and rested on land, or water, towards and following high water. Teal used the permanent freshwater soaks for drinking, thus ameliorating the effects of salt taken in with food (mainly molluscs, particularly Glossaulax sordidus, polychaetes and other marine invertebrates). Saline areas, such as Corner Inlet, holding relatively large numbers of waterfowl in non-breeding seasons are apparently few in Victoria. Since they may represent habitat of importance, particularly to Chestnut Teal, development of them requires consideration of waterfowl requirements.

Total mercury concentrations in wing muscle of 10 species of waterfowl (Anatidae) collected during 1977 and 1978 in south-eastern Australia ranged from 0.08 � 0.04 (mean � SD) g g-1 wet weight in Australian shelduck Tadorna tadornoides and Pacific black duck Anas superciliosa, to 0.17 � 0.08 g g-1 in freckled duck Stictonetta naevosa. No significant differences in concentrations of mercury in muscle were found between sexes or between juvenile and adult birds. Total mercury concentrations in feathers were 3.01 � 0.09 g g-1 dry weight in Pacific black duck and 3.27 � 1.11 g g-1 in grey teal Anas gibberifrons. A significant positive correlation (r= 0.7783; P

In March 1977 one wing was collected from each duck of 12 species from 10 sites in south east Australia. Feathers were removed and the wing was ground for estimation of organochlorine residues. In 1978 there were 25 whole male Pacific black ducks (Anas superciliosa) analysed. Total DDT ranged from 0.03 to 316.1/106 wet weight between individual Pacific black duck wings and from 0.02 to 15.10/106 in pooled samples of wings for each species. There were significant positive relations between total DDT residue in wing and those in liver, brain, breast muscle and fat of individual Pacific black ducks. Residues may be important in breeding of ducks and because the ducks are shot and eaten by man.

The results of six annual surveys of waterfowl hunters in New South Wales by mail card are reported. The aims of the survey were to ascertain reported distribution of hunting effort, size and composition of hunters' bags, and state of hunter origin. Hunting effort and waterfowl harvests were highest in southern inland New South Wales. Seasonal bag sizes varied between 15.8 and 27.2 ducks per hunter. Pacific black duck, grey teal and maned duck made up 88.6% of hunters' bags. About half the hunters in New South Wales originated from Victoria. Bag size and species composition, effect of reducing bag size on total harvest, regional bias in hunting effort and harvest, and annual variation in licence sales are discussed.

Populations of waterfowl of three game species, the Pacific black duck Anus superciliosa, grey teal A. gibberifrons, and maned duck Chenonetta jubata, were assessed by aerial survey in October 1983 within a survey region of 2 697 000 km2 of eastern Australia. The numbers of each species were assessed on all surface waters of over 1 ha, and on a sample of smaller surface waters within 10 survey bands each 30 km wide and spaced at intervals of 2� latitude from 20�30' to 38�30'S. The area within the survey bands was 324 120 km2, which gave a sampling intensity of 12.0% of the land surface area. The area of features shown as wetlands or water impoundments within the survey bands on 1 : 2 500 000 topographic maps was 19 200 km2 or 11.2% of the total area of these features in the survey region. The area of surface waters surveyed was assessed at 465 300 ha. Assessments of populations of each species were tallied for wetlands by grid cells of 6 min of 1� longitude along the survey bands (258-309 km2 depending on latitude). Distributions were then mapped, with log*10 indices of populations in each cell. Distributions of the black duck and grey teal showed a pattern of intense aggregation in limited numbers of cells, that of the maned duck was more evenly distributed. The major concentrations of the Pacific black duck were recorded in northern New South Wales and the south-eastern, western, central eastern and central coastal regions of Queensland; those of the grey teal were in south-western, western and northern New South Wales and central-eastern Queensland; the maned duck was broadly distributed over inland New South Wales with the exception of the far west, inland southern Queensland, and central northern Victoria.

'Monthly waterbird counts from February 1974 to June 1977 at six wetlands in the Richmond River valley in northern coastal New South Wales were analysed to investigate relationships between numbers of each species, and season and water variables. Black swan, Pacific black duck, purple swamphen, dusky moorhen, cattle egret, comb-crested jacana and sharp-tailed sandpiper were strongly influenced by season. Grey teal, straw-necked ibis, little black cormorant, Pacific heron and black-winged stilt numbers were related to Murray River discharge, an index of inland wetland availability in New South Wales, northern Victoria and parts of southern Queensland. Numbers of most waterbirds were highest on the coast from late summer to the end of winter. Their seasonal abundance patterns conform with the results of some previous studies but differ somewhat from others.

The movements of ducks to refuges in response to hunting pressure were investigated during the opening of the 1981 duck season. Grey teal, Pacific black duck, hardhead and Australasian shoveler actively sought refuge whilst pink-eared duck did not. Some implications for management are discussed.

Bag sizes of game ducks in New South Wales between 1977 and 1984 were compared with antecedent annual rainfall in eastern Australia. Mean bag size is equivalent to 'catch-per-unit-effort', an index of population abundance. Annual rainfall is an index of habitat availability for waterfowl. Bag sizes of Pacific black duck and all game species combined were significantly (P