American Wigeon Research Articles

Effects of Climate Change and Land Use on Duck Abundance in Canadian Prairie‐Parklands

Recent declines in the number of breeding ducks in the Canadian prairie‐parklands have been hypothesized to be due to loss of habitat to agriculture. However, prairie‐parkland also has experienced wetland loss to drought as well as to agriculture. If habitat restoration is to be implemented and monitored successfully, it is important to separate the effects of anthropogenic changes to the landscape on duck populations from those caused by changes in climate. We used data from annual air–ground surveys and from precipitation records to develop relationships between indices of abundance of each of 10 species of ducks and indices of wetland conditions during 1955‐1974. We used these relationships to predict annual abundance of each species during 1975‐1989. We compared predicted and observed abundances over the period 1975‐1989 to distinguish declines in duck abundance greater than those accounted for by drought alone and to determine the magnitude and location of real "deficits" in duck abundance. Average annual deficits within Canadian prairie‐parkland over the period 1975‐1989 were estimated at 1.2 x 106 birds for both Mallard (Anas platyrhynchos) and Northern Pintail (A. acuta), 480 000 for Blue‐winged Teal (A. discors), 190 000 for American Wigeon (A. americana), 175 000 for Northern Shoveler (A. clypeata), 50 000 for Gadwall (A. strepera), 10 000 for Green‐winged Teal (A. crecca), 40 000 for Canvasback (Aythya valisineria), 25 000 for Lesser Scaup (A. affinis), and 5000 for Redhead (A. americana). Overall, the effect of agricultural expansion in the east on prime waterfowl habitat since 1951 appears to have been negligible. There, as much as 90% had been already lost prior to 1951. In the west, however, where prime waterfowl habitat was still relatively abundant in 1951, agricultural development has encroached substantially. The relationship between the lost area of the best breeding habitats and the size of population deficits for Mallards and Northern Pintails in the entire Canadian prairie‐parkland region was significant for both species (P < 0.0027 and P < 0.0001, respectively). Consequently, habitat restoration programs located where the highest quality waterfowl habitat and the lowest quality agricultural lands overlap most should have the greatest potential to affect recovery of breeding duck populations in the Canadian prairie‐parklands.

Influenza A viruses isolated from waterfowl in two wildlife management areas of Pennsylvania.

A survey was conducted at two wildlife management areas of Pennsylvania (USA) to evaluate an antigen capture enzyme-linked immunosorbent assay (AC-ELISA) for the detection of avian influenza viruses (AIV) in cloacal swabs from waterfowl and to determine the influenza A virus subtypes and the distribution of these viruses among waterfowl. We collected 330 cloacal swabs from hunter-killed waterfowl in the fall of 1990 and from cage-captured waterfowl in the summer of 1991. Thirty-one hemagglutinating agents were isolated by chicken embryo inoculation (CEI) of which 27 were influenza A viruses and four Newcastle disease viruses (NDV). The prevalence of AIV infection was 8.2%. Compared to CEI, AC-ELISA was only 15% sensitive and 61% specific. Based on the distribution of AIV by species of waterfowl, mallards (Anas platyrhynchos) and American wigeons (Anas americana) were at equal risk of AIV infection even though most of the AIV isolates came from mallards. Although significant crude effects of sampling site and season on AIV recovery could be established, juvenile age was identified as the primary risk factor of AIV recovery. Twelve AIV subtypes were identified by hemagglutination inhibition (HI) and neuraminidase inhibition (NI) tests. The most prevalent subytpes were H4N8 and H6N8. We concluded that AC-ELISA was not useful for the detection of AIV in cloacal swabs from waterfowl and that CEI, HI, and NI tests remain as the method of choice for AIV screening in waterfowl. Based on the results AIV infected preferentially the young which represent the high risk group in waterfowl populations.(ABSTRACT TRUNCATED AT 250 WORDS)

Habitats and tidal accessibility of the marine foods of dabbling ducks and brant in Boundary Bay, British Columbia

The role of birds in intertidal food webs is mediated by effects of tides on the habitat, distribution, and accessibility of food organisms. We studied effects of elevation, sediment characteristics, vegetation, and tidal cycles on waterfowl feeding and food organisms in Boundary Bay, British Columbia, Canada from September to March 1990–1992. Percent dry mass of esophageal contents was mainly Zostera japonica leaves (84%) for American wigeon (Anas americana Gmelin), and leaves of Z. japonica (57%) and Z. marina (41%) for brant (Branta bernicla L.). Northern pintails (A. acuta L.) and mallards (A. platyrhynchos L.) ate mostly the leaves, seeds, and rhizomes of Z. japonica (48 and 72%, respectively) and gastropods (12 and 28%). Green-winged teal (A. crecca L.) ate mainly amphipods (68%) and saltmarsh seeds (19%). The well-sorted fine sand (median 0.125 mm) to medium sand (0.25 mm), and the low organic carbon content (1.31±0.12% dry mass), did not appear to vary sufficiently along 2.1- and 2.6-km transects to affect macroinvertebrate distributions. Three habitat zones were recognized: (1) upper intertidal (sandflats); (2) mid-intertidal (largely monotypic Z. japonica); and (3) lower intertidal (mixed Z. japonica and Z. marina). These zones, although related to elevation, had greater influence on amphipod distributions than did elevation alone or detrital biomass. Biomass and numbers of most invertebrate foods of waterfowl were greatest in the eelgrass zones, with the upper elevational limit of Z. japonica occurring at about Mean Water Level (MWL). Accordingly, wigeon, pintails, and mallards fed mostly below MWL. Because of seasonal tidal cycles, daily accessibility of areas below MWL but within reach of surfacefeeding waterfowl decreased from a mean of 10.8 h in October to 9.6 h in December. In October only 10 d and <12 h available feeding time, whereas in December and January every day had <12 h available feeding time. Seasonal effects of tides on accessibility might limit sufficient feeding by some waterfowl species in intertidal areas, increasing their reliance on alternative feeding sites.

Fall Food Habits of American Wigeon at Long Point, Lake Erie, Ontario

We studied food habits of an abundant migrant, the American wigeon ( Anas americana), staging during the 1991 fall migration at Long Point, a World Biosphere Reserve and a Ramsar site on the north shore of Lake Erie. Food samples from 149 wigeons were analyzed; stems and leaves of aquatic plants (predominantly submerged macrophytes) comprised over 92% aggregate dry mass of the diet, seeds made up 7.8%, and animal matter 0.6%. A diverse array of plant species was identified; however, results indicate that wigeons were showing selectivity in plant species consumed. Stems and leaves of muskgrass ( Chara spp.), elodea ( Elodea canadensis) and bushy pondweeds ( Najas flexilus and N. guadalupensis) (aggregate percent dry mass 37%, 22%, and 18% for proventriculi, and 15%, 12%, and 38% for gizzards, respectively) comprised the bulk of the diet, although neither bushy pondweed nor elodea wholly dominated submerged macrophyte communities. Several submerged macrophytes, such as coontail ( Ceratophyllum demersum) and pondweeds ( Potamogeton spp.) which are common and widespread at Long Point and reported frequently as important in the diet of American wigeons elsewhere, were not found at all or only in trace amounts. Some sex, age, and seasonal differences in diet were detected; Chara spp. and tubers were eaten more frequently by adults than by immatures, Elodea canadensis was eaten in late fall by females but not by males, immatures ate Myriophyllum spicatum seeds more frequently than did adults, and Najas spp. was consumed more in late fall than in early fall.

Temporal components of genetic variation in migrating and wintering American wigeon

Data from allele frequencies of wintering American wigeon (Anas americana) from the Southern High Plains (SHP) of Texas were used to monitor changes in genetic characteristics of the wintering population through time, and to estimate the average proportion of total genetic variation partitioned among parent breeding populations. Wigeon were surveyed electrophoretically for genetic variation at 25 biochemical loci. Changes in total gene diversity were observed throughout the study period (5 October 1988 to 15 March 1989) at numerous loci. Significant temporal changes in the genetic composition of the wintering population were detected, and a minimum of 7% of the total genetic variation in these wigeon was thought to be partitioned among the breeding populations represented on the SHP. A new influx of migrating wigeon, weather-related movements of wigeon, or spatial subdivision of breeding populations on the SHP may be responsible for shifts observed in the genetic characteristics of the wintering population. Significant heterozygote deficiencies in the sample of wintering wigeon suggest that this species maintains some degree of genetic structure on the breeding grounds. Genetic data collected from wintering waterfowl may provide minimum expectations of the degree of genetic subdivision among breeding populations and may help waterfowl biologists to detect changes in the composition of wintering waterfowl populations through time.

Response of Canada geese to a turf application of diazinon AG500.

We investigated the effects of a turf application of the insecticide diazinon AG500 on Canada geese (Branta canadensis) on a golf course in coastal Washington (USA). On both 19 and 26 March 1987, 1 ha of turf on a golf course located in Birch Bay, Washington was treated with diazinon AG500 at a target application rate of 2.2 kg active ingredient per hectare (AI/ha). Treated areas were then irrigated with 6 mm water. Grass and water samples were collected from three different sites one day before and 1, 3, 7 and 14 days after each application. Diazinon residues > or = 20 ppm were found in golf course grasses for one week after each application. Diazinon residues in study area ponds and creeks were > or = 17 ppb. Samples from two irrigation puddles one day post-application had 1.00 and 0.20 ppm of diazinon, respectively. Numbers of geese present declined following diazinon application; however, no goose mortality was observed. Geese spent 422 and 538 min feeding on the treated areas after the first and second diazinon applications, respectively. One goose feeding in treated areas demonstrated signs of poisoning (lethargy, ataxia) for several hours. Two other geese feeding in the treated areas may have been slightly intoxicated. During carcass searches, three American wigeon (Anas americana) carcasses were found. Based on brain cholinesterase (ChE) levels and gastrointestinal (GI) tract residues of diazinon present, we concluded that these wigeon died from diazinon poisoning. Numerous songbirds (Passeriformes) also fed on the treated turf but no apparent response to the insecticide was observed.

Mallard X American Wigeon Hybrid on the Southern High Plains of Texas

Mallard X American Wigeon Hybrid on the Southern High Plains of Texas

American wigeon mortality associated with turf application of diazinon AG500.

Nine fairways of a golf course located in Bellingham, Washington were treated with diazinon AG500 at a target application rate of 2.2 kg active ingredient (AI) per ha. The chemical application with a "boomless" sprayer resulted in a variable distribution of diazinon residues on the turf (associated with a deep thatch layer) that ranged from 1.0 to 6.2 kg AI/ha. The diazinon-treated turf was irrigated with 1.3 cm of water immediately following application. The post-irrigation diazinon residue levels ranged from 100 to 333 ppm (mean = 209; SD = 88; n = 8). These residue levels were higher than expected based on results of turf studies in other regions of the United States. Eighty-five American wigeon (Anas americana) died after grazing on one treated fairway on the day of application following irrigation. The brains of all 85 wigeon were analyzed for acetylcholinesterase (AChE) activity. Wigeon that died on the study area (n = 85) showed 44% to 87% depression of AChE (mean = 76%; SD = 7.1%) when compared to control wigeon (n = 3; AChE Activity = 1.86) AChE levels. Upper GI tract contents of 15 of the 85 dead wigeon contained 0.96 to 18.1 ppm diazinon. Extensive carcass searches revealed no other avian mortality attributable to diazinon toxicity on the treated study area. Although initial post-irrigation diazinon residues in grass samples were higher than expected, diazinon levels in grass samples on day seven post-application had declined to an average of 29 ppm. American wigeon appear to be vulnerable to exposure to diazinon.(ABSTRACT TRUNCATED AT 250 WORDS)

CORRELATIONS OF DAILY ACTIVITY WITH AVIAN CHOLERA MORTALITY AMONG WILDFOWL

We tested the hypothesis that wildfowl activities can influence the risk of avian cholera (Pasteurella multocida infection) for susceptible birds at Centerville, Humboldt County, California (USA). Avian cholera mortality characteristics from past epizootics were correlated with variations in flock size, habitat use and 11 feeding and nonfeeding behaviors among six empirically defined groups of wildfowl: American coots (Fulica americana), tundra swans (Cygnus columbianus), American wigeon (Anas americana), northern pintails (A. acuta), northern shovelers (A. clypeata)/mallards (A. platyrhynchos), and teal (A. discors, A. crecca, A. cyanoptera). The position of these wildfowl groups in past mortality sequences was directly correlated with mean flock size, time spent on land, and time spent grazing on land or in shallow water. We propose that variations in bird density, habitat use and frequency of grazing may serve as predisposing factors to avian cholera among wildfowl.

Some Problems and Approaches in Avian Mate Choice

Some Problems and Approaches in Avian Mate Choice

Epizootiological features of avian cholera on the north coast of California.

An avian cholera (Pasteurella multocida) epizootic was observed among wildfowl at the Centerville Gun Club, Humboldt County, California (USA) in January 1978. Compared to their live populations and use of the area, coots (Fulica americana) died in proportionately greater numbers than any other species. Coots collected by gunshot were evaluated for sex and age composition, and morphometry from November 1977 through mid-January 1978 at this site. There was no substantial difference in the sex, age or morphometry between birds dying of avian cholera and from those dying from gunshot. Assuming coots dying of gunshot are representative of the general population, it appears there was little selection among coots by P. multocida. There was evidence for a sequential mortality similar to that reported previously at this site: coots were the first birds to die, followed by American wigeon (Anas americana) and northern pintails (A. acuta acuta); northern shovelers (A. clypeata) and mallards (A. platyrhynchos) died late in the epizootic.

Northern Harrier Kills American Wigeon

Northern Harrier Kills American Wigeon

CHAUCER'S MONK: AN ERRANT EXEGETE

In the General Prologue to Chaucer's Canterbury Tales, Daun Piers the Monk is the fifth pilgrim to be described in detail and the first to receive the full force of the narrator's irony. Critical discussion on the Monk commonly centres on the physical evidence pointing towards carnal indulgence, this in turn being seen as not merely laxity in respect of his rule but downright defiance of it.1 The Monk's worst failings, however, lie not so much in the fleshly sins ofgula and, probably, luxuria as in inobedentia and accidia, whose consequences become manifest in his tale. There the mishandling of his exemplary material, particularly events in biblical history, reflects his wasted opportunities as cloisterer and thereby links tale with teller to degree of congruency which at one time went unappreciated. The shining bald pate, the glistening fat face, the plump body, and especially the rolling, bulging, gleaming eyes all offer character clues made familiar in the physiognomies, such as 'dull and luxurious inwit' and 'concupyscence of fleschy lustes' as well as tendency to be lecherous, envious, shameless, slothful, disobedient, and a clatterer and foole— these and other signs of moral turpitude are evidenced, according to several versions of the Secreta Secretorum, by the Monk's physiognomy. His eyes alone give him away. The token of shameless man is ryst opyn eighyn and glysinynge and of lecherous man fatte heyghen, and rollynge Swyftly in syght like wode man.2 Coupled with the physiognomical evidence against the Monk go the more direct innuendoes planted in the narrator's choice of imagery. The phrases that lovede venerie and a fat swan loved he best of any roost,3 to say nothing of the hunting terminology, bear suggestive double mean ings.4 When the whole picture is put together, there emerges an ironically presented indictment of wordly cloisterer whose gluttonous habits and immoral conduct only too pointedly confirm charges of this kind familiar in Chaucer's era. That Harry Bailly the Host certainly draws this conclusion his ribald suggestions later reveal:

Age-Class Determination of Ring-Necked Ducks

A quantitative technique was developed to distinguish adult from yearling ring-necked ducks (Aythya collaris) during the breeding season using wing feather criteria. This method requires removal and measurement of the 5th secondary (S 5) and 12th greater secondary covert (GSC 12). Bursal and other plumage characteristics were evaluated for use in the field during the breeding season. Cloacal characteristics are of no value in distinguishing adult and yearling males after arrival on breeding areas (Apr), but bursal depth >10 mm is characteristic of yearling females into their Ist breeding season. Although not all adult females have white head feathers (e.g., flecking), the presence of flecking on mature females strongly indicates adult status. J. WILDL. MANAGE. 50(3):442-445 The ability to distinguish age classes within waterfowl populations is important in understanding aspects of their reproductive biology and population dynamics (Serie et al. 1982). However, determining age classes of waterfowl that reproduce in their 1st year often is difficult, especially during the breeding season. Cloacal (Gower 1939) and rectrix (Pirnie 1935) characteristics are commonly used during the fall and winter to distinguish immatures from adults but are unreliable for birds captured in spring (Hochbaum 1942). Use of qualitative wing feather criteria for determining age class and sex is possible for some species: mallards (Anas platyrhynchos) (Krapu et al. 1979, Gatti 1983), blue-winged teal (A. discors) (Dane 1968), American wigeons (A. americana) (Wishart 1981), canvasbacks (Aythya valisineria) (Serie et al. 1982), and redheads (A. americana) (Dane and Johnson 1975). Unfortunately, these methods do not work well for ring-necked ducks (Carney 1964). Remiges and associated coverts are retained by juvenile waterfowl until the prebasic II molt and are replaced annually thereafter during the prebasic molt (Humphrey and Clark 1961). Multivariate statistical procedures using wing feather measurements have been used to determine age of springand summer-caught mallards (Krapu et al. 1979, Gatti 1983), gadwalls (Anas strepera) (Blohm 1977), American wig ons (Wishart 1981), canvasbacks (Serie et al. 1982), and redheads (Dane and Johnson 1975). Here we describe a quantitative technique for accurate age class separation of male and fema e ring-necked ducks in spring and early summer. Additionally, bursal and other plumage characteristics are evaluated for use in the field during the breeding season. We wish to thank B. D. J. Batt, R. D. Crawford, and M. W. Weller for their helpful comments on earlier drafts of the manuscript. We were assisted in the field or laboratory by J. S. Barzen, D. O. Carlson, L. A. Fluggeman, and J. W. Grimm. Financial support was provided by the North Am. Wildl. Found. through the Delta Waterfowl and Wetland Res. Stn., Univ. Minnesota (Dep. Fish. and Wildl., Comput. Cent., Agric. Exp. Stn., and Graduate School), Minn. Dep. Nat. Resour., and Minn. Waterfowl Assoc. This is J. Pap. 13837 of the Minn. Agric. Exp. Stn., St. Paul, Minn.

Gastrointestinal helminths of the Mexican duck, Anas platyrhynchos diazi Ridgway, from north central Mexico and southwestern United States.

Twenty-five species of helminths, recovered from the gastrointestinal tracts of 129 Mexican ducks from Mexico and the United States, were all new host records. The species included: Echinoparyphium recurvatum, Echinostoma revolutum, Hypoderaeum conoideum, Notocotylus attenuatus, Prosthogonimus cuneatus, Zygocotyle lunata, Anomotaenia ciliata, Cloacotaenia megalops, Diorchis bulbodes, Diorchis sp., Drepanidotaenia lanceolata, Echinocotyle rosseteri, Fimbriaria fasciolaris, Fimbriarioides sp., Hymenolepis sp. 1, Hymenolepis sp. 2, Sobolevicanthus gracilis. Corynosoma constrictum, Polymorphus minutus, Amidostomum acutum, Echinuria sp., Epomidiostomum crami, Hystrichis varispinosus, Rusguniella arctica, and Tetrameres sp. Fimbriarioides sp. occurred predominantly in ducks from south-central Chihuahua, Mexico. The distributions for the other 24 species of the helminths were not significantly different among the four collecting areas. The helminth fauna for the 32 complete specimens and 97 intestinal tracts was distributed relatively evenly among the hosts with a calculated mean evenness of 0.77 +/- 0.15 and 0.89 +/- 0.03 respectively. The parasite fauna was more similar to those of the black duck Anas rubripes Brewster of eastern North America (53%), the mallard, Anas platyrhynchos (L.) (49%), and the mottled duck, Anas fulvigula Ridgway, from Florida (45%), than to the green-winged teal, Anas crecca (L.) (36%), the gadwall, Anas strepera (L.) (30%), and the American wigeon, Anas americana Gmelin (26%), collected in the Southwest.

Winter Condition of Mallards on the Southern High Plains of Texas

Body composition and condition of mallards (Anas platyrhynchos) wintering on the Southern High Plains (SHP) of Texas were studied from October to March 1979-82. Lipid reserves, and usually body weights, of all sex and age classes were lowest in autumn. By mid-winter, however, lipid reserves increased 49-62% for adults and 21-30% for juveniles and averaged 13-18% of body weight. The majority of these reserves (56-100%) were acquired from autumn to early winter. Adults and juvenile females then lost lipids from mid-winter to late winter (9-15%), but juvenile males increased reserves by 20%. Adult females mobilized more lipids than adult males during late winter (15 vs. 9%) and previously had acquired a larger reserve (20 vs. 7%). Body weight and lipids increased before spring migration. Overall, mallards on the SHP maintained better condition than those wintering farther north. J. WILDL. MANAGE. 50(1):52-57 Body weight and carcass composition of waterfowl are not stable during winter (Peterson and Ellarson 1979, Raveling 1979, Reinecke et al. 1982). These changes may be influenced by body condition, which has been defined as an individual's ability to meet present and future needs (Owen and Cook 1977). In this paper we refer to condition as the relationship between an individual's endogenous energy reserves and energy demands for maintenance, productivity, and activity. The SHP of Texas is an agricultural region where wintering mallards have adopted a fieldfeeding strategy; they join northern pintails (A. acuta), American wigeons (A. americana), and green-winged teal (A. crecca) in morning and evening field-feeding flights for waste corn (Baldassarre and Bolen 1984). More than 90% of the diet, by volume, consisted of corn during a 2-year study sampling 324 mallard crops and gizzards (Moore 1980). Corn is higher in energy than seeds of native plants occurring in the numerous playa lakes that serve as wetland habitat for waterfowl on the SHP (Baldassarre et al. 1983). This high energy content influences body condition as available carbohydrates are converted into endogenous lipids (Hazelwood 1976). Lipids, in turn, become important reserves used by birds during periods of winter stress (Blem 1976). However, although mallards wintering on the SHP have access to high energy foods, they also encounter temperature stress during certain periods (Whyte and Bolen 1984). The objective of this study was to determine the relationship between winter stress and carcass composition, especially lipid reserves, of mallards wintering on the SHP. Financial support was provided by the Caesar Kleberg Found. Wildl. Conserv. and the U.S. For. Serv. (F. A. Stormer, Proj. Leader, Great Plains Wildl. Habitat Res. Lab.). J. D. Myrick, J. R. Davis, C. L. Lee, H. A. McLain, D. W. Brown, W. J. Hill, and T. J. Hill granted access to private property. R. J. Baker, K. T. Scribner, J. J. Juen, E. E. Quinlan, G. E. Huber, R. H. Lunn, and R. D. Godfrey aided collection of mallards during hunting seasons. R. D. Godfrey, J. A. Templer, and J. J. Peterson assisted with laboratory work. L. J. Celentano and D. B. Webster provided advice during statistical and computer analysis of the data. We are grateful to all. This is contribution T-9-370 of the Coll. Agric. Sci., Texas Tech Univ., Lubbock.

Range extension of the American Wigeon, Anas americana, to the island of Newfoundland

Range extension of the American Wigeon, Anas americana, to the island of Newfoundland

Moult chronology of American Wigeon, Anas americana, in relation to reproduction

Moult chronology of American Wigeon, Anas americana, in relation to reproduction

Pairing chronology and mate selection in the American wigeon (Anas americana)

The American wigeon (Anas americana) was studied during winter in southwestern British Columbia and on its breeding grounds in south-central Saskatchewan. Sex ratios ranged from 52.4 to 59.6% males. Wigeons courted in small groups but not all birds did so concurrently. However, by April all females were paired. Some winter pair bonds were temporary and observations of wild birds as well as a group of captives indicated that males and females exhibited mate preferences. Persistent aggression, dominance, mate attentiveness, and the performance of functional displays and aerial chases by males were important in acquiring a mate. Adult males in full alternate plumage tended to pair earliest. Those unable to obtain a mate were generally smaller and had lower protein and lipid reserves. These characteristics with which mate choice was correlated were also those which were important during nesting later on.

Short vs long scalp flaps in the treatment of male pattern baldness.

Hair transplantation has been used to restore the bald pate for 25 years. The dissatisfaction of some physicians and patients with the difficulty in obtaining natural density and the length of time necessary to achieve cosmetically acceptable coverage has been a stimulus to the development of scalp flap surgery. The flaps have the advantage of transferring large amounts of hair that give immediate and continuous coverage, normal density, and an improved hairline. Surgeons have applied this technique to areas affected by disease and trauma, as well as male pattern baldness. There are differences between the short temporoparietal flaps and the larger Juri flaps with regard to patient selection, planning, design, technique, complications, and most importantly, results.