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Showing 1 to 14 of 14 for “"Aythya affinis"”.
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Environmental Factors Influencing Spring Migration Chronology of Lesser Scaup (Aythya affinis)
Weather likely affects the timing and rate of migration by waterfowl to their breeding grounds. I hypothesized that timing of migration by lesser scaup during spring is affected by annual variation in temperature, precipitation and ice cover. I used satellite telemetry data, waterfowl survey data …
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Diet and Body Composition of Migrating Lesser Scaup (Aythya affinis) in Eastern South Dakota
<p>The decline of the continental lesser scaup (Aythya affinis) population has become an important conservation issue among waterfowl biologists. Several hypotheses have been proposed to explain why the population is declining including over- harvest, contaminants (mercury, selenium, lead, etc.), …
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Modeling Wetland Use By Spring-Migrating Lesser Scaup (Aythya affinis) in Eastern South Dakota
The continental population of lesser scaup (Aythya affinis [Eyton]; hereafter scaup) has been in decline since the 1980s, leading researchers to speculate that reduced feeding efficiency and subsequent lowered body condition during spring migration may have adverse impacts on reproductive success. …
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Hepatic Element Concentrations and Gross and Histological Examinations of Spring Migrating Lesser Scaup (Aythya affinis) in the Upper Midwest
… in the continental scaup population (lesser [Aythya affinis] and greater [A. marila] scaup combined) for the past 20 years, although many other waterfowl species have recovered from similar declines during this same time period. Key areas of concern identified as essential to address this …
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Impacts of habitat and landscape characteristics on reproductive ecology of female lesser scaup (Aythya affinis) in the boreal forests of Alberta
The lesser scaup (Aythya affinis, henceforth scaup) population decreased during the 1980s and has remained below conservation objectives. With two-thirds of the breeding population nesting in boreal forests, it is imperative to understand how changes in habitat features and landscape changes could …
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A Physiological Assessment of Wetland Habitats for Spring-migrating Ducks in the Agricultural Landscapes of the Southern Prairie Pothole Region
… circulating in plasma of female lesser scaup (Aythya affinis) and bluewinged teal (Anas discors) to understand refueling performance of migrants using wetlands with variable biotic and abiotic characteristics. Duck abundance, refueling performance, and prey abundance were generally similar …
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Distribution and Importance of Stockdams, Dugouts, and Natural Wetlands To Breeding Waterfowl In South Dakota
… wood duck (Aix sponsa), canvasback (Aythya valisneria), redhead (Aythya Americana), lesser scaup (Aythya affinis), and ringneck (Aythya collaris) were most often associated with class III and IV ponds in 1973 and 1974. Stockdams were used by a larger segment of all populations in 1974 …
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Lesser Scaup use of Wetlands in Eastern South Dakota
… that the continental population of lesser scaup (Aythya affinis) has been steadily declining, about 150,000 per year, over the past 20 years. Due to the temporal length of their population decline, scaup have received widespread attention by resource management agencies and private conservation …
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Characteristics of Wetlands Used by Breeding Diving Ducks in Eastern South Dakota
… diving ducks in eastern South Dakota. Redheads (Aythya americana) and ruddy ducks (Oxyurajamaicensis) were the primary breeding species of diving ducks in eastern South Dakota in 1995 and 1996. Canvasback (Aythya valisineria) and lesser scaup (Aythya affinis) broods were uncommon. Distributions …
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Drivers of Productivity of Montane and Boreal Breeding Ducks
… growth in many duck species. For lesser scaup (Aythya affinis; scaup), a species of conservation concern, productivity can be particularly influential to population growth, although our understanding of factors affecting production is incomplete. I sought to identify local drivers of …
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The Role of Climate Variability in Duck Population Ecology
… of a late-breeding species, lesser scaup (Aythya affinis), had slower growth rates when hatched late relative to their cohort but I detected no effect of spring phenology. Hatch date effects did not carryover to influence postfledging survival. In contrast, a negative effect of conspecific …
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Intestinal helminth infections, distributions, and associations with health parameters of spring-migrating female Lesser Scaup in the upper Midwest
… continental breeding population of Lesser Scaup (Aythya affinis) reached a record low of 3.2 million in 2006 and has since remained below the goal of 6.3 million set by the North American Waterfowl Management Plan. Although many factors have been identified as possible contributors to the decline, …
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FORAGING BEHAVIOR OF DUCKS DURING SPRING MIGRATION IN THE WABASH RIVER REGION, ILLINOIS
… wood duck (Aix sponsa), ring-necked duck (Aythya collaris), and lesser scaup (Aythya affinis) devoted to feeding, identify the specific behaviors used, and estimate feeding stint lengths and frequencies. I used these metrics as an index of risk that ducks were willing to engage in for a …
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Validation and use of novel techniques to study the impacts of large-scale environmental changes on the health of wild waterfowl
… growth. In Chapter 2, captive lesser scaup (Aythya affinis) were surgically implanted with CORT or placebo pellets during the natural moult period to test this assumption. Additionally, I used deuterium-labelled CORT (2H-CORT) pellets to evaluate the relative deposition of exogenous and …