Browsing by Subject "trumpeter swan"

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    A multi-faceted evaluation of a reintroduced waterfowl species: Migration ecology, ecotoxicology, and population genetics of trumpeter swans in the Midwest
    (2024-06) Wolfson, David
    Trumpeter swans (Cygnus buccinator), the largest waterfowl species in North America, were widespread throughout much of the continent prior to European colonization. Due to unregulated market hunting, trumpeter swans were nearly extirpated, and reached an estimated low of ~70 individuals in the lower 48 U.S. states during the 1930s. The creation of new protected areas coupled with management efforts allowed trumpeter swan abundance to recover, and they were successfully reintroduced to the western Great Lakes region in the late 20th century to re-establish the Interior Population (IP). However, a general lack of information about IP trumpeter swan ecology has hindered conservation decision-making. I partnered with agency biologists from seven U.S states and one Canadian province to gather information on IP trumpeter swan annual movements and migration patterns, the prevalence of lead (Pb) in free roaming swans, and the genetic makeup of trumpeter swan populations in North America. Before addressing the previously mentioned aspects of trumpeter swan ecology, in Chapter 1, I provide a review of piecewise regression, a flexible type of breakpoint analysis. I provide an overview of piecewise regression and then describe six case-studies, using piecewise regression on a variety of datasets that include a range of species, data types, ecological responses, statistical signals, and timeframes. In Chapter 2, I use the methodology described in Chapter 1 (i.e., piecewise regression) to quantify annual movements and migration patterns in IP trumpeter swans. We (multiple state agency biologists and other collaborators) deployed 133 GPS-GSM transmitters on trumpeter swans across the current IP breeding range (i.e., the greater Midwest) during 2019–2022. Individual tracking data revealed that IP trumpeter swans are partial migrants, with a continuum of strategies each year, from local movements to long-distance migration. Much of the variability in movement patterns was related to factors tied to natural history demands (e.g., breeding status) and response to environmental conditions (e.g., through associations with breeding latitude). In Chapter 3, I present a baseline assessment of the prevalence of lead in all trumpeter swans associated with the dissertation and an additional flock in Nebraska. I estimated blood lead concentration for 119 IP trumpeter swans and detected lead in all individuals. However, 91% of swans had blood lead levels in the ‘background’ range (not considered to produce negative physiological effects), 7.5% of swans had blood lead levels in the ‘sub-clinical’ range, and only 1.5% of swans had blood lead levels in the ‘clinical’ or ‘severe’ range of lead toxicity. Finally, in Chapter 4 I present a comparative assessment of the genetics of trumpeter swans in North America. I collected 150 genetic samples from IP trumpeter swans captured during 2019–2022 and also obtained 79 reference samples from the other two North American trumpeter swan populations. These samples provide evidence that all three populations are genetically distinct and that the High Plains flock of the IP has lower genetic diversity compared to the other groups, likely a result of smaller population size, relative geographic isolation, and potential founder effects.