Double-crested Cormorants are expanding their breeding range to historic wintering and migratory regions, such as Guntersville Reservoir in Alabama. This study lends insight into how cormorants breeding in a temperate ecosystem impact plants, trees, soil and bird communities as well as home range and movement of cormorants during the breeding season and whether they reside on this reservoir year-round. Results suggest that breeding cormorants have a negative impact on this ecosystem and do not move far from colony sites. Stable isotopes from cormorants and prey fish suggest that cormorants are migrating from this system after breeding, potentially to a marine source. This study corroborates past studies of negative impacts of cormorant colonies, and provides novel results of how southeastern cormorants use and move on Guntersville Reservoir. This thesis can provide biologists information on how best to control populations and mitigate impacts on this and other similar southeastern systems.

Submitted by dayse paz (daysepaz@hotmail.com) on 2016-04-06T14:41:40Z No. of bitstreams: 1 Diserta_o_Vanessa_Brito.pdf: 1599477 bytes, checksum: 07d436c3a3d3c4454a7866d4dfa32c22 (MD5) / Approved for entry into archive by cleuza maria medina dos santos (cleuzamai@yahoo.com.br) on 2016-04-07T00:06:42Z (GMT) No. of bitstreams: 1 Diserta_o_Vanessa_Brito.pdf: 1599477 bytes, checksum: 07d436c3a3d3c4454a7866d4dfa32c22 (MD5) / Made available in DSpace on 2016-04-07T00:06:42Z (GMT). No. of bitstreams: 1 Diserta_o_Vanessa_Brito.pdf: 1599477 bytes, checksum: 07d436c3a3d3c4454a7866d4dfa32c22 (MD5) Previous issue date: 2013 / O presente trabalho investigou a dieta de Platalea ajaja (colhereiro) e Ardea alba (garça-brancagrande), em 2011/2012, em um ambiente límnico (banhado do Aguirre) e outro estuarino na Lagoa dos Patos (ilha dos Marinheiros), Rio Grande, RS, no sul do Brasil. Foram analisados regurgitados espontâneos, conteúdos gastrointestinais, pellets, lavagem estomacal e isótopos estáveis. Os itens alimentares mais importantes na caracterização direta da dieta de P. ajaja no estuário foram os insetos (PSIRI% = 47,2), seguido de crustáceos (PSIRI% = 30,4) e peixes (PSIRI% = 12,6). No ambiente límnico P. ajaja teve uma dieta com predomínio de insetos (PSIRI% = 59,9), seguido de peixes (PSIRI% = 19,8). No estuário a dieta de A. alba foi predominantemente piscívora (PSIRI% = 53,3), seguido em importância pelos crustáceos (PSIRI% = 30,8). Entretanto, no ambiente límnico A. alba teve os insetos como item alimentar principal (PSIRI% = 58,9), seguido de peixes (PSIRI% = 27,9). Sangue de filhotes com mais de três semanas de vida e presas/alimentos potenciais tiveram os isótopos estáveis de carbono (δ 13C) e nitrogênio (δ 15N) analisados. No ambiente límnico A. alba apresentou valores médios de δ 15N semelhantes a P. ajaja límnico, diferenciando-se de A. alba e P. ajaja estuarinos. Os valores médios de δ 13C nas duas espécies e locais foram semelhantes, porém menor em sangue de A. alba estuarina. O modelo linear generalizado (GLM) explicou 44% na variação dos dados de δ 15N, diferindo entre os locais e influenciado pelo tamanho do filhote. O GLM com os valores de δ 13C explicou 22% da variação nos valores, indicando que A. alba alimenta os filhotes com outros itens alimentares dependendo do local, enquanto os filhotes de P. ajaja possuem uma alimentação límnica nos dois ambientes. Os modelos bayesianos de misturas de isótopos (SIAR) indicaram presas límnicas para P. ajaja nos dois ambientes, corroborando os resultados do GLM e dos métodos de estudo de dieta tradicionais. Portanto, A. alba utiliza as áreas próximas ao local de reprodução para se alimentar, não apresentando preferência por área de forrageamento estuarino ou límnico. Em ambiente límnico as duas espécies podem utilizar recursos alimentares semelhantes, enquanto no ambiente estuarino a sobreposição na dieta diminui, por alimentaremse em diferentes locais e distintos itens alimentares. Através de diversas metodologias verificouse que P. ajaja alimenta-se de presas límnicas, apesar de reproduzir-se em ambos os ambientes, enquanto A. alba alimenta-se de presas límnicas e estuarinas dependendo do local onde ocorre sua reprodução. / This study investigated the diet of Roseate spoonbills (Platalea ajaja) and Great egrets (Ardea alba) in 2011/2012, in two colonies, one in a freshwater (Aguirre marsh) and another in the Lagoa dos Patos estuary (Marinheiros island), both in Rio Grande municipality, Rio Grande do Sul state, southern Brazil. Spontaneous regurgitations, gut contents, of dead chicks, pellets, stomach flushing and stable isotopes of chicks were analysed. The most important prey items for estuarine spoonbills were insects (PSIRI% = 47.2), crustaceans (PSIRI% = 30.4) and fish (PSIRI% = 12.6). In the freshwater colony, spoonbills had diet composed mostly by insects (PSIRI% = 59.9) and fish (PSIRI% = 19.8). In the estuary, egrets had a predominantly piscivorous diet (PSIRI% = 53.3), followed in importance by crustaceans (PSIRI% = 30.8). However, in the freshwater colony egrets had insects as the main food items (PSIRI% = 58.9), followed by fish (PSIRI% = 27.9). Blood of chicks over three weeks and tissues of potential food items had stable isotopes of carbon (δ 13C) and nitrogen (δ 15N) analised. In the freshwater environment, egrets had mean δ 15N values similar to freshwater spoonbills, but different from egrets and spoonbills from the estuarine site. Mean values of δ 13C in both places and sites were similar, but higher in estuarine egrets. A generalized linear model (GLM) explained 44% in the variation in δ 15N values, differing between sampling sites and influenced by chick size. The GLM on δ 13C values explained only 22% in data variation, suggesting that egrets feed their chicks with different prey items, depending on the place where the colony is placed. On the other hand, spoonbills had limnetic feeding only, no matter the place where they are breeding. Bayesian stable isotope mixing models (SIAR) indicate that limnetic prey were important for spoonbill chicks in both colonies, in line with GLM analysis and dietary data using traditional methods. Therefore, egrets forage in areas near breeding places, without preferences for freshwater or estuarine habitats. In the freshwater colony egrets and spoonbills could rely on similar feeding resources, while in estuarine environments competition seems to be relaxed by feeding on different places and prey items. By using different methodologies it was possible infer that spoonbills feed on freshwater food items, no matter where they breed, while egrets use both limnetic and estuarine food items, depending where the colony is placed.

Interactions among commercial fisheries and birds have been studied in open ocean ecosystems and at aquaculture facilities. On the Great Salt Lake (GSL), Utah, USA, a commercial harvest of brine shrimp (Artemia franciscana) eggs (i.e. cysts) occurs annually during fall and winter. Coinciding with commercial harvest is the use of the GSL by millions of waterbirds which has the potential to result in conflict among industry and birds. The objectives of my research were to examine fall and winter ecology of birds using the GSL and interactions with the brine shrimp cyst harvest. I examined the influence of temperature and food availability on the number and distribution of waterfowl and eared grebes (Podiceps nigricollis). I also assessed the diets of the same species to see how much cyst biomass is being consumed by birds compared to removal by commercial harvest. A mass die-off (i.e. downing) of migrating eared grebes occurred during my research, so I assessed differences among birds that died and those that did not to better explain this phenomenon. Finally, I assessed the breeding origin of northern shovelers (Anas clypeata) wintering on the GSL using stable isotopeand banding data.I found that commercial harvest boats did not influence duck population numbersor distribution; rather temperature and food availability most influenced abundance and distribution, though this influence varied by species. Compared to commercial harvest, northern shovelers, green-winged teal (Anas crecca), and eared grebes removed a small fraction of the total amount of cysts that were removed from the GSL. Waterfowl diets were mainly wetland plant seeds during fall and spring, but when freshwater marshes were frozen in winter, ducks ate mostly brine shrimp cysts and brine fly (Ephydra spp.) larvae. Eared grebes are highly associated with saltwater habitats and they consumed adult brine shrimp most of the fall. Eared grebes that perished during the downing had mercury and selenium concentrations above levels seen in pre- and post-downing birds and higher than observed concentration that impact bird species, providing a potential ultimate cause of death during snowstorms that accompany most downings. Stable isotope analysis indicated northern shovelers that winter on the GSL had breeding origins throughout the specie’s range, but most came from local or southern Prairie Pothole Region breeding populations.

Primary objectives of this study were: (1) to compare the food habits of healthy and botulism intoxicated American avocets and blacknecked stilts for qualitative and quantitative differences, (2) to determine .which invertebrates found in the tracts of intoxicated and healthy birds contained type C toxin, and (3) to explain apparent susceptibilities among different sexes, ages and species of birds. Based on percent utilization and occurrence of food items in the esophagus , the diets of healthy and intoxicated birds were similar. However, intoxicated avocets consumed higher proportions of Gastropoda and intoxicated stilts more Hydrophilidae larvae than did healthy birds. Because of similarities in diets of healthy and intoxicated birds, birds probably became intoxicated from eating randomly toxic foods and not because of differences in diet or food preference. Examinations of esophageal contents of avocets and stilts better described recently consumed food items than did examinations of gizzard contents. Soft-bodied invertebrates were rendered unidentifiable in the gizzard. The esophageal contents of juvenile avocets and stilts contained greater proportions of animal matter than did those of adults. Only three of 86 food samples analyzed were definitely positive for type C botulism toxin. These were: one sample of Tendipedidae larvae and two of pooled gizzard contents which included fragments of Corixidae, Hydrophilidae adults, seeds and vegetative fibers. Only three of 86 food samples analyzed were definitely positive for type C botulism toxin. These were: one sample of Tendipedidae larvae and two of pooled gizzard contents which included fragments of Corixidae, Hydrophilidae adults, seeds and vegetative fibers.

<p>Hamilton Harbour is one of the most polluted sites on the Great Lakes, affected by airborne and sedimentary contamination as a result of both heavy vehicle traffic and thousands of kilograms of industrial steel emissions. Polycyclic Aromatic Hydrocarbons (PAHs) are ubiquitous mutagenic byproducts of incomplete organic combustion; they are present at very high concentrations in the air and sediment of Hamilton Harbour. We quantified DNA mutation rates in three different nesting colonies of Double-crested Cormorants (<em>Phalacrocorax auritus</em>) using five microsatellite markers. These colonies were located at various distances from sources of PAHs and other contamination. We compared pollution-exposed and reference colonies, hypothesizing that cormorants living closest to pollution will have higher rates of germline microsatellite mutations than those living farther away from pollution sources. Using a pedigree approach, we identified mutations when chicks showed microsatellite alleles not found in either parent, and other explanations such as extra-pair parentage had been ruled out. Microsatellite mutation rates were 4.4 times higher at the Hamilton Harbour site closest to the industrial sources of PAH contamination than the other Hamilton Harbour site, and both were higher than the reference colony. Metabolites of the PAH benzo[a]pyrene in cormorant tissues from both Hamilton Harbour sites were identified by LC-MS/MS, demonstrating that cormorants in Hamilton Harbour are exposed to, and metabolizing, PAHs. Diet was not substantially different between the two Hamilton Harbour colonies when measured with regurgitated samples and fatty acid analysis. This suggests airborne pollution in Hamilton Harbour induced germline mutations in cormorants.</p> / Master of Science (MSc)

5 Abstract This thesis is aimed at spatial variability of population structure of our four most common and the most numerous species of ducks wintering in the Czech Republic. These analysed species are Mallard (Anas platyrhynchos), Tufted duck (Aythya fuligula), Common Merganser (Mergus merganser) and Northern Goldeneye (Bucephala clangula). The field data were collected by January International Waterbird Census in the Czech Republic between 2004 and 2013. Analysed habitat variables include: type of wetland, altitude, population size, level of urbanisation (size of settlement) and mean January air temperature in the investigated site. There was found no significant effect of type of wetland and local population density on population structure in any of these bird species. The next factor, altitude of sites was confirmed as significant only for Mallards, when increasing altitude decreased proportion of males in the population. Furthermore, effect of urbanization was found also in Mallard, when proportions of males increased with level of urbanization, i.e. in larger cities. Finally, , temperature of sites was confirmed to be significant factor affecting population size in the three analyzed species, i.e. in Mallard, Tufted Duck and Northern Goldeneye. Except Common Merganser, ratio of males grew with...