A phenomenon of large, upland breeding colonies of cattle egrets in residential areas of Central Texas has been observed since the early 1960s. These large concentrations of breeding birds can be a nuisance to nearby residents and their management has been difficult. To help understand why cattle egrets choose upland, residential breeding sites, and predict where these might occur, the geographic extent of the phenomenon was bounded within Texas, a habitat suitability model constructed, and reproductive success compared by breeding habitat type to evaluate if residential nesting confers an adaptive advantage.. Records of upland cattle egret colonies were found only in Central Texas, not other parts of the state. The habitat suitability model was constructed using total edge of three land use classes: water, forest, and developed classes. The model classified 78.6 % of upland colonies in very high or high suitability classes and 7.1% of colonies in low or very low suitability classes. This distribution was significantly different than expected considering the overall ratio of suitability scores in the entire raster model (p = 0.036). Nineteen active colonies were found in or bordering the Post Oak Savannah and Blackland Prairie ecoregions. Colonies were in residential, urban, island, and flooded tree and shrub habitat. Nests were found in 12 different tree and shrub species. Residential colonies had more breeding pairs, greater nest survival, and were less productive than non-residential colonies on average, but these differences were not statistically significant. Colonies where nest substrate was removed were not reused and no breeding was initiated nearby the next year. Propane cannons discouraged reuse of colony after prolonged application. Herons and egrets likely use residential sites when wetland habitats are limited. Their overall breeding distribution reflects state wide rainfall and wetland availability patterns with upland nesting in Central Texas, wetland nesting in eastern and coastal regions, and little large scale nesting in western Texas. Egrets and herons may use edges of development as breeding sites to limit predation by ground predators when flooded tree and shrub or island habitats are absent, but this hypothesis needs more testing.

This study investigates the colonization of Barbados, the seasonality of breeding, and the function of breeding plumes in the cattle egret Bubulcus ibis ibis. Colonization occurred around 1956, and the island now has 4 colonies. Numbers of birds at each colony are still increasing. Colonies are evenly spaced around the island. Plumage scores varied seasonally, and males had higher scores than females. Breeding activity peaked in July-August and November-March. Conspecific interference may force poorly plumed birds to breed when environmental conditions are poor. Chick mortality was primarily from starvation during periods of low breeding activity, and primarily from conspecific attack during high breeding activity. Fledging success did not increase with breeding activity. Plumage scores correlated positively in breeding pairs. Well-plumed males fed chicks more often than poorly plumed males and had the higher fledging success. Males contributed more to nest and nestling attendance when their mates were well plumed. Plumes appear to indicate the potential paternal care and the genetic quality of a mate.

No description available.

Thesis (M.S.)--University of Hawaii at Manoa, 2006. / Includes bibliographical references (leaves 62-77). / ix, 77 leaves, bound ill. (some col.), maps (some col.) 29 cm

Made available in DSpace on 2016-06-02T20:21:27Z (GMT). No. of bitstreams: 1 3889.pdf: 1235045 bytes, checksum: 2746983be0ebda15a37ceeb2635ac9c2 (MD5) Previous issue date: 2011-08-19 / Universidade Federal de Sao Carlos / The Cattle Egret (Bubulcus ibis) is a median sized bird, of African origin, considered as an invasive and exotic species in the American continent. In Brazil, first record was in the north, in 1964. The species have been maintaining a pattern of constant population growth, endangering the reproduction and survivorship of native species, as observed in the archipelago of Fernando de Noronha. The purposes of this work were the isolation of microsatellite loci for the species in question and to genetically characterize Brazilian populations, as a starting point in a study that contributes for the comprehension of the colonization process occurred in the country. Thereafter, two partially enriched genomic libraries were obtained, in which the generated fragments were posteriorly sequenced and analyzed for the presence of microsatellite sequences; being the cloning efficacy of 15.74%. Thirty-two microsatellite loci were selected for the analysis, of which eleven proved to be polymorphic. Content of polymorphic information for these loci varied between 0.079 and 0.453. Fragments of expected size were amplified in the eleven polymorphic loci in other six species from the same family as the Cattle Egret. Six populations from different latitudes in the country were genotyped in seven polymorphic loci. A low variability was found, with mean values of expected heterozigosity in the populations varying between 0.408 and 0.562. The population holding the higher diversity was the northern one, closest to the point of the first historic record of the species in the country. Low genetic structuring by AMOVA was detected, and some values of pairwise Fst and Rst proved to be significant when the pair contained populations from South and North of the country. Effective size (Ne) of the Brazilian population was 6.6 individuals (95% CL: 5.7-7.7). Diversity indices and population parameters analyzed did not show evidence that the dispersion of individuals occurred in a north-south axis, occurring more in an opportunistic and erratic manner. Fernando de Noronha s population, which have been managed by a population control program since 2007, presented diversity levels and population parameters comparable to the mainland populations, what indicates that the species will not be easily eliminated from this area. / A garça-vaqueira (Bubulcus ibis) é uma ave de médio porte, de origem africana, considerada espécie exótica invasora no continente americano. No Brasil, o primeiro registro foi na região norte, em 1964. A espécie vem mantendo um padrão de crescimento populacional constante, ameaçando a reprodução e sobrevivência de outras espécies nativas, como observado no arquipélago de Fernando de Noronha. Os objetivos desse trabalho foram isolar locos de microssatélites específicos para a espécie e caracterizar geneticamente as populações brasileiras, iniciando um estudo que contribui para a compreensão do processo de colonização ocorrido no país. Com esse intuito, foram construídas duas bibliotecas genômicas parciais enriquecidas, cujos fragmentos gerados foram posteriormente sequenciados e analisados quanto à presença de sequências de microssatélites, sendo de 15,74% a eficiência de clonagem. Foram selecionados 32 locos de microssatélites para as análises, dos quais 11 mostraram-se polimórficos. O conteúdo de informação polimórfica para esses locos variou de 0,079 à 0,453. Fragmentos de tamanho esperado foram amplificados nos onze locos polimórficos em outras seis espécies da mesma família. Seis populações de diferentes latitudes do país foram genotipadas em sete locos polimórficos. Uma baixa variabilidade foi encontrada, com valores médios de heterozigosidade esperada variando de 0,408 à 0,562 nas populações. A população detentora de maior diversidade foi a da região norte, mais próxima do ponto do local do primeiro registro histórico da espécie no país. Foi detectada baixa estruturação genética pela AMOVA e alguns valores de Fst e Rst par-a-par se mostraram significativos quando o par incluía populações da região sul e norte do país. O tamanho efetivo (Ne) da população brasileira foi de 6,6 indivíduos (95% CL:5,7-7,7). Os índices de diversidade e os parâmetros populacionais analisados não mostraram evidências de que a dispersão dos indivíduos tenha ocorrido segundo um eixo- norte-sul, mas sim de maneira oportunista e errática. A população de Fernando de Noronha, que vem sendo manejada por um programa de controle populacional desde 2007, apresentou níveis de diversidade e parâmetros populacionais comparáveis às populações do continente, o que indica que a espécie não será facilmente exterminada nessa área.

Made available in DSpace on 2016-06-02T20:20:34Z (GMT). No. of bitstreams: 1 4932.pdf: 1990172 bytes, checksum: 7025c9dd589a8c2a6771bc24539895b5 (MD5) Previous issue date: 2013-03-05 / Universidade Federal de Sao Carlos / The genetic diversity of the cattle egret (Bubulcus ibis) was analyzed to investigate reproductive behavior and characterize Brazilian populations of the species. Genotypes at seven microsatellite loci were used to investigate the occurrence of more than one female laying eggs in the same nest, characterizing the occurrence of multiple maternity. DNA was extracted from swabs collected from the outer surface of eggs and sexed; males were excluded. Forty-eight clutches from two breeding seasons (2010 and 2011) were genetically analyzed. Thirty-nine eggs laid by a second or third female were recorded. In five nests, the first egg of the clutch was from a different female, the laying happening prior to that of the incubating female. Suggesting nest takeover by another pair of egrets that kept the pre-existing eggs together with its own clutch. In the other 43 nests, the hypothesis of brood parasitism was posed to explain why one or two additional females were found laying eggs in a nest. A 463-bp fragment of the mitochondrial DNA control region Domain I was amplified for 148 individuals from seven Brazilian populations to investigate genetic-population and demographic parameters. Genetic diversity indices, the population structure tests Fst and AMOVA, a haplotype network, mismatch distribution and neutrality tests (Tajima s D, Fu s Fs, Fu and Li s D* and F*, Ramos-Onsins and Rozas R2) revealed the following: i) a high level of diversity was recorded for the cattle egret in Brazil in comparison to other closely related species studied in the country; ii) genetic diversity levels determined for the Brazilian regions are similar; iii) genetic structuring was not observed between the seven studied populations; and iv) the different tests performed to determine demographic expansion revealed no significant results. This is the first genetic characterization study for Bubulcus ibis to date and the findings indicate a high degree of plasticity in reproductive behavior and confirm a marked dispersion behavior of the species, leading to the homogenization of Brazilian populations. / A diversidade genética da garça-vaqueira (Bubulcus ibis) foi utilizada para se investigar o comportamento reprodutivo e para se caracterizar populações brasileiras da espécie. Genótipos em locos de microssatélites foram utilizados na detecção da presença de mais de uma fêmea ovipositando em um mesmo ninho, o que pode caracterizar a ocorrência de maternidade múltipla. O DNA extraído dos swabs coletados na superfície externa dos ovos foi sexado e eventuais amostras de machos foram excluídas. Quarenta e oito ninhadas, de duas temporadas reprodutivas (2010 e 2011) foram analisadas geneticamente. Foram registrados 39 ovos ovipositados por uma segunda ou terceira fêmea. Em 33 ninhos foram encontrados genótipos distintos de duas fêmeas e em seis ninhos genótipos de três fêmeas. Em cinco ninhos o primeiro ovo na sequência de oviposição mostrou-se ser de uma fêmea diferente, tendo a oviposição acontecido previamente àquela da fêmea incubante. Esse achado foi explicado supondo a tomada de ninho por um segundo casal de garças, com a manutenção do ovo pré-existente juntamente com os da própria ninhada. Nos outros 43 ninhos, a presença das fêmeas extras foi explicada hipotetizando a ocorrência de parasitismo de ninho intraespecífico. Um fragmento de 463 pb do Domínio I da região controladora do DNA mitocondrial foi amplificado para 148 indivíduos para a investigação de parâmetros genéticopopulacionais e processos demográficos nas sete populações estudadas. A estimativa de índices de diversidade genética, testes de estruturação populacional Fst e AMOVA, a construção de uma rede de relação entre haplótipos, a análise de mudanças no tamanho populacional pela mismatch distribution e a realização de testes de neutralidade (D de Tajima, Fs de Fu, D* e F* de Fu e Li, R2 de Ramos-Onsins e Rozas) permitiram identificar: i) um nível alto de diversidade genética para B. ibis no Brasil, quando comparado a espécies proximamente relacionadas estudadas no país; ii) níveis semelhantes de diversidade genética determinados para as regiões brasileiras; iii) ausência de estruturação genética entre as sete populações estudadas; e iv) ausência de sinais de expansão demográfica pelos testes realizados. Os resultados aqui apresentados são os primeiros resultados genéticos na espécie até o momento e apontam para uma alta plasticidade no comportamento reprodutivo e confirmam a dispersão bastante acentuada da espécie, levando a homogeneização das populações brasileiras.