Thesis (M.S.)--Eastern Illinois University.

Thesis (M.S.)--Southern Oregon University, 2005. / "A thesis submitted to ... Southern Oregon University in partial fulfillment of the requirements for the degree of Master of Science ..." Includes bibliographical references (leaves 70-73). Also available via Internet as PDF file through Southern Oregon Digital Archives: http://soda.sou.edu. Search Bioregion Collection.

Thesis (Ph.D.)--Aberdeen University, 2009. / Title from web page (viewed on Oct. 5, 2009). Includes bibliographical references.

This study relates the species composition, numbers, and habits of a hole-nesting avifauna to its environment in successional stages of a coniferous forest in southwestern British Columbia. Emphasis is placed upon explaining an observed presence or absence of nest-site competition. In two breeding seasons, the hole-nesting avifauna was found to be low in numbers of both species and individuals. Most of these birds were able to excavate their own nesting cavities, and commonly did so, for which activity the habitat generally provided ample opportunity. As the species present often differed widely from one another in the type and placement of their preferred nest cavities, there was usually a surplus of different cavity types present. Secondary hole-nesters either concentrated their activities around the buildings in the nearby town, neglecting the more "natural" sites available; were not obligated to use cavities when nesting; or occurred in such low densities, and were so positioned in the available suitable habitat, as to suggest that nest-site competition had no effect upon the populations. Only scattered indications of nest-site competition were observed in wooded areas. Four species nested in crevices in buildings and in bird boxes in a small town, where their breeding population densities were much higher than in the surrounding countryside. Nest-sites were judged to be present in excess, and nest-site competition, observed infrequently, was so rare, and apparently without significant harmful effects, that it was judged to be of negligible importance as a population-regulating factor. The overall absence of nest-site competition is contributed to not only by the preferences of the species regarding their nest-sites, but also by the fact that the results of their habitat selection processes, and their living habits within these habitats, tend to keep them ecologically distinct. / Science, Faculty of / Zoology, Department of / Graduate

The role that climate plays in the ecology of organisms is perhaps the most pronounced where the earth’s environments are most extreme. In arid-zones, organisms have to deal with large seasonal shifts and/or extremes in temperature and/or moisture levels. As a result, arid-zone species are sensitive to climatic changes. I assessed the physiological and behavioural adjustments of an arid-zone endemic passerine, the rufous-eared warbler (Malcorus pectoralis), to seasonal changes in the Karoo semi-desert of South Africa. Respirometry measurements in the field showed that the warblers’ basal metabolic rate was lower and set point body temperature (Tb) was higher in summer compared to winter. At high air temperatures (Ta) evaporative water loss (EWL) rate was significantly lower in summer compared to winter, while Tb showed a clear pattern of heterothermy that was similar in both seasons. Compared to winter, the warblers in summer were able to remain calm, and tolerate higher Ta’s, before their Tb’s increased to potentially detrimental levels. Behavioural observations showed that free-living warblers exhibited significant temperature-dependence in their behaviour; they increased panting behaviour, and reduced activity levels, time spent preening, and foraging effort at high Ta’s in summer. The warblers also displayed a considerable decrease in foraging success, and a shift in microsite use, at high Ta’s in summer. I hypothesise that the flexible responses the rufous-eared warblers show are aimed at increasing their heat tolerance in summer, and help them balance their energy and water demands in an arid environment that exhibits wide seasonality in Ta, in addition to high summer Ta. My findings emphasise the importance of identifying, as well as understanding, the associated costs of physiological and behavioural responses to environmental variables. This information is valuable in terms of predicting biologically meaningful responses (and hence, vulnerability) of arid-zone avian communities to climactic shifts.

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Many theories have emerged to explain how ageing and longevity are mediated.  Two theories are the ‘Rate of Living’ (ROL) theory (the live fast, die young concept) and the uncoupling to survive hypothesis.  The ROL theory postulates a positive link between energy expenditure and longevity whereas the uncoupling hypothesis predicts a negative association.  For a given mass, birds tend to live longer than mammals despite having higher energy expenditures. This study began by re-examining the relationship between body mass, energy expenditure and longevity in birds using published accounts of resting metabolic rate (RMR), daily energy expenditure (DEE) and maximum lifespan potential (MLSP). It was found that, after removing the confounding effects of body mass and phylogeny, RMR and DEE were not significantly related to MLSP.  There was also a significant negative association between lifetime RMR and DEE per gram, which contradicts the suggestion that this should be body mass independent.  The study then elucidated the age-related changes in energy expenditure in two long-lived companion birds, budgerigars (<i>Melopsittacus undulates</i>) and cockatiels (<i>Nymphicus hollandicus</i>).  Using indirect calorimetry to determine RMR and the doubly labelled water technique to estimate DEE, it was fond that these birds did not have age-related decreases in energy expenditure.  These two species, along with free-living fulmars (<i>Fulmarus glacialis</i>) do not have increased oxidative damage during ageing and no age-related changes in antioxidant protection.  It was also found that dietary fatty acids have no effect on oxidative damage but possibly influence antioxidant protection in fulmars.

A dissertation submitted to the Faculty of Science University of the Witwatersrand Johannesburg, South Africa in fulfilment of the requirements for the degree of Master of Science. June 2017 / Southern Africa boasts a high avian diversity with five Cossypha (robin-chat) species (C. heuglini, C. caffra, C. humeralis, C. natalensis, C. dichroa) distributed at varying levels of sympatry and allopatry. Due to the effects of global anthropogenic change many species which were once ecologically separated may now overlap, leading to possible genetic introgression and hybridization. This project investigates the genetic diversity and degree of relatedness between the five Cossypha robin-chat species that occur in South Africa. Genomic DNA was extracted from blood of all five species (n=92 individuals) using the standard phenol:chloroform extraction method. Mitochondrial and nuclear markers were analyzed using Likelihood and Bayesian methods to establish phylogenetic relationships and to determine speciation patterns. MtDNA barcoding using the cytochrome c oxidase subunit 1 (CO1) gene was used to assign individuals to species. The construction of a neighbour-joining and a maximum likelihood tree provided graphic representations of the pattern of divergences between the five Cossypha species. Individuals from a species clustered together with strong bootstrap values. These procedures were accomplished using MEGA software. PopART was used to construct a minimum spanning network. This network illustrated similarity between the five species with regards to the CO1 barcode. Only seven of thirteen novel microsatellite markers were able to cross amplify in all five species. The Bayesian clustering analysis using the statistical programme STRUCTURE identified three genetic clusters (K=3) with the three distinct species being C. dichroa, C. natalensis, and C. caffra. Cossypha heuglini cluster amongst C. dichroa, C. natalensis, and C. caffra, while C. humeralis clusters amongst C. natalensis. Despite the hybridization events recorded between C. dichroa and C. natalensis these two species do not appear to be each other’s closest relatives according to microsatellite and mtDNA analysis. The hybridization events indicate their ability to overcome reproductive isolation mechanisms such as vocalisations. / MT 2017