The epaulets of male Red-winged Blackbirds (Agelaius phoeniceus) function in both intersexual and intrasexual contexts, but there is little evidence that they covary with reproductive success in this well-studied species. We used path analysis of male/territory traits, mating success, and reproductive success of unmanipulated males to estimate current directional selection. Territory size had a positive effect on number of within-pair mates. Number of extra-pair mates had a positive effect on number of extra-pair fledglings, and number of within-pair and extra-pair fledglings had positive effects on total number of fledglings. We also reddened epaulets of free-living territorial males to determine whether manipulated and control males differ in territorial behavior, mating success, or reproductive success. Compared with control males, males with reddened epaulets incurred elevated rates of trespassing and territorial challenges, lost their territories more often, and were unable to produce extra-pair offspring. Despite these differences, however, the realized reproductive success of experimental and control males did not differ significantly, perhaps because males with reddened epaulets devoted more time to anti-predator vigilance and were more aggressive toward a simulated predator than were control males. An apparent lack of current sexual selection on epaulet color may be a form of counter-balancing sexual selection in which male aggression against redder epaulets opposes female preference for redder epaulets, or it might be the result of males compensating for lost extra-pair fertilizations by increasing their parental care.

No description available.

In an effort to determine type, extent, and distribution of agricultural damage by blackbirds, county-wide damage appraisals were conducted in the fall of 1960. Crops checked included corn, peanuts, and milo. Based on the 96 fields examined throughout Nansemond County, the average monetary loss to the corn crop was slightly less than $.05 per acre. This loss can be reduced by planting a variety with a high degree of ear drooping and planting as early as possible. The peanuts appeared to be the crop most heavily damaged. An estimated 50 per cent of the crop was picked before blackbirds arrived. Of the part of the crop left exposed after the arrival of the blackbirds, only a small portion sustained damages amounting to above $5 per acre. By harvesting peanuts at an early date, losses to blackbirds can virtually be eliminated. The 1960 milo crop was not damaged by birds nearly so severely as previous crops were reported to have been. Anthracnose, a fungal disease, accounted for about 86 per cent of the damage previously called "bird damage." An estimated 15 per cent of this crop was destroyed by anthracnose, insects, and birds. In the case of all three crops, it was noted that the first and most severe damage was to those fields nearest nesting and roosting habitat. / Master of Science

No description available.

North American populations of white-winged scoters (<i>Melanitta fusca deglandi</i>) have declined markedly over the past several decades. The causes for decline are uncertain, but likely involve a complexity of events occurring on wintering and breeding areas. To gain insight into potential cross-seasonal effects, I delineated Atlantic and Pacific wintering scoter populations and linked them to a shared breeding area using stable isotope analysis of carbon (δ13C) and nitrogen (δ15N) ratios in feathers. By applying this methodology to a marked breeding population at Redberry Lake, Saskatchewan, I assigned females to putative wintering areas and determined: (1) population structure; (2) the extent of winter site philopatry; and, (3) differences in vital rates and other variates in relation to winter origin. Discriminant function analysis of isotopic ratios in feather samples from known wintering locations resulted in classification probabilities of 96% (<i>n</i> = 149) for Pacific and 78% (<i>n</i> = 32) for Atlantic wintering scoters. Using this methodology, I determined that the Redberry Lake breeding population is comprised of approximately 75% Pacific and 25% Atlantic wintering birds, and its members exhibit high degrees of winter region philopatry based on the classification of successive recaptures over three field seasons. Annual variations in population structure, as well as differences in nest initiation dates and blood contaminant loads in relation to winter area suggest seasonal interactions may influence survival and reproductive success of this population. To gain insight into potential seasonal interactions, I examined nest success and female survival in relation to winter area. No significant differences in nest success in relation to winter area were found, but nests that failed before mid-incubation were not sampled. Adult female survival rate for 2000-2004 was estimated as 0.85, with no significant difference detected between wintering areas. This study demonstrated that it is important to link breeding and wintering areas to better understand the factors influencing population dynamics and to effectively address conservation issues.

North American populations of white-winged scoters (<i>Melanitta fusca deglandi</i>) have declined markedly over the past several decades. The causes for decline are uncertain, but likely involve a complexity of events occurring on wintering and breeding areas. To gain insight into potential cross-seasonal effects, I delineated Atlantic and Pacific wintering scoter populations and linked them to a shared breeding area using stable isotope analysis of carbon (δ13C) and nitrogen (δ15N) ratios in feathers. By applying this methodology to a marked breeding population at Redberry Lake, Saskatchewan, I assigned females to putative wintering areas and determined: (1) population structure; (2) the extent of winter site philopatry; and, (3) differences in vital rates and other variates in relation to winter origin. Discriminant function analysis of isotopic ratios in feather samples from known wintering locations resulted in classification probabilities of 96% (<i>n</i> = 149) for Pacific and 78% (<i>n</i> = 32) for Atlantic wintering scoters. Using this methodology, I determined that the Redberry Lake breeding population is comprised of approximately 75% Pacific and 25% Atlantic wintering birds, and its members exhibit high degrees of winter region philopatry based on the classification of successive recaptures over three field seasons. Annual variations in population structure, as well as differences in nest initiation dates and blood contaminant loads in relation to winter area suggest seasonal interactions may influence survival and reproductive success of this population. To gain insight into potential seasonal interactions, I examined nest success and female survival in relation to winter area. No significant differences in nest success in relation to winter area were found, but nests that failed before mid-incubation were not sampled. Adult female survival rate for 2000-2004 was estimated as 0.85, with no significant difference detected between wintering areas. This study demonstrated that it is important to link breeding and wintering areas to better understand the factors influencing population dynamics and to effectively address conservation issues.

We have previously shown that the arcuate organization of cell fates within the ventral midbrain critically depends upon the morphogen, Sonic Hedgehog (SHH), which is secreted from a signaling center located along the ventral midline, called the floor plate (FP). Thus, it is ultimately the specification of the FP that is responsible for the patterning and specification of ventral midbrain cell fates. Interestingly, we have found that the chick midbrain FP can be divided into medial (MFP) and lateral (LFP) regions on the basis of gene expression, mode of induction and function. Overexpression of SHH alone is sufficient to recapitulate the entire pattern of ventral cell fates, although remarkably it cannot induce MFP, consistent with the observation that the MFP is refractory to any perturbations of HH signaling. In contrast, overexpression of the winged-helix transcription factor FOXA2/HNF3[beta]robustly induced the MFP fate throughout ventral midbrain while blocking its activity resulted in the absence of the MFP. Thus, by analyzing the differences between SHH and FOXA2 blockade and overexpression, we were able to attribute functions to each the LFP and the MFP. Notably, we observed that FOXA2 overexpression caused a bending of the midbrain neurepithelium that resembled the endogenous median hinge-point observed during neurulation. Additionally, FOXA2 misexpression led to a robust induction of DA progenitors and neurons that was never observed after SHH expression alone. In contrast, we found that all other ventral cell types required HH signaling directly, at a distance and early on in the development of the midbrain when its tissue size is relatively small. Additionally, HH blockade resulted in increased cell-scatter of the arcuate territories and in the disruption of the regional boundaries between the ventral midbrain and adjacent tissue. Thus, we bring new insight into the mechanism by which midbrain FP is specified and ascribe functional roles to its subregions. We propose that while the MFP regulates the production of dopaminergic progenitors and the changes in cellshape required for bending and shaping the neural tube, the LFP appears to be largely responsible for cell survival and the formation of a spatially coherent pattern of midbrain cell fates. / text

Several factors have contributed to impeding the progress of migratory waterfowl spatial modeling, such as (1) waterfowl’s reliance on wetlands, (2) lack of understanding about shifts in distributions through time, and (3) large-scale seasonal migration. This doctoral dissertation provides an array of tools to address each of these concerns in order to better understand and conserve this group of species. The second chapter of this dissertation addresses issues of modeling species dependent on wetlands, a dynamic and often ephemeral habitat type. Correlation models of the relationships between climatic variables and species occurrence will not capture the full habitat constraints of waterfowl. This study introduces a novel data source that explicitly models the depth to water table, which is a simulated long-term measure of the point where climate and geological/topographic water fluxes balance. The inclusion of the depth to water table data contributes significantly to the ability to predict species probability of occurrence. Furthermore, this data source provides advantages over traditional proxies for wetland habitat, because it is not a static measure of wetland location, and is not biased by sampling method. Utilizing the long-term banding bird data again, the third chapter examines the behavior of waterfowl niche selection through time. By using the methods developed in chapter two, probability of occurrence models for the 1950s and the 1990s were developed. It was then possible to detect movements in geographic and environmental space, and how movements in these two spaces are related. This type of analysis provides insight into how different bird species might respond to environment changes and potentially improve climate change forecasts. The final chapter presents a new method for predicting the migratory movement of waterfowl. The method incorporates not only the environmental constraints of stopover habitat, but also includes likely distance and bearing traveled from a source point. This approach uses the USGS’ banding bird database; more specifically, it relies on banding locations, which have multiple recoveries within short time periods. Models made from these banding locations create a framework of migration movement, and allow for predictions to be made from locations where no banding/recovery data are available. / text

The Blue-winged Kookaburra is among the species of birds in which there is a sex dimorphism manifested in two characteristics. The first is the more pronounced coloration of the tail of the male; the second is the weight difference between the sexes. The female is about 70 - 100 grams heavier than the male. These differences do not occur earlier than after the first year of life. Although globally, there are 133 individuals of the Blue-winged Kookaburra (61 males, 58 females, 14 young) in human care in 45 institutions in 5 regions, it is successfully reproduced in only 9 institutions. Ostrava Zoo, as one of the three zoos and zoo parks in the world, keeps the Blue-winged Kookaburras in a group of eight, which is the optimal number of individuals forming a breeding cooperative group. In breeding seasons 2011 - 2016, Ostrava Zoo showed excellent results in breeding these Coraciiformes, with 15 successfully raised individuals. It therefore provided the data, together with Prague Zoo. This diploma thesis is a summary of own ethological observations at Ostrava Zoo and of a short observation at Prague Zoo. Summarizing the data from these two zoos, the thesis assesses weight differences of fertilized and unfertilized eggs, ontogenesis, growth rate and sex of the Blue-winged Kookaburras. On the basis of the growth and weight differences between the sexes, it deals with the sex determination of the young. It further describes social behaviour and vocalization within a breeding group with a predominance of females, evaluates general group relationships, and compares the results with a wild population

This study considers the visual representation of the alchemical idea of the philosopher’s stone (lapis philosophorum) in the Harry Potter films: Harry Potter and the Philosopher’s Stone (Columbus 2001), Harry Potter and the Chamber of Secrets (Columbus 2002), Harry Potter and the Prisoner of Azkaban (Cuaron 2004), Harry Potter and the Goblet of Fire (Newell 2005), andHarry Potter and the Order of the Phoenix (Yates 2007). The lapis philosophorum was believed to turn base metals into gold and produce an Elixir of Life. As such, it is envisioned as the ultimate alchemical idea, and this study emphasises how the lapis can function as a signifier for an alchemical worldview within the Harry Potter films. Because the concept and symbolism of the Harry Potter films is largely based on JK Rowling’s (1997; 1998; 1999; 2000; 2003; 2005; 2007) original novels, this study provides a detailed comparison of how alchemical imagery is used in the novels and contrasts this with the visual imagery of the films. This study undertakes a hermeneutic analysis of the transmission of alchemical ideals from the literary to the visual medium. It also provides a detailed analysis of interrelated visual icons in the Harry Potter films that represent the idea of the lapis as an embodiment of alchemical perfection. In addition, by studying the interplay between alchemical imagery in the Harry Potter novels and films, and comparing the worldviews represented by each, this study is able to analyse the dynamics of the hermeneutic process. This study concludes with a consideration of how alchemical theory relates to the discipline of hermeneutics, how it influences the process of interpretation, and ultimately the relationship between the alchemical worldview and current perspectives on authorship. / Dissertation (MA)--University of Pretoria, 2008. / Visual Arts / unrestricted