Thesis (M.S.)--Oregon State University, 2008. / Printout. Includes bibliographical references. Also available on the World Wide Web.

Thesis (Ph. D.)--University of Chicago, Committee on Evolutionary Biology, March 2001. / Includes bibliographical references. Also available on the Internet.

Acidified catchments are known to hold significantly reduced dipper Cinclus cinclus populations throughout the year relative to circum-neutral rivers, although the processes leading to these declines remain unclear. This study considered the population ecology of dippers within the circumneutral River Devon catchment, Central Scotland, and focused primarily on determining the factors influencing survival, breeding probabilities and reproductive success. It aimed to examine the role of spatial variation in 'habitat quality' on the population (and meta-population) dynamics of dippers, based on measures of seasonal and lifetime reproductive success, and the balance between survival and reproduction; in particular, to assess if the reduced reproductive success of dippers on acid rivers is likely to lead to population declines. Within the Devon catchment, approximately 81% of all adults survived from spring (March/April) to autumn (September/October), with 65% of these birds surviving from autumn to the following breeding season. Overall, these estimates predicted annual adult survival rates of c.53%, with no significant differences between years. Population density had no detectable effect on adult mortality rates, although juvenile over-winter survival was significantly lower than the adult rate at between 40 and 58%, and negatively related to the total size of the autumn population. There was no evidence of sex differences in juvenile over-winter survival, or any significant influence of weather or river flows on the rates for adults or juveniles. The local post-fledging survival of females was significantly lower than for males, however, apparently reflecting sex differences in post-natal dispersal. On average, less than 6.5% of all eggs laid, or 10.4-14.5% of male and 6.3-9.2% of female fledglings raised within the Devon catchment survived locally to breeding age. Juvenile, although not adult, recapture rates in spring were significantly lower than for birds known to have bred previously and negatively related to spring river flows. This suggested that with recapture dependent on a breeding attempt that was successful at least until laying, either more first year birds failed during the initial stages of nesting or that full breeding was not achieved at age one. The birds fledging the most young, both within a season and over a lifetime, all bred at 'prime' lowland sites characterised by wide, shallow rivers of intermediate gradient, although with less than 10% of all birds attempting to raise a second brood each year, no significant habitat differences were identified in any component of reproductive output measured until fledging. River width, altitude and gradient were all significantly inter-correlated and related to laying date, however, and post-fledging survival was significantly reduced for late fledged young. On average, lowland birds laid earlier than upland breeders, and were significantly more likely to produce autumn 'recruits' due to the enhanced post-fledging survival prospects of their young. This suggested that broad measures of river structure can provide a biologically appropriate classification of habitat quality. The size of the breeding population of dippers within the Devon catchment appeared to be related to the availability of critical resources, most likely food, roost sites and ultimately breeding territories through density-dependent changes in over-winter mortality and recruitment. The relative importance of resource abundance and recruitment levels in determining autumn population densities on acid streams still remained unclear, although reference to published relationships between acidity and reproductive success suggested that with adult survival at the rate estimated for the Devon catchment, many dipper populations are unlikely to produce sufficient recruits to match all adult losses, and may only persist with continued immigration from more productive (circumneutral) catchments elsewhere.

The functions of the elongated tails of birds have been the subject of much discussion in recent years. It is clear that in some cases the tail represents a sexually selected ornament, playing a vital role in mate choice. However. what is becoming increasingly apparent is that the tail can also play vital aerodynamic roles during flight, and can thus be a result of natural selection. Tail length manipulation experiments carried out during this work have shown that elongated graduated tails have an aerodynamic role during gliding flight. A function in the maintenance of stability (ring necked pheasants (Phasianus colchicus)) and optimising gliding performance (black-billed magpie (Pica pica)). thus these elongated graduated tails have been shown to be a product of natural selection. The question of whether correlated evolution occurred between the advent of gliding flight and the graduated tail shape was investigated. It was found that graduated tails did not co-evolve with gliding flight. However, it was shown that graduated tails had correlated evolution with tail elongated. It has been suggested that the forces acting on a triangular tail can be predicted through the application of slender lifting surface theory and the tail being analogous to a delta wing. This would predict that the tail functioned as a consistent lift producing surface. This study considered whether the tail functioned as a lift producer or a control surface. Stereo video of Harris' hawks (Parabuteo unicinctus) was used to assess tail function of a triangular tail. However, the results did not provide conclusive evidence for either theory. In this thesis I show that elongated avian tails perform a number of naturally selected aerodynamic roles during flight.

The interrelationships between species composition, resource-use and availability, breeding and competition were studied in two hill habitat raptor communities in a conserved reserve and an unprotected communal land in Zimbabwe in 1995 and 1996. The conserved Lonestar Study Area (LSA) and the unprotected Communal Land Study area (CLSA) had 38 and 31 raptor species, high and normal diversities for the area sizes respectively. An estimated 147 pairs of 21 raptor species bred in 40km² in the LSA compared to only 26 pairs of 22 raptor species per 40km² in the CLSA. Six species (African Hawk Eagle Hieraaetus spilogaster, Black Eagle Aquila verreauxii, Crowned Eagle Stephanoaetus coronatus, Little Banded Goshawk Accipiter badius, Barn Owl Tyto alba,and Barred Owl Glancidium capense made up 69% of breeding raptors in the LSA, while African Hawk Eagles, Little Banded Goshawks, Barn Owls and Barred Owls made up 58% of the breeding raptors in the CLSA. The abundance of Black, Crowned and African Hawk Eagles in the LSA was linked to abundant hyrax, Heterohyrax brucei and Procavia capensis and juvenile bushbuck Tragelaphus prey, and the high reproduction rates of Natal Francolin Francolinus natalensis (0.7 per ha when not breeding). Little Banded Goshawk and Barn Owl abundances were linked to their ability to change prey preferences according to prey availability. A fairly high rate of breeding attempts by eagles in the LSA in both years (60 - 76% of all pairs per year)was probably also linked to prey abundance, Most breeding failures were predator related, and were more common in areas of relatively low nesting densities indicating lower parental vigilance there. High eagle breeding densities were associated with small mean territory sizes in the LSA (7.7 - 10.7km² for the main eagle species). Eagles in the LSA usually nested closer to another eagle species than a conspecific, resulting in regular distributions of nests and no territory overlap within species. Differences in daily flight activity of eagles in both study areas, and in the onset of breeding between LSA eagles probably reduced interspecific aggression. Interspecific competition food and nest sites amongst LSA eagles was possibly lessened by slight ditferences in resource selection. Raptor resources were mostly unaffected by human activities in either study area during the study period. Differences in the raptor communities were probably as a result of natural habitat differences. The CLSA raptors potentially face resource loss through forest clearing and hunting. An expansion of the present CAMPFIRE program will protect the CLSA raptors.

Forest birds located by their calls were related to mapping units of different land resource maps using a new method. The method involved computer programs which use mathematical descriptions of landform, forest canopy heights, and the nature of the bird's call to predict the area censused for each bird species from each listening station. Computer programs were also used to display locations made from each station, and to associate the locations and areas censused with different mapping units. Yellow-bellied Sapsucker (Sphyrapicus varius), Chestnut-backed Chickadee (Parus rufeseens), Steller's Jay (Cyanocitta stelleri), Winter Wren (Troglodytes troglodytes), Varied Thrush (Ixoreus naevius), and Swainson's Thrush (hylocichla ustulata) were each related to both serai stages and vegetation taxonomic units; while Hairy Woodpecker (Dendrpcopus villosus), Common Flicker (Colaptes cafer), Red-breasted Nuthatch (Sitta canadensis), and Olive-sided Flycatcher (Nuttallornis borealis) were each related only to seral stages. Most species showed a consistent pattern of selection for mapping types with repeated census. Results for the Steller's Jay indicated some change in the use of seral stages between census periods. However, there was no clear trend in use over time, and the observed changes may include effects of flocking which would violate the statistical assumption that locations were independent. Each species had a unique pattern of selection of seral stages and of vegetation types. Species with similar patterns of selection were grouped to form five groups for seral stages and three groups for vegetation types (groups not mutually exclusive). Only Chestnut-backed Chickadee with Yellow-bellied Sapsucker, Swainson's Thrush with Winter Wren, and Varied Thrush with Winter Wren were grouped together both for seral stages and for vegetation types. A more definite preference among seral stages than vegetation types was detected for most of the species studied. However, the Steller's Jay preferred only two of the vegetation types, while it used all seral stages somewhat equally. Most of the species studied preferred older seral stages. Common Flicker, Steller's Jay, and Olive-sided Flycatcher also used younger stages; while Swainson's Thrush selected for stages of medium age. Of the species related to vegetation types, only Chestnut-backed Chickadee did not show some preference for taxonomic units associated with high soil moisture. The preference was most pronounced for Steller's Jay, which concentrated its use on the two wettest types. The preference by Yellow-bellied Sapsucker may be explained by the older trees and snags that survived logging and fire in wet areas. All of the species also used many of the drier types. The data support the hypothesis that land resource maps can be used to predict the occurrence of wildlife. The results suggest that habitat for a wildlife species can be predicted over vast areas if the areas have been mapped, and if significant differences in the habitat value of different mapping units have been documented. The results indicate that the prediction can be improved by combining the predictions from two or more maps. The predicted area and spatial distribution of high-quality habitat can be compared with management policy objectives for the wildlife species. The predicted change in available habitat with planned forest management activities can provide criteria for habitat management. The same land resource maps may be used for many wildlife species, thereby facilitating multi-species habitat management. / Forestry, Faculty of / Graduate

A study of muscle spindles in two synergistic avian muscles was undertaken to determine whether morphological or quantitative differences existed between muscle spindles residing in a slow-red (tonic) muscle and a fast-white (twitch) muscle. The avian anterior (ALD) and posterior (PLD) latissimus dorsi muscles were chosen since they are unique among vertebrates as paradigms of a slow-red and a fast-white muscle respectively. Serial frozen sections of muscle were stained with Haematoxylin and Eosin or Gomori triehrome and muscle spindles residing in the ALD were assessed and compared with those in the PLD with regard to organization, distribution and density, Contents of muscle spindles were examined for intrafusal fibre size, number and morphology. Attention was also directed to the relationship between muscle spindles and the surrounding extrafusal muscle in which they were located. Differences were found between muscle spindles residing in the two muscles. In the slow ALD, muscle spindles were relatively evenly distributed, whereas in the fast PLD, they were concentrated around the single nerve entry point into the muscle. The ALD muscle spindle index was the highest yet published for chicken muscle and was 2.3 times higher than that of its fast counterpart. A bimodal trend in intrafusal fibre diameter was noted in the ALD, and a trimodal trend was found in the PLD. The former had 42% fewer intrafusal fibres than the latter. Muscle spindles were shorter in the ALD, with an average length of 1.9mm compared with 2.3mm in the PLD. An interesting feature of the slow muscle was the monofibril muscle spindle, containing a single intrafusal fibre. With a few exceptions, ALD muscle spindles were located within the interfascicular perimysium close to a neurovascular trunk. PLD muscle spindles were rarely seen in these areas but were frequently found within a muscle fascicle, surrounded by closely apposed extrafusal fibres. Moreover, neurovascular trunks were less frequently seen in the PLD. As an adjunct to this study, three ALD-PLD pairs from the Storrs Connecticut strain of muscular dystrophic chickens were also examined to compare muscle spindles in these muscles with those of normal animals. In the PLD, which is known to exhibit early and progressive pathological change, muscle spindles appeared relatively normal until marked extrafusal fibre degeneration had occured. By this time evidence of muscle spindle involvement included capsular hypertrophy and intrafusal fibre splitting. Whereas the slow ALD has been reported to retain apparent normalcy in muscular dystrophy, subtle changes were seen in some of the muscle spindles examined. These included an increase in number of intrafusal fibres per muscle spindle compared with those in the normal. / Land and Food Systems, Faculty of / Graduate

I studied foraging ecology of black oystercatchers (Haematopus bachmani) in the rocky intertidal. The aims of this study were: 1) to analyze prey choice and patch choice by adult black oystercatchers and evaluate how well their foraging performance was predicted by foraging theory; 2) to study development of foraging in young oystercatchers; 3) to indirectly examine the relationship between parental foraging performance and fitness by measuring chick growth and chick production. The following conclusions were reached: 1) Prey selection by oystercatchers was generally as predicted by theory, but birds showed partial preferences for prey. Patch choice followed general theoretical predictions, but profitabilities achieved within particular patch types were highly variable. Reasons for this are discussed. 2) Growth and physical maturation are important components in development of foraging. During the period of this study, chicks were heavily dependent on parental feeding, and the ability of chicks to forage independently developed after chicks left their natal area at about 50 days of age. 3) Chick growth varied between one-chick and two-chick broods, and this may be related to parental foraging performance. However, during this study chick production was constrained by weather and predation, and no relationship between parental foraging performance and fitness could be defined. / Science, Faculty of / Zoology, Department of / Graduate

One of the more interesting and unique of the natural habitats in the state of Utah is its chaparral zone, extending along the western foothills of the Wasatch Range. The purpose of this study has been to make an analysis of the bird population of this region in order to determine the comparative abundance of the species, their seasonal distribution within the area, and their ecological preferences.

No description available.