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Master of Arts / Department of Geography / J. M. Shawn Hutchinson / Prairie dogs (Cynomys spp.) are social, ground-dwelling rodents native to North American short- and mixed-grass prairie. They are also the main prey of the Federally-endangered black-footed ferret (Mustela nigripes). At the same time, prairie dog colonization is highly opposed by most agricultural landowners. Therefore nonlethal population management techniques must be investigated. This paper presents the results of research on the effectiveness of ungrazed vegetative barriers composed of native plants at limiting prairie dog dispersal away from a ferret reintroduction site in northwest Kansas. Data was collected on barrier quality and condition as well as estimates of population densities of immigrant prairie dogs, dispersing through the vegetative barrier to reoccupy previously extirpated colonies on properties surrounding the ferret reintroduction site. Using strip transects and aboveground visual counts to estimate population densities and visual obstruction ranking techniques to sample barrier condition, statistical analysis of the data indicated that while barrier condition increased over time, it was not effective at limiting prairie dog emigration from the black-footed ferret reintroduction site.

Selected quarries and adjacent areas of xerophilous grassland in Bohemian karst were examined for the presence of velvet spider burrows. Selected microhabitat valuables were collected and their significance for ladybird spider analyzed.

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The Blue Penguin (Eudyptula minor) is assumed to be declining over much of its range, largely due to introduced predators. Anecdotal evidence suggests that one of the areas of declining population is the West Coast of the South Island. The purpose of this study was to determine the reasons for the assumed decline of blue penguins in South Westland. This was done by studying breeding ecology at several blue penguin colonies to assess the importance of breeding success and adult mortality on the penguin population. Three blue penguin colonies in South Westland, at Five Mile and Three Mile beaches south of Okarito, and at the Wanganui River mouth near Harihari, were monitored throughout the 2008/09 breeding season. During each burrow visit the number of eggs and chicks were recorded as well as the date of laying, hatching or fledging. Five colonies of blue penguin were also monitored in Buller over the same breeding season in a study conducted by the West Coast Blue Penguin Trust, a community trust based on the West Coast. The results of both studies were compared to determine the effect of predator control on breeding parameters, such as breeding success. Of 137 eggs laid in South Westland, 108 chicks survived until fledging, giving an overall breeding success of 78.8%. In Buller, 64 chicks survived to fledging from 101 eggs laid, resulting in an overall breeding success of 63.4%. Breeding success was significantly higher at penguin colonies in South Westland, compared to the Buller colonies. There was no evidence that predator control had an effect on breeding success in South Westland or Buller. The mean number of chicks fledged per pair that produced eggs was 1.55 in South Westland and 1.16 in Buller. The overall proportion of occupied breeding burrows compared to the total number of suitable burrows at the South Westland sites was 73.8% (n = 103). At the Buller sites, only 60.3 % (n = 151) of the total number of burrows was occupied. Road kills are a major threat to blue penguins in Buller due to the proximity of colonies to the state highway. Fortunately, incidences of road death in South Westland are rare and due to the distance from roads, do not pose a significant threat to South Westland blue penguins. Further study of blue penguin colonies in South Westland is needed to learn more about annual variation in breeding productivity and to determine if breeding success is consistently high over an extended time period. If this is the case, then the cause of blue penguin decline on the West Coast is unlikely to be due to problems with breeding as the breeding success during this study is one of the highest recorded for blue penguins. Although there was no apparent effect of predator control on breeding productivity during this study there is evidence from other locations that predators, in particular stoats, have contributed to the decline of blue penguin populations. More research into the impact of predators on penguins over a longer period of time is needed on the West Coast before a change is made to how predators are managed.

[Truncated abstract] Ecosystem engineers are organisms that physically modify habitat in a manner that modulate resource flows and species within ecosystems. Ecosystem engineering is distinct from classical interactions (competition, predation, parasitism and mutualism) in that it does not involve direct trophic exchange between organisms. The term ‘ecosystem engineer’ is a recently adopted one, and we are just beginning to investigate the occurrence and impact of engineers in ecosystems. My thesis explores the ecosystem engineering actions of Wedge-tailed Shearwaters, Puffinus pacificus, in a Mediterranean island, heathland ecosystem. I have approached this by (1) describing and quantifying the physical impact of these engineers, and (2) describing and quantifying the effects that these actions have on three major ecosystem components: the soil, the vascular plants, and the vertebrate fauna. Wedge-tailed Shearwaters are procellariid seabirds that excavate nesting burrows on offshore islands. The birds are colonial nesters, and on Rottnest Island, 17 km off the mainland coast of south-western Western Australia, their colonies have expanded considerably in recent decades. The expansion fits the trend observed in other tropicalorigin seabirds that breed in south-western Australia. In the last ten years, two new colonies have appeared (in a total of six) and the number of burrows on the island has almost doubled, to 11 745 ± 1320SE. In the same period the area occupied by the birds has increased by almost half ...