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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Habitat refuges and the management of predators for conservation

Carter, Stephen Paul January 2002 (has links)
No description available.
2

Rodent ecology and seed predation in logged and unlogged forest, Uganda

Stanford, Angela January 2000 (has links)
No description available.
3

Population models with harvesting and delay stability of equilibria /

Astaburuaga, Maria Angelica. January 1978 (has links)
Thesis--Wisconsin. / Vita. Includes bibliographical references.
4

Effects of risk on foragers a simulation /

Niemeyer, Nancy Marie. January 1984 (has links)
Thesis (M.S.)--University of Wisconsin--Madison, 1984. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 69-75).
5

Resource recovery delays in harvested predator-prey models

Griesmer, Stephen Joseph 11 1900 (has links)
This thesis investigates the effect of resource recovery delays, both continuous and discrete, on the behaviour and population dynamics of harvested predator-prey systems. Three models were tested with respect to local stability, global stability, and state-space trajectories. The method of D-partitions was used to determine local stability properties while simulations were performed to discover global properties. Generally, delays were found to induce multiple transitions between locally stable and unstable equilibria as harvest rates are changed. This phenomenon occurred under the management strategies of constant-effort harvesting and constant-quota stocking and harvesting. In addition, in the predator-prey models with delay, a high conversion efficiency and a high satiation limit for the predators can effect instability; this is not possible without delays. Global investigations confirmed the local results and extended them to the simultaneous harvesting of the predator and prey for constant-quota harvesting and stocking. The simulations also showed bifurcations in limit cycles as the carrying capacity was altered and as the stocking rates were varied. Nutrient-limited phytoplankton cultures in chemostats were analyzed with the mathematical techniques. It is shown that multiple stability transitions with changes in dilution rates are theoretically possible but observed delays are not large enough to produce this behaviour. / Graduate and Postdoctoral Studies / Graduate
6

Seed predation and potential dispersal of Ceratocaryum argenteum (Restionaceae) nuts by the striped mouse (Rhabdomys pumilio) / Joseph Douglas Mandla White

White, Joseph Douglas Mandla January 2013 (has links)
This study aimed to better understand the role of rodents as seed predators and dispersers in the fynbos biome at De Hoop Nature Reserve, South Africa in May and June, 2013. Based on previous studies I hypothesised that the large, nut-like seeds of Ceratocaryum argenteum (Restionaceae) are scatter-hoarded by rodents and that rodent seed choices and seed fates are affected by seed size and hull thickness. Field trials using three seed types showed that smaller seeds with a high reward and low processing cost were consumed significantly(p<0.01) more than large, thick hulled seeds. Application of wire tags to facilitate discovery of relocated seeds had no significant influence on seed choice (p>0.05), but further research should be conducted to determine if spooling of C. argenteum seeds influences rodent seed choice. Smaller seeds with a high-reward and low processing cost showed a significantly greater percentage of usage (p<0.01) where seed stations were encountered and exploited. Rhabdomys pumilio was confirmed as being the most common murid at the study site, however, it seems unlikely that it scatter-hoards C. argenteum seeds, as no consumption or burial of seeds was observed. However, R. pumilio did show an interest in C. argenteum seeds and attempted to consume some seeds or carried seeds over distances not significantly different (p>0.05) from the observed distances between nearest neighbour C.argenteum plants before discarding them on the soil. Additionally, the maximum distance R. pumilio moved C. argenteum seeds was commensurate with the maximum distance between nearest neighbour C. argenteum stands, so the end fate of the seeds remains unknown. Further research should account for seasonal variability in scatter-hoarding behaviour.
7

A STUDY OF THE ROLE OF INTRAGUILD PREDATION IN THE POPULATION DYNAMICS OF THREE SPECIES OF RHYACOPHILA

Wright, Charles Stewart IV 05 July 2011 (has links)
Intraguild (IG) predation, where species within the same guild prey on each other, is common in aquatic communities. I used the abundance and distributional patterns of three species of Rhyacophila (Trichoptera), derived from a survey of 25 streams in Nova Scotia, Canada, to test several predictions of IG theory. I first sampled microhabitats and conducted behavioural observations to establish that the species do co-occur and prey on each other. Abundance patterns did not conform to two key model predictions: (1) Neither of the IG prey (R. minor, R. vibox) was excluded from the most productive streams, and (2) IG prey densities were not inversely related to productivity in streams with the IG predator (R. fuscula). It remains possible that intraguild predation occurs between these species of Rhyacophilia, the measured abundances do not indicate any measurable effects from IGP, the abundance being determined instead by the availability of prey.
8

Cougar response to roads and predatory behaviour in southwestern Alberta

Banfield, Jeremiah E Unknown Date
No description available.
9

Seasonal Wolf Predation in a Multi-Prey System in West-Central Alberta

Knamiller, Peter Thurston Unknown Date
No description available.
10

Mechanisms of prey selection in the ladybeetle Coleomegilla maculata Lengi Timb. (Coleoptera:Coccinellidae)

Roger, Caroline. January 1999 (has links)
Foraging generalist predators are frequently confronted with a diversity of prey types that differ in profitability. Optimal foraging models predict that predators should select and exploit the most profitable prey types and reject unprofitable ones. The goal of this research was to evaluate the mechanisms underlying prey selection, prey exploitation and predation efficacy in the generalist predator Coleomegilla maculata lengi Timb. (Col., Coccinellidae). / The influence of prey species, prey size and predator age on predation efficacy and prey consumption by C. maculata was determined using non-choice laboratory tests. The three lepidopterous species occurring in cruciferous crops, namely, Artogeia rapae (L.), Plutella xylostella (L.) and Trichoplusia ni (Hubner), were used as prey. Results showed that, within a given prey instar, C. maculata preyed more on P. xylostella than on the other two species and that predation efficacy increased with increasing predator age. These experiments also revealed that coccinellid larvae had a higher prey weight consumption rate on intermediate-sized prey compared to smaller or larger prey even though they killed a higher number of small prey. It is suggested that this higher efficacy on prey of intermediate size could be a consequence of higher costs associated with the consumption of prey at both ends of the size spectrum. / To evaluate behavioral parameters of prey selection in C. maculata larvae, an image analysis system, initially developed for parasitoids searching for hosts, was modified. This system was programmed to locate the eggs used as prey and to detect and follow the movements of the C. maculata larval head. This user-friendly system can detect and follow the movements with less than 0.1% of error. / Using this tracking system, the discriminatory capacity and the prey selection behavior of C. maculata larvae were evaluated in choice situations in which prey differed in quality (unparasitized, parasitized, young or old T. ni eggs). Coccinellid larvae did not exhibit any preference between parasitized and unparasitized eggs of the same physiological age. However, when physiological age differed, coccinellid larvae always preferred the younger eggs despite parasitism. Longer handling time and detrimental effects on immature developmental time and survival was always observed on the less preferred egg type. / This study also revealed that coccinellid larvae can learn to gradually reject the less suitable parasitized eggs, thereby improving their prey selection behavior. It was also demonstrated that these learned behaviors could be forgotten and that previous experiences on other prey types could influence the initial preference of coccinellid larvae. This study clearly indicates that the generalist predator C. maculata can select and exploit prey according to their profitability by using discrimination and learning abilities.

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