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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.
11

Improving success of translocating southern Idaho ground squirrels (Spermophilus endemicus)

Busscher, Katie Lea. January 2009 (has links)
Thesis (M.S.)--Boise State University, 2009. / Title from t.p. of PDF file (viewed May 19, 2010). Includes abstract. Includes bibliographical references (leaves 41-45).
12

Methods for assessing the susceptibility of freshwater ecosystems in Southern Africa to invasion by alien aquatic animals

De Moor, Irene J January 1994 (has links)
Two methods for predicting regions susceptible to invasion by alien aquatic animals were developed for southern Africa (excluding Zimbabwe and Mozambique). In the "traditional" (data-poor) approach, distributions of three categories of alien "indicator" species (warm mesothermal, cold stenothermal and eurytopic) were compared to seven existing biogeographical models of distribution patterns of various animals in southern Africa. On the basis of these comparisons a synthesis model was developed which divided southern Africa into seven regions characterised by their susceptibility to invasion by alien aquatic animals with particular habitat requirements. In the "data-rich," geographic information systems (GIS) approach, the distribution of trout (Oncorhynchus mykiss and Salmo trutta) in selected "sampled regions" was related to elevation (as a surrogate of water temperature) and median annual rainfall (MAR) (as a surrogate of water availability). Using concentration analysis, optimum conditions for trout were identified. Regions within a larger "predictive area" which satisfied these conditions, were plotted as a digital map using the IDRISI package. Using this method seven models of potential trout distribution were generated for the following regions: northern Natal (two); southern Natal/Lesotho/Transkei (three), eastern Cape (two) and western Cape (two). Since two of the models were used to refine the methods, only five models were considered for the final assessment. In a modification of the GIS method, another model of potential trout distribution, based on mean monthly July minimum air temperature and MAR parameters, was developed for the region bounded by 29º - 34º S and 26 º - 32°E. This model showed marked similarities to another model, developed for the region bounded by 29 º - 32°S and 26º - 32°E, which was based on elevation and MAR parameters. The validity of the models developed was assessed by independent experts. Of the six models considered, four received favourable judgements, one was equivocal and one was judged to be poor. Based on these assessments it was concluded that the GIS method has credibility and could be used to develop a "data-rich" model of the susceptibility of southern Africa to invasion by alien aquatic animals. This method represents an alternative to the bioclimatic matching approach developed by scientists in Australia. The GIS method has a number of advantages over the "traditional" method: it is more amenable to testing, has greater flexibility, stores more information, produces images of a finer resolution, and can be easily updated. The traditional method has the advantage of being less expensive and requiring a less extensive database.
13

Restoration Techniques for Northern Bobwhites

Newman, William L. 05 1900 (has links)
Isolated populations of northern bobwhites (Colinus virginianus) have declined causing many quail managers to attempt population restoration by releasing captive-reared bobwhites or translocating wild bobwhites. I evaluated three restoration techniques: (1) release of captive-reared bobwhites, (2) translocation of bobwhites from high densities to low densities, and (3) release of captive-reared and translocated bobwhites acclimated on site prior to release. These results show that captive-reared birds have reduced survival and fewer nesting attempts when compared to translocated birds and that acclimation time was not a factor. I hypothesized that high mortality rates were caused by captive-reared birds exhibiting different predator avoidance behavior than wild birds. Captive-reared and wild-trapped bobwhites were subjected to independent predator simulations and their responses were recorded on high definition video. Threat recognition time, reaction type, and reaction time was recorded for comparative analysis. Pen-reared birds recognized the simulated raptorial and terrestrial predator threats quicker than wild-trapped birds, but reaction times were not different among groups. However, the type of reaction was different among groups where pen-reared birds typically flushed immediately upon recognizing either simulated predator as compared to wild-trapped birds which typically ran or held when subjected to the raptorial threat and showed little to no observable reaction to the terrestrial threat. These results reveal a potential loss of a holding trait in pen-reared birds, resulting in a quicker revealing of their position in the presence of a threat, thereby increasing their risk of predation.
14

Factors limiting the colonization success of an introduced exotic fish (Carassius auratus)

Richardson, Michael John January 1996 (has links)
No description available.
15

Factors limiting the colonization success of an introduced exotic fish (Carassius auratus)

Richardson, Michael John January 1996 (has links)
The goldfish (Carassius auratus) is a hardy exotic species that have established sporadically distributed feral populations throughout North America. In one shallow seasonally anoxic pond goldfish formed a large stunted population of 15-17,000 ind ha$ sp{-1}$, with 53% being small young of the year. Goldfish were predominantly benthic herbivores with little diet overlap with resident red-spotted newts (Notapthalmus v. viredescens). Thus in relatively simple systems lacking fish predators goldfish can be very successful. However in systems with a complex native fish community, goldfish have had less success in colonizing. This could be related to an inability of goldfish to cope with native predators. / Tests for assortative shoaling between brown and gold coloured morphs showed that gold coloured fish exhibited no colour based assortive shoaling, while brown fish showed slight but significant colour preferences for like-coloured fish. This level of shoaling preference did not improve after visual exposure or interaction with native predators, indicating that goldfish showed limited behaviourial responses to predators, and that they were unable to modify their response to a predation threat. Further trials allowing goldfish to interact with either pike (Esox lucius) or bass (Ambloplites rupestris), in both single species groups of predator-naive goldfish, and mixed species conditions of goldfish with predator-experience minnows, showed that goldfish did not alter their behaviour in the presence of minnows (Pimephales notatus) when the predators were not present. However, with the predators present goldfish altered their activities to a more minnow-like pattern and showed a significant improvement in anti-predator behaviour. This improved behaviour continued by goldfish when they were retested on their own, indicating that the goldfish were reacting to the predator and not the minnows. Goldfish colonization may therefore be limited not so much by predation or competition from native cyprinids, but more by the absence/presence of a suitable, native, predator-experienced fish from which to copy the appropriate anti-predator behaviours.
16

On the ecology of invasive species, extinction, ecological history, and biodiversity conservation

Donlan, Charles Joseph. January 2008 (has links) (PDF)
Thesis (Ph. D.)--Cornell University, 2008. / Title from PDF t.p. (viewed on Apr. 20, 2009). Vita. Includes bibliographical references. Mode of access: World Wide Web.
17

Population fragmentation and white sucker introduction affect populations of bluehead suckers, flannelmouth suckers, and roundtail chubs in a headwater stream system, Wyoming

Compton, Robert I. January 2007 (has links)
Thesis (M.S.)--University of Wyoming, 2007. / Title from PDF title page (viewed on Feb. 17, 2009). Includes bibliographical references (p. 64-79).
18

Identification of life history variation in salmonids using otolith microchemistry and scale patterns implictions for illegal introductions and for whirling disease in Missouri River rainbow trout /

Munro, Andrew Roy, January 2004 (has links) (PDF)
Thesis (Ph. D.)--Montana State University--Bozeman, 2004. / Title from PDF t.p. (viewed on June 12, 2006). Chairperson, Graduate Committee: Thomas McMahon. Includes bibliographical references.
19

Implications of the introduction and transfer of non-indigenous marine species with particular reference to Canadian marine aquaculture /

Nichols, Danielle, January 2001 (has links)
Thesis (M.M.S.)--Memorial University of Newfoundland, 2002. / Bibliography: leaves 93-105.
20

Environmental valuation, ecosystem services and aquatic species /

Kataria, Mitesh, January 2007 (has links) (PDF)
Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv., 2007. / Härtill 4 uppsatser.

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