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Population dynamics and human crocodile conflict of the Nile crocodile, Crocodylus niloticus, in the lower Zambezi valley

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Title: Population dynamics and human crocodile conflict of the Nile crocodile, Crocodylus niloticus, in the lower Zambezi valley
Authors: Wallace, Kevin
Item Type: Thesis or dissertation
Abstract: The lower Zambezi valley is an important conservation area for both Zambia and Zimbabwe, encompassing areas of varying levels of habitat and wildlife protection. Crocodiles have an important role in the ecosystem a well as a significant economic value, both attributes require careful management to ensure their preservation. This study investigated depredation of crocodile nests and estimated the population with a view to parameterising models which could be used to simulate harvesting strategies. Combined with a social survey the results are discussed in terms of enlightened crocodile management. The methodology encompassed four main areas: 1) An artificial crocodile nest experiment to ascertain levels of depredation at the egg stage. 2) Crocodile population surveys to estimate the abundance and size structure. 3) Deterministic stage-based and integral projection models compare observed to predicted population structure and the influence of harvesting regimes. 4) A questionnaire survey to determine the scale of human crocodile conflict and the associated issues. The local habitat characteristics of simulated crocodile nests correlated with depredation probability and time to nest death. The crocodile population shows evidence of increasing but differed from the predicted model stage structure, indicative of a population not yet at equilibrium. Crocodile density increased in areas that had higher levels of wildlife/habitat protection. An integral projection model indicated the complex inter-relationships between population biology parameters. Perturbations affecting the smallest as well as breeding size crocodiles may cause a significant impact to lambda and fertility selection. The current human crocodile conflict mitigation is minimal and ineffective. Canoe fishing is the highest risk activity followed by collecting water. The most popular mitigation suggestions were additional water access points in villages and for selective or total removal of crocodiles. An underlying dislike of crocodiles by the local populace needs to be addressed in order for successful long-term conservation.
Issue Date: 2011
Date Awarded: Feb-2012
URI: http://hdl.handle.net/10044/1/9226
DOI: https://doi.org/10.25560/9226
Supervisor: Coulson, Tim
Sponsor/Funder: Financial support and volunteer assistance was provided by Earthwatch Institute. Funding was greatly appreciated from the National Environment Research Council (UK) and the IUCN-SSG Crocodile Specialist Group - Student Research Assistance Scheme. Sponsorship and support was appreciated from Engineering Services Corporation Ltd (Zambia), Samil Motor Corporation (South Africa), Pertec International (South Africa), Imperial College London (UK) and University of Stellenbosch (South Africa).
Department: Biology
Publisher: Imperial College London
Qualification Level: Doctoral
Qualification Name: Doctor of Philosophy (PhD)
Appears in Collections:Biology PhD theses



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