- Title
- Population ecology and viability of the green and golden bell frog (Litoria aurea)
- Creator
- Pickett, Evan
- Relation
- University of Newcastle Research Higher Degree Thesis
- Resource Type
- thesis
- Date
- 2012
- Description
- Research Doctorate - Doctor of Philosophy
- Description
- An understanding of a species’ population ecology can be used to determine the impacts of threatening processes and to estimate the probability of local extinction. For this thesis I estimated the major demographic rates of a population of the green and golden bell frog through the use of mark recapture studies at Sydney Olympic Park, Australia. Through the analysis of historic and contemporaneous data we found that the mitigation of habitat destruction with habitat offset resulted in no net loss and an approximate 2-fold increase in population size. However, this required the construction of 19 times the amount of pond area than was destroyed. Females were detected less frequently during surveys suggesting they may have a smaller population than males. Analysis that included capture probability indicated that this difference was because females were more difficult to detect and the sex ratio was near parity. Mark recapture also estimated low survival, high recruitment and rapid growth of post-metamorphic frogs. Additionally, survival and recruitment were found to be highly variable which resulted in variable population sizes. Growth rate also varied on a spatial scale which may suggest a difference in productivity in different areas. This demographic information was used to construct a model of population viability with sensitivity analyses. The high variability in demographic rates resulted in highly variable predictions of population size, with a 42% chance of extinction over 100 years. Sensitivity analysis predicted that the probability of extinction was most sensitive to changes in female survival with male survival and growth rate also having considerable impact. We then ran a posthoc experiment to validate an assumption that the recruitment rate was not density dependent by increasing the survival of females over the winter. We found that breeding of mature females was not restricted by density dependent factors, which was in concordance with the population viability model. Together, these results have expanded the knowledge of the population ecology of this species which should induce targeted management actions to female survival and improve habitat offset programs through knowledge that such programs require substantial offset ratios. The use of these findings should therefore provide better conservation outcomes for the species as a whole.
- Subject
- amphiban; conservation; population viability analysis; habitat offset; sex ratio; mark-recapture; wildlife demography; adaptive management; thesis by publication
- Identifier
- http://hdl.handle.net/1959.13/1037336
- Identifier
- uon:13427
- Rights
- Copyright 2012 Evan Pickett
- Language
- eng
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| View Details Download | ATTACHMENT02 | Thesis | 2 MB | Adobe Acrobat PDF | View Details Download |