Abstract
Animal spatial movement is an integral component of ecological and evolutionary processes.Individual decisions and how they interact with the environment ultimately shape population and
community dynamics, as well as the distribution of their genes across the landscape. Therefore,
analysing animal movement patterns and how they impact population genetic structuring can provide
valuable information for managing threatened species. However, these data can be hard-won,
especially for species with small, highly mobile individuals, such as birds, and in remote areas with
limited access. The objective of this thesis was to trial a novel biotelemetry methodology of tracking
the spatial movements of granivorous finches as they free-ranged across vast areas of tropical savanna
in search of grass seeds. The individual-based movement information was assessed alongside
individual genetic information to assess the impact that the movement of individuals can have on the
structuring of the population. This is relevant because an increase in the intensity and frequency of
grass fires throughout Australia’s tropical savannas has changed the abundance and distribution of the
finch's food resource and has been attributed to a decline in Gouldian Finch (Erythrura gouldiae)
populations.
To monitor finch movement at the appropriate spatial and temporal scale, an array of passive VHF receivers was deployed across more than 1,000 km2 of savanna, and over 100 Gouldian (Erythrura gouldiae) and long-tailed finches (Poephila acuticauda) captured and attached with very small (0.2 g) coded VHF transmitters. During the capture process, a blood sample was taken from each bird for genetic sequencing. The VHF telemetry enabled the simultaneous tracking of multiple birds for around nine months.
My research found that the data provided by automated VHF telemetry was of sufficient frequency and accuracy to tease out the short-term impacts of extreme heat on the behaviour of the finches. This showed that Gouldian Finches presented significantly different activity patterns on hot days compared to cooler days, with higher activity levels earlier in the morning and a second activity
peak in the afternoon. The genetics analysis found that the Long-tailed Finch population showed higher levels of fine-scale genetic differentiation than the Gouldian Finches. As hypothesised, this was attributed to their differences in foraging ecology, which causes differences in their fine-scale movement behaviour across the landscape. Finally, the link between individual movement and fine scale genetics was assessed within the Gouldian Finch populations, and we found a significant correlation between pairwise relatedness and pairwise association strength.
Though integrating genetics and biotelemetry data is rarely done, there is a growing body of literature combining these two disparate fields. Here, I have confirmed that it is fairly easy to obtain an individual genetic sequence, as tissue samples can be taken when the animal is captured for the attachment of the telemetry device. This data can then be used to match the genetic relatedness between individuals with how they move in relation to each other and through the landscape. Animal movement is often the glue that binds ecological processes together, hence why these findings are important in understanding the link between the spatial distribution of resources and the population processes.
Date of Award | 2024 |
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Original language | English |
Awarding Institution |
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Supervisor | Hamish Campbell (Supervisor) & Sam Banks (Supervisor) |