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Unpredictable environments present several challenges for animals that need to gather information to track ecological fluctuations to ensure access to resources and optimise life-history decisions. Part of the environmental unpredictability is linked to a heterogeneous distribution of resources, both temporally and spatially. Additionally, extreme climatic events (e.g. heatwaves) can prove physiologically and behaviourally challenging. In my thesis I integrated approaches from spatial and behavioural ecology to overcome current difficulties in the study of animal behaviour in the Australian arid environment. I focused research on wild zebra finches (Taeniopygia guttata) foraging behaviour. Insight into environmental heterogeneity came from classical vegetation surveys and the most up-to-date freely available remote sensing data, focusing on the spatial distribution of the primary nutritious source for the zebra finch - Enneapogon grasses. Enneapogon abundance and productivity varied at a local scale, both temporally and spatially, primarily driven by local environmental determinants. This variation was detectable using Sentinel - 2A imagery, although with some limitations, validating its use in Australian arid areas, as tool for understanding primary productivity . Furthermore, I demonstrated that in arid landscape, zebra finches have to overcome the challenge of finding food in a patchy environment and cope with extreme climatic conditions. I demonstrated that over two consecutive heatwave events, zebra finch temporal, social and spatial foraging patterns were constrained by the heat. Finally, by experimentally manipulating both food availability and brood size I demonstrated variation in individual foraging behaviour, with some birds using a greater variety of food sources and more persistently checking depleted patches. This behavioural variation in foraging strategy related to reproductive success, providing empirical support for optimal foraging theory . Overall, my results promote the use of a spatial framework for the study of animal behaviour to given valuable insight to the challenges and constraints individuals face in harsh, heterogeneous and unpredictable habitat. |
