Avian life histories in a changing world: Combining remote sensing with long-term monitoring of the superb fairy-wren Malurus cyaneus in Australia
Creators: name: Turner, Richard
Publisher: name: The Australian National University
Year: 2023

description: Two fundamental challenges in ecological research are the ability to identify and understand the factors that shape the evolution and plasticity of behaviours, life histories, and population dynamics of organisms. The effective management and conservation of imperilled species increasingly relies on this information. However, a major obstacle hindering progress in this field is the limited collection of suitable environmental and ecological data at appropriate spatial and temporal scales. A potential solution to this problem lies in the increasing accessibility of remotely sensed terrestrial, airborne, and satellite data, which are often free to use and available at local, regional, national, and global scales. Here, I investigate the effects of environmental and ecological change on avian life history variation by combining remote sensing data with three decades of individual-level monitoring of a wild population of superb fairy-wren Malurus cyaneus in southeastern Australia. Chapter one explores temporal patterns of nest predation in order to understand its role on the long-term decline of the study population throughout the study period (of more than 50%, up until 2020). By examining predation rates at different temporal scales, I show that predation is rarely ever constant. However, I find no evidence of within-season trends differing between years, and little evidence of a directional change in nest predation over the study period. This suggests that increased nest predation is not driving the population decline. I discuss the influence of the primary nest predator, the pied currawong Strepera graculina, on these patterns. Chapter two combines measurements of vegetation structure, derived from airborne laser scanning (ALS), with breeding data to investigate the influence of vegetation structure on nest-site selection and breeding performance - specifically nest success and post-fledging survival rates in relation to predation risk. I find that greater groundstorey vegetation volume and lower mean height of understorey vegetation are associated with increased nest presence. However, nest success rates decreased with increasing groundstorey vegetation volume, and effects of vegetation structure on post-fledging survival involved complex interactions. These findings indicate that the preferred vegetation structure of nest-sites chosen by superb fairy-wrens is not beneficial under current predation pressures. I discuss the factors that may have influenced these results and the implications of using ALS to study behaviour and life history variation in wild animal populations. Chapter three combines life history data with weather records and Landsat satellite imagery to explore associations between climate, vegetation productivity, and spatiotemporal variation in superb fairy-wren mortality and breeding success. I find associations between climate and vegetation productivity, when considering concurrent and lagged effects, and between vegetation productivity and these life history traits. These findings illustrate the potential of using Landsat imagery to investigate whether associations between animal life history traits and climate are mediated by vegetation and to what extent temporal trends are driven by climate change. Chapter four presents a case study of a fan-tailed cuckoo Cacomantis flabelliformis parasitising a superb fairy-wren nest, and the female superb fairy-wren returning and actively ejecting the cuckoo egg. This represents the first recorded evidence of egg ejection behaviour in this species. This chapter demonstrates the potential of using remote sensing trail cameras to uncover new insights into animal behaviours and life histories, with implications for the study of brood parasitism. Overall, my thesis provides valuable insights into the impact of environmental and ecological change on avian life histories and highlights the potential of remote sensing technologies in animal ecology research.