Doctor of Philosophy
Environment and Sustainability
MacDougall-Shackleton, Scott A.
Changes in weather patterns and extreme weather events are becoming more common with the onset of climate change. This predicted increase in severe weather globally is alarming and it draws concern for the adaptability and ultimate survival of many species. It is clear that birds are able to cope with and respond to inclement weather with physiological and behavioural responses in many circumstances, but as environmental conditions become more severe, the adaptive coping responses of many species may be pushed to their limit. As such, it is important to understand the effects that such changes in environmental conditions will have on birds. Most of our current understanding of how birds respond to inclement weather relies on observational field studies, but these types of studies are unable to draw conclusions about which specific weather variables, or the changes in such variables, are mainly responsible for physiological and behavioural responses. Through experimental studies simulating inclement weather cues, my doctoral research investigated a general question: how do white-throated sparrows (Zonotrichia ablicollis) respond to exposure of inclement weather cues? Within this thesis, I examined the effects of recurrent inclement weather cues (Chapter 2), and also acute exposure to inclement weather cues (Chapter 5) in a controlled setting to investigate the responses of birds to individual weather cues. I also investigated how temperature alone can influence migratory behaviour (Chapter 3). To complement these experimental studies, I also examined the effects that natural storm systems had on birds in a controlled setting (Chapter 4). I found interesting effects that were sex- and season-specific throughout. White-throated sparrows are able to detect changes in both temperature and barometric pressure, and respond to each cue differently depending on the season. For example, exposure to acute changes in temperature alone influenced behavioural responses in spring, but acute exposure to both temperature and barometric pressure elicited a stronger response of both physiological and behavioural measures in the winter. Food availability had limited effects throughout, suggesting that a variety of alternative external and endogenous factors influence the response of birds to storm exposure. Combined, these projects provide further evidence of the complexity of responses of birds to inclement weather, but these responses are dependent upon a variety of factors. Thus, it is difficult to draw a linear conclusion from these studies. This thesis reflects other multi-directional findings within the published literature, highlighting that white-throated sparrows must use a variety of cues to respond to inclement weather, and that multiple other factors including season, sex and food availability can influence this response. However, further research is needed to understand how external and endogenous factors interact to modify birds’ responses to inclement weather.
Boyer, Andrea C., "Weathering the Storm: Physiological and Behavioural Responses of White-Throated Sparrows to Inclement Weather Cues" (2019). Electronic Thesis and Dissertation Repository. 6215.