Date of Award
2-5-2025
Publication Type
Thesis
Degree Name
M.Sc.
Department
Biological Sciences
Keywords
Behaviour; Climate Change; Common Eider; Conservation Biology; Physiology; Sea Duck
Supervisor
Oliver Love
Supervisor
Christina Semeniuk
Rights
info:eu-repo/semantics/openAccess
Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial-No Derivative Works 4.0 International License.
Abstract
Rising ambient temperatures driven by climate change can heighten an endotherm’s risk of heat stress, eliciting a physiological and behavioural response. Cold-specialist species may be particularly vulnerable to over-heating due to their adaptive ability to retain body heat in cold environments. Moreover, their risk of heat stress may be exaggerated during reproduction, when body temperatures and energetic workloads approach their annual maxima. In this study, I investigated whether a cold-specialist seaduck, the arctic-breeding common eider (Somateria mollissima), experiences heat stress during their incubation by examining their heart rate and incubation behaviour at Qikiqtakuluk (East Bay Island), a long-term breeding colony in the Qaqsauqtuuq (East Bay) Migratory Bird Sanctuary, Nunavut. Hens fast for roughly 25 days while incubating their eggs on sun-exposed nests. I used heart-rate data collected from incubating hens using a 3D-printed microphone egg in each nest during the summers of 2019, 2022, and 2023 (N= 62), as well as incubation behaviour recorded via temperature fluctuations from thermal probes in each nest in summers 2018, 2019, 2022, and 2023 (N= 86). Recorded nest-level temperature was also recorded at each nest using hobo temperature pendants, and site-wide ambient temperature and weather factors (e.g. wind) were also measured using heat-stress tracking devices. I found significant temperature thresholds at which eiders begin to increase their heart rate and increase behavioural adjustments on the nest in response to heat stress. However, eiders are not yet experiencing high-enough temperatures in their environment to show statistically significant changes in their heart rate and behaviour. In addition, we found that weather factors contribute to eiders' physiological responses but not behavioural responses to heat stress. Further, hens' heart rates and behavioural adjustments increase later in the breeding season and during later stages of incubation, with later-laying hens also having higher heart rates. We conclude that eiders are not yet significantly heat-stressed during their incubation, but as temperatures continue to rise beyond our found temperature thresholds, incubating eiders may begin to experience significant energetic and behavioural costs of heat stress, particularly later into the season and their incubation, with late-laying hens being especially vulnerable to energetic costs. We show that eiders have the capacity to respond to climate change, but that these responses can interfere with their reproduction. As such, the revealed temperature thresholds and assessment of eiders' vulnerability to heat stress under climate change’s warming of arctic summers may aid in informing their timely management and encourage protective policy action in this declining seaduck.
Recommended Citation
MacDonald, Emily Charlotte, "Sitting Ducks: The physiological and behavioural responses of incubating common eiders (Somateria mollissima) to heat stress in the Canadian Arctic" (2025). Electronic Theses and Dissertations. 9652.
https://scholar.uwindsor.ca/etd/9652