The current project lasted two years, from April 2021 until March 2023. The activities carried out during this period can be divided into three main groups: egg collection and gosling hand-raising, data collection, and data analysis. These phases alternated throughout the duration of the project.
The egg collection and gosling hand-raising phase took place in spring (March - June). To investigate ontogeny, we used two different cohorts of goslings, one in 2021 and another in 2022. During the first two spring months, my colleagues and I monitored the areas surrounding the institute and mapped the presence of nesting pairs of Canada geese. Once found, the nests were regularly monitored until the eggs were laid, at which point we collected them and incubated them at the institute until hatching. The newborn goslings were then hand-raised and imprinted on the experimenters, which allowed them to be naturally motivated to participate in the experimental sessions.
Between June and November, we conducted a data collection and analysis phase, which involved regular experimental sessions with the geese. During these sessions, the geese swam multiple laps along the length of the floating aviary following our inflatable boat, while we collected video and accelerometer data to investigate sleep-swimming in a gradient of increased workload, as well as the physiological need for sleep. Several experimental sessions were conducted across the entire period in order to investigate how the occurrence of sleep-swimming varies across development. We also collected continuous 24-hour data on undisturbed animals either before or after each experimental session to study sleep-swimming in a more natural context. Once the geese's skulls reached an adult-like size, we mounted a small logger that allowed us to confirm electrophysiologically whether the closing of the eyes indicated sleep. To analyze the vast amount of data, I automated the video analysis and extracted paddling data from the accelerometer data, with guidance from Dr. Paul Antoine Libourel (CRNL, SLEEP Team, Université Claude Bernard Lyon 1, France) whom I visited twice for training on this type of analysis on MATLAB.
Our preliminary findings indicate that Canada geese can actively move their legs while their eyes are closed, with a higher occurrence of sleep-swimming with both eyes closed when the distance swam increased. Moreover, we observed an increase in the total amount of sleep-swimming across the number of trips swam. This finding suggests that geese use sleep-swimming to meet an increased need for sleep, indicating an important role of this behavior in maintaining sleep homeostasis and potentially managing energy during movements within their habitat. Finally, our preliminary results show a decrease in the occurrence of sleep-swimming that correlates with the individual's growth, further suggesting a correlation between energy demand and sleep pressure. While conclusive results require further data analysis, our EEG data confirms that geese can sleep while actively swimming. Based on this, I am pleased to report that the objectives of this project have been achieved.
Throughout the project, I actively promoted it to both academic and non-academic audiences, including participating in the MPI-BI open-day, featuring in two documentaries (one of which was aired on German TV), being interviewed by the Italian TV show Newton, delivering a seminar at the Italian Society of Ethology, speaking at a workshop organized by the University of Vienna, and having an article published about our project in a local newspaper. Although preliminary results have only recently been obtained, they will be disseminated next summer through my participation in two conferences: the European Ornithological Union Meeting 2023 and Behavior 2023. Additionally, I kept important milestones visible on social media platforms like Facebook and Twitter.
