Heart Rate Slows During Egg Incubation, Study Shows

Jenn Hoskins
25th July, 2024

Heart Rate Slows During Egg Incubation, Study Shows

To enable the discovery of a slow, energy-conserving heart rate during prolonged fasting, this study monitored an incubating Blue petrel (Halobaena caerulea) (a) using a non-invasive electrocardiogram (ECG) logger housed within a specially designed dummy egg (b).

Image adapted from: Bonadonna et al. / CC BY (Source)

Key Findings

  • Researchers from the University of Montpellier studied blue petrels on Verte Island in the Kerguelen archipelago
  • They used a non-invasive dummy egg with a heart rate monitor to study the birds during egg incubation
  • Blue petrels showed significant heart rate changes to manage energy during prolonged fasting periods
Seabirds such as penguins and petrels, residing in the harsh climates of the Antarctic and sub-Antarctic regions, face unique challenges during their breeding seasons. These birds often need to travel vast distances, sometimes spanning hundreds or even thousands of kilometers, to forage for food. Consequently, they have adapted to endure prolonged fasting periods during egg incubation, allowing their partners to embark on these extensive foraging trips. While it is known that these seabirds accumulate and utilize fat reserves during fasting, the extent of their physiological adaptations remains unclear. This knowledge gap is partly due to the remote nesting locations and the birds' extreme sensitivity to human interference. To address this, researchers from the University of Montpellier developed a non-invasive device to monitor the heart rate (HR) of burrow-nesting blue petrels (Halobaena caerulea) during egg incubation[1]. They encapsulated a small-size logger within a dummy egg to record electrocardiograms (ECGs) through the featherless incubation patch of the birds. This innovative approach allowed the researchers to gather data without disturbing the birds, providing new insights into their physiological adaptations during fasting. The study's findings reveal that blue petrels exhibit significant physiological changes to cope with prolonged fasting. By continuously monitoring HR, the researchers observed how these birds manage their energy expenditure during the incubation period. This approach is particularly relevant given previous studies that have shown the relationship between HR and metabolic rate in other bird species. For instance, research on wandering albatrosses demonstrated that HR is a reliable indicator of metabolic rate, which varies with factors such as stress and environmental conditions[2]. This correlation allowed the researchers to infer the energy expenditure of blue petrels based on their HR data. The use of a non-invasive HR monitoring device is a significant advancement, especially considering the challenges faced in previous studies involving direct manipulation of the animals. For example, earlier research on common swifts employed indirect methods like monitoring nest temperature and measuring metabolic rate through respirometry to infer energy-saving strategies like daily torpor[3]. These methods, while effective, still involved some level of disturbance. In contrast, the dummy egg logger provides a more accurate and less intrusive means of data collection. The study also builds on the understanding of how environmental variability impacts the physiology of ectotherms, as highlighted in earlier research[4]. While the focus of that research was on aquatic ectotherms and the effects of temperature variability, the principles of physiological adaptation to environmental stressors are broadly applicable. The blue petrels' ability to adjust their HR and energy expenditure during fasting periods is another example of how animals can adapt to challenging environmental conditions. In summary, the development of a non-invasive HR monitoring device by the University of Montpellier researchers has provided valuable insights into the physiological adaptations of blue petrels during prolonged fasting. This method overcomes the limitations of previous studies that required more invasive techniques, offering a clearer understanding of how these seabirds manage their energy expenditure during critical periods of their life cycle. This research not only enhances our knowledge of seabird physiology but also underscores the importance of developing innovative methods to study wildlife in their natural habitats.

WildlifeBiochemAnimal Science

References

Main Study

1) Blue petrel electrocardiograms measured through a dummy egg reveal a slow heart rate during egg incubation

Published 24th July, 2024

https://doi.org/10.1186/s40317-024-00374-1

Related Studies

2) Heart rate and energy expenditure of incubating wandering albatrosses: basal levels, natural variation, and the effects of human disturbance.

Journal: The Journal of experimental biology, Issue: Vol 205, Issue Pt 4, Feb 2002

3) Cool birds: first evidence of energy-saving nocturnal torpor in free-living common swifts Apus apus resting in their nests.

https://doi.org/10.1098/rsbl.2021.0675

4) The importance of incorporating natural thermal variation when evaluating physiological performance in wild species.

https://doi.org/10.1242/jeb.164673


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