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Updated: Oct 5, 2025

Using a Thermal Camera to Measure Heat Loss Through Bird Feather Coats
Published on: June 17, 2020
Egg-laying increases body temperature to an annual maximum in a wild bird
Magella Guillemette1,2, David Pelletier3,4
1Département de Biologie, Université du Québec à Rimouski, 300, Allée des Ursulines, Rimouski, QC, G5L 3A1, Canada. magella_guillemette@uqar.ca.
Abstract:
Most birds, unlike reptiles, lay eggs successively to form a full clutch. During egg-laying, birds are highly secretive and prone to disturbance and predation. Using multisensor data loggers, we show that average daily body temperature during egg-laying is significantly increased (1 °C) in wild eider ducks (Somateria mollissima). Strikingly, this increase corresponds to the annual maximum body temperature (40.7 °C), representing a severe annual thermogenic challenge. This egg-laying-induced rise in body temperature may prove to be a common feature of wild birds and could be caused by habitat-related thermoregulatory adjustments and hormonal modulation of reproduction. We conclude our findings with new perspectives of the benefits of high body temperature associated with egg-laying of birds and the potential effect of heat stress that may occur with the future advent of heatwaves.
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