Stay cool to save energy
The study published in the Journal of Experimental Biology, used thermal imaging technology to measure the body surface temperature of the small songbird, the Great Tit, when faced with temporary food shortage.
The measurements showed that shortly after food became unavailable, the birds allowed their bill to cool. Bill temperature remained below the temperature of when food was left available until food was returned. However, the bill temperature began to gradually rise roughly an hour into the food restriction, suggesting both a level of control over how much the bill is allowed to cool and that cooling of the bill may have unwanted consequences, such as reducing functionality of the bill.
Lead author, Lucy Winder, who undertook the study at the Institute’s feild station, Scottish Centre for Ecology and the Natural Environment (SCENE) and is now at the University of Sheffield, said: “What these findings tell us is that birds reduce heat loss from their bill by selectively restricting blood flow well before they enter a state of starvation. So when a reliable food supply is cut off, birds are predicting they will face energetic shortfalls in future and are pre-emptively acting to prevent this from occurring.
Dr Dominic McCafferty, Senior Lecturer at the University’s Institute of Biodiversity, Animal Health and Comparative Medicine, said: “Our findings provide evidence that birds selectively allow the bill to cool when a predictable food supply is suddenly disrupted, likely as a means of minimising depletion of body reserves for a perceived future shortage in energy. This was an interesting finding as it demonstrates how small animals must respond to winter conditions, when habitats are challenging and food is limited.”
First published: 22 April 2020