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In winter, birds often sit quietly on a branch for hours. Do they actually sleep more, or is it just a way to conserve energy?
Mike Follows
Sutton Coldfield, West Midlands, UK
When birds sit quietly on a branch for long periods during winter, they aren’t usually sleeping, but rather conserving energy. When food is scarce, active foraging can waste valuable energy, so remaining still is often a better survival strategy. Also, by fluffing up their feathers, birds trap heat and stay warm while burning less stored fat.
However, some species enter torpor, a short-term state in which metabolism and body temperature drop for a few hours or overnight, further reducing energy loss. The common poorwill (Phalaenoptilus nuttallii) is the only bird known to go into extended torpor and teeter on the cusp of true hibernation.
John Davies
Haverbreaks, Lancashire, UK
In winter, birds have to sit on a branch for a long time, as the night is longer than in the summer. And with less food, they must forage and feed even more diligently in winter. I fear that a bird “sitting on a branch for hours” is ill.
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When food is scarce, active foraging can waste a bird’s energy, so remaining still is often a better survival strategy
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