Seeing birds remain local during the winter months isn’t uncommon. Most species choose to migrate to warmer climates, and many British birds make an appearance in southern Europe and Africa during our winter.
It’s worth considering how some birds even migrate to Britain from even colder locations with higher elevations. A large proportion of the Robins seen over the coldest season actually hail from the Scandinavian region.
Birds have a number of handy tricks available to them to keep them warm during the hostile winter period, and it’s interesting to take a look at just how they function.
An initially counterintuitive technique, birds are able to alter their temperatures to within a few degrees of the norm. This is handy for most of the year, but during the winter it becomes far more extreme. By entering a state of torpor, a temporary mode similar to hibernation, some species are able to reduce their temperatures by a stunning half of their normal levels. The benefit is that energy consumption is reduced substantially, allowing them to survive on less hard-to-find nutrients.
Birds try to avoid spending too much time in their torpor state, even during the night. Their reactions are slowed considerably, and they’re seriously at risk of predators during their rest.
There’s a reason down pillows and jackets are such warm, popular choices. Fluffing up some feathers and allowing air space to rest between them is an excellent method of insulation, and one that birds are clearly suited for. Particularly smaller birds like Robins can be seen puffing up their feathers throughout the season in an effort to keep the heat in.
Birds are fully capable of maintaining a small supply of fat to contain additional energy and insulate themselves against the cold. If food is available they’ll eat heavily, particularly any worms and other live feeds turned up by gardeners. They mainly gorge themselves during the autumn period in order to prepare for the months ahead.
While birds’ legs and feet are scaled to defend from heat loss, they attempt to protect themselves even further by tucking their extremities into their feathers. It’s not unusual to see a bird hiding its head under a wing, or standing on one leg to warm the second.
There’s no surprise in seeing large numbers of birds flocking together in trees and hedging to warm each other during the nights. Gardeners with housing features for their birds can often expect to see a far larger number of simultaneous visitors than normal during the winter season, if there are enough birds locally.