Tomorrow – Friday 22 December – is the shortest day of the year. Where I live in Somerset there are roughly eight hours between sunrise and sunset; but on the Shetland island of Unst, just six degrees below the Arctic Circle, there are less than seven hours of daylight.
For small birds, which need to eat between one-quarter and one-third of their body weight each day, the short daylight hours mean it is a race against time to get enough food to maintain their body weight during the 16 hours or more when they are unable to feed. That’s why our national pastime of feeding garden birds is so essential for their survival.
Finding enough food isn’t the only issue facing small birds: the weather conditions at this time of year are also important. If we experience a cold snap – especially one that lasts more than a few days, with heavy snow – then they need to stay warm at night.
Birds such as long-tailed tits huddle close to one another and fluff up their feathers to retain as much warmth as possible. But even larger species such as starlings gather on winter evenings, before going to roost. One theory is that birds that are struggling to find food look out for healthier, fatter ones and follow them the next morning, as they know where the best food sources are to be found.
