As the winter nights draw in, it is not only humans that want to be tucked up in bed. Many familiar birds huddle together in nestboxes to stay warm overnight — but how common is this behaviour? Householders can help to find out by taking part in the BTO's Garden Sleepover.
Nestboxes are a common feature of UK gardens, with some 4.7 million provided nationally. During the spring and summer these are a hive of activity, with species such as Blue Tit and Great Tit to-ing and fro-ing industriously to feed their young. However, these same boxes might also play an important role during winter by providing safe, warm places for birds to escape the long, cold nights.
Little is known about this behaviour and, with increasing urbanisation and nestboxes in gardens becoming more numerous, the BTO needs the help of householders to find out more. Garden Sleepover participants will choose one evening this December to see if, and how many, birds use a nestbox in their garden. Observations can be made using a nestbox camera, by watching at dusk, or by counting bird droppings in the nestbox in the afternoon before and the morning after the sleepover evening.
It is hoped that some participants will also observe spectacular goings-on — the record number of Wrens seen roosting together in one box is 63. Any artificial nest site in a garden can be watched as part of the survey, from traditional nestboxes to House Sparrow terraces, House Martin and Swallow nests or bespoke roosting pouches.
Dr Tim Harrison of the BTO Garden BirdWatch team commented: "The BTO Garden Sleepover will identify which species roost in nestboxes most frequently and the number of individuals that will scrum down together overnight. Are Wrens more sociable than Blue Tits? Will the larger Great Tit rule the roost? These questions can only be answered with the help of householders. Factors that influence the use of nestboxes by roosting birds will also be examined. Currently, there are many unknowns: does night-time temperature affect roosting behaviour? Are there regional differences in roosting behaviour across the UK? These exciting possibilities will be explored through this citizen science survey."
For more information, and to take part in the survey, visit www.bto.org/gbw.