Birds of a feather sleep together

01 Dec 2010 | No. 2010-12-56

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 garden nest boxes to stay warm overnight – but how common is this behaviour? Householders can help to find out by taking part in the British Trust for Ornithology’s (BTO’s) Garden Sleepover.

An artificial nest site in a garden can
be watched as part of the survey

Nest boxes 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 Tits and Great Tits to-ing and fro-ing industriously to feed their young. However, these 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 urban areas ever-expanding and nest boxes in gardens becoming more numerous, the BTO needs the help of householders in order to find out more. Garden Sleepover participants will choose one evening this December to see if, and how many, birds use a nest box in their garden for a kip. Observations can be made using a nest box camera, by eye at dusk, or by counting bird droppings in the nest box in the afternoon before and the morning after the sleepover evening.

Some participants might observe spectacular goings on. The record number of Wrens seen roosting together in one box is 63, with each tiny individual a cosy component of the resultant feathery mass. Any artificial nest site in a garden can be watched as part of the survey, from traditional nest boxes to House Sparrow terraces, House Martin and Swallow nests or bespoke roosting pouches.

Dr Tim Harrison, BTO Garden BirdWatch, commented: “The BTO Garden Sleepover will identify which species roost in nest boxes 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.”

He added: “Factors that influence the use of nest boxes 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.”

Please go to: for more information and to take part in the survey.

Notes for Editors

  1. Results of the BTO Garden Sleepover: results will be shared on the BTO website –
  2. The BTO is the UK’s leading bird research organisation. Over thirty thousand birdwatchers contribute to the BTO’s surveys. They collect information that forms the basis of conservation action in the UK. The BTO maintains a staff of 100 at its offices in Norfolk and Stirling, who analyse and publicise the results of project work. The BTO’s investigations are funded by government, industry and conservation organisations.
  3. The BTO Garden BirdWatch is the only nationwide survey of garden birds to run weekly throughout the year, providing important information on how birds use gardens, and how this use changes over time. Currently, some 15,000 people take part in the project. The project is funded by participants’ contributions and is the largest year-round survey of garden birds in the world. For more information see

Contact information 

Tim Harrison (BTO Garden BirdWatch Development Officer)
Office: 01842 750050
Email: gbw [at]

Paul Stancliffe (BTO Press Officer)
Office: 01842 750050 (9am to 5.30pm)
Mobile: 07585 440910 (anytime)
Email: press [at]

Images are available for use alongside this News Release
Please contact images [at] quoting reference 2010-12-56

The BTO has an ISDN line available for radio interviews
Please contact us to book an interview
Office: 01842 750050 

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