Valentine’s Day sees the start of the BTO National nest box week. Now’s the time to put up nest boxes in time for the start of the bird nesting season.
The Countryside Restoration Trust is encouraging landowners and farmers to put up bird boxes to encourage farmland birds. Nesting sites have declined over recent years because of agricultural intensification and development old farm buildings, and by putting up a box you are providing an ideal breeding site for common and vulnerable species of farmland bird. Even if you think you may have suitable sites on your land a few boxes could enhance the site by attracting additional farmland bird species.
The CRT has many bird monitoring projects underway on its farm properties and these include nest box schemes for birds such as Common Redstart and Barn Owl, but also to assess the breeding success of common species from year to year.
You can get your bird box by building one yourself, or buying one of a suitable design.
Buying a nest box
There are a range of boxes on the market some of which will not provide a suitable nesting site for birds. Here are a few points to consider:
- The box should be well insulated and made from suitable material such as wood or WoodcretePLUSTM. The walls should be at least 15 mm thick. Only non-toxic wood preservative should be used on the outside of the box.
- An entrance hole of 32mm is recommended to allow entry to small hole-nesting birds such as tits. If it is a wooden box a metal plate may be needed around the hole of the box to prevent woodpeckers from enlarging the hole.
- Boxes should be easily accessed for cleaning and maintenance after the breeding season has finished (and monitoring purposes).
- Boxes should not be too small; the internal floor area should be 130cm2, to allow enough room for a large clutch of eggs. Small holes or side slits should be present in the base of the box to allow drainage.
- Ensure the outside of the box does not have any footholds for squirrels and woodpeckers to reach in through the hole. The deeper the box the better as this will make it difficult for predators to reach the nest.
Where to site a bird box
- Ideally the box should be one to three metres from the ground on the trunk of a tree. The bird should have easy access into the entrance hole and not be inhibited by vegetation, where predators can also perch.
- The box entrance should be sheltered from the weather including strong sunlight.
- If erecting more than one box, do not place them close together because birds establish territories around their nesting sites.
- Ensure that cats cannot access to the box, i.e. via a fence or other platform.
- Use galvanised nails to attach the box to the tree.
- Do not erect bird boxes close to feeding sites because nesting birds will not want other birds entering their territory.
- Boxes can be put up any time of the year, but it is best to do so in the winter or early spring. Birds start to pair up to nest in February, and some birds; like blue tits, use nest boxes as roosting sites throughout the winter months.
- Ensure that the box is sited so that it is visible to passing birds so that they can come and investigate it.
Details of bird box templates can be found on the BTO website.
You may also wish to consider erecting boxes for other species of birds such as the Swift and the House Martin. The CRT farm at Pierrepoint had swift boxes erected into the new dairy building, and we are due to install swift and house martin boxes under the eaves of the new education centre at Turnastone Court Farm. The CRT also has successful barn owl box schemes on several of its farm properties.
Monitoring Officer (Herefordshire)