Natural nest sites are disappearing
Many of the natural nesting places for our favourite garden birds are disappearing every year as holes in houses are filled and woods and hedges are trimmed and cleared. By putting up a nest box in your garden, you can not only help the valuable conservation work of the BTO but also get pleasure from seeing wild birds set up home.
Gardens are an important wildlife habitat
Gardens are fast becoming important habitat for wildlife in modern Britain. Gardens account for a vast area of green space in Britain - it is estimated 20% of London's area is garden. Whilst gardens offer excellent feeding areas for birds, they do not always naturally provide good or safe nesting sites. The addition of one or two well-positioned bird boxes can make even a small urban garden a haven for birds.
Choosing the right bird box
First you need to choose a bird box. Bird boxes are essentially are a box with a hole, but the entrance hole can dictate which bird species will use it. Have a look at which birds visit your garden and choose a design suitable for such species - consult an identification guide if you're not sure you can tell a blue tit from a starling! 25mm holes are good for smaller tits such as blue, coal and marsh tits. 32mm holes are better for encouraging larger tits, nuthatches and sparrows. Some birds such as robins, wrens and pied wagtails prefer an open-fronted box. Wooden boxes are an economical option that can be stained (using wildlife-safe preservative) to fit in with your garden décor. Alternatively you can have a go at making your own wooden bird boxes - BTO provides instructions for boxes with entrance holes or open-fronted designs. Woodcrete boxes, though more expensive, are extremely durable and have excellent occupation rates. To find out more see Schwegler nest boxes article.
Putting up your nest box
It is recommended to put up boxes outside of breeding seasons; generally August to February is best. Site nest boxes so that they are sheltered from the wind, rain and strong sunlight. If they are in full sun, the chicks could overheat and die. Boxes should be positioned 1.5 to 5m above ground to mimic natural nesting sites. This will also provide protection from predators such as cats - especially important for open-fronted boxes. It's important that the chicks have somewhere to perch when they first leave the nest, so put the box near some smaller branches that won't hold the weight of larger predators, but will support fledglings. Avoid putting up boxes in busy areas of the garden, such as near a bird table or feeders. Robins and wrens in particular look for nesting sites in good cover. You don't need to place nesting material in a new box; birds will do this for themselves. You can put out pet or human hair in spring for them to collect, or but do not provide man-made fibres or knitting wool as that can be dangerous to birds.
Nest box aftercare
Bird boxes should be cleaned out in the autumn when there's no risk of disturbing the occupants as diseases and parasites can easily spread to new occupants. Clean the box out with boiling water or buy specialised cleaning products. Your box might not be used in the first year, as birds often choose a nesting site during the autumn, winter or early spring. Persevere - leaving your box up in winter may provide a useful roost in bad weather. If you find unhatched eggs in the box you can only legally remove them between October and January and they must then be destroyed (Wildlife and Countryside Act 1981).
