How big does the hole need to be?
The entrance hole size depends on the species you hope to attract:
· 25 mm for blue, coal and marsh tits
· 28 mm for great tits, tree sparrows and pied flycatchers
· 32 mm for house sparrows and nuthatches
· 45 mm for starlings.
The small box (with 100 mm high open front) may attract robins or pied wagtails.
A wren would need a 140 mm high front panel, while spotted flycatchers prefer a low 60 mm front to the box.
You can purchase metal plates to protect the hole of the box from being damaged by predators such as wood peckers.
Choosing the location
Things to consider when choosing where to position your nest box include:
· Boxes for tits, sparrows or starlings should be fixed two to four metres up a tree or a wall.
· Unless there are trees or buildings which shade the box during the day, face the box between north and east, thus avoiding strong sunlight and the wettest winds.
· Make sure that the birds have a clear flight path to the nest without any clutter directly in front of the entrance. Tilt the box
forward slightly so that any driving rain will hit the roof and bounce clear.
· House sparrows and starlings will readily use nest-boxes placed high up under the eaves. Since these birds nest in loose colonies, two or three can be sited spaced out on the same side of the house. Keep these away from areas where house martins normally nest.
Two boxes close together may be occupied by the same species if they are at the edge of adjoining territories and there is plenty of natural food. While this readily happens in the countryside, it is rare in gardens, where you normally can only expect one nesting pair of any one species. The exceptions to this are house and tree sparrows and house martins, which are colonial nesters. By putting up different boxes, several species can be attracted.
Attaching your nest box
Before you put up your nest box, remember to keep in mind the following:
· Fixing your nest box with nails may damage the tree. It is better to attach it either with a nylon bolt or with wire around the trunk or branch. Use a piece of hose or section of car tyre around the wire to prevent damage to the tree. Remember that trees grow in girth as well as height, and check the fixing every two or three years.
· Open-fronted boxes for robins and wrens need to be low down, below 2m, well hidden in vegetation. Those for spotted flycatchers need to be 2-4m high, sheltered by vegetation but with a clear outlook. Woodpecker boxes need to be 3-5m high on a tree trunk with a clear flight path and away from disturbance.
· Nest boxes are best put up during the autumn. Many birds will enter nest-boxes during the autumn and winter, looking for a suitable place to roost or perhaps to feed. They often use the same boxes for nesting the following spring. Tits will not seriously investigate nesting sites until February or March.
Maintaining your box
· We recommend that old nests be removed in the autumn, from September onwards once the birds have stopped using the box.
· Use boiling water to kill any remaining parasites, and let the box dry out thoroughly before replacing the lid. Insecticides and flea powders must not be used.
· Unhatched eggs in the box can only be removed legally between September and January (August-January if you’re in Scotland) – and must then be disposed of. Take care to ensure the nest is no longer active as some species can nest right through September.
· If you place a small handful of clean hay or wood shavings (not straw) in the box once it is thoroughly dry after cleaning, small mammals may hibernate there, or birds may use it as a roost site.
· It is quite normal for a few eggs to fail to hatch, or for some young to die. Blue and great tits lay up to 14 eggs to allow for such losses. Cold weather and food shortage may lead to nest desertion, or to only the strongest young surviving. The death of one parent or interference from animals or humans may also cause desertion.