Native trees are most valuable for birds. Yew, hawthorn and holly provide safe nest sites from predators and provide berries. Cotoneaster horizontalis also provides berries and cover for invertebrates.
Ivy provides good nest sites. It feeds a variety of insects and birds feed on the berries as well.
Woodpiles make homes for wrens, robins, dunnocks, warblers as well as hedgehogs.
Nest boxes, ranging in size from blue tit to owl are easily available. The autumn is the best time to put them up but they can be put up as late as January when birds are starting to hunt for nest sites.
Where they are sited is important or they may remain uninhabited.
The type of box and its site, depends on the species the box is intended for.
Boxes for tits, sparrows and starling should be fixed two to three metres up a tree or wall. Unless there are trees or buildings which shade the box during the day, face the box between north and east, thus avoiding strong sun and wet, windy weather. Make sure the birds have a clear flight path to the nest box. Don’t place near feeding table, as the coming and going will disturb the birds.
House sparrows and starlings will use nestboxes placed high up and since these birds nest in loose colonies, two or three can be placed together. Keep them away from areas where house martins nest.
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 in a quiet place.
Fixing in place
Fixing to a tree with nails may damage the tree and so it is better to attach with wire around the trunk or branch. A piece of hose pipe over the chain or wire, will protect the tree. This fixing should be checked every two or three years as trees grow wider as well as taller.
Put boxes up in autumn as many birds start looking for a place to roost or feed in the autumn and then will re-use the site in spring. Tits will not start looking seriously until February or March.
The nests of most birds harbour fleas and other parasites. The boxes should be removed after the nesting season when the boxes are empty. Use boiling water to kill any remaining parasites and let the box dry completely before replacing. Do not use insecticides and flea powders. Do not breathe in the dust from the nest boxes while cleaning.
If there are unhatched eggs in the box they can only legally be removed between August and January and must be disposed of.
Place a small handful of clean hay or wood shavings (but not straw) in the box once it is completely dry and before replacing in its tree.
Making a nestbox
This information is from the RSPB Advice Page.
What you Need
Natural nest holes do not come in standard sizes, so use these dimensions only as a guide. Any plank or sheet of about 15mm thick weatherproof timber is suitable. However do not use CCA pressure treated timber, as the leachates may harm the birds.
Cut each section as per diagram below.
The diagram gives measurements for a small and a large box. Use only the left or right hand figures in any one box. For starlings and great spotted woodpeckers, use the dimensions for the larger box (left side), all the other species need the smaller one.
The bottom of the entrance hole must be at least 125mm from the floor. If it is less, young birds might fall out or be scooped out by a cat. The inside wall below the entrance hole should be rough to help the young birds to clamber up when it is time for them to leave.
Putting it Together
Drill drainage holes in the base of the box and use galvanised nails or screws to assemble. It is always best to leave the box untreated. As it weathers, it will blend into its surroundings better. Softwood boxes may be treated with a water-based preservative which is known to be safe for animals and birds, such as Sadolin. Apply it only to the outside of the box and not around the entrance hole. Make sure the box dries and airs thoroughly before putting up.
A woodpecker box should be filled with a block of balsa wood, rotting log or wood chips – woodpeckers like to excavate their own nesting cavities.
Do not nail down the lid, since you will need to clean out the box in the autumn. Attach the lid with a brass or a plastic hinge that will not rust, or hinge it with a strip of leather or rubber (an old piece of bicycle inner tube is suitable). Fasten it down with a good catch.
How big does the hole need to be
The entrance hole size depends on the species you hope to attract:
- 25mm for blue, coal and marsh tits
- 28mm for great tits, tree sparrows and pied flycatchers
- 32mm for house sparrows and nuthatches
- 45mm for starlings
- 50mm for great spotted woodpeckers
The small box with 100mm high open front may attract robins or pied wagtails. A wren will need 140mm high front panel, while spotted flycatchers prefer a low 60mm front to the box.
Never put a perch on the front of a box – the birds don’t need one and it encourages intruders.
Reproduced with permission of North West Parks Friends Forum