How to make a bird’s home a happy one
PUBLISHED: 12:47 19 February 2018
Planning to do your bit for National Nest Box Week? Experts
offer 9 tips to make sure you get the best nest boxes.
If you are planning to put up a nest box during National Nest Box Week
and beyond, the British Trust for Ornithology and the RSPB are warning
that, while some boxes provide a perfect breeding cavity for birds,
others are far from ideal.
You may be tempted to buy eye-catching brightly coloured nest boxes and
quirky types shaped like caravans, farmhouses, eggs and windmills, but
the RSPB warns that attractive and elaborate bird boxes aren’t
necessarily safe or effective for nesting birds.
So, what should we be going for? The BTO offers the following
1. Make sure it’s insulated
Only choose a box made from an insulating material such as wood or a
special waterproof wood/concrete compound like Woodcrete, used for the
National Nest Box Week ‘official’ box.
2. Avoid metal and ceramics
Don’t choose a box made from dense materials like metal or ceramics as
the interior can become too hot or too cold for chicks to survive. Nest
boxes with metal roofs retain too much heat and can have fatal effects
for baby birds on warm, sunny days. Metal and plastic nest boxes also
suffer from condensation causing baby birds to get damp and cold.
3. Choose a type with thick walls
To provide insulation and be durable, the walls of wooden boxes should
be at least 15mm thick. Wooden boxes can be safely treated on the
outside with a preservative provided it is non-toxic and water-based. A
box made from cedar, oak or beech will far outlive one made from
softwood such as pine.
4. Check the hole size
Choose a box with a 32mm entrance hole as this is the ideal size for all
small hole-nesting birds such as sparrows and tits. Choose a smaller
26mm hole only if you want to restrict the box to blue tits.
The box should not be too small inside as birds may lay fewer eggs in
smaller boxes. The internal floor area should at least 130 square cm (20
6. Avoid perches
Perches are not necessary and may even act as a foothold for squirrels
or weasels as they reach into the box to grab eggs and chicks.
7. Maintain easy access
A good box should provide easy access for human observers who wish to
record the contents and to clean out the disused nesting material at the
end of the season.
8. Place them strategically
The ideal height for a small-hole type nest box is between 1m and 5m
above the ground with a clear flight path. Care must be given to make
sure the box isn’t easily accessible to predators.
There are different kinds of nest boxes for different species of bird.
Cavity nesting birds like nest boxes with entrance holes, and the size
of hole will depend on the target species.
For example, blue tits prefer boxes with a small hole (25mm), Starlings
on the other hand would need slightly larger holes (45mm). Other birds
like open-fronted nest boxes, such as robin and spotted flycatchers.
Steer clear of brightly coloured nest boxes. The more inconspicuous they
are, the better. Make sure they are not made from flimsy materials as
many boxes fall apart when any weight is put inside.
Don’t let them be too shallow as young birds could leave prematurely by
falling out, and don’t let them be too deep as young birds may have
problems getting out when they are ready to leave.
National Nest Box Week, a joint project between the BTO and Jacobi Jayne
& Co, runs from February 14-21. For details visit www.bto.org.