Building a Kestrel nestbox
Kestrels do not construct nests of their own, but lay their eggs either in the old nests of crows, or in cavities in trees, or ledges on cliffs and buildings.
A nestbox of the following design is best sited about 20 feet high on a solitary tree in farmland, using a stout batten, firmly screwed to the box, attached directly to the trunk by means of galvanized nails, 4 inches or longer. The entrance should face east, and the box tilted back slightly to keep the eggs and young to the rear.
It may be possible to wire the box to a branch, or to use a horizontal batten and wedge it into the fork of two branches. If there is dense foliage, prune away a few branches to give a clear flight-path to the box.
The nestbox should be constructed from 0.75 inch thick timber or resin-bonded exterior ply, and the dimensions below will produce a box of minimum acceptable size:
- 2 sides :- 12 x 20 inches
- 1 floor :- 12 x 21.5 inches
- 1 roof :- 12 x 26 inches
- 1 back :- 12 x 12 inches
- 1 front :- 12 x 4.5 inches
Thicker timber can be used, but adjust the sizes to give the same internal dimensions.
The box is assembled using waterproof glue and 2 inch screws or galvanized nails. The fixing batten should be about 28 inches long, or 4 x 1 inch timber.
A small branch about 1 inch diameter should be fixed at the front as a perch, since both young and adult Kestrels spend a large amount of time perching at the nest entrance.
About a dozen drainage holes should be drilled in the floor, about 0.25 ich diameter, and a layer of wood shavings or straw scattered over the floor.
This is a heavy nestbox and will require at least two people to erect it, using ropes and a ladder.