Kestrel nest box

There are many factors to consider when choosing a bird of prey nestbox. Please read our advice carefully before purchasing.

Instructions For Installing Your RSPB Kestrel Box

Installation and health and safety considerations

Owners must choose a suitable site (please see the following section) and then plan how to install the box safely. Given the varying locations and methods for installation, the RSPB does not provide detailed instructions for installing the box. Some general principals to consider for each location include:

• Take account of the weight and bulk – how are you going to get the box safely up to the place that you have chosen?
• How will it be fixed in place – do you need to do any preparation first?
• Do you need others to help – e.g. holding ladders, passing tools and equipment, keeping others away.
• Do you need any protective clothing – e.g. the person below holding the ladder may be advised to wear a helmet!

Where to site your kestrel nest box

Kestrels are falcons that would choose a natural site on a cliff ledge, ledge on a building, disused stick nest or a tree hollow. Nest boxes should be installed at a height above 15ft in an isolated tree or edge of woodland or on the side of a building.

Although kestrels are more at home in a farmland environment, they can adapt to live in a variety of habitats and can be found in towns and cities if prey is available - in urban settings, successful birds hunt along railway cuttings and on brown-field sites. This hovering falcon is an adaptable bird of prey, feeding on a wide range of prey including small mammals, birds, insects and amphibians,

Siting advice

• Site the kestrel nest box on a suitable isolated tree or edge of woodland, on a building or similar ‘open aspect’ high point with clear flight path.
• The entrance should face East/NE/SE - away from the prevailing wind.
• The addition of branches or ledges within reach of the box will be beneficial as perches for fledglings.
• Ensure the front of the box is not obstructed and there is a clear flight path into the box.
• The height of the top fixing point should be a minimum height of 5m (15 ft)
• Fix the box at the top and bottom fixing points using a suitable strong fixing. Ensure the fixing is tightened securely to avoid the box moving, but make allowance for the natural bend in the tree trunk and do not over-tighten against the bend, as this may result in damage to the box fixing plate. If necessary, brace the box using additional fixings to ensure that it is firmly fixed.
• Avoid siting the box above water-filled ditches, which may present a hazard to chicks if they were to fall from the box.
• The risk to kestrels from roads or motorways is less than it is to low-flying owls so it is acceptable to site boxes near these places, which may offer useful hunting habitats
• There is no need to add nest material to the box.

Signs of Occupancy & Monitoring

Kestrels will sometimes use nest boxes as shelter during the winter months. The breeding season is from April onwards and once a box is claimed as a nest site kestrels will be regularly seen sat on the ledge/perch and in the near area around the box. They may also be seen mating in the vicinity. 

Following this an adult may be seen bringing prey into the box through the day - this is likely to be the male bringing food to the female as she incubates the eggs. Once the eggs have hatched and the chicks develop both adults will be seen bringing food in to the growing family - the fledglings will eventually be seen sat in the box opening and on nearby perches.

In some situations other birds of prey may use a kestrel box, such as little owls, tawny owls and (rarely) barn owls.

Maintenance 

To avoid flushing a kestrel on eggs or with newly hatched young it is important that you follow these guidelines when considering any maintenance to your kestrel nest box:

• Annual inspection is recommended to ensure box is clean, secure and ready for the new season.
• Inspections should be preferably carried out in the autumn/winter (Sept - Feb)
• It is best to inspect boxes during dry calm weather to avoid flushing a bird into rainy or windy weather. If there are visible signs that a kestrel is in the box, monitor it from a distance as it may not be appropriate to disturb the bird.
• Boxes that have been inhabited by grey squirrels or jackdaws may be filled with twigs or leaves - this should be cleared out (please ensure that any birds’ nests are not in use).
• It is advisable to wear a dust mask and heavy duty gardening type gloves when clearing out boxes.
• Any bird or squirrel disturbed in a box will probably exit rapidly - be aware of the risks of this when at the top of a ladder.
• RSPB boxes are treated with an eco-friendly water based preservative where required - if re-coating ensure that the preservative is also an environmentally friendly water-based product.

Camera clip supplied.