The following information is provided by Schwegler: The Kestrel is a very adaptable species. As a synanthropic bird, i.e. living in a habitat made or altered by humans, it has settled successfully in the human environment.

Based on our Kestrel nest Box no. 28, which has been used very successfully for more than 25 years, a modern version has been developed especially for use on buildings.

Apart from the ornithological needs of the animals, attention was paid to proper, technically perfect attachment to the building.

Thanks to the curved shape and light-grey colour, the nesting aid does not constitute a visual foreign body on the building but instead integrates harmoniously on the structure.

Thank to the large entrance, the Kestrel Box 2TF can be cleaned and inspected conveniently from time to time or if necessary.
To accelerate settlement by Kestrels, we recommend placing a mixture of moist, coarse sawdust, wood shavings and washed sand in the nest Box. Scroll down for more images.
 

Installation:

At least 6 - 8m (18'-24') installation height, on the external walls of buildings, walls, chimneys, industrial plants. 
A mounting surface at least 30 cm (12") wide is required.

Distance between the nest boxes at least 400 m (1200') (depending on the feed available).

This nestbox measures: 18" Wide, 14" Tall and 16" Deep.      

Material: Weather-resistant SCHWEGLER wood-concrete, stainless steel X-bracket

Information from the manufacturer in Germany:Schwegler Website 

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