Thursday 17 March 2011

Swift Nest Boxes in Church Belfries

Update: the text of this was updated in October 2012 and again in March 2018

Contributed by Dick Newell

St Mary the Virgin, St Neots
It is becoming a popular idea to place nest-boxes behind the louvres in church belfries. Many churches have lost their Swifts under the eaves as a result of roof renovations, so it is a good idea to try to get them back.

The pre-requisites for embarking on a project like this are a team with energy, enthusiasm and stamina, mains power near the belfry, as well as a sympathetic vicar, bell captain, church wardens and parochial church council. In making your case, you can say that Swifts are declining at 3-4% per annum, they are amber listed 'Endangered' and they make a fantastic show in the summer screaming around the church tower and, unlike some species that nest in buildings, they make little or no mess. It should be regarded as a 2 or 3 year project - and that is just to get the Swifts started. You can read elsewhere on this blog about CD playing, concave nest platforms and ideal nest-box sizes.

A common question is whether Swifts are negatively affected by the sound of church bells. As far as we know, the answer is no. There are many examples of Swifts nesting successfully within a few feet of bells that are regularly rung. In Haddenham Church, a Tawny Owl nested successfully, for several years, within a few feet of the bells.

Our experience has been with making tailor-made box-shaped cabinets, containing multiple nest chambers. Typically, the nest chambers are ~350mm long by ~200mm wide with a height determined by the spacing between the louvres. The entrance should be 65-75mm wide x 30 28mm positioned near the floor of the nest chamber and towards one end. Entrances can be anywhere in the gaps between louvres.

Boxes destined for St Mary's Ely
In larger cabinets, with many entrances, it may be a good idea to 'randomize' the position of the entrances at the left and right hand ends of the box. A Swift needs to be able to easily recognise an entrance the second and subsequent times that it looks for it. It is also necessary to treat the front of the box with wood preservative/sealant, using a dark colour so that the boxes appear invisible behind the louvres.
Boxes installed in St Mary's, Ely
[Update 2014 - at least 30 boxes occupied by Swifts]
[Update 2016 - estimated 55 boxes occupied]

Many louvres are covered with anti-bird netting. You can either replace the whole area of the netting with the front of the box, but it is often easier to make a hole in the netting, larger than the entrance in the box, by cutting the sides and the top of a rectangle with wire cutters, then bend the wire inwards and downwards.

Louvres are typically supported in a wooden frame, with two substantial vertical side members. The width of the box can overlap these members, so that, with the back off, the box can be screwed securely to them. But first ensure that the louvres and frame themselves are secure.

It is prudent to start with a modest installation of boxes to see if you can get the Swifts started, then follow up with a more ambitious installation in later years.

Swifts seem to have a tendency to go for the top and bottom louvres, so boxes behind the top two or bottom 2 louvre openings, say, is a sensible way to start.

12 boxes installed in St Mary the Virgin, St Neots.
Here, the tops of the louvres were out of reach
[Update 2014 - 9 boxes were occupied by Swifts]
The direction in which the louvres face is not an issue, as, even on a south facing aspect, the boxes are unlikely to get overheated

Access for maintenance can either be carried out after the end of the breeding season by removing the whole back, or simple access doors, secured by a single bolt through the top can be built which can be rotated to open. Disturbance earlier in the season will likely cause the birds to desert.

This has summarised much of our experience, and Swifts certainly take to this arrangement of boxes. However, there are other successful arrangements, including boxes placed behind one louvre spacing, with a bottom entrance accessed through the louvre spacing below.

For examples of details of church projects and other stuff about Swifts and churches see here

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