Update 28th July 2012
We have usually assumed that Swifts prefer larger spaces to smaller spaces. However, some recent experiences seem to indicate that smaller boxes may be OK.
Our installation of air brick liners in the old factory site in Brook Street St Neots gave us 12 nest places with a floor area of 200 x 175mm and a height of 100mm. At least two pairs of Swifts took up residence, and one may have produced a chick.
We recently examined the contents of the nest-boxes in St Mary's Ely. We compared two basic sizes of box:
- 16 narrow boxes are 100mm x 300mm (a few widened to about 125mm)
- 80 wide boxes are 200mm x 400mm (most of these only recently installed).
In the narrow boxes we found 9 boxes containing 15 chicks = 1.67 chicks per box
In the wide boxes we found 9 boxes with 14 chicks = 1.75 chicks per box
The narrow boxes have been installed for a longer period than the wide ones which is why occupancy rates are different. Now, we do not know how many other boxes had failed; another uncertainly is that the narrow boxes have entrances in the floor, whereas the wide boxes have entrances in the side, but it seems that swifts are as productive in narrow boxes as wide ones.
Of course, we need to collect more data, but perhaps we need to be a little more open minded about small and narrow boxes.
Posted by Dick Newell:
Swifts can, apparently, nest in anything from a House Martin's nest to a whole roof space though the success rate in the former may be questionable. They nest in holes in trees in Scotland and in northern Europe in what must be quite confined spaces. Examples of successful commercial nest boxes have internal dimensions like 140mm x 300mm floor area, height 140mm. Erich Kaiser's very successful colony in Kronberg, Germany, has large nest-boxes about half the size of a tea-chest.
