Model Number: NESTCONC
We are now offering nest concaves made from recycled polyurethane car interiors as an additional item for improving our swift boxes.
A nest concave is not essential and of course in natural nests swifts do not have them. However as Dick Newell explains in this blog post they can help to increase the chances of swifts breeding in the first season, and they can also improve the breeding success of nesting pairs by reducing accidental losses caused by eggs being moved into cold corners by the parents.
You can also make your own concave from papier mache, polyfilla or plaster of paris, and as Dick suggests, sticking some feathers on is a great way to involve children in a swift nest box project.
The concave in the block is 15mm deep x 85mm diameter.