For the country dweller, the summer might bring the hypnotic call of the cuckoo or the song of the skylark tumbling down from the open blue sky. In Oxford it is the skirling cries of flocks of swifts that are a sure sign of summer. Their dark shapes flicker overhead at terrific speeds like the jet fighters of the bird world. They seem never to land: in fact, they never do.

A swift on the ground is in trouble; their wings are much longer than their short bodies so they need a launch pad to take off. I still remember seeing one shuffling helplessly in my school playground and throwing it up to release it back into its natural element.

Swifts are one of our shortest staying migrants. They arrive from North Africa in late April and have usually left by the end of August, although it is much easier to remember the first sighting than to be aware of their absence. Oxford offers a good environment as the broad meadows on the river floodplain are full of insects and some of this bounty provides food for the birds above. Swifts can be seen in headlong pursuit of airborne food across the tops of the waving grasses.

Swifts originally nested in crevices on cliffs or old trees. A new opportunity arose once humans began to construct buildings taller than about five metres.

Many of our buildings are sufficiently old to offer gaps into attic spaces and beneath roof tiles where they can raise a family.

The most famous swift colony in the world is in the University Natural History Museum in Oxford where they use specially-shaped tiles to enter the pointed tower above the main entrance.

Much of our knowledge of these creatures comes from a study published as ‘Swifts in a Tower’ in 1956 by David Lack, a researcher. The nesting birds are still studied and can be seen on a CCTV screen in the museum.

In the conservation world we are concerned about falling numbers of swifts in this country.

Modern building techniques and renovations steadily reduce the available nesting spaces. By simply building in these opportunities or by adding nesting boxes to existing buildings, swift numbers could recover and their future as a welcome presence in towns and cities may be assured. Special blocks are made which can be incorporated to provide nesting spaces.

Swift nest boxes are rather different to the usual blue tit box. They have much more floor space and can have the oval entrance on the front or even underneath as the birds will fly up into them. These large boxes should be grouped as swifts like to nest communally Last year I built four boxes, each with two compartments, and arranged for them to be attached to our local primary school in Hertford Street which is a tall Victorian brick building that often has swifts whipping around it. The boxes are grouped high on a north-east-facing wall to avoid getting too hot on sunny days.

There has been no immediate interest from the birds. Swifts are very faithful, both to each other as a pair and to their regular nest site.

Next year I am going to try attracting potential tenants by rigging up a speaker attached to a CD player with a recording of swift calls.

This technique has worked elsewhere and I hope that the children in the playground will one day be able to watch swifts careering over their heads, charging with pinpoint accuracy into the entrance holes.

If only a handful of them are fascinated by the sight it will have been doubly worth the effort.

  • To join your local Wildlife Trust, find out about nature reserves near you and wildlife events and activities this autumn please visit www.bbowt.org.uk or tel. 01865 775476.
  • To find out more about swifts, which have shared our buildings ever since the Romans came to Britain, why they matter, and how you can help them survive and thrive, visit the Swift Conservation website at www.swiftconservation.org.uk