By Bob Hume
Illustrations by Mike Langman

Swifts are remarkable, even sensational, creatures. Unable to walk or perch properly, they are among the most aerial of all birds. They catch their food in the air, find their nest material in the air, even sleep in the air. But, for all their abilities, are they facing trouble in the future? Rob Hume investigates.

Swifts eat insects caught in the air. Their beaks are extremely short, but very wide, and the big gape helps them catch small insects in the mouth. It is like living on beans and peanuts, eating every meal by tossing them in the air and catching them in your mouth as you run along. Clouds of midges or aphids blown high up by the wind are ideal for swifts but, in good weather, they take the largest food they can comfortably swallow. They eat larger moths if they are abundant and eat stingless drone bees and many hoverflies (but somehow, mysteriously, avoid wasps and bees with stings).

Swifts have no crop (the elastic pouch in the lower throat of most birds) but collect food for their you in the mouth, in large b alls containing hundreds or thousands of insects. To help bind food together in the mouth, they have large salivary glands, which enlarge even more in spring when they use saliva to help stick nest material together.

Swift families need prodigious numbers of insects. One study calculated that 3,000 pairs of swifts in Gibraltar, plus their young, required 18 million insects every day. In an aphid plague in Oxford, one food ball alone contained 726 aphids, 48 leafhoppers, 22 spittle bugs, 23 crane flies, 18 dung flies, 13 ladybirds, 120 ants and various other insects. Even spiders can be eaten in large numbers as they descend from trees or sail across the skies leaving trails of silk thread on a summer's day.

Swifts are in the UK from the end of April until early September, but most arrive in May and leave in August. They are emblematic birds of the high summer, living high in the air or screeching around the rooftops. They normally forage within a few miles of the nest, but, if the weather turns bad, they simply fly away as far as necessary to avoid it, or gather in frenzied feeding flocks low down over lakes and reservoirs.

Jim Flegg, in his new book Time to Fly, tells of radar studies that showed swifts gathering over London and moving off beyond the coasts of Lincolnshire and Norfolk, to feed on vast numbers of insects along a cold front across the North Sea. After feeding to the full, the swifts returned to their London nests or to fly all night high over the capital.

How do swifts know, or sense, the presence of insects (or the right weather conditions) so far away? Are they the best meteorologists around?

If bad weather threatens, swifts appear to head into the wind, to cut through the shortest route to reach fine weather where they can feed. They can travel as far as 600 miles each way to do this, sometimes being away for several days. Young swifts, meanwhile, survive the absence of their parents, faling in to a kind of semi-hibernation, with slower heart and breathing rates and reduced body temperature.

Swifts live for 10 to 15 years or more. They migrate to and from Africa, via France and Spain, spending our winter around the Congo, Zimbabwe and Mozambique. Migration is just a continuation of their aerial lifestyle.

Young swifts are never fed by their parents once they leave the nest (their lives depend on being expert from the moment they see the world outside). They migrate to Africa and may not breed for three or four years, many probably not landing during that time, while others visit nest sites, but do not breed.

When they nest, they simply zoom in to the nest hole and disappear, although it may take several attempts before they succeed.

Swifts fly in groups, screaming together, in summer: you might detect a 'duet' between males and females calling at slightly different pitches. They call as they approach holes, apparently to find out whether another swift is already at home. Pairs are more faithful than in most birds, usually re-forming each spring for life. The female lays two or three eggs (rarely one or four), which hatch after three weeks. The chicks fly after about six weeks, but this may be as long as eight weeks in poor weather.

So what threatens swifts?

Swifts nest in buildings: only a handful in the UK may still nest in holes in cliffs. Years ago I saw swifts, well known for nesting in crevices in limestone cliffs, entering such holes on the Gower in South Wales. Many nest in pre-war housing or in large old buildings, sometimes churches, but they occasionally use houses built in the 1960s or later.

In most towns and villages, there are obvious streets that have swifts, while most do not. They like spaces under the eaves and roof tiles, or holes in walls. Pairs investigate likely holes close to a colony, but are reluctant to explore farther away, so encouraging a new group is difficult.

Most house renovation, demolition and rebuilding is carried on with no thought for swifts. Unless local authorities and conservationists become more concerned, the current decline is swift numbers is likely to accelerate. For information on saving nest sites and creating new ones, visit www.concernforswifts.com

The conservation group, Concern for Swifts, rightly points out that nothing will happen unless someone does something. In Sandy, not far from the RSPB's UK headquarters, swifts have bred in the roof of a town centre pub for years but, in November 2004, the roof was being repaired. Most of us bemoaned the fate of the swifts, but Peter Newbery, responsible for the RSPB's swift conservation action, did better. He met the builders and told them about the swifts. Fortunately the site manager has swifts in his own roof, so was sympathetic. They made sure the repairs would not affect the entrance holes and the site manager informed the pub owners, Charles Wells. The repairs went ahead but swifts will still be able to enter the roof.

Concern for Swifts says that the most important thing for swift nest sites is to leave them alone, if they are damaged, however, you can make new holes to maintain access, make new nest sites inside roofs or, as a last resort, use external nest boxes.

Boxes can be bought from RSPB shops (telephone 01767 680541 for details) or from dealers such as Jacobi Jayne, which sell boxes made of compressed fibre and concrete. Internal dimensions are 150 mm high, 340 mm wide and 150 mm from front to back, slung beneath the eaves, with an entrance hole 50 mm by 50 mm at one end of the front panel.

Getting swifts to take an interest in your box can be difficult unless they have already nested close by. You can use a special CD of swift calls to attract them, if you are prepared to play it loudly from a speaker in or beside the box all summer. Jacobi Jayne sells such a disk at £24.95 but you may be able to get it more cheaply form Europe - see for example www.ample.de/swift

Nest boxes should only be attached to buildings, at a height of at least three, preferably six, metres. No trees should obstruct the flight path. The best time to play the response calls is between the beginning of May and the beginning of June, especially early morning and in the evening.

What can you and the RSPB do to help swifts?

We are in the early stages of raising the profile of the problems facing swifts and what can be done to help them. In a pilot project, residents in St Neots, Cambridgeshire, have been asked to count swifts and identify buildings with nesting colonies. The local planners will be asked to make sure that these nesting sites are protected during any repair of renovation work. We hope this can soon be extended to villages, towns and cities across the UK. We need local volunteers (local groups, bird clubs, individuals) to count swifts, initially as a baseline, with repeat counts to assess changes in numbers over time. It is essential that buildings with breeding swifts are recorded, so efforts should be made to combine these counts with the identification of buildings occupied by nesting colonies.

Local planning authorities should be made aware of the buildings identified as nesting sites. Try to get an agreement that, if repair or redevelopment proposals come in, provision is made for continued occupancy by swifts. Local RSPB staff can advise developers and owners of the best ways of achieving this.

Solutions for breeding swifts are fairly straightforward and cheap. The best and simplest solution is to leave well alone. If possible, leave the entrance hole and roof space open when repairs are carried out.

If the existing entrance needs to be closed, create a new access point to the roof close by.

If the roof space needs to be changed, create new nest ledges in a suitable part of the roof.

Install specially-designed swift nest boxes into the wall immediately under the eaves. These are rectangular and can be cemented into courses of bricks - they are available from a number of suppliers at around £30-40.

Make contact with the major building companies and promote the idea of incorporating swift bricks into new housing or industrial developments. Attracting swifts to new sites may require the use of tape/CD-lures.

Although protecting existing colonies is the top priority. The increase in new housing across the country presents a fantastic opportunity to create new nest sites on a enormous scale. Nest boxes can be incorporated at minimal cost, and provide a permanent feature, with no problems for the home owner.

If you can help swifts, that would be wonderful. Meanwhile, enjoy them while you can: they will be gone again by late August.

SWIFT

Not closely related to swallows and martins. Long, stiff, scythe-shaped wings.

Does not pearch on wires, twigs or roofs.

Flies fast in tight flfocks with loud, screaming calls. Feeding flight m uch slower with irregular wingbeats, stalls and twists, often high up. Accelerates with deeper, stiff beats, wings swept back.

All dark brown-black, except for whitish throat (juvenile has fine white feather fringes).

Shoots in to nest holes under eaves, in old towers etc without pausing, but may need several attempts before succeeding.

SWALLOW

Often perches on wires or bare, exposed branches.

Flies with wings angeld back, more flexible than swift; feeds low over ground with rolling, swooping, flowing action, slightly 'rowing' wing movement; the most elegant of the group.

Dark, blossy blue above, creamy to pale orange-buff beneath; dark chin and throat.

Tail has long fork and a row of white spots shows when it is spread.

Liquid, trilling and twittering calls, song includes fast trill.

Nests on beam or ledge in open shed, barn or other building.

HOUSE MARTIN

Often perches on wires and roofs, gaathers mud from the ground.

Nest is rounded 'pot' of mud, with entrance at the top, stuck to eaves of buildings.

Blackish above with broad white band above tail; w;hite below without dark throat.

Flies with fluttery, backwards-flick action of stiff, triangular, broad-based wings. Feeds relatively high up in fine weather, above houses, not low to the ground. Dry, hard twittering call and song.

SAND MARTIN

Smallest martin; mid-brown above, white below except for brown band across chest.

Flight fluttery, wings flicked backwards into arrow-shape, almost closed between beats. Usually low often twisting and banking over water. Quiet, twittering calls.

Nests in tunnel dug into bank of earth of soft sandstone, usually in colonies, from a handful to 100 or more holes.

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