Swift Facts

Swifts are amazing, beautiful birds. Supreme aerialists, they spend almost all their life in the air, a lot of that at low level, feeding on airborne insects, but we have personally seen them flying at about 9000 feet (about 2743 metres). If they need to they can fly twice that high; they have been observed migrating at 18,700 feet (5,700 metres) over Ladakh in the Himalayas. They feed, drink, mate and sleep on the wing, and only land to breed. So a young Swift will spend its first two or three years in constant flight before it nests. Because they never land on the ground, and are so fast and so totally aerial, Swifts are very hard to study. There's still an awful lot that we don't know about them, making them a real Mystery Bird. See this article for more information:

Swifts are in London for just three months each Summer, then they migrate to Central and Southern Africa to spend our Winter there.
While they are with us they fill our Summer evenings with aerobatic, amazingly fast flight, elfin screams, daring and drama.

Since Roman times, Swifts have nested here in man-made buildings. Originally cave, tree-hole and cliff nesters, they switched their nesting
to high man-made structures, under tiles, in the eaves, in lofts, spires and towers.

Fully protected by UK and EC laws (it is illegal to kill or harm them, to damage their nests or take their eggs) Swifts do no harm, make little or no mess. They eat flying insects such as aphids, flying ants, mosquitoes, hoverflies and small beetles, catching huge numbers every day. The parent birds also eat most of the chicks' droppings (possibly to recycle the mineral content); there are no great piles of droppings beneath their nests.

Swifts nest almost only in pre-1944 buildings. While 10% of homes built before 1919 can house Swifts, the figure for inter-war housing is 7%, and for post-1944 housing only 1.4%. Post-2000 it is probably nil. This is because the techniques and materials used in modern buildings deny Swifts access to breed, it's the same with refurbished or re-roofed older buildings.


Modern loft ventilation grilles create Swift-proof eaves on this new house in St Neots, Cambridgeshire. This estate will never host Swifts. Photos © E Mayer	An ancient timber house in Rye,Sussex, has its eaves netted to keep out birds. Why when Swifts have shared our roofs harmlessly for over 2000 years?

We are losing our Swifts fast! Between 1995 and 2016 we lost over half of all the Swifts breeding in the United Kingdom. Why? There are five obvious causes. Large sums of money have been given by the National Lottery to refurbish decaying historic buildings, quite often sites for nesting Swifts. More significant in terms of the numbers affected, since 1997 there has been a major refurbishment of social housing, a popular place for nesting Swifts. Demolition of old buildings is also a cause of nest site loss; the replacement buildings invariably exclude Swifts. On top of all that, it is now fashionable to convert old factories and warehouses into apartments and offices, and they too were often prime Swift nesting sites. These old buildings are always refubished or rebuilt to modern standards, with sealed roofs and walls, and no space left for harmless, beautiful and life-enhancing Swifts. Finally, insecticides. Most of the UK's arable land is sprayed with insecticides. Some crops such as oil-seed rape can be srpayed over 20 times per crop. Populations of insects are declining very fast as a result. Some research speaks of 80% losses in recent years, and Swifts eat flying insects. There appears to be no likely solution to that problem in even the long term future.


Dead Swifts - These birds have tried and failed to get back into their nest sites, after they were blocked off by scaffolding and building wrapping.	Stunned by repeated desperate attempts, they have fallen to the ground below, and on the left, drowned in a puddle, and on the right, been crushed by a vehicle. Photos © Jorge Sanz

Insecticides kill insects. The result is less food for insectivorous birds like Swifts, House Martins, Swallows, Warblers, Cuckoos, Wagtails and Spotted Flycatchers, and poisons released to linger on in the environment. Eliminating large numbers of insects will eventually affect the other creatures further up the food chain, fish, reptiles, amphibians, and mammals, and may even cause serious problems for humans too. Photo © E Mayer	Much of the UK's arable farm land is sprayed, often many times every growing season and now, even in winter too with insecticides, molluscides, fungicides and herbicides. The purpose is to eliminate crop pests, but the result is that wildlife exposed to these treatments may suffer directly or indirectly, either poisoned or finding its food resource gone. How long can we keep on doing this and still have any wildlife left at all? Photo courtesy of Wikipedia

As well as Swifts, many other birds are affected. The Swallow, House Martin, Sparrow and Starling have all suffered population crashes. They all rely on buildings for many of their nest places, they all rely on insects and other invertebrates for their food.

The last Government identified the profusion and richness of wild bird life as one of its "Quality of Life Indicators". Local authorities are asked to maintain and if possible enhance the biodiversity of their areas. The London Borough of Camden has identified the Swift as a "Flagship Species for the Built Environment", and is taking action to arrest its decline. You can ask your local authority to do the same.

The decline of Swift populations can be halted, even reversed. Local authorities in Amsterdam, Aylesbury, Basel, West Sussex and Zurich have taken action to maintain their populations of these dramatic birds. If they can do it, so can you!

Making a place for Swifts costs little. Swifts will use DIY or commercially available nest boxes, built in nest bricks and trays which can be installed into old or new buildings. This doesn't imperil the structure, preserves the birds from extinction, and contributes much to our environment and quality of life.

Architects, Local Authorities, Developers and Builders have a special responsibility to protect the natural world, and Swifts come high on the list of vulnerable species their work may endanger. Minor low-cost coordinated initiatives in design and building will ensure that Swifts still fly in our skies and in our children's skies too.