Common swift: the bird profiles


I am particularly interested in garden wildlife which is why I did my Master's degree with a focus on "animal ecology". I am convinced that beneficial insects and wildlife are a sustainable and effective alternative to many of the products we use on our plants. I am also a passionate birdwatcher and rarely go for a walk without my binoculars.

Favourite fruit: kiwi, apple and redcurrant
Favourite vegetables: tomatoes and green beans

How do you tell the difference between swifts and swallows? What does the perfect nesting box for a common swift look like? What should you do if you find a swift? Find out in this article.

Three common swift birds in flight
Swifts are always on the move [Photo: Mircea Costina/]

The common swift (Apus apus) is a real aerobatic showman. The bird is built for flying and does practically nothing else. The swift spends its entire life in the air, with the exception of a brief breeding season. Even at night, the birds do not land to sleep, but let themselves be carried by the wind and merely fall into a kind of semi-sleep. During the breeding season, swifts are found foraging in many places in our country. The birds can be spotted flying at breakneck speed high in the air, above the surface of water or between buildings, hunting for flying insects. Read on to find out how to identify the swift by its song, how to support it in your garden and much more.

Common swift: key facts

SizeAround 16-17cm
WeightAround 40g
Breeding seasonMay-July
LifespanUp to 20 years
HabitatAnywhere with flying insects
Food preferencesAny kind of flying insect
ThreatsLoss of nesting places and food sources

How to identify the common swift

Swifts are rather plainly coloured birds. Their plumage is uniformly dark with the exception of a light throat patch that is barely visible in flight. Because swifts rarely land, the only way to identify them is by body shape and flight pattern. The birds usually hunt in groups and enjoy performing fast and dangerous-looking flight manoeuvres. They are easily identifiable by their forked swallowtail, uniformly dark plumage and long, narrow, sickle-shaped wings.

What is the difference between swifts and swallows?

Swifts and swallows are often lumped together but they are two quite different species. However, as these species like to hunt together it makes it tricky for us to tell them apart. Fortunately, swifts stand out clearly from our two most common swallow species with their uniformly dark underside. This is because both the house martin and the barn swallow have pale undersides. And, while swallows also have narrow, pointed wings, they pale in comparison to the swifts’ long, sickle-shaped wings.

House martin in flight with white underside
The house martin can be identified by its light-coloured underside [Photo: Dennis Jacobsen/]

What does the common swift’s call sound like?

In flight, the swift can be easily recognised not only by its shape but also by its call. Especially when hunting in larger groups, its voice can often be heard: “Sriii-sriii”. It does not, however, have a specific song.

How can you identify a baby swift?

Newly hatched swifts are an extremely rare sight, as the babies are raised in caves or crevices. It is hard to tell the difference between the young birds that are ready to fly and the adults. Their plumage is only lightly fringed, so does not look quite as dark as that of the parents. But even the young are only very rarely spotted sitting still, and in flight this subtle difference is difficult to make out.

How to identify common swift eggs

The swift’s eggs are slightly more elongated than a typical bird’s egg. Each season, female common swifts lay two to three matte white eggs. Their cavity nests are made of fine stalks and feathers that the parents catch in the air or scavenge in mid-flight. The rather loosely and haphazardly arranged nesting material is then glued together with fast-hardening saliva.

Common swift flying with nest material
Swifts also catch nesting material in flight [Photo: Dilomski/]

What does the common swift‘s habitat look like?

When it comes to choosing a habitat, common swifts mainly have their food supply in mind. An abundant supply of flying insects is essential. The swifts are not overly picky and hunt over fields and meadows as well as in villages and towns. They also prefer areas with large bodies of water over which the hunters can find plenty of insects even when it rains.

Where does the swift build its nest?

Originally, swifts were rock-breeders and nested in rock crevices. Later they came closer and closer to human settlements. Even today, most of them still nest in holes in building façades and wall crevices. However, these nesting sites are becoming increasingly scarce, as modern façades and renovated buildings usually no longer offer any space for the swifts. Occasionally, the swifts can also be observed nesting in tree hollows.

When do swifts breed?

The common swift starts breeding in May. The breeding period can last up to 27 days. This is the only time in their lives that the swifts spend mainly sitting. The partners take turns brooding and foraging the rest of the time. After hatching, the young birds are initially featherless, blind and entirely dependent on their parents. Over the next few weeks, they are fed vast quantities of flying insects. After about 40 days, they are mature enough to fly the nest. Then life in the air begins straight away, because after this point, they only sleep in flight, just like the adults.

Young swifts being fed by their parent
Baby swifts are fed lots of insects by their parents [Photo: Neil Bromhall/]

Where do common swifts go in winter?

Swifts stay in their breeding grounds for just over three months. Even the latest birds are already on their way south in August. The swifts fly to Africa and migrate along the Atlantic coast to their wintering grounds. And even after arriving, many swifts continue on, following the rainfall to meet their demand for insects. In spring, the swifts arrive back here between April and May.

How you can help support swifts

The swift population is slowly but surely declining. The renovation of old buildings in particular is causing their usual nesting sites to vanish. And the loss of insects is also causing problems for the hunters. Keep reading to find out how you can help the swift in your garden.

What do swifts eat?

Swifts are insectivores. They eat mosquitoes, moths, aphids and a variety of other flying insects. They are not fussy! When the food supply becomes scarce due to the weather, the swifts follow the rain over long distances and leave everything else behind. In such cases, young swifts can go up to 14 days without food by going into a kind of “starvation sleep” and greatly reducing their energy requirements.

common swift flying to find food
Swifts hunt for insects in flight [Photo: Drakuliren/]

What nesting boxes are suitable for swifts?

With the loss of nesting sites, swifts are increasingly dependent on artificial nesting aids. You too can provide a home for the swifts by installing a special nesting box. A swift box should be wider than it is tall, at least 28 centimetres wide and 17 centimetres deep, with a horizontal, oval entrance hole of 64 x 32 millimetres. Since swifts often breed in colonies, we recommend installing several boxes at once. Find more tips on the right wood, location and cleaning in our article on building your own nest box.

Tip: Alternatively, so-called stone nest cups or nest bowls are also suitable for swifts, which can be built directly into the wall of the house or into a wall.

What to do if you find a swift

If you find a young swift outside the nest, you need to check two things: What condition is the bird in? And how developed is it? If you find a nearly fully grown bird, wait and see if it flies away again on its own as perhaps it just needed to recover from a failed flight attempt. If, on the other hand, the bird is still very small or even featherless, try to locate the nest and gently put the young bird back. If you cannot find the nest or have found an injured or traumatised bird, contact the RSPB immediately. Raising a young bird is more complicated than you think and can go wrong very quickly for non-professionals.

When handling found swifts, watch out for possible swift louse flies. These are parasites that nest in the feathers of swifts and swallows. The little animals can also sting humans causing pain and itching, but are otherwise not harmful.

Picking up fallen young swift
Finding young birds is not always reason to panic [Photo: Nailia Schwarz/]

What else can you do to support the common swift?

As swifts only search for food in flight and they spend the winter in Africa, there is no need for the usual winter feeding. Nevertheless, it is possible to support the food supply of these artistic flyers. The idea here is: insect protection is bird protection. So, when shopping, pay attention to organic farming methods that protect insects. Also avoid insect-toxic sprays in your own garden and opt for sustainable alternatives. You can even go one step further by planting a beneficial insect meadow.

Other bird species also benefit from a bird-friendly garden. With a little patience, you will be able to observe a whole range of garden birds at home – for example the European serin or the tree sparrow.