It is now the middle of April and the swifts will soon be back in our British skies with their daring, high-speed aerobatic stunts and screaming cry – the sound of summer. I love swifts – they are one of my favourite birds and I bet, once you read some of the amazing things about them, you’ll look at them with a new respect as well.
1. Swifts spend most of their lives airborne – their legs are very weak so they can hardly walk or grip. They eat, sleep and mate on the wing, only landing in order to nest and lay eggs. Young swifts start breeding at two to three years old, so between when they leave the nest and that time, they never land anywhere. Imagine that.*
2. They normally inhabit the skies at low levels due to feeding on the insects that are around. However at night you can watch them circling higher until they are out of sight, going up to around 10000 ft (3048 metres). However, they can go even higher as they have been seen migrating at over 18,700ft (5,700m) over Ladakh in the Himalayas.
3. We only get the swifts here for a few months in the summer. They usually arrive the end of April and leave end of July/beginning of August. During that time they breed and raise young. When they leave they migrate to central and south Africa as our winter is too cold for them (and there wouldn’t be enough insects).
4. They eat flying insects on the wing: mosquitoes, flying ants, aphids, beetles, hoverflies and small moths. When nesting they also eat the droppings of their young, possibly to recycle the mineral content of them). As for drinking, this is done by gliding over areas of smooth water and taking sips.
5. Swifts originally nested in caves and tree/cliff holes (some still do) but ever since Roman times they have become more and more dependent on man-made structures for their nest sites. You can find them in the eaves of houses, under tiles, and in spires and towers. New builds are much harder for them to get in to so they tend to prefer pre-1940s buildings that have not had their eaves sealed up. They return to the same nest site every year.
6. With older buildings being refurbished and new buildings replacing their old sites, their nesting places are disappearing. And when they lose places to breed, their numbers start to decline. It is estimated that between 1995 and 2011 we lost about a third of all the swifts nesting in Britain. A third! That is a big hit on their population.
7. Another probable cause for their decline is the use of pesticides. Most of the arable land in production in the UK is sprayed each year with an insecticide. Less insects/food equals fewer swifts (as well as fewer helpful insect species).
8. In level flight, a group of swifts is the fastest of all birds (peregrines reach greater speeds but only when in a stoop). The top speed recorded and verified for a swift’s flight was 69.3 mph (111.6 km/h). Therefore they don’t have many predators – even hobbies and kestrels only catch those that are sick or old. They do however suffer with parasites – ticks and mites, but these have evolved along with the swift and are completely different from species found on other birds.
9. When they sleep on the wing, only one half of their brain is asleep at any one time. The other half is still conscious and able to ensure that they do not drift with air currents as they sleep. This ability to orient themselves using the wind is thought to be unique although further studies need to be done on other bird species to assess whether this is true or not. Although unmated swifts will still sleep at height at night, breeding pairs actually sleep in the nest with their young.
10. On average a swift will live for around five and a half years, although a ringed specimen was recorded after its death at 16 years. Considering it had been ringed as an adult it is quite possible the swift was around 18 years old.
As mentioned above, swifts desperately need our help if their numbers are to bounce back to their old levels. One thing everyone can do is to provide a place for them to nest. If you already have old eaves or a place where swifts are seen going in and out, leave well alone – especially in the summer months. If you have to have, or already have uPVC soffits instead of eaves there are other things you can do such as cutting small holes in the plastic or, if you don’t want to do that, buy or make a swift box and fit them either to the soffit or an external wall. Swifts don’t cause any harm and rarely make any mess, so don’t worry about your house. If you see swifts where they are being endangered by building work, inform the RSPB Wildlife Crime Unit. Swifts are protected under UK law.
* If a swift ends up on the ground it will be trapped as it is unable to take off again under its own steam. If you ever find a grounded swift that does not have any obvious injuries or health problems, take it to an upstairs window or any other high place. Place it on the flat of your hand, head facing outwards and raise and lower your arm a few times so that it can feel the air under its wings. It should then launch itself back into the element it belongs in. If it won’t go or else ends up on the ground again, place it into a box and take it to your nearest animal hospital. Don’t try to care for it yourself as they are very tricky to rehabilitate and need specialist care.