Part 2: Nest Boxes and the Attraction of Swifts
Swifts are amazing!
In Awe of Swifts
We’ve been in awe of swifts ever since living in Lewes opposite St Anne’s Church, and sitting there in the garden on a summer evening watching the screaming party of about 10 birds come roaring over head.
From our top bedroom at the front of the house we could occasionally see an adult swift disappearing under the roof tiles on the tower … a true sign that summer was with us.
Reading “Devil Birds – The Life of the Swift” by Derek Bromhall, increased our wonder of these amazing creatures.
When we moved to Hastings swifts were less evident in our area. We had to go to Combe Valley reserve to see them hunting over the reedbeds. It was there that I first realised just how difficult they are to photograph!
Nest Boxes
Last year however we saw small screaming parties on several occasions close to the house, and thought perhaps it may be worth installing boxes, particularly as we have a north facing wall which has a sun-free aspect, at a good height under the eves of the three storey house, with a fairly clear line of flight.
Three boxes went up in the spring, each with a camera installed. A directional tannoy speaker was used to broadcast the nesting defensive call to attract birds looking for a potential nest site … and that’s it, now wait for the swifts.
If Only It Was That Simple
Intitially that’s what we did, half hoping a swift would appear and take on a box, but of course nothing like this happeded. We played the swift call from 4.00 am to 9.00 pm, with a break during the middle of the day. Later we reduced this to just morning and evening.
We also began to watch carefully for swifts during set periods and kept a record of what we saw … and what we saw had to be put in the context of what we know about swift nesting behaviour.
Swift Nesting Behaviour
Swifts can live up to 20 years or more, and don’t start breeding until about their fourth year. Males and females share the incubation and parenting tasks.
They are monogomous, and the pair return every year to the same nestsite. They are also colonial nesters, and if the space allows, many pairs can occupy a single building.
Unmated young birds will be looking for a suitable nestsite during their first two or three years, and will be attracted to an existing colony – hence the importance of using the swift caller to attract birds to a new site.
Swifts start to arrive in the UK at the beginning of May, and depart around the end of July.
They arrive in the UK in two waves. The first group are the breeding birds. Unless their old site has been destroyed they will not be looking for a new place to nest.
The juveniles return to UK a couple of weeks later. In a sense they are our target. They are the ones on the look out, and the older the bird, the more seriously it takes on the quest. By their fourth year they should have found their nesting site, combined with a mate, and established themselves there for a spell. The following year they will be back with the intent to breed. Therefore in late May and into June we should be most watchful of boxes.
Our Observations during 2023
Initially we just expected that something would happen, and were disappointed no swifts appeared. But of course the more you watch the more you see.
Towards the end of June we started watching systematically from around 8.00 to 9.00 am and around 7.00 to 8.00 pm.
We recorded three types of observations: occasional single high flying birds darting, dodging and obviously feeding; small groups at a lower level circling; low flying small groups at roof height.
During the early observations we never saw more than four birds together, and assumed they were the “local” group. Later we saw groups of up to 20 birds, but such sightings were rare.
The days passed in a mixture of excitement or puzzlement … there were times when we thought the swifts were taking a real interest in the house and the boxes, and others when our view of them was fleeting.
The period of peak activity was around the end of June and through early July. This was when the so called screaming parties were evident. Group sizes increased over the course of July. Over the weekend of the 22nd/23rd the weather was appalling, and we had no sightings. Four birds were seen briefly on the 24th and one on the 26th, and then no more.
We didn’t once see a swift approaching a box, but who knows what might have happened when we weren’t watching. When they flew close, their speed appeared to be incredible – how could they possibly notice the boxes as they pass at such speed?
We speculated on their presence and absence. What we do know however, is that speed and distance are all part and parcel of a swift’s life. If weather systems are bad, swifts will make daily round trips of hundreds of miles to avoid these conditions and find good feeding spots.
Late Departures:
6th and 7th of August lone swifts seen feeding over Combe Valley reedbeds – good to see!
Their Dusk / Dawn Flights
It has been known for many years that the Common Swift roosts on the wing at high altitude, but it was only recently that research using weather system radar has revealed the extent of this high flying behaviour and begun to unravel the mystery of why.
Soon after dusk large numbers of swifts rapidly ascend to high altitudes, and then slowly decend to spend the night at lower altitudes, sleeping on the wing. Before sunrise, they increase altitude again before rapidly descending.
A number of therories have been put forward to account for this behaviour, including it being a mechanism for orientation, and / or high level surveillance of weather systems that enable them to target the best feeding locations for the day. However it is also apparent that the birds undertake these rapid ascents in large flocks, suggesting perhaps that there is also a strong social bonding factor built into this.
See for instance Cecilia Nilsson’s 2019 post: https://bou.org.uk/blog-nilsson-common-swift-twilight-ascents/
What drives this remarkable behaviour remains unclear. It is just part of an endlessly fascinating puzzle.
European Swifts
In this blog we’ve referred to the Common Swift, Apus apus. However, four species of swift occur in Europe. The Pallid Swift, which is very similar to the Common Swift; the larger Alpine Swift; and the White-rumped Swift. The White-rumped Swift is a rare species, and is unusual in that it often remains in Europe until well into autumn before embarking on its southern migration.
All four species can be found in our favourite birding spot of Extramadura in Spain, see Martin Kelsey’s blog, Celebrating Swifts: https://www.birdingextremadurablog.com/2010/08/celebrating-swifts.html.
And finally, promoting the use of Swift Bricks – the national and local debate
In “Swifts and Us – The Life of the Bird That Sleeps in the Sky” Sarah Gibson not only provides a fascinating picture of the life of the swift, but also describes the dedicated work of small groups of people from across the world who have battled to promote the conservation of swifts. And part of this story is the development of the Swift Brick as the perfect low cost nesting site for swifts.
Read about the national debate in parliament, and in our own Borough of Hastings on the use of swift bricks in “new build” housing schemes: