The Common Swift and Nest Boxes – 2026 update
This is part of a series of notes and observations on Swifts and our attempt to persuade a pair to adopt one of our nest boxes. It is also the context for describing the amazing and complex behaviour of these wonderful birds. The more we learn about them the more fascinating they become.
Although they are sometimes referred to as the European Swift (Apus apus) they spend relatively little time in Europe. They arrive here between the end of April and beginning of June and depart as early as the beginning of August, heading for their wintering grounds across Central Africa.
And when they are here we don’t necessarily see that much of them. They fly high and fast, and when weather conditions are poor they can easily depart to feed up to a 100km away from where they are nesting.
They are at their most prominent when the juveniles arrive in early June, and form noisy groups that scream with excitement as they fly at speed, especially during evening time. These groups of juveniles contain birds from one to four years old. The older juveniles will be on the lookout for mates and a suitable nesting site for the following year.
They nest in small colonies and will be attracted to existing nesting sites with breeding adults – hence the importance of using a swift caller when trying to encourage the first pair to adopt a box.
The Story So Far – 2023 to 2025
Three boxes went up in 2023. A camera went into each in the hope of seeing something of the nesting behaviour of these extraordinary birds. To attract them to the boxes we set up a small directional speaker on an adjacent window sill to project a recording of the territorial / defensive call of the Swift towards the box – see Part 2: Nest Boxes and the Attraction of Swifts:
The result was plenty of Swifts, but all ignored the boxes. One possibility was that the call wasn’t sufficiently directed to a box, and so in 2025 we fitted a camera and small speaker inside a new box and added this to the row of three.
We started the internal caller in mid-April 2025 and continued to use the directional speaker on the windowsill. Although we saw less Swift activity during the summer than in previous years we finally got the result we were after, a number of juvenile Swifts entered the box, including a pair that returned regularly for several days.
The layout of the new box and the behaviour of the Swifts in relation to the internal caller is described and explained (as far as we are able!) in The Common Swift and Nest Boxes – 2025 update:
May 2026 to date – a diary:
A cold dry April and early May, and no views of Swifts until the 20th when we began to have regular views of ones and twos flying high and feeding.
On the 20th we saw the start of an exceptionally warm dry spell, with temperatures well into the twenties.
On the 25th we had our first view of a pair of Swifts flying low in the proximity of the boxes. On the same day at 4.00pm two entered the box and stayed until after 4.00am … a 12 hour stint.
For the next five days they maintained this schedule of about 12 hours in the box and 12 hours out, although on the 26th and 29th they also returned during the day for an hour and a half.
Our assumption is that these birds are the pair that explored the box in 2025. They entered the box quickly. There was nothing tentative and exploratory about their behaviour, as we saw from them last year. Also, as yet we haven’t seen or heard the screaming parties of unmated birds that usually arrive in the UK in early June.These come well after the established pairs have returned to claim their nesting sites from the previous year – they are nest-site faithful year on year, and will defend their site against prospecting youngsters.
It is wonderful see their intimately entwined bodies on the nesting pad. Rarely still for more than a few minutes, they are constantly preening themselves and each other. Sleep as we understand is fleeting, but of course this is for birds that sleep on the wing when they are not at the nest. There is still so much to learn and understand about these birds.
see The Intimacy of Nesting Swifts:
An On-going Diary
The Swifts have been established in the box for six days. They have settled into a clear routine of leaving the box at around 7.00am and returning 12 hours later to spend the night there.
We would expect the pair to start building a rudimentary nest as their next step. They have made a start with this. One evening, one of the birds returned with material gathered on the wing and proceeded to stick small bits around the edge of the nesting pad – but nothing more since then.
Day 7, the pair returned to the box at 7.00pm. The following morning they were still there at 11.00am. One, the male, had briefly been to the entrance to the box on three of four occasions and returned to the female. It was then that saw a single egg laying to the side of the pad. They then left the box and the egg sat on the edge of the pad.
Day 8 the egg was off the nest pad lying against the wall of the box. It seemed to be ignored by the birds.
Day 9, the egg appears to have been abandoned. It has now rolled away from the nest pad and out of view of the camera, presumably nudged there while the birds were shuffling towards the nest box entrance.
No apparent progress with building a nest. The birds are spending more time in the box. There has been an abrupt change in the weather which is now cold, wet and very windy.
On the morning of Day 10 a second egg was on the nest pad in the same position of the first. This was rolled a little by the female and ended up wedged in the far corner of the box and given no further attention.
7th June, Day 14, the cold, wet, windy weather has continued for the last four days. The Swifts have remained in the box for long periods, venturing out only when there has been a break in the weather. The morning of 7th was brighter and the Swifts had left the box by 8.00am. One returned around 7.45pm, started to preen and nibble round the edge of the nest pad, and then picked up the second egg in its wide gape and carried towards the front of the box, out of view of the camera. The second Swift returned just as it was getting dark.
8th June, a day of rain and long sunny spells. The Swifts were in and out all day. The female (we think) brought in 2 large feathers in the space of hour, and tried to stick them down on the nest pad. Also, the egg has come back into view and is resting near the pad.
9th to 13th June: a mix of long sunny spells, high cloud and occasional rain. The birds were spending most of thew day out, but making occasional short visits to the box. During this time only one or two feathers were added to the nest. The 11th however was wet and cold and one bird stayed in the box most of the day and the other returned at 3.30 pm and they both remained in until the following morning.
14th June: sunny but with plenty of high cloud. Both departed at 7.00am one returned at 9.45 with a large feather … they seem to be getting the idea about nest building. For the rest of the day, they were frequently in and out. Three feathers were brought in, two by different birds, demonstrating that both male and female contribute to this, although the female may be the one primarily responsible for sticking them down. Even if they manage 2 or 3 feathers each day it is still a very slow process.
Diary to be continued …..
Screaming Parties:
The highlight of the 14th June was when we saw our first group of juveniles of this year. Two Swifts circled the house, flying low and close to the nest boxes while our two were still inside. We later saw a group of five, although our box was empty and so the group may have included our birds. This was the first sightings of any Swifts other than ours since early May.