Swifts diary

The colony of swifts that nests in the Museum tower has been the subject of a research study since May 1948. It is one of the longest continuous studies of a single bird species in the world, and has contributed much to our knowledge of the swift.

6 May 2024

They're back! The first swift was seen flying past the tower on 30th April and the next day several were back for May Day morning with the warm southerly breeze. Our first survey on 6th May revealed that these first arrivals weren't wasting time, with several nestboxes showing signs of occupancy. One adult pair was on the nest and another single adult had obligingly occupied one of our boxes with a camera that streams live to our website.

13 May 2024

The warm weather of the last week has seen swifts returning in larger numbers and screaming parties of up to 14 birds have been whizzing past the tower and filling the skies overhead with their cries. More boxes are showing signs that they have been visited and another pair and another two single birds were observed on their nests. Last week's pair have been busy and we have our first egg!

20 May 2024

As the weather warms, more swifts are arriving. We now have 31 nestboxes showing signs of activity inside while screaming parties of up to 14 birds at a time whizz excitedly past the tower outside. This morning's cool weather saw 17 adult pairs snuggled together on the nest as well as 6 lone adults, some of whom sat hunched with feathers fluffed; likely incubating their first eggs. There are certainly more than 5 eggs already but there are adult birds sitting on the nests, meaning it is hard to tell exactly how many. We need to be as quiet and careful as possible not to disturb them as we lift the blinds to peek into the nest boxes. At least the birds on our webcam have been generous enough to produce a couple of eggs! As the weather warms, we should have more arrivals occupying more boxes, and perhaps even our first chicks next week!

27 May 2024

Today's survey revealed 35 nests showing signs of occupation and 29 eggs. With some birds sitting tight there are undoubtedly other eggs that are not visible. The wet weather has meant that the start to the season has been slow and some nestboxes that have been occupied for several years remain empty. We can only hope that the tenants are yet to arrive and will be with us in the next two crucial weeks.

One box revealed how ferociously territorial swifts can be over their nest sites. Lifting the blind to look inside we were met with the sight of three dead adults. A pair had obviously taken up residence and been visited by an intruder hoping to nest there itself. The ensuing fight had left at least one dead bird blocking the entrance hole. Unable to leave, or mortally wounded, another bird had perished next to it whilst a third, trapped by the others, was found recently dead at the back of the box. None of the birds were ringed meaning these were most probably first-time breeders staking a claim to their first nest site. These sites are so cherished that the same adults will occupy them faithfully year after year and will fight, sometimes to the death, to claim and defend them.

3 June 2024

This morning we were greeted at the Museum by large screaming parties of over 20 birds. Inside the tower, our survey revealed that we now have 38 active nests, around 60 eggs and our first 3 chicks! There is still time for more birds to arrive over the next week or so and we hope that with the warmer weather and change in wind direction we will see more nesting activity, and hopefully some more chicks, although we still have a way to go to reach last year’s high of 57 nesting attempts.

10 June 2024

A brisk, cold north wind was blowing today and the swifts were sitting tight over eggs and young with very little activity outside the tower. With the adults hunkered down on their nests, counting eggs and young proved difficult with some young only making themselves known by their whickering calls but we now have 42 active nests and over 31 chicks. Some of these had only hatched within hours but last week's hatchlings are already in pin, showing the very beginnings of their first coat of downy feathers. As well as the young we also have over 26 eggs still to hatch. We must hope that the weather improves over the next week or so, so that their insect food becomes more readily available.

17 June 2024

After a cold and windy week, the swifts are doing pretty well and we now have 53 young ranging from tiny and very recently hatched, naked, blind chicks to those that hatched last week and now have their eyes open and are covered in downy feathers and growing fast. Looking at them it is hard to believe that only a week ago they were as small as some of their neighbours and good to see that their parents are obviously managing to catch enough insects to feed them during such disappointing weather. There are also over 15 eggs still to hatch.

24 June 2024

With the return of some hot summer weather, the swifts are thriving. The chicks are growing quickly, although some of the more developed young seem to be seeking cooler areas of the nestbox rather than sitting together in the nest. We now have 72 chicks and more than 7 eggs still waiting to hatch, and several new pairs have taken up residence rather late in the season in previously empty boxes bringing the total number of boxes showing signs of occupation to 44.

1 July 2024

The warm weather we’ve had has been a boon to the swifts and the young are growing fast. We now have 77 chicks, the oldest 11 of which were big enough to have their identification rings fitted today, and in a few weeks will be showing off their flashy new bangles as they depart for Africa.

There are still 8+ eggs waiting to hatch, although several of these have been ejected from the nest and so will now be unviable, but overall so far it is looking like a good year for our birds.

8 July 2024

It was perfect weather for swifts to feed today, warm and still, which was very evident in the tower as we were surrounded by the sounds of begging chicks and adults regularly coming and going. The young continue to grow fast with some looking like they may even fledge in the next week or so. This means it’s a busy time and we put rings on another 34 birds including an adult as well as recording the ring number of an adult in another nestbox.

15 July 2024

There is now a huge range of chicks at different stages of development and still eggs to hatch. Some young have fledged in the last week and nests that last week contained three young are down to a single chick, and their boxes will be empty by next Monday. At the other end of the range, one box contained two tiny, naked and blind chicks and as we were examining the nest box we were extremely lucky to witness the third egg hatching.

Spreading breeding over several months can pose an equal risk for early, mid-season and late breeders, as success very much depends on the weather during the summer which impacts the supply of insect food and feeding opportunities. With different birds spreading their breeding over this period, overall many will survive the unpredictability of the British summer. Hopefully conditions will improve over August. Warm, clear skies will see an increase in insect food, and these last birds to hatch will also fledge and head to Africa in around 42 days' time.

22 July 2024

Life in the colony is rapidly progressing and today's visit found that 34 chicks have already fledged and left for Africa with several of these leaving during our visit. That leaves 45 chicks still in the nest and if all of these successfully fledge, we will have seen 79 young raised this year. We were also accompanied by two visitors this week –Siena and Joel are both architecture students researching the various designs and types of architecture best suited to creating nest spaces for swifts, which is incredibly important for this species obliged to only nest in human-built spaces in England. It was also heart-warming to meet a new generation of architects who are intently focused on how to design buildings to live alongside and encourage biodiversity, rather than exclude it.

29 July 2024

It has been a quieter week in the tower as many of our chicks have taken the chance of warm, calm weather to fledge and are now on their way to Africa. Only 13 active nest boxes and twelve chicks remain. Several of these active boxes had pairs of adults sitting together without eggs or young. These are prospecting pairs – too young to breed this year but staking a claim to sites for their return next year.

Last week's mass exodus of fledglings was not without drama. On 24th July we were alerted to a swift that had crash-landed outside the Museum. Luckily the swift had been ringed that week and seemed undamaged so we were able to replace it in its box in the hopes of a second successful attempt at fledging. Later in the day, another downed swift was reported on the Museum lawn. Its ring identified it as the sibling of the earlier crash-lander. On taking it back to its box we were relieved to see that the first bird had successfully left on its second attempt. Today's survey saw the box totally empty meaning both siblings have now fledged, and have hopefully learned from their mistakes!

5 August 2024

The tower was very quiet as we approached this morning with only a solitary swift seen flying around it outside. Inside it became apparent that most of our birds have now left with only 5 active nests remaining and 7 chicks still waiting to fledge. Several of these are still downy and will still be with us for another couple of weeks and be the last birds to leave to start their migration back to Africa.

12 August 2024

It was particularly hot and humid in the tower today on what is predicted to be the hottest day of the year so far. There are now only 4 occupied nest boxes with 6 chicks remaining, most of whom are well developed and we expect will have fledged by next week’s survey.

26 August 2024

Only 3 swifts remain in the tower and, judging by their development, these will almost certainly have left by next week and another season will be over leaving us to clean the nest boxes and wait for next summer to see who returns.

2 September 2024

It's overcast with a light drizzle but humid and warm. The tower colony is silent; I dislike this time of year. As predicted last week, all the 147 nesting boxes are empty of swifts so it's time to start cleaning!   

Swifts are reasonably clean birds by nature but we are aware that any pests such as feather lice, moths and even beetles could cause harm to the priceless exhibits downstairs in the museum so all the nests are removed, bagged and labelled ready for freezing to kill any pests. They will be replaced in the spring ready for the arriving birds.   

2024 was a good year for the swifts, we ringed 77 young, all of which fledged; 10 new adults were ringed and 9 more, which had been ringed in previous years, were identified.   

So with the birds gone and the boxes cleaned, helped this year by my two lovely assistants, it is time to lock the tower doors until the birds return in spring 2025.