Swifts diary

The colony of swifts that nests in the Museum tower has been the subject of a research study since May 1947. 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.

 

16 May 2022

They're back! Two weeks late but, nevertheless, there are swifts in our boxes. I think they were probably delayed by the storms in Spain and the cool wet week in the UK, but it's good to welcome them back to the colony and to hear them screaming around the tower. The first bird noted was in a box with a camera on 12 May. By this morning there were two adults sitting tight and at least 8 nests showing signs of occupation, whilst at least a dozen birds were screaming around the tower. Hopefully, they will quickly settle down to breed.

 

24 May 2022

The weather has been overcast with recent rain, but is mild with light winds. More birds have arrived and there are now signs of use in 36 boxes and possibly in a further 4 making a total of 40.   

Pairs of adults were present in 13 boxes and single adults were sitting tight in a further 6 boxes.   

A total of 27 eggs were visible although there were certainly more which were hidden by sitting birds.    

The weather over the next fortnight will determine the success of the breeding season as warm, dry conditions at this time of year usually result in higher numbers of successful nests.

 

30 May 2022

A cool day with light intermittent showers and a light breeze meant that there were few swifts to be seen flying around the tower.

Inside the nesting colony was a different story, however. Birds were calling from the boxes, 33 of which contained birds that were sitting tight. This makes recording difficult as we were unable to count the eggs without disturbing the birds, which could lead to the swifts abandoning the breeding attempt.

 

6 June 2022

This Monday dawned dry with a light breeze following a night of heavy showers and a week of miserable wet weather, including thunderstorms.   

There were, however, swifts screaming around the tower, which is always a welcome sight.   

Up in the colony, it was reassuring to find birds sitting tight, a sure sign that they are on eggs. Only 1 egg had been ejected and this was carefully replaced next to the bird so that it would roll into the nest cup when the bird moved.   

A less welcome sight was that three boxes each contained a single egg but no adult, this may have been a result of the weather causing less experienced birds to abandon the nest or may just be that the adults were off feeding prior to completing the clutch, time will tell.   

An egg count was not possible with the birds sitting tight. However, based on last week's count and estimating that each bird should have a minimum of 2 of the 3 eggs hatch, we can look forward to at least 70 chicks this year unless the cold, wet weather continues.
 

13 June 2022

There are 39 nests showing signs of activity with birds sitting today. At least 29 newly hatched young and 23 eggs are visible but there will be many more under birds that are sitting tight.   

It seems that the rain showers and cool weather did not affect the birds although there may be 3 nests which have failed as no eggs were seen despite adults being present in the box.

 

20 June 2022

Following a week of hot weather, in fact a mini heatwave, there were 37 nests active today; however, 2 of these nests may not be as they seem. One still contains 4 eggs that have been there for about 3 weeks, whilst another contains 2 eggs, but neither has an adult in attendance. All 6 of these eggs were warm so let's hope that perhaps the adults were just out feeding.   

Today there were 14 eggs visible and 57 chicks; plus 33 adults were sitting, so these counts are minimums as many other eggs and/or chicks will be hidden by those adults which are sitting tight and which cannot be disturbed to check the nest contents.   

Chicks range in age from just born, (pink, naked and blind), to downy chicks about 3 weeks old which are starting to grow their wing feathers.   

The weather is forecast to be fine and sunny so things are looking good for a successful breeding season.

 

27 June 2022

Recent rain and a drop in temperature was a worry when combined with the amount of noise being generated by the various construction work being done around the Museum, but it seems that the swifts are content to ignore it all and are getting on with breeding.

Today there are 42 active nests with 70 chicks and 21 eggs visible. In the nests, 28 adults are either attending chick or sitting on eggs, so 9 more nests may have eggs or young chicks that cannot yet be seen.

The key to success now is insect food. I have noted an increase in insects on the car windscreen this year so this may indicate a good feeding year for the swifts.

 

4 July 2022

The current spell of warm weather appears to suit the swifts, probably because there is more insect activity, enabling many adults to raise 3 chicks. We now have 85 young and there are still some birds incubating eggs. Activity is apparent in 41 of the nestboxes – 16 of these contain 3 chicks and 14 others contain 2 chicks. The remaining 11 boxes contain a single chick or sitting adult covering either eggs, or perhaps very small newly-hatched chicks.

Swift adults are becoming more settled now that they have young. These young range in age from newly-hatched and blind chicks to fully-feathered large young that will be leaving the colony in a week or two.

 

11 July 2022

The heat-wave continues and the swifts are loving it, although some of the chicks are panting due to the heat. Birds are screaming around the tower, the colony is alive with sound; the calls of adults and of begging chicks are heard whenever an adult arrives with food.  

One of the adults was kind enough to present us with the remains of a food ball (Bolus) this week and this will be analysed in Entomology to see what the swifts are eating at the moment. It is beginning to become apparent that they are opportunistic feeders taking whatever small insects are on the wing in the local area.

We now have 82 chicks in residence in 41 nests and 5 eggs still to hatch. The chicks range in size from naked, newly born through to fully feathered, almost ready to leave the nest for the migration to Africa where they will spend the winter months.  

 

25 July 2022

Despite the recent rain, or perhaps because of it bringing more insects, the swifts are doing very well this year. Only 3 very small, late hatching chicks have died out of the 90 which hatched (out of 107 eggs). These 3 were in nestboxes which have not been used for years, so the parents are probably inexperienced birds that are breeding for the first time.

There are still 21 active nests with 35 chicks of varying ages, some of which will fledge during this week. Last week there were 38 active boxes and some of the young have already left the nest; I know of 52 young that have fledged although 1 did not survive the first flight. Being more positive, however, it has been the most prolific breeding season for nearly 20 years.

The colony is monitored weekly and both adults and young are ringed when it is safe to do so – this has many purposes. It enables us to track which adults return and to which box; it allows us to keep track of the young birds so that we do not double count or miss any; and it gives us survival information on both adults and young. So far this year, 64 young have been ringed and 23 adults either ringed or identified. In addition, there are still another 23 young to be ringed when they are closer to fledging.

So, in summary, there are 87 chicks out of 90 that hatched from 107 eggs. This far exceeds the annual totals of chicks since 2008.

 

1 August 2022

The day was overcast with a light breeze but it was mild and dry. Very little swift activity was noted around the outside of the tower and it was silent inside. Both the cameras were switched off as the nests had no activity. The cameras were moved to nests with young still in them so will be switched on again.  

Inspection of the nests showed that there were still 12 nests with 10 chicks of varying ages which are yet to fledge. Some are almost ready to go and will probably leave within the next few days whilst others look as if they will be around for a few weeks yet.  

Another adult food ball was regurgitated and this has been sent to the Entomologists for examination. At first glance it seems to hold a more diverse collection of bugs and beetles with a few small flies included. The previous one had large quantities of just a few species so it will be interesting to compare. This will also help us to understand the diet of swifts and how it might change during the breeding season according to insect availability.

Check back for regular updates...

 

PREVIOUS YEARS

The average numbers of young swifts ringed each year over the last 50 years are:

 

1963–72: 36.7

 

1973–82: 70.4

 

1983–92: 100.0

 

1993–2002: 99.2

 

2003–12: 81.1