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.


What is happening this year?

Details of nesting pairs and their chicks will be updated each week throughout the summer months on this page. The live feed below is from one of two webcams placed in nests in the tower and will stream images throughout the nesting and fledging season each year. Below is a week by week diary of how they are faring.



Swifts Diary 2020

  • 1 May 2020
    The good weather at the end of April seems to have brought the swifts back early this year. The first swift was seen flying around the tower on 27 April and two birds were recorded sitting in the nest boxes on 30 April. On average the first swifts in the tower arrive around 5 May. Hopefully, if the good weather continues, this early arrival is a portent of a good breeding year.
  • 7 May 2020
    Fine weather has seen an increase in activity around the tower, with screaming parties of up to nine swifts surveying the nest boxes. Inside the tower we have now seen two pairs sitting and four single birds sitting, facing the entrance holes and vigorously screaming back at all comers to defend their sites. There is also evidence of some new nest material being added in other boxes as feathers caught on the wing glisten with the fresh saliva used to glue them down.
  • 13 May 2020
    Strong cold north-easterly winds have significantly lowered temperatures this week but despite far from ideal conditions for flight and foraging we counted seven pairs of birds and one single bird in the boxes. Unfortunately, though in nest boxes nearby, none of these birds has chosen to take up residence in our webcam box. As temperatures are expected to warm next week we expect more swifts to arrive and have our fingers crossed that you will soon be able to watch a pair on the nest live for yourselves!

  • 20 May 2020
    Rising temperatures and the easing of the northerly winds have seen an increased number of birds arriving and nesting, and we have recorded the laying of the first eggs of the year. This week we counted 21 birds on the nest, with others clearly out feeding, and also ten eggs.

  • 28 May 2020
    The continued warm weather has brought an increase in occupied nests and breeding activity. There are now 27 occupied nests, with signs of activity in others. The nestcam boxes have finally been occupied with one pair displaying a clutch of two new eggs.

  • 5 June 2020
    We have 39 nests occupied, most with birds sitting in them, so only 23 eggs were visible but we also have our first chicks. Four were observed but eggshell and faint cheeps from other nest boxes suggest there are more.

  • 10 June 2020
    The swifts have had another good start to the breeding season. There have been 41 breeding attempts this year so far; of these 33 are currently active with eggs or young. The remaining eight either did not lay or in two cases laid but deserted. On this visit, 30 adults were sitting tight but 33 eggs were visible, as were 38 young. The young were all no more than ten days old and indeed some looked to be newly hatched. If all are successful there should be at least 70 young fledging this year.

  • 16 June 2020
    The fine weather continues to encourage the swifts. Today 36 nests are in use. There are 29 adults in the boxes, with 34 eggs and 45 young, plus at least six boxes where the adults are sitting tight and hiding whatever they are sitting on. Humid conditions are perfect for insects and that means more food for the swifts; the young seem to be well-fed with little begging being heard until an adult enters a box. Should the weather continue as it is at present, we could expect there to be over 80 young this year.

  • 22 June 2020
    Swifts were very active and noisy today, screaming around the tower in the sunshine. Inside the breeding colony we now have 40 active nests plus one more containing a single cold egg. There were 30 eggs visible and 56 energetic young but also one dead chick; four adults sat tight so may be on eggs or small young, time will tell. In total, 27 birds were sitting in the nestbox and four of these were accompanied by their partner. Nestboxes N8A, E8A and S6B are now occupied and seem to be starting late with at least one egg in each box.

  • 29 June 2020
    Today we have a strong gusty breeze but it is dry. There are very few swifts around the tower despite the warm weather. Inside the tower, however, we have 38 active nests with 24 adults and six pairs in the boxes. Most of the small young are being brooded, especially on the west side which is where the breeze is coming from. There are 74 young visible today and 16 eggs, another six nests have adults sitting tight so they may be on either eggs or newly-hatched young.
    There is quite a spread of ages, some of the young have wing feathers half full length, others are newly hatched or fresh eggs, and there are youngsters of every stage in between. It seems to be a good breeding year for swifts thanks to a warm sunny May.


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