Statistics for 2011
This year the first swifts were spotted around the Museum tower on 29th April. Details of nesting pairs and their chicks will be updated week by week through the summer months.
See below for the week by week diary.
- 6th May 2011
Just 2 nests started.
- 13th May 2011
The swifts are building their nests in the nest boxes- 21 nests underway.
- 20th May 2011
There are now 46 active nests, including 9 with eggs. There is one bird sitting, but as we can't disturb her to see what she is sitting on, we are not sure if she is incubating. Swifts often sit in, and sometimes on an empty nest, at this stage.
- 27th May 2011
There are still 46 active nests, 38 of them complete, and 14 have eggs.
- 3rd June 2011
There are now 51 active nests, and 18 of them have eggs.
- 10th June 2011
Today there are 37 completed nests. Of these, 16 have eggs, 8 have no eggs yet, 10 have adults sitting (so probably eggs or chicks), and 3 of the nests each have 3 chicks being fed by their parents.
- 15th June 2011
There are now 7 nests, each with an average of 2 chicks, another 20 nests with an average of 2 eggs each, and some birds are sitting in boxes with no nesting material. There are also 2 deserted nests, one with eggs, the other with chicks. The average growth rate of the chicks is currently 2.2 grams per day.
- 21st June 2011
There are 11 nests with chicks, and another 20 nests with eggs. The average growth rate of the chicks is now 2.4 grams per day.
- 3rd July 2011
There are 32 active nests, of which 25 have chicks, which on average grow 2.1 gram per day, and of which 7 still have eggs. The west side of the tower is most popular (that's the front of the museum), with 11 nests, followed by 8 nests East and South, but only 5 nests on the North side.
In some nests parents seem to struggle: 3 nests with small chicks have been abandoned, and 1 nest with eggs. Those are not counted towards the 32 which are still going. There are also still 8 nests with adults sitting but no eggs yet. These adults could well be young birds that do not breed yet, but have started nestbuilding. The swifts add to their nests every year, so by making one this year, these birds can prepare for breeding next year.
- 20th July 2011
The swifts seem to be struggling this year. With the date of last egg laying behind us, we can now confirm that only 37 clutches were initiated, in comparison to 50 last year. Of those 37, we're sad to say 6 were deserted at an early stage. Over the last two weeks, 4 clutches with large chicks were also abandoned. The chicks in two of these have been placed into nests that are doing okay, and the other four chicks have been taken into care, to be handreared until fledging. Six chicks have fledged from the colony so far, while 24 nests still have chicks in, and in 1 nest the adults are still incubating eggs! Fingers crossed for all of these.
- 31st July 2011
12 young swifts have fledged from 7 nests so far, and we still have 18 nests with chicks in. The growth rates of these chicks are quite variable between these nests, and there are a few nests which are likely to need help in order to fledge their young. If all goes well, fledging will continue until the 20th of August.
- 1st August 2011
The second chick has fledged from W19. This was the only active nest near the base of the tower. Facing west, it is at the front of the museum, allowing a clear access for the parents even from a low nest. Chicks also fledged from three other nests, making 20 fledged from 11 nests in all so far. An adult identified today as SE24749 had been ringed in the tower as a chick in 2008. Five more chicks, in three nests, were ringed today. These are all at good weights of more than 45g each. There are now 26 chicks remaining in 14 nests. Although chick weights vary, only one gives cause for concern at this stage.
- 4th August 2011
Seven more chicks from four nests fledged since Monday, making 27 from 15 nests in all. Most are making reasonable progress, but one brood of two gives cause for concern and will be taken into care, and one chick that hatched very late has died. This leaves 19 chicks in 10 nests.
- 9th August 2011
Six more chicks fledged from five nests since Thursday, making 32 from 18 (second chick to go in some cases) nests in all. Two chicks went to care over the weekend. This leaves 11 chicks in 7 nests. Most of these are near to fledging, but the two youngest chicks in the tower, are giving some concern now and may have to be taken into care.
- 11th August 2011
Six more chicks fledged from four nests since Tuesday, including one of the chicks on camera. That makes 38 chicks fledged from 21 nests in all. The two chicks that have given concern were taken into care today. This leaves just three chicks in two nests, both of which have cameras on them. They are 33 and 35 days old, and so should fledge within a week. It would be great to see them fledge on camera.
- 15th August 2011
All three chicks still in the nest and doing well.
- 17th August 2011
The second chick from N5a left early this morning. The two chicks in S2b are still doing well, and visitors to the museum today witnessed a feeding visit by an adult fully on camera. As they are now at 41 days, they could go at any time. The other cameras have now been switched off, but the camera on S2b will stay on until the brood fledges. If you are visiting the museum, this nest is the very topmost left nest (top left air vent) on the south (RSL side) side of the tower.
- 20th August 2011
The last two swift babies have fledged! That makes 42 fledglings in total, while 9 chicks were taken into care. It's been a tough year for the swifts, but let's hope they'll all have a safe flight to Africa and will have better luck next year.
The average numbers of young swifts ringed each year over the last 40 years are:
- 1963-1972 36.7
- 1973-1982 70.4
- 1983-1992 100.0
- 1993-2002 99.2