Statistics for 2013
This year the first swifts were spotted around the Museum tower on 25th 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.
- 29th April 2013
One nest started high up on the south side of the tower. The first swifts occupy the higher nest boxes as it is easier to take off from a greater height.
- 6th May 2013
There are now three nests started including last week's, plus an adult resting in a fourth box.
- 13th May 2013
This morning there is activity in 9 boxes, including the 5 that already have nests. In the other boxes the adults are sitting in. No eggs yet.
- 20th May 2013
There is now activity in 18 boxes: 15 nests and 14 adults seen either on nests or sitting in. Still no eggs visible.
- 27th May 2013
There are 20 active nests. Only three eggs visible and three adults sitting.
- 3rd June 2013
21 nests are active, with eggs in at least 5, and at least 7 eggs in total. Swifts often sit on the nest prior to incubation, and as they are very sensitive to disturbance, it can be difficult to tell whether they are on eggs yet. One egg had been rejected from a nest. We don't know why they sometimes do this as the eggs seem to be viable if replaced in the nest, but it is not uncommon. Swifts can be slow to take the plunge, lay a clutch and incubate. A nest in one nestbox has been complete for two weeks, although there are no eggs in it yet. However, two adults were sitting in the box today, one with its wing over the other in what looked like a gentle embrace. They may have just completed copulation, which can occur in the nestbox or on the wing, in which case we can expect more eggs soon. Although the number of nests is down compared with this time last year, final outcome was very poor last year because of stormy weather. We are hoping for better weather from now on, in which case we can expect better fledging figures, and the colony can start to recover from the decline of the last six or more years.
- 10th June 2013
There are still 21 active nests. Now there are at least 18 eggs in 9 nests, and adults sitting on a further 8 nests.
- 18th June 2013
Still just 21 active nests. 15 of the nests with either adults sitting or eggs present.
- 24th June 2013
There are still 21 nests. Unfortunately however, only 13 of them have adults sitting. The colder than average weather, and consequent poor food supply, may have prompted some of the birds to reject their eggs.
- 2nd July 2013
Better news this week: there are 21 chicks in 13 nests. There are also 5 eggs in 4 nests (3 are the same nests as have young.) And there are 8 empty nests.
- 9th July 2013
The fine weather is excellent for the swifts and the chicks are growing fast. Today there are 23 chicks in 13 nests. There are also 3 eggs that still may hatch.
- 15th July 2013
The 23 chicks are all doing really well and are growing fast. The exceptionally good weather means insects are plentiful. 6 young in 3 nests were ringed today. There is one bird incubating, and 3 other nests have adults sitting.
- 23rd July 2013
There are now 24 chicks in 14 of the 23 nests. One other empty box has an adult pair resting in. These birds were left undisturbed; they may be 'prospecting' for a nest site for next year. A further 13 chicks in 7 nests (one brood of 1 and six broods of 2) were ringed. The oldest chick, ringed last week, is large enough to fledge, but has not yet gone, and the youngest just hatched in the last day or two. All the chicks are growing well, benefiting from the warm weather which encourages insect abundance.
- 1st August 2013
The first 3 chicks have fledged and 4 more chicks were ringed this morning. The youngest chick is growing well.
- 15th August 2013
All 23 of the 24 chicks have now fledged. The youngest chick has been ringed, and is growing well, and looks well fed. Its wing length is 128mm so it will be another ten days at least until it fledges.
- 28th August 2013
The last chick has fledged. The swifts will be on their way back to Africa now.
Ringing a swift chick
The average numbers of young swifts ringed each year over the last 50 years are:
- 1963-1972 36.7
- 1973-1982 70.4
- 1983-1992 100.0
- 1993-2002 99.2
- 2003-2012 81.1