Winchester’s Swifts in 2018 and 2024

Of all the large towns or cities in Hampshire, Winchester is probably the one that has been most extensively surveyed for breeding swifts. In 2018, Hampshire Swifts was invited by the University of Winchester to survey all their student housing in the city for evidence of swifts nesting. As these houses and flats were located in nearly all areas of the city, we decided that this was an opportunity to carry out a survey of these areas to try to locate where swifts were breeding. Since that time, we have continued to do yearly surveys in Winchester, surveying some areas that are particularly important for breeding swifts every year, and other areas less frequently. The data collected during this period allow us to estimate approximately how many occupied swift nest sites there were in the city in 2024, compared to 2018, and to examine how swifts’ nesting habits have changed.

Adult Common Swift looking out of a Model 30 Swift box. Photo: © Pauline Weeks

The table below shows the approximate number of nest sites known to be occupied by swifts in 2018 and 2024 in different areas of Winchester. Numbers are presented according to whether the nests were in natural sites (i.e. cavities in buildings) or in a nest box. For those areas of Winchester that were not surveyed in 2024, numbers for that year were based on data from the most recent available survey of that area.

Approximate number of occupied Swift nests in Winchester in 2018 and 2024

Area	Natural sites 2018	Nest boxes 2018	Natural sites 2024	Nest boxes 2024
Abbots Barton	0	0	0	0
Badger Farm	0	0	0	0
Cathedral	0	0	0	16
The Close	2	0	4	0
Centre	16	0	13	2
College	30	0	30	0
Fulflood	27	3	21	32
Harestock	0	0	0	3
Highcliffe	17	2	5	43
Hyde	7	0	9	1
Kingsgate	26	2	14	11
St Cross	6	0	4	15
St Giles Hill	0	0	0	3
Stanmore	68	0	40	0
Teg Down	0	0	0	1
Weeke	16	0	4	6
West Hill	18	1	26	12
Winnall	0	0	0	0
Total by nest type	233	8	170	145

Total overall for 2018 is 241 compared with 315 in 2024.

The most striking observation is the huge increase in the number of swift nests that we found in boxes, up from 8 in 2018 to 145 in 2024. At the same time there has been a decrease in the number of natural sites that we identified as in use, down from approximately 233 in 2018 to 170 in 2024. This decrease is unsurprising given the widespread loss of natural nest sites as houses are renovated or re-roofed and wooden fascias and soffits replaced with uPVC versions. It can take time for swifts to view swift boxes as potential nest sites, but in areas of Winchester where many boxes have been installed, for example Highcliffe and Fulflood, annual surveys show there has been an increasing take-up of the boxes by swifts each year.

The original impetus to these box installations was the loss of swift nest sites brought about when Winchester City Council was found to be replacing the roofs, soffits and fascias of the many houses they owned in the Highcliffe area of the city. This work, which we believe started in 2017, was happening during the nesting season, with many nest sites being lost. We came to an agreement with the Council that all tenants would be offered a swift box when their house had such work carried out. This arrangement, together with growing interest from other Highcliffe residents in helping swifts, led to 126 swift boxes being installed in Highcliffe by the end of May this year. It is noteworthy that we found only 5 pairs of swifts in natural sites in Highcliffe in 2024, whereas we found 43 pairs in nest boxes. This is in marked contrast with the figures for 2018, when we found 17 pairs in natural sites, but only 2 in boxes. This change in nesting habits over time reflects both the growing scarcity of natural nest sites in this area, and the increased availability of swift boxes. The rise in the total number of breeding pairs found nesting in Highcliffe between 2018 and 2024 also demonstrates how a swift population can grow if enough nest sites are available to enable the birds to breed with ease.

Double Model 30 box

The Fulflood area of Winchester, in contrast to Highcliffe, has retained quite a lot of natural swift nest sites. The number of nests observed in natural sites was 27 in 2018, while the figure for last year was 21. These nests are in gaps under the barge boarding or eaves of the many, often substantial, Victorian houses that characterise this part of Winchester. Here too, many residents are keen to help swifts by having nest boxes installed. As a result, the number of breeding pairs observed using boxes in Fulflood rose from 3 in 2018 to 32 in 2024, and the total number of breeding pairs found increased from 30 to 53.

The data presented here are highly likely to underestimate the number of natural nest sites used by swifts in Winchester in 2018 and 2024. As swift surveyors know well, finding buildings that contain occupied natural swift nest sites and determining accurately how many nests are present can be hard. Swifts may nest on sides of buildings that are inaccessible to those trying to locate active nests. Furthermore, swifts enter and leave their nest quietly, discreetly and at great speed so they are easy to miss. Identifying which nest boxes are occupied by swifts is usually easier, but it can still take a lot of time to determine occupancy. The number of swift nest boxes installed in Winchester is now so large that we are unable to monitor them all, so apart from boxes in Highcliffe and Fulflood which are surveyed yearly, our data on nest box occupancy are also inevitably an underestimation.

Common Swift © Robert Booth

Our data suggests that in Winchester as a whole, swifts are now more likely to be nesting in boxes than in natural nest sites. Between 2018 and the end of May this year (2025), we installed 526 swift boxes in the city.  In some parts of the city there are still relatively few or no swift boxes. In other areas, local swift enthusiasts have encouraged people in neighbouring streets to contact us to arrange for boxes to be put up. In Teg Down, for example, where I have seen swifts seen searching unsuccessfully for nest sites, the distribution of a flyer about swifts’ need for nest sites has resulted in orders for 43 boxes so far. We know from areas of the city that we survey regularly that the provision of multiple nest boxes since 2018 has been accompanied by a rise in the numbers of breeding swift pairs. For Winchester as a whole, our data on the total number of swift nests in 2018 and 2024 are necessarily approximate, but the finding that numbers rose from 241 in 2018 to 315 in 2024, an increase of 31%, suggests that the provision of large numbers of artificial nest sites for swifts can boost their numbers. Without the installation of nest boxes, Winchester might have had only around 170 pairs of swifts in 2024, a decline of 27% in six years.  

Catharine Gale, Hampshire Swifts

Note:  If you see a swift enter a cavity in a building or a nest box either in Winchester or elsewhere in Hampshire, it would be very useful if you could report it to us each year by using the Hampshire Swifts Survey form www.hampshireswifts.co.uk/survey