Swift

Listen to example recordings of the main vocalisations of Swift, provided by xeno-canto contributors.

This species can be found on the following statutory and conservation listings and schedules.

UK Birds of Conservation Concern	Red listed
Species of European Conservation Concern	Near Threatened
IUCN Red List of Threatened Species (global)	Least Concern
Schedule 1 license required (to disturb)	No
Birds Directive Annex 1	No
Listed on the Annexes of	Bern(III)

Swifts were not monitored before the inception of the BBS. Their monitoring is complicated by the difficulty of finding occupied nests, by the weather-dependent and sometimes extraordinary distances from the nest at which breeding adults may forage, and by the often substantial midsummer influx of non-breeding individuals to the vicinity of breeding colonies. Since Swifts do not normally begin breeding until they are four years old, non-breeding numbers can be large. BBS results indicate that steep declines have occurred in England, Scotland and Wales since 1995. Many Swifts seen on BBS visits will not necessarily be nesting nearby, however, and the relationship between BBS transect counts and nesting numbers has not yet been investigated. The BBS map of change in relative density between 1994-96 and 2007-09 indicates that decrease has been widespread, with some limited increases in parts of Wales and western Britain. On the strength of the BBS decline, Swift was moved from the green to the amber list of conservation concern in 2009 (Eaton et al. 2009) and then to the red list in 2021. A moderate decrease has been recorded in the Republic of Ireland since 1998 (Crowe 2012). Numbers across Europe have been broadly stable since 1980 (PECBMS: PECBMS 2020a).

UK breeding population

-60% decrease (1995–2020)

Swifts have a broad breeding distribution, with higher densities in warm, dry areas such as East Anglia, and lower densities in northern and western regions. In Britain & Ireland they nest almost exclusively in buildings and distribution and abundance maps show a close match to the built environment, with concentrations in towns and cities.

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Occupied 10-km squares in UK

No. occupied in breeding season	2273
% occupied in breeding season	75
No. occupied in winter	4
% occupied in winter	0.1

European Distribution Map

European Breeding Bird Atlas 2

Breeding Season Habitats

Most frequent in

Towns

Relative frequency by habitat

Relative occurrence in different habitat types during the breeding season.

In Britain the overall number of occupied 10-km squares has shown little change, but in Ireland there has been a 26% range contraction since the 1970s.

Swifts are summer visitors, arriving from late April with birds gradually departing from mid July; most birds usually departed by mid September but odd birds can appear even as late as November.

View a summary of recoveries in the Online Ringing Report.

Foreign locations of birds ringed or recovered in Britain & Ireland

View number ringed each year in the Online Ringing Report

Maximum Age from Ringing	17 years 11 months 5 days (set in 1999)
Typical Lifespan	9 years with breeding typically at 4 year
Adult Survival	0.808

Wing Length	Adults	175.1±3.7 | Range 169–181mm, N=2130
	Juveniles	169.3±6.6 | Range 157-177mm, N=99
	Males	176.2±3.3 | Range 170–181mm, N=57
	Females	174±4.1 | Range 168–181mm, N=143

Body Weight	Adults	39.5±3.36 | Range 34.0–45.2g, N=1160
	Juveniles	32.1±5.0319 | Range 27.4–44.0g, N=97
	Males	40.8±4.06 | Range 34.1–45.5g, N=24
	Females	41.9±3.68 | Range 37.3–47.0g, N=93

Feather measurements and photos on featherbase

Ring size	SO
Field Codes	2-letter: SI | 5-letter code: SWIFT | Euring: 7950

For information in another language (where available) click on a linked name

Causes of change

The causes of the decline are unclear, although a recent analysis of BTO monitoring data (Finch et al. 2023) suggests that changes in juvenile (but not adult) survival are the most likely driver of the decline. 

Further information on causes of change

Analysis of phenological change suggests that Swifts both arrive and depart in the UK earlier than in the 1960s, with the length of stay consequently remaining unchanged (Newson et al. 2016). Low juvenile survival appeared to be associated with poor weather conditions (Finch et al. 2023), implying a reduction in availability of aerial insects was causing additional mortality. Modern building design and refurbishment of old buildings are likely also have contributed to the decline by depriving Swifts of nest sites, but the complications in monitoring trends and nests (as described in the Status Summary) make it difficult to confirm the primary drivers of change.

Information about conservation actions

This species is difficult to monitor and hence the main drivers of the decline are uncertain. Given confirming the cause of decline is challenging and likely to remain so for some time, it would be prudent to take some precautionary actions whilst research is ongoing. Provision of additional nesting space to counter any reductions in availability of nest sites as a result of modern building designs and refurbishment of older buildings, either in the form of Swift nestboxes and Swift bricks which can be integrated into new buildings and renovations, as supported by Action for Swifts, Swift Conservation and similar organisations, are a relatively straightforward and inexpensive conservation action which can be taken by local groups and individuals, and can also be incorporated into wider development planning. Swifts are known to use these artificial nests (e.g. Schaub et al. 2015). The availability of nest sites could also be increased on a wider scale by implementing policies or regulations which encourage or legislate the provision of nest boxes or Swift bricks on new buildings. Swift Towers are another option which have been used in Europe. Further information and advice about providing boxes and attracting Swifts to them is available on the Swift Conservation website.

Swifts can forage over an extremely wide area during the breeding season, so other conservation actions such as habitat management in the vicinity of nest sites (to attempt to increase the availability of prey) are unlikely to be successful, unless they can be undertaken on a wider landscape scale. Whilst actions to increase levels of invertebrates across the wider countryside may benefit Swifts, further research is required, both to confirm whether changes to invertebrate abundance might be a cause of the Swift decline, and if so to identify the habitats which will provide the optimal requirements for foraging Swifts.