Apus apus (Linnaeus, 1758)
Family: Apodiformes > Apodidae
Swift is the long-distance migrant most associated with people, as it chooses to nest amongst our urban dwellings.
We await the return of Swifts to Britain and Ireland in early May and they are given the accolade of bringing the summer with them. Written about in poetry and prose, the dark scythe-winged silhouettes of Swifts wheeling about in a blue sky are often accompanied by their screaming calls.
Although widespread across much of Britain & Ireland, Breeding Bird Survey data have documented a significant decline in their populations. The reasons for these losses are likely to include poor summer weather, a decline in their insect food and continued loss of suitable nesting sites.
Select a topic for more facts and statistics about the Swift
Swift identification is often straightforward. The following article may help when identifying Swift.
With their swept back wings and aerial lifestyle hirundines (Swallow, Sand and House Martins) and the similar, but unrelated, Swift often cause ID headaches. Let us help you to separate these amazing summer visitors.
Listen to example recordings of the main vocalisations of Swift, provided by xeno-canto contributors.
Develop your bird ID skills with our training courses
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Status and Trends
Population size and trends and patterns of distribution based on BTO surveys and atlases with data collected by BTO volunteers.
This species can be found on the following statutory and conservation listings and schedules.
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.
Occupied 10-km squares in UK
|No. occupied in breeding season
|% occupied in breeding season
|No. occupied in winter
|% occupied in winter
European Distribution Map
Breeding Season Habitats
|Most frequent in
Relative frequency by habitat
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.
Change in occupied 10-km squares in the UK
|% change in range in breeding season (1968–72 to 2008–11)
|% change in range in winter (1981–84 to 2007–11)
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.
Information about movement and migration based on online bird portals (e.g. BirdTrack), Ringing schemes and tracking studies.
An overview of year-round movements for the whole of Europe can be seen on the EuroBirdPortal viewer.
Lifecycle and body size information about Swift, including statistics on nesting, eggs and lifespan based on BTO ringing and nest recording data.
|Number of Broods
|25×16 mm Weight = 3.5 g (of which 6% is shell)
View number ringed each year in the Online Ringing Report
|Maximum Age from Ringing
|17 years 11 months 5 days (set in 1999)
|9 years with breeding typically at 4 year
|175.1±3.7 | Range 169–181mm, N=2130
|169.3±6.6 | Range 157-177mm, N=99
|176.2±3.3 | Range 170–181mm, N=57
|174±4.1 | Range 168–181mm, N=143
|39.5±3.36 | Range 34.0–45.2g, N=1160
|32.1±5.0319 | Range 27.4–44.0g, N=97
|40.8±4.06 | Range 34.1–45.5g, N=24
|41.9±3.68 | Range 37.3–47.0g, N=93
Feather measurements and photos on featherbase
|2-letter: SI | 5-letter code: SWIFT | Euring: 7950
For information in another language (where available) click on a linked name
Interpretation and scientific publications about Swift from BTO scientists.
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.
A 30,000-km journey by Apus apus pekinensis tracks arid lands between northern China and south-western Africa
Exciting research conducted by an international team shines a new light on Swift migration.
Are the declines of birds and invertebrates linked by climate change?
Many of the detected effects of climate change on biodiversity have occurred through impacts on food chains.
Demography of Common Swifts Apus apus breeding in the UK associated with local weather but not aphid abundance
Ringing and Nest Record Scheme data suggest weather is a better predictor of Swift breeding success than the availability of insect prey
New research explains Swift migration patterns and some of the challenges they face that may be contributing to their decline.
Identification of putative wintering areas and ecological determinants of population dynamics of Common House-Martin <i>Delichon urbicum</i> and Common Swift <i>Apus apus</i> breeding in Northern Italy
To identify the causes of population decline in migratory birds, researchers must determine the relative influence of environmental changes on population dynamics while the birds are on breeding groun
Links to more information from ConservationEvidence.com
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