Aerial feeders in Scotland

01 Aug 2014 | No. 2014-49

They say that “one swallow doesn’t make a summer”, but there’s no doubt that the arrival in Scotland of our aerial feeders – swallows, martins and swifts – from south of the Sahara in Africa is greeted with joy by many people. The latest results from the Breeding Bird Survey (BBS) reveal that House Martins increased by 125% in Scotland but fell by 27% in England between 1995 and 2012 – but why are House Martins faring better in Scotland than England?  

Research into habitat requirements tells us that House Martins need mud for nest building to be within about 300m of the nest site, as well as good food availability within 1km. Building design and home improvements also potentially impact on nest site availability. While these could be limiting factors at a local scale, little is known about the extent to which they are responsible for national population changes.  Their wintering grounds, south of the Sahara, are poorly known and conditions there, or on their migration route, may be playing an important role.  The BTO plans to work with its skilled volunteers to find out more about House Martins in the UK via a dedicated survey in 2015.

In contrast to House Martins, the latest results show that Scottish Swifts show more ubiquitous declines, by 62% in Scotland and 38% across the UK as a whole between 1995 and 2012. A familiar species around our towns, cities and villages, Swifts are thought to have been affected by a decline in suitable nest sites as modern building design and refurbishment of old buildings can deprive them of places to nest, although public awareness has been raised and good advice for homeowners and the building industry is now available. As long-distance migrants, negative changes on their wintering grounds or on migration routes again, probably have a major role to play.

Swallows, more characteristic of farmland, have increased by 37% between 1995 and 2012 in Scotland. The long-term information held by the BTO shows that Swallow populations in the UK have fluctuated markedly through time, with regional variations in food availability due to land management changes across the UK thought to be a key influence. Increases in areas of pasture for livestock in the north and west of the UK are considered to have provided more foraging habitat for Swallows in recent decades. Our fourth aerial specialist, the Sand Martin, is a little more localised around wetland habitats and the latest BBS suggests no significant changes in overall Scottish population levels since 1995.

These results for Scottish aerial feeders are just some of the important stories told by this year’s new survey results. The results lend powerful support to the growing body of monitoring information showing how badly most wading birds are faring in Scotland – for example showing that breeding Curlews declined by 55% and Lapwings by 58% in Scotland between 1995 and 2012. Drainage of farmland, changes in agricultural practices and other habitat loss in the lowlands, and reduced breeding success in the uplands, in some places driven by increased forestry and more generalist predators, are likely problems that require further research to understand their relative impacts.

The BBS is the main scheme for monitoring the population changes of common breeding birds in the UK and its constituent countries, using counts made by volunteer birdwatchers. Population trends for 62 bird species in Scotland have been calculated in the latest BTO/JNCC/RSPB Breeding Bird Survey annual report.

Sarah Harris, BBS Organiser at the British Trust for Ornithology, said “It is great to see an increase in volunteer coverage in 2013 across Scotland again and data submitted from some very dedicated, long-standing volunteers. For a species that nests on our homes, it is worrying that the reasons for House Martin declines across the UK as a whole are not fully understood. The contrast in their latest population trends in Scotland compared to England could hold a clue.”

Chris Wernham, Head of BTO Scotland, said “These latest BBS results show once again the importance of monitoring by skilled volunteer birdwatchers to provide regular updates on how our birds, and the habitats that support them, are faring. We are very grateful to all those volunteers who have taken on new BBS squares in Scotland, including many in the uplands, in the last two summers. With such rich information from this and other surveys now available to us, the challenge for the conservation science community is to work together to use it wisely and in a timely way to ensure the best objective evidence is available to guide conservation decision-making in Scotland.”

Jeremy Wilson, Head of Conservation Science at  RSPB Scotland, said ”The Breeding Bird Survey continues to be a critical barometer of the health of bird populations and the wider environment in Scotland, and  RSPB’s Centre for Conservation Science is carrying out urgent research to help understand the causes of the rapid declines of Kestrels, Curlews and Swifts in Scotland.”

Notes for Editors

  1. The latest report can be found at
  2. The Breeding Bird Survey is run by the British Trust for Ornithology (BTO) and is jointly funded by BTO, the Joint Nature Conservation Committee (JNCC) (on behalf of the Council for Nature Conservation and the Countryside, Natural England, Natural Resources Wales and Scottish Natural Heritage), and the Royal Society for the Protection of Birds (RSPB).
  3. The BTO/JNCC/RSPB Breeding Bird Survey (BBS) is a UK-wide project aimed at keeping track of changes in the breeding populations of widespread bird species. The BBS involves around 2,800 participants who survey more than 3,600 sites across the UK, enabling us to monitor the population changes of over 100 bird species. Knowing to what extent bird populations are increasing or decreasing is fundamental to bird conservation.

    The information provided by the BBS provides a cornerstone for conservation action for birds in the UK.

    This important survey is carried out by volunteer birdwatchers throughout the UK, who receive no financial reward or expenses for their efforts. We are indebted to them for their tremendous support.
  4. In 2013, 471 BBS squares were surveyed in Scotland. This was a marked increase on the number surveyed in 2012, and, in particular, many new upland squares were taken on by volunteers, increasing coverage of important Scottish habitats. We are grateful to the Scottish Ornithologists’ Club, Scottish Natural Heritage and many other partners who have supported us in engaging more volunteers via the What’s Up? upland monitoring initiative (see
  5. For further advice on Swift conservation can be found at and the RSPBs webpage
  6. The BTO is the UK's leading bird research charity. A growing membership and up to 60,000 volunteer birdwatchers contribute to the BTO's surveys, collecting information that underpins conservation action in the UK. The BTO maintains a staff of 100 at its offices in Thetford, Stirling, Bangor (Wales) and Bangor (Northern Ireland), who analyse and publicise the results of surveys and projects. The BTO's work is funded by BTO supporters, government, trusts, industry and conservation organisations.

Contact Details

Sarah Harris
(Breeding Bird Survey Organiser)

Office: 01842 750050
(9am to 5.30pm)
Email: sarah.harris [at]

Paul Stancliffe
(BTO Media Manager)

Office: 01842 750050
(9am to 5.30pm)
Mobile: 07585 440910 (anytime)
Email: press [at]

Ben Darvill
(BTO Scotland)

Office: 01786 466562
(9am to 5.30pm)
Email: ben.darvill [at]

Louise Cullen
(RSPB  Communications Officer, Scotland)

Office: 0131 317 4136
Email: louise.cullen [at]

Dr. Andy Douse
(Policy & Advice Manager, Ornithology, Scottish Natural Heritage)

Office: 01463 725241
Email: andy.douse [at]

Images are available for use alongside this News Release.
Please contact images [at] quoting reference 2014-49

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