Every spring we eagerly await the return of our House Martins. They are familiar to us due to their habit of nesting on buildings, where they build a nest made of over 1,000 beak-sized pellets of mud. House Martin can be found throughout the UK, apart from the Orkneys and the Western Isles.They seem to prefer villages and towns away from both the most densely-populated and least-populated areas. Data from the Bird Atlas 2007–11 suggest House Martin is most abundant in eastern Ireland, the Welsh borders and in parts of the south-west, Yorkshire and Lincolnshire.
House Martin is easily identified if seen well by a combination of white underparts and dark blue upperparts (often looking black), with a distinctive white rump. Watch the BTO Bird ID workshop to help resolve any confusion with Sand Martins and Swallows.
Nests made of mud
House Martins are semi-colonial, with some pairs breeding on their own while others breed in large colonies of more than 30 nests. A new nest may take up to 10 days to build, though birds will often repair and re-use old nests. The presence of damp mud is an important factor in the choice of breeding sites, and studies have suggested that this needs to be within 300 metres, and ideally within 150 metres of the nest site. Nests are normally constructed underneath an overhang such as eaves or the top of a gable. House Martins will also make use of specially constructed artificial nests. A small number of House Martins continue to use natural nest sites such as coastal cliffs in north-west Scotland and inland cliffs such as Malham Cove in North Yorkshire.
Raising two broods a year
Unlike many summer visitors, House Martins do not always start breeding immediately after they return to the UK in April. Despite this, House Martins still manage to raise two broods and some may even raise three broods. In some instances the young from the first brood have been recorded helping to feed the young from later broods. The breeding season can last longer than many other species, and a small number of House Martins may still have young in the nest in September or even October.
House Martins are thought to winter in southern and western Africa south of the Sahara. However, we know very little about their wintering areas, making House Martin a priority species for tracking when suitably small tags are available. There has only been one recovery of a British-ringed House Martin from within the winter range. This was found in February 1984 in Southern Nigeria. The reason there are so few recoveries compared with Swallows, is that they do not form a communal roost at ground level where they can be easily caught.
House Martins are poorly surveyed by traditional methods but results suggest that the UK population has declined by 16% between 2001–2011, though long-term monitoring at sites in England, where they are faring worst, suggests a decline of 65% between 1967–2011.
House Martin is listed as a species of medium conservation concern (Amber) because of population declines in the UK, and because it is a species of conservation concern in Europe.
Their population trend in England is of high concern in comparision with the rest of the UK.
Why are House Martins in decline?
The possible causes of House Martin decline include -
- Limited aerial insect availability during the breeding season,
- Reduced suitable habitat and food during the winter in Africa,
- Adverse effects of weather conditions during migration,
- Limited access to mud for nest-building
- Restricted nest site availability (for example, on new houses)
Research suggests that bad weather conditions during spring migration can cause mass mortality. We also know that House Martins are affected by rainfall in Africa, causing big changes year to year rather than longer-term.
Volunteers have helped us to collect information about breeding House Martins on their houses via a small-scale survey during 2009–13, and we’ve been encouraging ringers to carry out project work. During the summer of 2014 we tested methods for surveying House Martins and their breeding colonies on a larger scale and we hope that this work will lead to a national survey in 2015 and 2016. We hope to establish a reliable population estimate, investigate how the population is distributed in the built environment and look at the position of nests, timing of nesting and number of broods from a wide geographic area.
How can I help?
The pilot work was funded by the 2013/14 BTO raffle but we are currently seeking funds to help us to carry out the two elements of a full survey in summer 2015 and 2016. We will be launching an appeal this October but, if you would like to support the project now, you can support this work by making a donation to help us to find out more about House Martins.
Scottish Birdwatchers' Conference
Every year the Scottish Ornithologist's Club arrange a one-day Scottish Birdwatchers’ Conference, organised by a local branch of the SOC, in conjunction with BTO Scotland.
Diversity in birding: why it matters
BTO's Jamey Redway reflects on diversity in birding, and how organisations like BTO play a role in making birding more inclusive.