House martin

One of the signs that summer will soon arrive in our village is the house martins building their nest under the eaves of the house over the road. Every year they return to raise a brood, and leave again as autumn approaches. In the meantime they swoop busily around the neighbourhood, catching insects on the wing to feed themselves and their young.

The house martin (Delichon urbica) is related to the swallow, as well as the sand martin, in the Hirundinidae family, but is only a distant cousin of species such as the purple martin which are more familiar in North America.

Appearance

House martins are about thirteen centimetres long, so they are smaller than swallows but slightly larger than sand martins. Like swallows, they have forked tails but the forks are much shorter, and the house martin is a more compact bird than the slender swallow.

Males and females have similar plumage, which is blue-back above and white underneath and on the rump, with brown wings and tail. The house martin has a clear “chirrup” voice and a longer song consisting of many twitters.

Breeding

Swallows build their nests on the inside of buildings but house martins prefer the outside, such as under eaves and on projections such as decorative brickwork on older houses. The nests are built from pellets of mud which the martins gather from puddles and pond margins, mixing it with their own saliva and pushing the pellets together to create a nest structure with a small hole at the top. The nest is then lined with soft material such as feathers and moss.

The clutch is usually of four or five eggs which both parents incubate for up to fourteen days before they hatch. The parents then work tirelessly to feed the nestlings as described above, catching flies, spiderlets and other airborne food to bring back to the nest. House martins often gather in colonies, with several nests joined together. This can mean that many birds are swooping between the houses throughout the day, which is a sight worth seeing. However, the carpet of droppings that forms on garden paths and on doorsteps is less delightful to the average householder!

The young birds will take wing at around 22 days but continue to use the nest as a roost for several days longer. They will need plenty of flying practice before they start their journey south for the winter, a flight of several thousand miles to southern Africa in September or early October. Next year they will return, with the parent birds probably repairing their old nest and the next generation starting nests of their own or taking over an abandoned nest.

According to the RSPB, the house martin is declining in numbers in the UK but not alarmingly so. They therefore count as having “amber” status.

© John Welford