Hello Liverpool Nature Nerds,
Summer is almost upon us and it time for more migratory birds to arrive in the UK from Africa. We’ve had a few already but I for one can’t wait for the swifts, swallows and martins.
These three amazing birds are often confused with each other (I know I always have a problem with their identification, so I want to talk about their differences, distribution in the UK, habits and characteristics. This one is about house martins and sand martins.
House martin (Delichon urbicum, order Passeriformes)
These are small birds, in the same family as swallows, with glossy blue-black upper parts and pure white under parts, white rumps and forked tails. House martins feed on insects caught in flight. It winters in Africa and migrates to climates where flying insects are plentiful. They arrive in March/April and can be seen across the UK (though scarce in north and west Scotland), both open country and near human habitation. Because they feed on flying insects, their preferred areas are areas of mixed agriculture, near water and woodland. They migrate back to Africa in October.
Some facts about house martins from the RSPB
- They eat insects on the wing
- UK Breeding Populations: 510,000 pairs
- Length: 12cm, Wingspan: 26-29cm, Weight: 15-23cm, Beak: black, short and thin
- UK conservation status: Amber
Traditionally, they made their nests (out of wet mud, grass, lined with feathers and vegetable matter) on cliff faces but since the 19th century they have been using buildings, which has allowed them to expand their range to urban areas. Colonies of four to five nests are built on outer walls of buildings under the eaves and sometimes inside roofs or in sheds. Larger colonies of tens or even hundreds have also been reported. The colonies in towns are smaller than those in rural areas.
House martins breed when one year old and May to August is the breeding season, when insects are plentiful, the female laying four to five eggs (egg laying can be delayed if the weather is bad). Both adults incubate for 14 to 16 days and unlike swifts, all chicks hatch together. Sometimes, chicks can still be in nests till September. Feeding is also the responsibility of both parents, with the health, development and survival of chicks dependent on weather (due to the availability or not of flying insects). Chicks do have the capacity to survive a few days of bad weather by going into torpor and using their fat reserves. Fledging occurs after 22-23 days, again depending on weather, with the fledglings returning to the nest to roost and to be fed for several days. They remain in the colony for weeks before joining pre-migratory flocks, ready to embark on their return journey to Africa. They can have two or even three broods in one season, and the older chicks help their parents feed the younger ones. These birds are not long-lived and generally breed for one year (though some can have five to six breeding seasons). The oldest known wild bird was 14 years 6 months old.
Because their populations are greatly affected by weather, changes in climate have led to a decline in their numbers (47% reduction between 1970-2014 and 10% between 1995-2014 according to the RSPB). House martins need warm rainy weather so that there is a steady supply of insects and plenty of wet mud for their nests. Therefore, cool and dry weather causes problems with nesting and breeding. If there are house martins around your area you can help them by making an area of wet mud (a muddy pool or puddle) in dry weather. Another problem is a loss of nesting habitat due to barn conversions and in Africa they have seen a degradation of their winter habitats. They can often be in conflict with house sparrows, which take over nests and attack adults, eggs and chicks.
Artificial nests are available that can be placed under eaves to encourage them to breed. Sometimes a house martin nest falls down with the chicks still inside. If you see this happen, using an ice-cream tub for a replacement can help. Place the remains of the fallen nest and the chicks inside, after making sure there are drainage holes at the bottom and an opening on the side. Make sure to close the lid of the tub and hang it next to the original nesting site. When parents hear the chicks they are likely to start feeding them again.
Sand martin (Riparia riparia)
Like the swallows and house martins these also belong to the hirundine family, constituting its smallest members. They have dark brown upper parts, dark under wings and pale under parts with a prominent dark chest bar. And like their other family members they are also agile fliers, feeding over water and perching on branches or wires. According to the RSPB, the European population has crashed twice in the last 50 years, as a result of drought in the birds’ African wintering grounds.
Some facts about sand martins from the RSPB
- They eat insects on the wing
- UK Breeding population:100,000 nests
- Length: 12cm, Wingspan: 26-29cm, Weight: 13-14g, Beak: black, short and thin
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- UK conservation status: Green
Sand martins arrive in the UK in March/April and stay here till October, when they return to their wintering habitat in Africa. They can be seen along rivers and other water bodies throughout the UK, as well as around man-made gravel pits where artificial nesting banks are sometimes provided.
Like their cousins the house martins, these gregarious birds also nest in colonies, which may have more than a 100 pairs. Both male and female adults excavate tunnels in sandy, dry vertical banks in sand pits and gravel pits, railway cuttings, riverbanks and sea-cliffs, and sometimes in drainpipes in walls, holes in brickwork and even active quarries.
Usually four or five eggs are laid in late May or early June in a nest of feathers, grass and leaves, with both parents incubating the eggs for about 14 days. There are usually two broods each summer. All eggs hatch at the same time and the chicks are fed by both parents for 19-24 days. They are still dependent on the parents for feeding after fledging for about a week or so. Between July to September they start their return journey toward the Sahel (south zone of the Sahara). These are their wintering grounds and they feed in damp places with plentiful supplies of flying insects.