Wildlife watcher Felix Alred explains how to see these delightful birds in Suffolk before they make their epic journey back to Africa
Early in spring, as the days begin to lengthen and growth starts to return, many visitors arrive at their summer holiday residence. Among them are the truly impressive sand martins, small birds belonging to the swallow family which breed along the Suffolk coast and across the country.
At just 12cm long the sand martin is the smallest bird in the swallow family and can be identified by white underparts with a distinctive brown band running across the chest. Its wings are dark brown, as is the tail which is also forked to enable quick aerobatic movements.
Each year sand martins leave their winter lodgings in eastern Africa to migrate to Suffolk, crossing numerous countries and thousands of miles – remarkable for a bird with a wingspan of just 30cm. They do it to escape the hot African summer, making the long, arduous trip north to the UK’s more suitable climes.
With long pointed wings and a streamlined body, sand martins have great manoeuvrability and their compact structure gives them endurance whilst flying. They are almost constantly on the move, frequently gliding. Sharp vision and a wide mouth for catching gnats and mosquitoes make them highly skillful hunters.
These agile fliers are gregarious and nest in colonies of up to 100 pairs or more. Soft rock, such as sandstone, close to rivers and seas makes an excellent breeding ground. As soon as they arrive they dig burrows up to one metre deep in riverbanks or cliffs, with a chamber at the end lined with grass and straw – an ideal home to raise young.
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Continuous communication among the colony is common. This chatter is not only social but is used to communicate danger when the group bands together to drive out threats. Situated high off the ground means nests are less susceptible to land predators such as weasels, but there is still constant risk from kestrels hovering close by.
Sand martins often navigate the same migratory flight path to return to old nesting grounds, usually resulting in a more successful breeding season. But familiar sites can become damaged especially in coastal areas constantly exposed to bad weather and stormy seas.
Fragile habitats are also prone to erosion from the dozens of holes drilled by the birds, forcing colonies to relocate. Cliffs can collapse at any moment, which means nests must be rebuilt in time for females to lay between three and seven eggs in late May to June.
Eggs are typically incubated for two weeks and chicks remain in the nest for another three weeks before taking the leap into the outside world. Fledglings then spend the next two months flying and catching insects before it’s time to make the long journey back to Africa with the rest of the colony.
Next spring they will be back. . . to raise their own little sand martin family.
Where and when to see sand martins in Suffolk
Sand martins are here from March to September
They are widespread - see them flying and feeding over open water, perching on overhead wires, nesting in cliffs on the coast and by rivers, lakes and flooded gravel pits, railway cuttings
Visit:
Carlton Marshes
Corton cliffs, Lowestoft
RSPB Minsmere