Sand Martins grow to 12 – 13 cm long with a wingspan of around 30 cm. Sand Martins are a bird species of the hirundinidae family. This term is often used by birders to describe a mixed group of Swallows and Martins, and Sand Martins are the smallest of this group and are migratory birds. Quite recently their numbers have diminished, caused by the drought that Africa has suffered where they overwinter. They are early visitors to Europe, arriving in March. The male Sand Martins arrive at the nesting grounds before the females. They use their beak to start burrowing into the river banks and as they progress they use their feet and wings to aid the tunnelling process. Once the tunnel is about 25 cm to 30 cm deep into the bank they are ready to attract a female. The male flies up and down the river bank close to the nesting site in pursuit of a mate. After pairing up both birds will continue to deepen the tunnel in the bank ready for egg laying. The nest consist of twigs, leaves, moss and anything that will make the nest warm, ready for their young. The female will lay up to 7 eggs and will incubate them for around two weeks and after around 3 weeks the young will fledge, sometimes returning in the evening to the security of the nesting site. The food sauce is invertebrates which are caught on the wing.