Swifts spend practically the whole of daylight in the air, except when on the nest. It is a rare thing to see one on the ground. One can easily distinguish the swifts, even among swallows, by their brown colour. Their bodies are bigger, and they scream as they pass excitedly in the air. They do not twitter as swallows and martins do. These birds feed exclusively on insects caught while flying.
The sand martin is not likely to be seen in gardens. It builds its nest on the face of sandy cliffs, such as high gravel pits or river banks. The nest is placed at the end of a short tunnel. These birds are slightly smaller than house martins, and have no white on the back. The back of the sand martin is a grey brown, and the under parts whitish in colour.