The cliff swallow, also known as the grey sand swallow, is a bird of the genus Swallow in the family Swallow, with a body length of about 11-14 cm, brown or sand grayish brown dorsal feathers, a gray-brown transverse band on the chest, white hairs on the abdomen and under the tail, and no white spots on the tail feathers. Adults have dark grey-brown upperparts, slightly pale coverts on the forehead, waist and tail, black brown at the eyes, grayish brown ear feathers, grayish white to the side of the neck, complete gray-brown chest bands, white hairs covering and under the tail feathers, flying feathers and coverts on the inside of the wings are the same color as the back, black brown on the outside of the flight feathers and coverts, gray brown on the axillary feathers, and black brown on the tail feathers. Gender homomorphism. The iris is dark brown; the mouth is dark brown; the toes are grayish brown, and the claws are brown.
They often live in groups of 30-50 birds, and sometimes hundreds of large groups. It is generally not far from the water, often flying in groups above the water surface or swamp, and sometimes it is seen flying in the air in mixed groups with house swallows and golden-loined swallows. Flying is brisk and agile, often shuttled to and from the surface of the water, and shouted while flying, but generally not flying high. Groups also rest on sand dunes, swamps or sandy beaches, and sometimes on roadside power lines and rice paddies.
Cliff swallows feed mainly on insects. Predatory activities in the air, specializing in preying on flying insects in the air, especially good at catching low-altitude flying insects close to the ground and water. The main food species eaten are Lepidoptera, Coleoptera, Hymenoptera, Homoptera, Diptera and Hemiptera, as well as zooplanktonic insects. The more common of these are mosquitoes, flies, flies, ants, leafhoppers, small beetles and ephemerals.