Sand martins are small, migratory birds belonging to the swallow family. They are known for their brown and white plumage, with a distinctive forked tail. These birds typically measure about 12 to 13 centimeters in length and are often seen flying low over water or open fields, catching insects in mid-air. Sand martins are unique for their nesting habits, as they dig tunnels into sandy banks or cliffs. They usually nest in colonies, where they lay 4 to 6 eggs. These birds are found across Europe, Asia, and North Africa, migrating to warmer regions during the winter months.