Swallows, of which there are about 75 species, are small, delicate, insect -eating birds found worldwide except Australia and New Zealand. Their wings are long, neck relatively short, body slender, feet small and apparently weak, and claws well developed. Although the bill is small, the mouth has a wide gape which is used to capture insects in the air. Swallows have much maneuverability and endurance in flight. Many are colonial and large flocks may develop at the time of migration. Nests contain three to seven eggs and may be built in sandbanks, on cliffs, in tree cavities, or on or in buildings.