Swallows are in the Hirundinidae family. They have sharply pointed, angled wings and forked tails. There are 75 different types of swallows worldwide. Eight of the seventy-five species can be found in the United States and Canada, which live in the northern hemisphere and migrate south for the winter. They fly around in large flocks, eating insects out of the air. A flock of swallows require about 6,000 bugs a day to survive. Some of the insects they eat include houseflies, bees, hoverflies, mayflies, bluebottles and sometimes moth caterpillars that hang from the trees. Swallows are territorial birds and usually return to the same nesting site each year. They build mud pellet nests on buildings’ eaves and other structures. They spend most of their time in flight looking for food.