What are the benefits of swallows to human beings?

Swallows can catch locusts in the fields, protect crops, make crops harvest every year, and let people get good benefits.

In winter, the food supply of swallows in temperate regions is greatly reduced, so many species migrate. But unlike most other passerine migratory birds, swallows migrate during the day and fly at low altitude.

In addition, they often feed during migration, so their fat reserves are lower than those of other migratory birds of the same size. Species that breed in Africa often migrate with rainfall patterns, but the specific situation is little known. Other species, such as the gray-waisted swallow, seem to wander around without a fixed migration route.

Extended data

A slender body can reduce the resistance when flying. Swallow's wing shape has a high aspect ratio, which means that it can produce great lift and little resistance. However, this aerodynamic efficiency is at the cost of reducing maneuverability (for example, compared with short and wide wings), but this disadvantage is partially compensated by the forked tail, because such a tail can improve the maneuverability of birds.

The tail feathers of some species are very long, which can increase the lift. It acts like the flap of an airplane, ensuring the airflow to pass through the wings smoothly, and can delay the airflow when the swallow is ready to land, so that the swallow can stop flying without increasing the resistance. Most species have short tarsal bones and weak legs, which are suitable for inhabiting rather than walking, but those who dig holes or nest on cliffs have strong claws.