2. Features

(1) Tails like scissors can reduce the resistance in the air and change direction with the wind direction.

(2) Yanshan flies fly in groups over the village and its nearby fields most of the time. She flies fast and agile, sometimes flying high, soaring in the air like an eagle, sometimes flashing close to the water, running here and there, up and down, with no fixed flight direction, and sometimes constantly making sharp and urgent calls.

(1) The scientific name of Swallow is the general name of 74 species of passeriformes. Small size, narrow wing tip, short beak and concave tail, weak feet and few feathers. Feathers are monochromatic, blue or green, with metallic luster; Most kinds of men and women are very similar. Swallows spend a lot of time catching pests in the air. It is one of the most flexible birds, mainly feeding on insects such as mosquitoes and flies, and is a well-known beneficial bird. Nest in tree holes or cracks, or make holes in sand dikes, or stick mud on walls or protrusions of corridors, roofs, eaves, etc. In urban and rural areas. 3 pounds per work? Seven eggs.

(2) Swallows are beneficial birds for human beings, and mainly feed on insects such as mosquitoes and flies. A swallow can prey on more than 500 thousand pests in a summer, thus protecting crops. Swallow is a famous summer migratory bird in China. Migrate to the north in early spring and spread all over the country in summer. After breeding, they move south in groups and overwinter in India, Nanyang Islands and Australia. [ 1]? Swallows feed on insects, and have always been used to preying on flying insects in the air, but they are not good at searching for insect food in cracks in trees and on the ground. They can't omnivore berries and seeds like grouse and Thunderbird, eat leaves in winter (some conifers don't shed their leaves even in winter), and they can't dig up larvae, pupae and eggs of latent insects like woodpeckers and woodpeckers. There are no flying insects for swallows to prey on in winter in the north, so they migrate.

References:

Baidu encyclopedia: swallow