1. Birds are good for people everywhere, especially for improving the natural environment. Birds are natural insect catchers and good helpers for farmers.

2.① A swallow can eat 500,000 to 654.38+00,000 mosquitoes, flies and aphids in a summer. ② An owl can kill 1000 voles in one summer, which is equivalent to protecting a ton of grain. (3) A thousand gregarious purple-winged starlings can exterminate 20 tons of locusts in the breeding season.

About birds

1. Birds, also known as birds. Definition: Egg-laying vertebrates covered with feathers. The main characteristics of birds are: streamlined bodies (spindle or spindle), most of which can fly.

2. The body surface is covered with feathers, and the forelimbs generally become wings (some kinds of wings degenerate); The pectoral muscles are developed; Short rectum, large appetite and fast digestion, that is, the digestive system is developed, which helps to lose weight; The heart has two atria and two ventricles, and its heartbeat is fast. The body temperature is constant.

References:

Baidu Encyclopedia: Birds