What hints can people get from bird calls?

Sparrows chirp, indicating that the weather is fine. The oriole meows, it's going to rain. The cuckoo "cuckoo, cuckoo" calls the farmers to sow in the fields. Seagulls make bursts of calls when fishing, and fishermen can find fish according to the calls.

Birds, also known as birds. Definition: Egg-laying vertebrates covered with feathers.

The main characteristics of birds are that their bodies are streamlined (spindle-shaped or spindle-shaped), and most of them are mainly flying and living. 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. In addition to the lungs, the respiratory organs also have multiple airbags to assist breathing, so that birds have oxygen passing through the lungs when inhaling and exhaling, that is, double breathing.

References:

Baidu encyclopedia-bird