When do swallows return to their nests?

The specific time is determined by geographical location. In South China and Yunnan, the early domestic swallow returned in June 5438+ 10; From February to March, domestic swallows began to return to the Yangtze River and the south in large numbers; From March to April, swallows began to return to the north of the Yangtze River in large numbers. April-May in Northeast China.

Swallows belong to passeriformes 1 genus. This genus of birds is relatively small, with a body length of 13 ~ 18 cm. The wing tip is long and the tail is forked. The back feathers are mostly gray, blue and black, so they were called mysterious birds in ancient times. The wing tip is long and good at flying, the mouth is short and weak, and the mouth is wide, which is a typical mouth shape of insect-eating birds. Short feet and strong claws.

Is there one in the world? Domestic swallows? Yan Yan, grey sand Yan, There are more than 20 species such as golden-waisted swallows and hairy-footed swallows. There are 4 species in China, among which domestic swallows and golden swallows are more common.