Why can swallows fly in the rain?

Swallows can fly in the rain because they can secrete an oil on their feathers and their wings will not get wet.

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. There are more than 20 species of domestic swallow, rock swallow, grey sand swallow, golden waist swallow and hairy foot swallow in the world, and there are 4 species in China, among which domestic swallow and golden waist swallow are more common.

The entries come from the Internet.