If the baby bird can't open its mouth, you can help it open its mouth with your hands and feed it with the prepared cotton swab. Better feed it now. It should be noted that the swallow is in poor health, so don't choose to feed it at this time.
It is suggested to put it in a warm and weak nest, let it recover its strength quietly, and then feed it. When it grows up and can flap its wings and fly, it can feed some bread worms properly.
Extended data:
Swallows are beneficial birds for human beings, and mainly feed on insects such as mosquitoes and flies. A swallow can prey on more than 500,000 pests in one summer, thus protecting crops.
Swallow is a famous summer migratory bird in China. It migrates to the north in early spring every year and spreads all over the country in summer. After breeding, they migrated south in groups and wintered in India, Nanyang Islands and Australia.
Swallows feed on insects. They have always been used to preying on flying insects in the air, but they are not good at finding insect food in tree gaps and ground gaps. There are no flying insects for swallows to prey on in winter in the north, so they migrate.