Detailed Instructions: In this task, you are given a paragraph, and your job is to generate comma-separated entities present in the given paragraph. Generate entities from a given passage in such a way that (i) they are present in the paragraph, (ii) they are non-duplicate, (iii) they underwent a state change during the process. Avoid creating entities that (i) aren't present in the process paragraph and (ii) aren't significant. 
Q: An egg is laid by a mother bird. A baby bird forms within the egg if it is fertilized. The baby bird begins pecking out of the egg. The baby bird is unable to fly to get food. The mother bird must feed the baby bird food. The bird grows stronger and grows wings. The bird is able to fly. The bird is able to leave the nest and find food. The bird is able to reproduce. 
A:
egg ,baby bird; bird ,wings 