Question

1. The bird is losing the feathers that help to keep it warm.

Answer 1

Here are the answers to the given questions above.
1. Based on the given sentence, the  subject that agrees with the verb help would be the word FEATHERS.
2. The  pronoun that agrees with the underlined indefinite pronoun would be his or her.
Hope this answers your question. 

Answer 2

1.feathers 2.their.  this is all