Answer:
The phrase which begins with a gerund and functions as a noun is called gerund phrase. It is a verb ending with -ing but functions as a noun and can also act as object, subject or complement in a sentence.Example: Cooking is a creative hobby. Here Cooking is the subject of the sentence.
He heard loud chattering of the blue jays- Chattering is the Gerund and Chattering is acting as a an object.