What part of speech is fluttering?

it means: (of a bird or other winged creature)

Explanation:

prime examples)

to fly with light, swift wing movements or to move the wings lightly and swiftly up and down in flight, as a bird. similar words: flit

to beat or pulsate swiftly or irregularly. Her heart fluttered when she heard the news

To fly with light, swift wing movements or to move the wings lightly and swiftly up and down in flight, as a bird. similar words: flit