noun
whistler
WISS-ler/wˈɪslɝ/
Someone or something that makes a whistling sound.
My brother is a talented whistler who practices every morning.

Etymology
The verb meaning “to whistle” plus an agent ending gives “one who whistles.” The ancestor named a piper; later use for birds with whistling notes shows the extension beyond human performers.
More examples
- That little bird is a loud whistler for its size.
- The kettle is a shrill whistler when the water boils.
- Two whistlers in the crowd cheer for the winning team.
Forms
whistler · whistlers
whistle verb — Make a high, clear sound using air.