The bird whistled an agitated sort of whistle.

The young birds whistle more shrilly than adults.

A ruffled-up bird in the vine whistled so like a flute that I did a bit of recitative as well.

Outside, the bird whistled again, and I felt as if I'd stepped away from a cliff.

Somewhere off to the side, what might have been a bird whistled something very mournful, a minor-key tune of endless variation.

Wind lulled, a bird whistled, sunlight baked odors out of the roses.

The window lightened; the white bird whistled softly, and said, "Kiss me again."

The bird whistled into the sky leaving the stench of burned jet fuel behind.

But some little bird on Nero's ship whistled a tune in Caesar's ear.

The bird whistled back, as if answering.