Researchers used the Sir Philip Sidney game to model how chick begging signals evolve among siblings.

Three bags full, sir, I'll do whatever you ask without question.

We sailed through the Sir Francis Drake Channel at sunrise, marveling at the crystal-clear water and scattered cays.

At the annual fair, children lined up eagerly to try the Sir Philip Sidney games.

At the village fair, the crowd gathered to dance Sir Roger de Coverley until sundown.

At the village fair, the band struck up a lively tune and the crowd joined hands to dance Sir Roger de Coverly.

The researchers were thrilled when they discovered Sir David's long-beaked echidna in the remote mountain forest, confirming the species' elusive presence.

Sir David's long-beaked echidnas foraged quietly beneath the ferns while researchers took careful notes.

Sir David's long-beaked echidnae foraged quietly among the ferns at dawn.

When the new officer addressed him as 'sir,' the senior enlisted man chuckled and said, don't call me sir, I work for a living.