Tom couldn't hear the cockerel crowing.

Did you hear a cockerel crowing as well?

The cockerel crows early in the morning.

Did you hear the cockerel crowing?

The cockerel, herald of the morning, wakes those of us sleeping.

Beware of the cockerel. It bites.

The cockerel's splendid red cockscomb is thought to play a part in determining gender and breed.