Rainsford, a famous hunter, does not recognize the sound of the hunted animal. What does this suggest he will find on the island?

"Raineford hears a sound. It came out of the darkness, yeah I screaming sound, the sound of an animal in an extremity of Anguish and terror. He did not recognize the animal that made the sound; where is fresh Vidality he swim Trevor where the sound. He heard it again; turn it was cut short by another noise, crisp, staccato."