When the old man was satisfied there would be no running away, he began Jerry's training.

By slow degrees he advanced the training until hours a day were devoted to it.
First of all Jerry learned a new name for himself, which was Bao, and he was taught to respond to it from an ever-increasing distance no matter how softly it was uttered, and Nalasu continued to utter it more softly until it no longer was a spoken word, but a whisper.

Jerry's ears were keen, but Nalasu's, from long use, were almost as keen.
Further, Jerry's own hearing was trained to still greater acuteness.
Hours at a time, sitting by Nalasu or standing apart from him, he was taught to catch the slightest sounds or rustlings from the bush.

Still further, he was taught to differentiate between the bush noises and between the ways he growled warnings to Nalasu.

If a rustle took place that Jerry identified as a pig or a chicken, he did not growl at all.