Big Idea/Passage unpack

Alright, so my passage is on page 7 in my book so it's probably a little later in the other editions. It's essentially the part in parentheses that starts with "(Papa tells me to keep still, tells me that the dog senses a bird somewheres right close...)" The memory is referring to the moment that Chief is currently in right now. He is trapped in the broom closet, escaping shaving duty before breakfast. The Nurse is the dog in this situation. She can sense fear, and is not like the other nurses, who are "fish-gut eaters and [have] no class a-tall"(7). She is different and more intimidating than the rest. As long as he stays still, Chief can escape the assigned work. He just needs to keep quiet, and other asylum-mates' fear will distract the Nurse and she'll choose them for the work instead of Chief. Finally, when the bird makes a break for it, he gets shot down by Papa's "birdshot"(7).  In this case, the "black boys"(6) are the birdshot and drag him into shaving even though he wasn't assigned to it. Basically, the Nurse is the tyrant in this situation. While her job is to help the asylum-mates survive, she is basically doing the opposite. She creates more fear than there is already. These people are obviously not in the right mental state and the fact that she continues to threaten them with terrible jobs does not help them at all.