Observing the hawk.
When you're an apprentice, you're probably learning more than the hawk is. If you have no prior hunting experience, you're learning to determine the likely places game will hide, the sounds game makes, and how to judge distance. These, in addition to watching for potential hazards (any other raptor, transformers, dingoes and feral cats, PETA activists and car-radio thieves), learning how to walk over coarse ground without looking at it, and balancing a hawk steadily on one hand while kicking bushes, can make hunting an exhausting experience already.
One can easily forget to look at the hawk in all this. When quarry flushes, what happens? You automatically look at the quarry -- it's impossible to avoid. If your hawk is just learning this quarry, make sure you look at her too. Is she interested? Looking somewhere else? Has she fled in terror?
The falconer's closeness of observation is a key issue in all areas of hawk ownership. The eyes have to be developed to spot minute differences, but it starts from the mind: the desire to make a habit of observing and cogitating about the causes of what you've seen.
You want to notice injuries before they blossom into infections. Bent and broken feathers quickly worsen and threaten their neighbors if they are not immediately attended to. Equipment must be checked regularly for wear and tear. New weathering areas, perching areas and fields must be checked for potential hazards.
I used to take my female passage redtail out for coffee. When I sat in one location, she bated constantly, but if I sat in another, she was fine. I realized that she liked to have something solid at her back, where she would feel certain that no weird threatening things would come from. Thereafter I always sat in the second chair. This also explained her nervous behavior in the car (I let them ride unhooded), which was fixed by hanging a towel in one window to create a similar solid surface. (See 'Choices and Independence'.)
It's difficult to compile a list of hawk behaviors and what they mean, because I'm sure that different birds will have different reactions. But if you develop the habit of observing you will learn.