Treehawking is a sort of falconry where you go around a lightly wooded area, taking along friends as "beaters" to flush out game. You tell dirty jokes, screw around, laugh a lot, and generally make a bunch of noise because that's what flushes out the prey---usually a rat or rabbit.
The hawk (in this picture, a female Harris Hawk named Valkyrie) keeps pace with the crew, staying near by flying from tree branch to tree branch as the crew moves along.
When something is flushed, you call out "Ho! Ho!" and the hawk swoops out of the tree and nails the prey.
It's a true thrill when a hawk streaks past you about waist high doing about forty miles per hour, tips upwards suddenly, then drops into the tallgrass to strike, within the space of a half dozen heartbeats.