My uncle is a guide at a local frm and, if the hunters (all members) expect he and his dogs to work for birds the next time they book him, he is tipped after the hunt. Tipping amount varies but it's usually between 15-20%.
If you hired a guide for "real" hunting you need to consider a lot of variables, but the rule of thumb is this....if the guide is wowing you and your partners you'll probably want him to be "available" next year too. Guides remember who tipped well the previous year. So tip well so he remembers you.
If the service is lousy or your expectations are not being met; the time to let your guide know is well before you tip him poorly.