My father-in-law was a big rabbit hunter and after he died, his sons found a diary (or log) that he had been keeping for many years. The diary detailed all the hunts, the dogs that were used, weather conditions, who hunted with him, and anecdotes about each hunt. This diary consisted of three big spiral notebooks. All we could figure was that after every hunt, the old man went to his room and jotted down pertinent facts about each hunt to remind him what covers were productive during each hunt and how the dogs worked under varying weather conditions.
A log like that is a good idea. I know that his sons took a great deal of comfort from it.