Hello @nobelcause, thank you for your upvote. You want to visit mara when there's alot of action - it happens during the wildebeest migration, approximately 1.5million of them cross river mara for feeding grounds.
Its is sad to see but they are food to the crocs in the water and other preys on land!
July August is the best time sometimes they cross in September too.
At this time the roads are a bit better as compared to April May when there is long rains.
Ps. Do your reservations on good time the hotels surrounding mara are always fully booked during that period.
Best wishes ☺☺