From my mother, Vickie:
Ok first off let's get real on the lion scare. The very large lion was doing what we learned male lions do - lying around while the women do all the work hunting and bringing his meals to him. As we watched him in awe of being so close, our guides explained the lion only sees the safari vehicle, not us as long as we were still, and that they do not attack two legged creatures. As he suddenly rose up to change his lying down position, he moved in the direction of the vehicle, which caused Anna to speak some inappropriate language and push everyone aside trying to get to the other side of the vehicle, causing the guides to instruct her to sit down and then, normally somber, they laughed out loud.
But on to the migration. Normally taking place in early to mid July and August, we were amazed to see thousands of wildebeest and zebra all moving in the same direction or waiting in groups while others caught up. Skip and the guides estimate 50,000+. When we got to the river, we saw herds of wildebeest on both sides. We watched two majorly slippery, muddy, steep inclines on both sides of the river and wildebeest bulls led the way as mothers and calves followed. As they reached the river they leapt into the water one at a time and started swimming across to a similar incline on the other side. Some calves would follow, while some would start and then turn around. The mother would swim back and forth to encourage the calf while a crocodile sunbathed just below. As one particular calf circled several times unable to get up the incline, our guides announced "crocodile bait." But those watching cheered as the calf finally scrambled up the trail and we were spared the kill. What an amazing experience. We learned the next day from a group we met that they had waited 4 hours at the same lookout on the same day and never saw the crossing!