These were baby limpkins, and as they dropped from the tree, fell into the water and were able to swim ashore. The leopard walked down to the river's edge, picked one chick, eat it and so on.
Then went to take a siesta.
But the next day in the same area, there were 4 males and one female. It became clear to me that the fight that I saw the previous day was not a game; they were fighting for the privilege to visit with the girl. By this time, the scores were settled and prevailing male was mating with the "she jaguar".
One day I followed a jaguar along the shores of the river from a boat while he hunted for capybaras. These giant rodents are very alert and can swim and dive swiftly. He saw a family of capybaras with a young one. As he paused, somehow the male capybara became aware of his presence, gave a sharp call to which the mom and baby responded by jumping from about 20 feet in height into the river. The male followed soon after.