We lucked out on this as we had not originally planned to do the Bat Flight. As it turned out the population was moderately high, ~ 50,000 and so after listening to a nice presentation by a Park Ranger on the history of the program as well as the bats we were presented with a nice view of the bats exiting the cave. It would have been nicer with a little more evening sunlight but it was nice to see them come swirling out and over the rim. Definitely watch the weather and time of night as both impact visibility and even whether the bats exit in quantities that can be detected. The return can be seen for free as well if you can manage a 0500 rise/drive to the visitor center :-) It was a wonderful experience.
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