Some of the largest bat populations on earth make their summer home here in several critical caves. Pregnant females in these huge maternity colonies each give birth to a single young. The evening emergences of millions of bats create some of nature's most spectacular sights, especially when young begin to fly in late July. During the night a large colony will consume many thousands of pounds of insects.
Bats sometimes emerge up to three hours before sundown, forming dense columns over the hills.
Hawks and owls are often seen at the same time as they cruise the skies, looking for a meal of their own among the exiting bats. Babies learn to fly in four to five weeks and begin storing fat for their long journey south to Mexico for the winter. At speeds of up to 40 miles an hour in level flight and much more with a good tail wind, they are capable of climbing as high as 10,000 feet during the trip. Free-tails begin to leave Texas in fall, riding the winds of one of the first cold fronts in late October or early November. They return early the next spring.