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Numerous bat caves are in Texas, in the limestone of the cretaceous formations being mostly west, northwest and north of Austin. In these caves, the bats stay during the day, coming forth about sunset and returning about daybreak. In northwest Burnet County, about one mile from the Colorado River, at an elevation of about 1,500 feet, there is a large bat cave in a hard, dark limestone, destitute of fossil, but probably of lower carboniferous age. During the late war, the bat deposits of this cave were used for the manufacture of saltpeter to make powder for the Confederate army.
A Mr. Allen, living in the river bottom about two miles below the cave, told me about it and its millions of bats, saying that it probably was very extensive, but that it only had been explored for a short distance. I proposed that we should explore and measure its extent, and arrangements were soon made. Our party of six men and boys, with candles and pine for torches, descended about 20 feet on an old ladder fastened to one of the perpendicular sides of the entrance by those making saltpeter. The opening to the cave has a diameter of about 20 feet one way and from 10 to 15 feet the other. At the bottom of the ladder, the entrance to the cave is about 10 feet high and 20 wide, going nearly horizontally, and enlarging at a short distance from the entrance.
We did not go far before the strong odor peculiar to the dwellings of bats became unpleasant. At 50 or 60 feet from the entrance, we began to see large numbers of bats hanging in clusters from the rocks above and on the sides of the cave. Our lights caused some of these to fly, but we kept onward, measuring the distance with a tape line. Entering a large right-hand opening, the top soon became lower, and our way was up and down over large deposits of bat manure. At about 300 feet from the entrance, the highest part of the cave was 8 to 10 feet; all along were bushels of bats above and on the sides of the rocky walls. Our lights and talk aroused them, and we soon had swarms of them flying around us, extinguishing our lights, compelling us to make a hasty retreat and putting a stop to farther explorations.
Next day, toward sunset, I rode with Mr. Allen on horseback to witness the egress of the bats. The sun was about an hour high when we arrived. There we had glorious views of the mountains and plains of Burnet and Llano counties and the valley of the Colorado River. Half an hour before sunset a few bats flew to the entrance of the cave, and after circling around a moment or two they returned to give notice that it was time to come out and begin work. About 15 minutes later, they began to come forth in large crowds, circling around until they were 25 or 30 feet above the ground, when they darted away in every direction in a galloping flight. So thick did the circling up column become as to form a dense mass of life. The rush and flapping of wings made a noise like a mighty wind. Never before had I seen such a grand exhibition of active life. They chatted gayly, and seemed as happy as school children when school is dismissed.
We watched the rush of bats until nearly dark, and when we left they were coming forth as thick and fast as ever. The scene to me was more wonderful than anything I had ever seen, for there must have been millions of bats in that cave. I was told that sometimes they did not return home again until sunrise. The inhabitants of that region are not troubled with mosquitoes and have few nocturnal insects.
Some years ago I occupied a room in the old land office at Austin which was then used for the geological collection. The ceiling above was of sheet iron, having a little attic above, next to the roof. To me, the attic was inaccessible. It was the home to thousands of bats, whom I could sometimes hear chattering during the day. I slept in the room below and just before daybreak I often heard the bats coming home jabbering in a lively way as they jumped along on the ceiling above, apparently talking of their adventures during the night. A jolly set they were.
Bats are not such somber, dismal things as they have been represented. Like the birds, they destroy our insect enemies, therefore bats are friends of the farmer and gardener, and should receive his protection. The bat caves of Texas will furnish a large amount of fertilizing material of great value to the agriculturist. At present the cheap rich lands in the vicinity of these caves seem to require little aid from fertilizers.
Samuel Botsford Buckley served as state geologist of Texas 1874–1875.