Monday, May 26, 2008

Bat Cave

For centuries, people responded to bats with superstition, fear and hatred. Upon finding bat caves in North America, many Europeans lined up along the entrance with shotguns--or dynamited them.

Fortunately, today people have grown to appreciate bats and the tons of insects they consume each night--a valuable ecological service. Instead of dynamiting bat caves, people now visit them to enjoy one of the great natural spectacles on earth.

I've seen some interesting bat emergences in Idaho, at the bat boxes of Ball Creek Ranch and in small caves in Hells Canyon. But the world's greatest bat flights are found in the Texas Hill Country.
The caves in the Hill Country contain the highest density of mammals on earth--with some caves containing millions of Brazilian free-tailed bats. The Nature Conservancy has protected important bat habitat here, including at the Eckert James River Bat Cave Preserve. At dusk, the cave is quiet save for cave swallows darting around. But before sunset bats start streaming out.
Frio Cave, where my dad and I recently visited, is home to 10-12 million free-tailed bats, plus a few hundred thousand myotis. Seeing them emerge is an astounding sight; within minutes bats stretch literally to the horizon. (As always, you can click on the photos in this blog to see a larger version). They eventually disperse, devouring insects on farm fields and ranches within 100 miles.
The bats now draw many tourists each summer, each paying fees to private ranches to enjoy the evening bat flight. In fact, many ranches now rely on abundant wildlife to help sustain their operations--through ecotourism, bat tours, birding and hunting. Because farmers recognize the value of bats, their populations are doing well in Texas. But in the eastern United States, thousands of bats are dying--and conservation biologists are trying to discover the cause.
Early settlers reported fires throughout their journey across Texas, but historians now believe the "smoke" they saw were bats emerging from caves. So dense are some swarms of bats that they show up as thunderstorm clouds on radar. At Frio Cave, it takes four hours for all the bats to emerge. It's one of those phenomena that reminds one of the grandeur that still exists in the natural world. --Matt Miller

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