Full Moon Hike, Bats at Night

A glowing full moon peaks through the clouds. The temperature plummets. I rummage through the coat closet in search of mittens, hats, and winter jackets. I pile my family into the car for the hour drive to Westcave Discovery Center near Austin.

I have been looking forward to the December Full Moon Hike for months. I am writing about listening and seeing, about silence and darkness in karst, and I am curious about nocturnal sounds.

I hope we are able to descend the steep and winding trail that leads to the canyon and the grotto and the cave, but I think the afternoon rain will make the stone steps too slippery.

My youngest son, flashlight in hand, follows closely behind our guide. I soon realize that bringing him along on a listening hike might have been the wrong choice. He asks tons of questions. His exuberance spills over into his voice that grows ever louder and fills the spaces around us. I'm sure that any of the secretive, nocturnal creatures - porcupine, bobcats, owls - have fled to their hiding spots at this point.

But there has also been a sudden drop in temperature, from the eighties to the forties, a warm day that has turned into a chilly night, and the creatures are not as active as we had hoped. I wrestle with my hood, adjusting it so that it won't cover my ears and interfere with sound.

Along the way, flashlights reveal glowing eyes in the leaf litter and vegetation on the sides of the trails. Spiders. We shine light into the branches overhead, looking for owls. And soon my son finds harvestmen (a.k.a daddy long-legs) scurrying across the dirt and rocks and across our shoes. Everywhere. At night in the forest, so much happens under the veil of silence.

Then we turn and start down the cave trail. Yes! I can't imagine how beautiful the cave will be by moonlight, the sound of the waterfall nearby.

Earlier in the day, our guide saw a tricolored bat checking out the cave. She is curious to see if it is still there. This species is considered a microbat. They live in tree crevices and eat insects that hover near the creek. But when it gets cold, the bats search for caves, for shelter.

Using an infrared light, one that won't disturb the bat, we tiptoe into the cave and scan the ceiling. And there it is, a tiny bat hanging upside down, wings folded, motionless. Its compact body has entered into a state of torpor; temperature and metabolic rate have slowed to save energy. The bat relies on the warmth of the cave.

And then a flutter nearby startles us. At first I think it is a moth, but no, its too big. Excitement hijacks our hushed voices. Look! There is another one!

We leave quickly, carefully making our way over the slick rocks in the dark. I turn back for a moment to look at the cave. I imagine bats swirling near the entrance, making their way home. I can't believe our good luck, the rare opportunity to see tricolored bats. I look to the moon and soak up the silent energy of a wild night.