by Bob Garrison and Jim Metcalf
Bat watching is taking off across the country. In downtown Austin, Texas hundreds of people gather each summer evening to watch thousands of Mexican free-tailed bats leave their day roosts under a bridge to hunt for insects. Wildlife viewers from around the world visit Bracken Cave in Texas to watch over 20 million free-tailed bats rise in huge columns at dusk in pursuit of over 250,000 pounds of insects each night. In California, bat viewing is a more subtle activity. Twenty-four species of bats live in California. They can be found in every part of the state, from mountains and deserts to urban neighborhoods. Most California species roost in small groups so you are more likely to see individuals or smaller numbers of bats on their evening flights.
Darkness offers a unique set of challenges that face both us as wildlife viewers and the animals that are active at night. Bats have conquered the dark through echolocation. Although bats can see quite well, they navigate and find food by emitting high-pitched sound waves that bounce off objects and back to the bats as they fly. A bat's hearing is so sensitive that not only can they find tiny insects using echolocation, but they can tell if it's a favorite variety of moth or beetle. Many insects can also hear the high-pitched calls of bats and swiftly take evasive flights to avoid being eaten. To capture wary insects, the California leaf-nosed bat uses sight to stalk its prey. With night vision better than the best human-made night scope, the leaf-nosed bat sneaks up on flying moths before using echolocation at the last second to catch the insect. We too can use echolocation at night, not to help us navigate, but to find bats. Many bats emit a high-pitched click or squeak that you can hear. Once you identify the sound, you can track the bats through the night sky.
Public interest in bats and bat viewing is coming at a time when over half of all bat species are in trouble across the nation. Once on the decline, bat populations can take decades to recover since bats generally produce only one baby a year. Insecticide poisoning, the closing of old mine shafts and caves used for day roosts, disturbance of day roosts by people, or the outright destruction of roosting and maternity colonies are the main threats to bats. Concerns about rabies have led to the unnecessary destruction of many colonies. About one bat in two hundred may carry the virus, but these individuals are usually too sick to fly and your chance of finding a sick bat is rare indeed. The most serious threat by wildlife viewers is the disturbance of day roosts. Do your part, stay clear of known roosts and restrict your viewing to times when the bats are flying.
The bat's nocturnal lifestyle makes them one of the most elusive of California's watchable wildlife species. You may not find bats on your first attempt, but follow these tips to improve your chances:
For more information on bats, building bat houses or to
join the effort in conserving bat populations contact:
Bat Conservation International
P.O. Box 162603
Austin, TX 78716