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Transcript for "Expedition Panama"

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EXPEDITION PANAMA: Echoes in the Night

What do bats do in the dark? Biologist Elisabeth Kalko has spent the last ten years at Barro Colorado Island, looking for answers to that question. Using a combination of modern technology and old-fashioned field observation, Kalko has made some astonishing discoveries about how bats use echolocation to identify and catch prey. Kalko's work studying bats in the tropical forest and interpreting bat calls will tell us more about these fascinating creatures of the night.

Curriculum Links
Activity 1: How Much Do You Know?
Activity 2: Echolocation Techniques



animal communication,
mammals, vertebrates

animal behavior


animal classification, pollination

acoustics, echolocation, sound


How often have you heard someone say, "I'm as blind as a bat!" Bats are the subject of many popular misconceptions and false information; people are both fascinated and repelled by them. No matter how much bats are disliked, they are under-appreciated. As major predators of insects, bats are beneficial and essential to the balance of nature. A common brown bat can devour 600 mosquitoes in one hour!

How much do you know about these creatures of the night?

True or False:

  1. Bats are blind.

  2. Bats are rodents.

  3. Bats are the only flying mammal.

  4. Some species of bats are threatened.

  5. Bat droppings (guano) are used to make some antibiotics.

  6. Bats cause a high percentage of rabies cases.

  1. False; many bats have poor vision; they are active at night and have developed a keen sense of sound; one suborder of bats uses sight and smell to find food.

  2. False; bats belong to the order Chiroptera; rodents like the paca belong to Rodentia.

  3. True.

  4. True; over 50% of American bat species are in severe decline or endangered.

  5. True.

  6. False; most of the fatal cases of rabies in the U.S. are caused by rabid dogs; bats very rarely bite those who handle them.


Elisabeth Kalko, seen on Frontiers, captures, identifies and tracks some of the more than 70 species of bat on Barro Colorado Island as they hunt for fish, fruit and insects. She uses a "bat detector" to convert bat calls so she can hear them.

Bats that use echolocation gauge distance by sending high-frequency, ultrasonic calls (as pulses) and measuring the time it takes for the reflected pulses to return (echo + location). Signals reflected back can also provide information on the type and size of a prey item. Humans can't hear many of the signals bats generate. Bat calls can range from low frequencies (9kHz) to very high frequencies (greater than 200kHz).

The game of Marco Polo is a little bit like echolocation. Can you make up a game that demonstrates echolocation? For example, one game might designate one person as the bat and other people in the group as various "prey" (frogs, fish, insects), each with its own audible code. The bat is blindfolded and has to locate each of its prey by sound. (Another kind of game might be modeled on the game Battleship. "Prey" use codes to designate their locations and the "bat" has to find them.)

  1. Compare the ways bats and other animals (dolphins, whales, some birds and shrews) use echolocation.

  2. How many references to bats can you find in movies and stories? Investigate some of the legends about bats. Compare the myths to reality. For example, how did the vampire bat get its name?

  3. Interested in finding out more about bats? You can find plans for bat houses and bat detectors on the Web. Start with this ultimate Web site for bats:

  4. Three of the animals featured in this episode of Frontiers (bats, bees, ants) are social creatures with complex societies. Compare their social organization.

  5. Listen to bat calls at this site:


Scientific American Frontiers
Fall 1990 to Spring 2000
Sponsored by GTE Corporation,
now a part of Verizon Communications Inc.