1. Seeing the World Through Their Ears: The Exotic World of Bats
# 32
Seeing the World Through Their Ears: The Exotic World of Bats
Dr. George Pollack
October 22, 2004
Produced by and for Hot Science - Cool Talks by the Environmental Science Institute. We request that the use of these materials include an acknowledgement of the presenter and Hot Science - Cool Talks by the Environmental Science Institute at UT Austin. We hope you find these materials educational and enjoyable.

2. Seeing the World Through Their Ears: The Exotic World of Bats
George D. Pollak
Section of Neurobiology
School of Biological Sciences
The University of Texas at Austin
Picture of a Mexican free-tailed bat, Tadarida brasiliensis mexicana.
Photo courtesy of Bat Conservation International, Inc. ( Used with Permission.

3. George Pollak in his lab
My field is neurophysiology, the mechanism by which the brain works. I study how sensory information is processed by the brain, and my focus is on how the auditory system processes and represents features of the external world.
Brain of a Bat
“Reality” is what our brains construct from information provided by our sensory organs.
What is so captivating about sensory physiology is that the world we perceive is not absolute reality, although we think it is. What we believe to be reality is only the world that our sensory receptors tell us about the various energies in the world; light, sound, chemicals in the air, etc.. But that is only half of what is required. Our brains then have to construct that sensory information into “perceptions”. In other words, how we perceive the world and everything in it is limited by the information provided by our sensory receptors and then by the particular computations that our brains perform on that information. Our reality is nothing more than that which our brains construct for us. Now comes the spooky part: If our receptors were different or if our brains operated differently, the world we perceive would be vastly different from the one we experience every day.
The image on the left is the brain of a bat. The schematic bars shows sound entering the ear and being processed by a nerve cell in the brain. The resultant electrical activity is being record as digital signals.

4. Our sensory receptors and brain create the world we know
Example of neural construction: color vision. We think of colors as an inherent attribute of objects: daffodils are yellow, your eyes are blue or brown or even green.
But, objects have no inherent color. The brain creates color using input from the photoreceptors in your retina (red, green & blue cones). If you had different photoreceptors, you would see different colors or no color at all.
A good example of a neural construction is color vision. We all think of colors as inherent attributes of objects: daffodils are yellow, the shirt you are wearing is green or red, your eyes are blue or brown or even green. It may come as surprise, but objects have no inherent color; color is constructed by the brain from the information provided by the three types of photoreceptors in your retina; the red, green and blue cones. If you had different photoreceptors, you would see different “colors”, just as people with color blindness do, or no color at all. And if your brain were not able to construct color, you would not see colors even if your retina were normal.
Rainbow image from:
If your brain could not create color, you would not see colors, even if your retina were normal!

5. Many animals are able to sense energies that we cannot
Rattlesnakes
(Pit Vipers)
Bees
Electric Fish
eye
pit
Now try to imagine how you might perceive the world if you had sensory receptors that were sensitive to energies to which our sensory receptors are insensitive, and that your brain had networks for interpreting that sensory information. This is what attracts many scientists to the world of exotic senses. We share our planet with a vast array of other living organisms, and they too have to monitor the world with their sensory organs and their brains have to then interpret that information as sensory perceptions. But each species is adapted to its own world, and both the sensing and perceptions of the world around them are often different, sometimes vastly so, from the way we sense and perceive the world.
Rattlesnakes:
Rattlesnakes are called pit vipers because they have two eyes: one is just like our eye while the other, the pit just below the eye, only sees infrared wavelengths that are emitted from the bodies of warm blooded animals. They see body heat, even in the dark!
Bees:
Bees see ultraviolet wavelengths, which we cannot see. We see flowers as having certain colors, but the same flowers look entirely different to bees than they do to us!
Electric Fish:
The electric fish of South America and Africa emit a weak electric field around themselves and “see” their world through the distortions in the field created by objects in their environment. The spikes in this picture show the electric signals put out by this fish.
Rattlesnake photograph from
Bee photograph from Photo by Mike Ash.
Electric fish photograph from:
Rattlesnakes have two kinds of eyes: one just like ours, and one that sees heat (infrared wavelengths) They see body heat, even in the dark!
Bees can see ultraviolet wavelengths, which we cannot. We see flowers as having certain colors, but the same flowers look entirely different to bees!
The electric fish of South America and Africa emit a weak electric field. They “see” their world through distortions in the field created by nearby objects.

6. This is how a dog appears to us or to a rattlesnake in daylight
Photo from InfraMation, Vol. 3, Issue 3, March 2002, Infrared Training Center, available at: used courtesy of Infrared Training Center and James Petersen.

7. This is how a dog appears to us in the dark
Photo from InfraMation, Vol. 3, Issue 3, March 2002, Infrared Training Center, available at: used courtesy of Infrared Training Center and James Petersen.

8. This is how a dog appears to a rattlesnake at night
Somebody was
Sitting here!
This is how a dog appears to a rattlesnake at night
This is how a dog appears to a rattlesnake in the dark because it sees the dog’s body heat with its infrared receptors.
Photo from InfraMation, Vol. 3, Issue 3, March 2002, Infrared Training Center, available at: used courtesy of Infrared Training Center and James Petersen.

9. This is how we see a yellow butterfly
This is how a bee sees the same yellow butterfly
This is how we see a yellow butterfly
Butterfly photos by WebExhibits:

10. I have not the slightest inkling of how electric fish perceive their world
Electric fish photograph from:

11. The Exotic World of Bats
Austin is known as the bat capital of the world, and Austinites love their bats. Every evening hundreds and sometimes thousands of people gather to watch the bats emerge from under the Congress Street Bridge. But long before Austin became enamored with bats, some wondered how bats could orient and maneuver with such speed and dexterity in the pitch dark, where vision is of no use.
Photo courtesy of Bat Conservation International, Inc. ( Used with Permission.

12. In the late 1800s the great Italian natural scientist, Lazzaro Spallanzani, was the first to study how bats could fly and avoid objects in the dark, where vision was of no use.
Lazzaro Spallanzani
The first scientific studies of bats, and the ensuing controversy, began in the latter part of the eighteenth century, with the studies by the Italian naturalist, Lazarro Spallanzani. This was a time when scientists were debating whether living organisms came from non-living matter; that is, whether life generated spontaneously, or emerged from pre-existing life. Spallanzani’s experiments were cornerstones in establishing the modern concept that all animals arise from other animals, but this was not the only scientific question that he solved. Spallanzani was also captivated by bats, and wondered how these animals, unlike other flying animals, could navigate through dark passageways without colliding with either the walls or objects in their path. Indeed, he was so intrigued by these abilities that he undertook a series of experiments to determine which of their senses allowed bats to do this. Spallanzani was a careful and thorough scientist. He eliminated each sense - vision, hearing, and touch - one at a time, and tested the abilities of his bats to fly in complete darkness with the same accuracy as they did in the light. What he found was that only when the ears were plugged did the animals' abilities to orient in the dark suffer. These, and other similar experiments by a contemporary, Louis Jurine who was a French surgeon, showed definitively that the ears are the sense organ that allows bats to orient by flight in the dark.
But very few in the scientific world at that time accepted the findings of Spallanzani and Jurine or their conclusions. Indeed, the explanation that became universally accepted was that bats were able to detect objects in the dark with an enhanced sense of touch, from receptors distributed on their wings. Even though Spallanzani had covered their wings and bodies with varnish and paste, which greatly reduced their sensitivity for touch, the scientific world simply could not accept the idea that bats use their sense of hearing for orientation and obstacle avoidance. There was, of course, no sound for the animal's to hear! At least no sound that humans could hear. Since what we know about the world around us is derived from our sensory organs, and since no sounds could be heard while bats flew, it followed naturally that bats could not possibly be using something that wasn’t present to detect things around them. Thus, ridicule was the order of the day, and one of Spallanzani’s contemporaries asked, "Since bats see with their ears, do they hear with their eyes?"
Spallanzani image from Busnel, R. G., ed., 1966, Animal Sonar Systems, Volume 1, Nato Advanced Study Institute, INRA-CNRZ,, Jouy-en-Josas 78, France.

13. Rediscovery of Echolocation
In 1939 two young graduate students at Harvard, Donald Griffin
and Robert Galambos, conducted a series of experiments which
showed that bats navigate in the dark and avoid obstacles by emitting loud, ultra-sonic sounds and listening to the echoes that bounce off of nearby objects.
In 1942 Griffin coined the term, echolocation, to describe
this form of biological sonar.
The Rediscovery of Echolocation in Bats
There the issue lay for more than 140 years, until the late 1930s, when two young graduate students at Harvard, Donald Griffin and Robert Galambos, once again took up the question of how bats orient in the dark. Griffin was a graduate student in biology, whose interests in bats began when he was a young boy growing up in New England. There he banded bats in their caves during the summer months and followed their return to the same caves year after year. Galambos was a graduate student in neurophysiology, whose interests were in the functioning of the auditory system. Between 1939 and 1942, Griffin and Galambos repeated the experiments of Spallanzani and Jurine, obtaining the same results, although they were unaware of their predecessors work at that time.
Griffin also recruited the services of an eminent engineer at Harvard, George Pierce. Pierce was experimenting with ultrasonic frequencies in his work with the newly emerging areas of radar and sonar, devices that were important for the military prior to and during the Second World War. He had a device that could record ultrasonic frequencies, frequencies or pitches far above those that humans can hear (humans can only hear frequencies from about 20 cycles/sec to 20,000 cycles/sec, but only if one’s hearing is very good). Griffin and Galambos convinced Pierce to let them bring bats into his laboratory. When the bats flew in Pierce’s laboratory, the instrumentation came alive with a steady stream of loud, ultrasonic chirps that the bats emitted as they flew around the lab. Pierce’s new instrumentation allowed Griffin and Galambos to, at last, hear the ultrasonic sounds of bats. The problem of the earlier period was now solved. There was indeed sound for the bats to use for obstacle avoidance, and the bats themselves were emitting those sounds. But since the bat calls were ultrasonic, they could only be detected by state of the art equipment, unless you were a bat. The final proof came a few years later, when Galambos, a student of auditory neurophysiology, showed that the ears of bats could actually respond to the same ultrasonic frequencies they emitted in their sonar calls. This form of biological sonar was indeed a new sensory ability, and Griffin called it echolocation.

14. Donald Griffin at his laboratory at Harvard
Donald Griffin in his laboratory at Harvard University.
Image from Busnel, R. G., and Fish, J. F., eds., 1979, Animal Sonar Systems, Plenum Press, New York, NY.

15. Bats use a form of biological sonar called echolocation to see their world
Bats do not “see” their world through their eyes the way we do. Rather they have substituted their sense of vision with their sense of hearing. They orient in their environment and recognize objects through a form of biological sonar called echolocation.
Bats use echolocation in a way similar to the way we use a flashlight to see the world around us in the dark. The light from the flashlight reflects from close by objects, and we see those reflections with our eyes. Bats make their own “flashlights”, so to speak. Instead of using light powered by a battery in a flashlight, bats use the power of their voices as an acoustic flashlight. As they fly, they emit a constant stream of loud, high frequency sounds. The frequencies are much higher then we can hear and thus are called ultrasonic sounds. The ultrasonic sounds they emit then bounce off of close by objects and return to the bat’s ears as echoes. Bats not only detect objects with echoes, their brains also form acoustic images from those echoes. In short, bats are not only able to detect objects in their environment, but more importantly, they can actually recognize and identify objects from the echoes they hear. It is quite amazing that they really do “see” with their ears”!
Image from Leen, N., and Novick, A., 1969, The World of Bats, Holt, Rinehart, and Winston, 171 p.

16. Watch Echolocation in Action
A mealworm is flipped in the air and a little brown bat tracks the mealworm with its echolocation calls and scoops it out of the air with its wing! This video segment was made at Harvard by Don Griffin and his colleagues more than 40 years ago. It is shown in slow motion.

17. Video of Brown bat catching a mealworm
MOVIE
Movie of a little brown bat catching a mealworm that was tossed in the air. Notice the cadence of the echolocation pulses that the bat emits as it homes in on the mealworm. At first the pulses are emitted with a long interval between each pulse. As the bat homes in on its target the pulse repetition rate progressively increases until the rate reaches a crescendo just before the bat intercepts the worm. The high repetition rate of emitted pulses just before capture is known as the “terminal buzz” and is considered a signature that always occurs when bats track and either capture insects or avoid targets.
Scientists generally believe that the first pulses, emitted at long inter-pulse intervals, indicate that the bat is searching its environment. Detection of a target is indicated when the pulse rate is initially speeded up. Now the bat is gathering information for target identification. During the terminal buzz, which is the final phase of echolocation, pulses are emitted at a high rate so that information about the target can be constantly updated and final adjustments of the body made to successfully catch an insect.
Video from film made by D. Griffin and F. Webster, Courtesy Donald Griffin.

18. It is not echolocation but rather the ability to fly that distinguishes bats from all other mammals. Bats fly with their hands!
These are their fingers
Bats are mammals. Like all mammals they give birth to live young and nurse their young with milk from their mammary glands. Bats, however, are different from all other mammals, because they are the only mammals capable of sustained flight. As shown on the next slide, their wings are formed by their fingers that are greatly elongated and are webbed by the thin sheets of skin that connect their fingers. For these reasons they are placed in their own group of mammal, the order Chiropteran, which means, “wing handed”.
You might have thought that it is their ability to echolocate that distinguishes bats from other mammals. But bats are not the only mammals that use echolocation. Many toothed whales, such as porpoises and beluga whales, also use echolocation to hunt in the oceans. And it is not only some whales and bats that can echolocate. There are even some birds that can use a more primitive form of echolocation to find their way in dark caves.
Image from Leen, N., and Novick, A., 1969, The World of Bats, Holt, Rinehart, and Winston, 171 p.

19. Bats Populate the Entire Planet and Eat Everything Available
The adaptations that allow bats to fly and “see in the dark” were among the most successful adaptations nature has ever created. Bats were so successful that they spread far and wide, invading almost every region on earth, tropical and temperate, except for the polar ice caps. Bats may well be the most successful mammal on Earth, in terms of the number of species (about 1000 species of bats are known) and absolute numbers of individuals. There are, for example, about 20 million bats in Bracken Cave in central Texas, and the vast majority of the Bracken bats are one species, Mexican free-tailed bats. Bracken Cave alone has a population of one species that is almost equal to the number of people that live in the entire state of Texas!
As bats invaded the four corners of the Earth, they exploited not only insects, but also any type of food that was plentiful. Each species adapted and became a specialist for one or another food resource. Many species use their biosonar to hunt insects in the night sky. Others adapted their biosonar to detect and catch large ground dwelling insects. A few species, the fishing bats, used their sonar to detect small fish swimming near the surface of a pond or lake. Other species, the infamous vampire bats of Central and South America, even dine exclusively on blood. Others used their echolocation to orient in the jungle to exploit the rich supply of tropical fruits, while others sought night flowering plants for their offerings of sugar and pollen. Some are even carnivorous, such as the frog-eating bats of Central and South America.
Each group tailored the physical features of their bodies - their tongues, teeth, noses, claws, as well as their biosonar calls - to their particular needs. These adaptations endowed that animal with the ability to exploit a food supply in a particular ecological niche.
Photo courtesy of Bat Conservation International, Inc. ( Used with Permission.
Bats Populate the Entire Planet and Eat Everything Available

20. A horseshoe bat detects a moth and begins to home in on its target
A series of photographs showing an echolocating horseshoe bat as it detects and begins to home in on a moth it has detected.
Image from Leen, N., and Novick, A., 1969, The World of Bats, Holt, Rinehart, and Winston, 171 p.

21. The bat uses its wing to scoop the moth out of the air and then eats the moth while still in flight
In the final stages of echolocation, the horseshoe bat scoops the insect out of the air with its wing, which it uses like an outfielder in baseball uses his glove to catch a fly ball. The bat then eats the moth while still in flight.
Image from Leen, N., and Novick, A., 1969, The World of Bats, Holt, Rinehart, and Winston, 171 p.

22. Returning home with a large insect
A big-eared bat has caught a katydid.
Photo courtesy of Bat Conservation International, Inc. ( Used with Permission.

23. The elegant fishing bat emits echolocation calls and detects a fish on the surface of the water
The elegant fishing bat emits echolocation calls and detects small fish from the echoes reflected from their fins on the surface of the water.
Image from Leen, N., and Novick, A., 1969, The World of Bats, Holt, Rinehart, and Winston, 171 p.

24. These claws are used to gaff fish on the surface
The fishing bat has detected a fish and prepares to drag its claws through the water to gaff its dinner.
Image from Leen, N., and Novick, A., 1969, The World of Bats, Holt, Rinehart, and Winston, 171 p.

25. Skimming the water to gaff a fish
Here the bat drags its long claws in the water and gaffs a small fish that it detected on the surface with echolocation.
Photo courtesy of Bat Conservation International, Inc. ( Used with Permission.

26. A fishing bat gaffs a fish!
Here again the bat gaffs a small fish that it detected on the surface with echolocation.
Image from Leen, N., and Novick, A., 1969, The World of Bats, Holt, Rinehart, and Winston, 171 p.

27. Oh, what big ears you have. All the better to hear you with
Oh, what big ears you have. All the better to hear you with! This bat can actually hear the beetle’s footsteps!
Some bats, called gleaners, orient in the environment with echolocation, and at the same time they listen for any sounds on the ground caused by insects moving around. They then locate the insects from the sounds they make and grab the insect with their teeth. All gleaning bats have very large ears. These bats can actually listen to two things at the same time! They listen to the echoes from their echolocation calls and the noisy sounds generated by insects.
Photo courtesy of Bat Conservation International, Inc. ( Used with Permission.

28. The frog-eating bat specializes on tungara frogs
The frog-eating bat specializes on tungara frogs. This little tungara frog is in big trouble!
The carnivorous frog-eating bats of Central and South America, Trachops cirrhosus, are unusual and illustrate the adaptations bats evolved which allowed them to tap into a particular source of food. Frog-eating bats were discovered by Merlin Tuttle, the Director of Bat Conservation International, Inc. whose headquarters are here in Austin, and Mike Ryan, who is now my colleague at the University of Texas and one of world’s leading evolutionary biologists. Merlin and Mike showed that frog-eating bats use biosonar for orientation, to find their way around the jungle, but they do not use their sonar to detect and locate their prey. Their favorite meal is a particular small frog, the tungara frog, hence the name, frog-eating bat. During the mating season, male tungara frogs sit in shallow ponds and entice fertile female frogs to mate by emitting a species-specific call, its advertisement call. Unbeknownst to the frogs, bats are cruising overhead, eavesdropping on their boisterous serenades. When the bat hears the male frog’s crooning, the bat swoops out of the sky, guided by the frog’s advertisement call, and grabs the unsuspecting frog.
Photo courtesy of Bat Conservation International, Inc. ( Used with Permission.

29. An unfortunate tungara frog provides this frog-eating bat with a late night snack
The frog-eating bats grab tungara frogs out of the water.
Photo courtesy of Bat Conservation International, Inc. ( Used with Permission.

30. Dining on the nectar offered by a night flowering plant
Bats are important for the pollination of many flowers.
Photo courtesy of Bat Conservation International, Inc. ( Used with Permission.

31. A sugar treat is offered by a night flowering plant
A nectar eating bat helps to pollinate night flowering plants. Notice the large tongue this bat has to gather the nectar from these plants. This is an example of a special adaptation bats have evolved which allows them to exploit a particular source of food.
Photo courtesy of Bat Conservation International, Inc. ( Used with Permission.

32. A bat returns to its cave with some ripe fruit
Some bats specialize on ripening fruit that is plentiful in tropical forests.
Image from Leen, N., and Novick, A., 1969, The World of Bats, Holt, Rinehart, and Winston, 171 p.

33. These are the infamous vampire bats
Vampire bats are super specialists and derive their food by drinking the blood of other animals.
Photo courtesy of Bat Conservation International, Inc. ( Used with Permission.

34. Although he looks goofy, those incisors are razor sharp!
The vampire bats use their razor sharp incisors to nick the skin of another animal.
Image from Leen, N., and Novick, A., 1969, The World of Bats, Holt, Rinehart, and Winston, 171 p.

35. Specialized for lapping blood
The sharp incisors are used to nick the skin without the victim even noticing. The bat’s saliva contains an anticoagulant to prevent the blood from clotting, while the special muscles in its tongue “ripple” the blood up with peristaltic actions.
Image from Leen, N., and Novick, A., 1969, The World of Bats, Holt, Rinehart, and Winston, 171 p.

36. Bats often live in caves where they form colonies that can number in the millions. They establish and maintain their social structure through vocal communication.
While bats are best know for their use of echolocation, they also use vocal signals to establish and maintain the social structure within their colony. Mexican free-tailed bats offer one of the most dramatic illustrations of the importance of vocal communication for bats. These bats are common in the Southwestern United States where they live in caves with populations that often number in the millions, as in Bracken Cave and under the Congress Street Bridge, both in central Texas. Males use vocal signals to establish dominance hierarchies, maintain territories, garner females into harems and defend their harems against intruding males. Mating occurs in the winter and in the spring the pregnant females segregate into enormous “maternity colonies”. Birth occurs within a week in mid-June, and millions of newborn bats form a blanket of pink pups that cover extensive portions of the cave walls. The problems facing both mothers and pups are formidable. The pups are vulnerable and have to be cared for and fed for up to six weeks following birth. Mothers leave the cave each evening to hunt, and upon returning to the cave each mother has to identify her own pup from the millions of other pups in the nursery colony, lest she spend her milk feeding an unrelated pup. This recognition is achieved with both olfactory and acoustic cues. The acoustic signals mothers use to recognize their own pups are the isolation calls, which are emitted by the pups immediately after birth, while the directive calls emitted by the mothers enable each pup to recognize and maintain contact with its mother. Thus, the isolation and directive calls are vocal signatures required for bonding and kin recognition.
Photo courtesy of Bat Conservation International, Inc. ( Used with Permission.

37. Your eyes are not deceiving you. The walls are covered with bats.
Colonies of Mexican free-tailed bats that live in caves often number in the millions.
Photo courtesy of Bat Conservation International, Inc. ( Used with Permission.

38. The nightly exit of bats from Bracken Cave in central Texas
It is estimated that 20 million Mexican free-tailed bats live in Bracken Cave in central Texas. Every evening the bats leave the cave to hunt insects in the night sky.
Video courtesy of Barbara French.

39. A large colony of Mexican free-tailed bats live under the Congress Avenue Bridge in Downtown Austin
Photo shows the bats that live under the Congress Avenue Bridge in Austin, Texas.
Photo courtesy of Bat Conservation International, Inc. ( Used with Permission.

40. We study the vocal communication calls of bats in the colony that Barbara French established and maintains in Austin
Barbara French at work
Barbara French is an astute biologist who has maintained a colony of Mexican free-tailed bats in Austin for the past 10 years. She not only cares for the bats, but she knows a great deal about each individual and how each bat fits into the social structure of the colony. Barbara knows her bats in the same way that Jane Goodall knew her chimpanzees. Barbara together with my students and I, study the vocal communication calls of the bats in her colony.
Photo credit: George Pollak.

41. This is Sid, one of the dominant males in Barbara’s colony
My students and I have been studying the vocal repertoire of a colony of Mexican free-tailed bats maintained in Austin by my colleague, Barbara French. Two of the calls that we recorded with Barbara are particularly dramatic and provide a flavor for the complexities of their calls and the contexts in which they use vocalizations for social communication. The first is the courtship call, emitted by males during the breeding season to entice females into their harems for breeding. An example is Sid, one of the males in Barbara’s colony, and we eavesdropped on Sid’s overtures when we recorded his courtship song. Here is how Sid entices the ladies: he douses himself with chemical secretions called pheromones, and then wafts his “perfume” to the females by flapping his wings, while he serenade the “ladies” with his courtship song. It is a very elaborate display performed with great flourish. It is really quite a sight and sound, as you can in this video clip of Sid.
Image credit: George Pollak

42. Sid woos the ladies with his courtship song
Video of Sid wooing the ladies with his courtship song. From the personal library of George Pollak.

43. Joshua is another dominant male in Barbara’s colony
Joshua is another dominant male in Barbara’s colony. Here Joshua is defending his territory and harem against an intruder.
A female in Joshua’s harem
Joshua
Intruder
The males not only have to entice females, they also have to defend their harems against other males who want to steal the females for their own harems. So during the breeding season, male bats are highly territorial and will warn any intruding male to stay away by singing their territorial songs. If the intruding male does not back away immediately, the male who is defending his territory will viciously attack the intruder. These fights can result in the death of one of the bats. Here Joshua, another male bat in Barbara’s colony, is warning an intruder with his territorial song and is defending his territory by attacking the intruding male.
Image from personal library of George Pollak.

44. Joshua warns an intruder not to enter his territory by singing his territorial call
Video of Joshua singing his territorial call and warning an intruder not to enter his territory. From the personal library of George Pollak.

45. I hope you have enjoyed this brief tour of the Exotic World of Bats
I hope you have enjoyed this brief tour of the Exotic World of Bats. Check them out for yourself. The exodus happens every night and can be seen at the Congress Avenue Bridge in downtown Austin.
The End
Photo courtesy of Bat Conservation International, Inc. ( Used with Permission.

46. Dr. George Pollack
George Pollak received his Ph.D. in Physiology from the University of Maryland Medical School in1970. After completing his postdoctoral work in the Department of Biology at Yale University, he joined the faculty at the University of Texas in Dr. Pollak has had extensive collaborations with scientists both in the U.S. and in Europe. He was a Visiting Scholar at the University of Frankfurt, the University of Munich, the Neuroscience Institute of Salamanca University in Spain, and at the Virginia Merrill Bloedel Hearing Research Center at the University of Washington Medical School. His research has earned numerous awards, including a Research Career Development Award from the National Institutes of Health, a prestigious Alexander Von Humboldt Award, and a Claude Pepper Award from National Institute of Deafness and Other Communicative Disorders in recognition of his contributions to auditory neuroscience. Dr. Pollak also received a President's Associates Teaching Excellence Award from the University of Texas at Austin. He currently serves on the Executive Committee of the Institute for Neuroscience at the University of Texas and is Professor of Neurobiology there.