do bats drink blood fascinating answers to questions about bats animal q amp a series

8/4/2019 Do Bats Drink Blood Fascinating Answers to Questions About Bats Animal Q Amp a Series

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Do Bats Drink Blood?


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Animal Q&A: Fascinating Answers to Questions about Animals

Animal Q&A books invite readers to explore the secret lives o

animals. Covering everything rom their basic biology to their

complex behaviors at every stage o lie to issues in conserva-

tion, these richly illustrated books provide detailed inormation

in an accessible style that brings to lie the science and natural

history o a variety o species.

Do Butterfies Bite? Fascinating Answers to Questions about Butterfies

and Moths, by Hazel Davies and Carol A. Butler

Do Bats Drink Blood? Fascinating Answers to Questions about Bats, by

Barbara A. Schmidt-French and Carol A. Butler


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DoBats Drink

Blood?Fascinating Answers toQuestions about Bats

Barbara A. Schmidt-Frenchand Carol A. Butler

Rutgers University PressNEW BRUNSWICK, NEW JERSEY, AND LONDON


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Library o Congress Cataloging-in-Publication Data

French, Barbara A. Schmidt

Do bats drink blood? : ascinating answers to questions about bats /

Barbara A. Schmidt-French, Carol A. Butler.

p. cm.(Animal Q&A)

Includes bibliographical reerences and index.

ISBN 9780813545875 (hardcover : alk. paper)

ISBN 9780813545882 (pbk. : alk. paper)

1. BatsMiscellanea. I. Butler, Carol A. II. Title.

QL737.C5F82 2009

599.4dc22

2008048065

A British Cataloging-in-Publication record or this book is available

rom the British Library.

Copyright 2009 by Barbara A. Schmidt-French and Carol A. Butler

All rights reservedNo part o this book may be reproduced or utilized in any orm or by

any means, electronic or mechanical, or by any inormation storage and

retrieval system, without written permission rom the publisher. Please

contact Rutgers University Press, 100 Joyce Kilmer Avenue, Piscataway,

NJ 088548099. The only exception to this prohibition is air use as

defned by U.S. copyright law.

Visit our Web site: http://rutgerspress.rutgers.edu

Manuactured in the United States o America

Disclaimer: Some images in the printed version of this bookare not available for inclusion in the eBook.


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Contents

Preace ix

Acknowledgments xi

ON E Bat Basics 1

1 What is a bat? 1

2 How are bats classifed? 1

3 How many species o bats are there in the world? 4

4 Where in the world are bats ound? 65 When did bats evolve? 7

6 Are all bats black? 9

7 How long do bats live? 11

8 Which is the biggest bat? 11

9 Which is the smallest bat? 12

10 How ar can bats y? 12

11 How ast do bats y? 12

12 How high do bats y? 1413 Are bats intelligent? 15

14 Do bats drink blood? 19

TWO Bat Bodies 22

1 How are bats dierent rom birds? 22

2Why do bats hang upside down? 233 Do bats have teeth? 27

4 Can bats walk? 28

5 How ast do bats grow? 29


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6 Are bats blind? 30

7 Why do bats have big ears? 31

T H R E E Bat Life 34

1 What do bats eat? 34

2 Where do bats live? 39

3 Why do bats like caves? 42

4 Do bats only y at night? 43

5 What do bats do during the day? 45

6 Do all bats live in groups? 46

7 What is bat guano? 478 Do bats migrate? 48

9 Do bats hibernate? 51

FOUR Bat Behavior 53

1 How does echolocation work? 53

2 How do bats navigate in the dark? 57

3 Do all bats use echolocation to fnd ood? 63

4 Are bats the only animals that use

echolocation? 64

5 How does a bats prey deend itsel? 64

6 How do bats communicate? 66

7 How do bats manage extreme heat? 68

8 How do bats manage extreme cold? 69

9 Can bats swim? 71

F I V E Bat Love 72

1 How does a bat attract a mate? 72

2 Are bats monogamous? 73

3 How do bats reproduce? 74

4 How many pups are in a litter? 76

5 Do bat mothers take care o their young? 77

6 Do bat athers take care o their ospring? 79

7 How long does it take beore newbornbats can y? 79

vi CONTENTS


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SI X Dangers and Defenses 81

1 Are bats aggressive? 81

2 Do bats bite people? 823 Do all bats have rabies? 82

4 Can people get diseases rom bats? 85

5 What is White Nose Syndrome? 89

6 Do bats have enemies? 90

7 How do bats avoid predators? 91

SEVEN Bats and People 93

1 Why are people araid o bats? 93

2 What dangers do bats ace rom people? 97

3 Are bats useul to plants? 99

4 Do people eat bats? 105

5 Do bats have any scientifc or medical value? 106

6 Are any bats endangered? 107

7 How can bats be saely evicted rom a building? 109

8 How can I build a bat house? 1129 How do scientists capture bats so they

can study them? 113

10 Can bats be domesticated? 114

11 How can I photograph bats? 116

12 What is a bat detector? 116

13 What is being done to protect bats and

how can I help? 117

Appendices 119

A Resources 119

B Suggestions or Further Reading 121

Reerences 123

Index 149

A color insert ollows page 82

CONTENTS vii


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Preface

Have you ever actually seen a live bat up close? For most people,

the answer is probably no, yet many cringe at the very idea o

seeing a bat. This reaction is probably based in part on horror

stories and creepy movies that depict bats ying around at night

causing mayhem. It is revealing that in countries where day-ying

bats are common, they are considered lucky omens and are even

thought o with aection. In general, bats in the wild are un-

threatening, and their instinct, when disturbed, is simply to yaway. Like many other mammals and their ospring, some bats

appear to be curious, aectionate, and even playul with one

another.

O the more than eleven hundred species o bats in the world,

most o the orty-six species ound in the United States are rela-

tively small, comparable in size to a canary. A common Ameri-

can species, the insect-eating little brown bat (Myotis luciugus),

weighs only seven to nine grams, the combined weight o anickel and a dime. The large bats in the popular imagination

are Old World ruit bats, ound in tropical areas o Asia, Arica,

and Oceania.

Bats are highly benefcial animals. Large colonies o bats liter-

ally eat tons o insects every night, reducing the amount o pes-

ticides that are needed on the crops armers grow and, in turn,

that end up in the oods we eat. Many bats in tropical areas polli-

nate plants and disperse seeds, making important contributionsto crops, habitat maintenance, and rain-orest regeneration.


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x PREFACE

In the last ew years, both traditional research and innova-

tive projects using advanced technology have resulted in a ood

o new and ascinating inormation about bats, their liestyles,and their habitats. In this book we hope to satisy your curios-

ity about bats, providing simple answers and including some o

the latest scientifc discoveries. It has been our goal to make the

inormation accessible and enjoyable and to replace any miscon-

ceptions you may have with appreciation and curiosity. I you

were already a bat groupie, we hope you will come to appreciate

these ascinating creatures even more than you did when you

opened this book or the frst time.


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Acknowledgments

We are grateul to the ollowing people and organizations or

allowing us to use their amazing illustrations and photographs

or this book: the American Museum o Natural History in New

York; Jesse Barber, Colorado State University; Alexander Baugh,

University o Texas at Austin; Kirsten Bohn, University o Texas

at Austin; Carol Bunyard and Gerald Carter, Cornell Univer-

sity; David Chapman; Michael Durham; Shawn Gould; Harvey

J. D. Garcia, Conservation International, Philippines; AmandaLollar, Bat World Sanctuary; Beverly Rivera-Walters; and Merlin

Tuttle, Bat Conservation International. Thanks to George West

or the bat drawings on the title page and to Donna Buonaiuto

or helping us connect with the ossil.

We are grateul to Laura Redish, Native Languages o the

Americas, or language translations and to Jesse Barber, Gerald

Carter, Paul Cryan, and John Whitaker Jr. or their helpul sug-

gestions as we wrote this book. The encouragement and supporto our agent, Deirdre Mullane, and o our bat-enthusiast editor,

Doreen Valentine, helped to make writing this book a reward-

ing experience. The authors enjoyed the opportunity to work to-

gether and to share our appreciation o bats with our readers.


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Do Bats Drink Blood?


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ON E

Bat Basics

Question 1: What is a bat?Answer: Bats are the only mammals that can truly y. Theyhave elongated fngers that are connected by membranes to their

torso, orming their wings. In common with all mammals, they

have hair or ur covering their bodies and they are endotherms,

which means they generate their own body heat instead o

being dependent on the environment to regulate their bodytemperature. Baby bats, called pups, develop in utero and are

born alive. They nurse on their mothers breast milk or the frst

ew weeks o lie. Most bats are relatively small. The largest bat is

the size o a cat, while the smallest bat is not much larger than a

bumblebee. They are second only to rodents with regard to the

large number o species and the diverse range o their habitats.

A special characteristic o bats is that they hang in a head-down

position. A bats legs are rotated 180 degrees at the hip so thatthe eet point backwards, and they cling to their roost with the

claws on their toes. Locking tendons in their toes allow them to

hang rom their eet without expending energy. Bats are clean

animals that groom themselves regularly, and when they need to

urinate or deecate in the roost, they turn themselves head-up.

Question 2: How are bats classified?Answer:Within the animal kingdom (Animalia), bats belong tothe phylum Chordata, which includes all animals with vertebrae,


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2 DO BATS DRI NK BLOOD?

Figure 1. Lavia frons, a monogamous yellow-winged bat, has blue-gray furand yellow-wings. (Photograph courtesy of M. D. Tuttle, Bat Conservation Inter-

national, www.batcon.org.)

and to the class Mammalia (mammals). Bats are the sole mem-

bers o the order Chiroptera, rom the Greek cheir, which means

hand, andpteron, which means wing. The order Chiroptera

is divided into two suborders: Microchiroptera, known as mi-

crobats, and Megachiroptera, or megabats. Microchiroptera

are generally quite small, ranging in length rom less than two

inches to just over six inches (approximately our to sixteencentimeters), with most species at the smaller end o the range.

They range in weight rom less than one-tenth o an ounce to

Image not available


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BAT BASICS 3

seven ounces (two to two hundred grams). To get a sense o the

size o a representative bat o this type, consider the little brown

bat (Myotis luciugus), a common species in many parts o theUnited States, which weighs as much as the combined weight o

a nickel and a dime.

There are seventeen amilies o Microchiroptera. Although

there are a ew exceptions to the rule, it is generally accurate

to say that Microchiroptera use echolocation, or sound, to navi-

gate and fnd ood, and megabats do not. Most microbats eed

on insects, although species in one amily, Phyllostomidae, eat

ruit or nectar, and a ew others eed on small vertebrates. Somemicrobats have a good sense o smell, and most have relatively

large ears that aid in echolocation. Some have unusual acial

eatures that are thought to ampliy sound, and although many

microbats have relatively small eyes, those that eed on ruit or

small vertebrates tend to have larger eyes.

Figure 2. Macrotis californicus, the California leaf-nosed bat, is an echolocat-ing bat with big ears. (Photograph courtesy of M. D. Tuttle, Bat ConservationInternational, www.batcon.org.)

Image not available


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All species o Megachiroptera belong to the single amily

Pteropodidae and are commonly called ying oxes. Megachi-

roptera weigh rom less than hal an ounce to just over three

pounds (ten to over fteen hundred grams), most weighing be-

tween one-hal to two pounds. They have prominent eyes, excel-

lent vision, relatively small ears, and a good sense o smell. Meg-

abats eed on ruit and nectar and they do not use echolocationto fnd ood. Members o only one genus o megabats, Rousettus,

use a rudimentary orm o echolocation to navigate in caves.

See also this chapter, question 5: When did bats evolve?

Question 3: How many species of bats are there inthe world?

Answer: There are over eleven hundred species o bats inthe world today, although this number continues to change as

Figure 3. Rousettus aegyptiacus, the Egyptian fruit bat, has large eyes likemost other megabats. It also uses a simple form of echolocation to navigate indark caves. (Photograph courtesy of Bat World Sanctuary, www.batworld.org.)


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Bats of the United States

Family MormoopidaeMormoops megalophylla, Peters ghost-aced bat

Family Phyllostomidae

Artibeus jamaicensis, Jamaican ruit bat

Choeronycteris mexicana, Mexican long-tongued bat

Leptonycteris nivalis, Mexican long-nosed bat

Leptonycteris yerbabuenae, lesser long-nosed bat

Macrotus caliornicus, Caliornia lea-nosed bat

Family Vespertilionidae

Antrozous pallidus, pallid bat

Corynorhinus ranesquii, Rafnesques big-eared bat

Corynorhinus townsendii, Townsends big-eared bat

Eptesicus uscus, big brown bat

Euderma maculatum, spotted bat

Idionycteris phyllotis, Allens big-eared batLasionycteris noctivagans, silver-haired bat

Lasiurus borealis, eastern red bat

Lasiurus blossevillii, western red bat

Lasiurus cinereus, hoary bat

Lasiurus ega, southern yellow bat

Lasiurus intermedius, northern yellow bat

Lasiurus seminolus, Seminole bat

Lasiurus xanthinus, western yellow bat

Myotis auriculus, southwestern myotisMyotis austroriparius, southeastern myotis

Myotis caliornicus, Caliornia myotis

Myotis ciliolabrum, western small-ooted myotis

Myotis evotis, long-eared myotis

Myotis grisescens, gray bat (myotis)

Myotis keenii, Keens myotis

Myotis leibii, eastern small-ooted myotis

(continued)


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Bats of the United States, continued

Family Vespertilionidae, continuedMyotis luciugus, little brown bat (myotis)

Myotis occultus, Arizona myotis

Myotis septentionalis, northern myotis

Myotis sodalis, Indiana bat (myotis)

Myotis thysanodes, ringed myotis

Myotis velier, cave myotis

Myotis volans, long-legged bat (myotis)

Myotis yumanensis, Yuma myotisNycticeius humeralis, evening bat

Parastrellus hesperus, canyon bat

Perimyotis subfavus, tri-colored bat

Family Molossidae

Eumops glaucinus, Wagners bonneted bat

Eumops perotis, greater bonneted bat

Eumops underwoodi, Underwoods bonneted batMolossus molossus, Pallass masti bat

Nyctinomops emorosaccus, pocketed ree-tailed bat

Nyctinomops macrotis, big ree-tailed bat

Tadarida brasiliensis, Brazilian ree-tailed bat

scientists use more sophisticated techniques to distinguish onespecies rom another. Only about 20 percent o these are mega-

bats; the other 80 percent are microbats.

Question 4: Where in the world are bats found?Answer: Species o microbats live on every continent exceptAntarctica; they are also absent rom a ew remote islands in

French Polynesia and the North Atlantic. Megabats live only inthe Old World tropics, which reers to tropical areas o Asia,

Arica, and Oceania.


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BAT BASICS 7

Question 5: When did bats evolve?

Answer: Bats represent 20 to 25 percent o all living mammalsand are the mammals with the second largest number o speciesater rodents. However, they have let very ew representations

in the mammalian ossil record, and many o the ossils are in-

complete; one that has survived, or example, consists o only a

single tooth. In 2008, a report was published by Nancy Simmons

o the American Museum o Natural History and her colleagues

describing the analysis o two ossils that represent a new spe-

cies o bat rom the early Eocene era (approximately 52 millionyears ago). Found in Wyoming in 2003, an almost complete skel-

eton was beautiully preserved in the fne sediment o a ossil

lake. The new bat (Onychonycteris nneyi) has eatures that are

more primitive than have been seen in other early specimens,

and scientists have concluded that this is the oldest species o

bat that has ever been ound. Analysis o its anatomy indicates

that it was an insect-eater, capable o powered ight but not o

echolocation. Its limbs and claws suggest that it probably was agood climber and was able to hang rom a tree branch, much

like present-day bats that roost in trees.

This new fnding supports the hypothesis that the ability to y

in bats evolved beore the ability to echolocate, a subject o con-

troversy or many years because the earliest ossils known prior

to this discovery represented bats that could both echolocate

andy, and there are no ossils o a transitional species between

bats and their non-ying ancestors. Evidence that ight evolvedbeore echolocation has major signifcance.

Karen Sears at the University o Colorado studied the devel-

opment o the elongated fngers or digits that provide the skel-

etal support or the wings o a bat. She ound the gene that con-

trols their specialized growth, and when she applied the protein

produced by this gene to the digits o a mouse embryo growing

in her lab, its digits elongated just like the digits o a bat. I the

same dramatic results observed in the mouse occurred whenthis gene became activated in the ancestors o todays bats, its

activation might explain the absence o transitional species.


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Figure 4. Onychonycteris finneyi, a fossil bat found in Wyoming, is the oldestspecies of bat that has ever been discovered. It was an insect-eater, capable of

powered flight but not echolocation. (Photograph courtesy of American Museumof Natural History, New York.)

The order Chiroptera has been divided into two suborders

and our superamilies. Multiple genes have been sequenced

rom representatives o all the bat amilies, and molecular evi-

dence now suggests that the ancestors o present-day bats origi-

nated rom a single order (monophyly) that evolved at least by

the late Paleocene era (65.0 to 54.8 million years ago), ater thedinosaurs became extinct. It is believed that bats evolved on

the supercontinent o Laurasia, which included most o todays


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BAT BASICS 9

northern continents, but the recent discovery o six new spe-

cies o late Eocene (37 to 34 million years ago) ossils by Gregg

Gunnell and his colleagues in northern Egypt has added to themystery. Finding the ancestors o modern species o microbats

in Arica suggests that primitive bat species may have dispersed

there along with the primates about 50 million years ago and

then later developed into the modern species that have dis-

persed across most o the world.

Question 6: Are all bats black?Answer: Although many bats are shades o black, gray, orbrown, there are others that are orange, red, or yellow in color.

Female red bats (Lasiurus borealis) have beautiul orange-red

ur, and a mother with her wings and uzzy tail tucked around

her babies resembles a piece o ruit hanging in a tree. Some o

the ying oxes have bright red, orange, or yellow collars around

their necks that are oten more prominent in males. The very

unusual-looking spotted bat (Euderma maculatum) has black urwith three white spots on its back. Most surprising are bats that

are actually white. White bats (Diclidurus), also known as ghost

bats, live in Latin America. Little Honduran white bats (Ecto-

phylla alba) are white with yellow ears and nose lea (see color

plate B).

Although ew bats are totally white, there are rare albinos

with pink eyes (see color plate H). The ur on the underside

o many bats is paler than the ur on the back, and some batshave ur that is dark at the base o each hair, but pale on the

tips. Hoary bats (Lasiurus cinereus) have beautiul, luxuriant

ur that is rosted at the tips with silver. The tri-colored bat

(Perimyotis subfavus) has tri-colored ur that is dark at the base

o each hair, yellow-grey in the middle, and dusky again at

the tip.

The skin on the wings and ears o many bats is black or dark

in color, but others have pale skin. For example, the ears andwings are yellow on the Arican yellow-winged bat (Lavia rons),

the ears are pink on the spotted bat (Euderma maculatum), and


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the edges o the ears o the hoary bat (Lasiurus cinereus) are

ringed in black. The pale yellow canyon bat (Parastrellus hes-

perus) looks like it is wearing a black mask, and the pale uraround the eyes o the spectacled bat (Pteropus personatus) makes

it look like it is wearing glasses. Markings oten help to camou-

age bats, or example, proboscis bats (Rhychonycteris naso) have

pale zigzags on their back that make it difcult to distinguish

them rom the tree bark where they roost. Several species, like

the Jamaican ruit bat (Artibeus jamaicensis), have pale vertical

stripes on their aces that help them blend into vegetation where

they eed.Males o some bat species are brighter than the emales, and

some have bright tuts o ur on the head or shoulders that at-

tract emales or mating. For example, the male Chapinis crested

ree-tailed bat (Chaerephon chapini) has a strip o long hairs on

the top o its head that stands erect like a Mohawk haircut.

Figure 5. In 2007, Jake Esselstyn and a team of researchers discovered the

Mindoro striped-faced fruit bat (Styloctenium mindorensis) on the island ofMindoro in the Philippines. (Photograph courtesy of H. J. D. Garcia.)

Image not available


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BAT BASICS 11

Question 7: How long do bats live?

Answer: The longest known lie span o a bat is about threeand a hal times longer than the lie span o other mammals osimilar size. This is likely inuenced by their low reproductive

rate and their relative lack o vulnerability to predation. For ex-

ample, rodents like mice or shrews only live three or our years

at the most, while the record or the oldest bat is over orty-one

years. This was a male Brandts bat (Myotis brandtii) captured in

Siberia. When the bat was frst caught, a band with an identiy-

ing number was put on its orearm, which allowed researchersto identiy it when it was recaptured orty-one years later. There

are now records o six species that have lived or more than

thirty years, and twenty-two species that have lived or more

than twenty years in the wild.

Researchers have ound that the lie span o a bat is aected by

its reproductive rate, so that bats that give birth to multiple pups

each year may not live as long as bats that give birth to only one

pup annually. Bats that hibernate tend to live a ew years longerthan bats that dont hibernate, perhaps because hibernation re-

duces the likelihood o starvation (see chapter 3, question 9:

Do bats hibernate?). Also, cave roosts minimize the exposure o

bats to predators, and the relatively stable temperature in a cave

limits exposure to extreme heat or extreme cold. It has been

established that caloric restriction increases longevity in some

other mammals, and researchers speculate that this element o

hibernation may also contribute to the longevity o bats.

Question 8: Which is the biggest bat?Answer: Most o the largest bats in the world are ruit-eatingMegachiroptera (megabats). The Philippine ying ox (Pteropus

vampyrus) and the golden-crowned ying ox (Acerodon juba-

tus) can weigh two pounds (one kilogram) or more and have

a wingspan o more than six eet (two meters). Another heavy-weight is the Indian ying ox (Pteropus giganteus), which can


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weigh up to three and one-hal pounds or about one and one-

hal kilograms. The Philippine ruit bat lives in Thailand, In-

dochina, Tenasserim, Malaysia, Indonesia, and the Philippines.The golden-crowed ying ox also lives in the Philippines, and

the Indian ying ox is ound in Pakistan, India, Nepal, Sikkim,

Bhutan, Myanmar, Sri Lanka, and the Maldive Islands.

Question 9: Which is the smallest bat?Answer: The smallest bat in the world is Kittis hog-nosed bat

(Craseonycteris thonglongyai). This insect-eating bat is so smallthat it is known as the bumblebee bat, weighing about as much

a penny. Kittis hog-nosed bat is an endangered species ound

only in Thailand and Myanmar.

Question 10: How far can bats fly?Answer: Most microbats eed within six to nine miles (ten to

fteen kilometers) o their daytime roost, although some y asar as fty miles (eighty kilometers). Large megabats may travel

more than thirty-one miles (up to fty kilometers) rom their day

roost to eed. The longest distances some bats travel occur when

they migrate between winter and summer roosts (see chapter 3,

question 8: Do bats migrate?). The distance traveled during mi-

gration varies rom one species to another, with some traveling

more than a thousand miles. There is even a record o a noctule

bat (Nyctalusnoctula) traveling rom southern Russia to Greece, adistance o over twelve hundred miles (two thousand kilometers).

Question 11: How fast do bats fly?Answer: Flight requires upward orce (lit) and orward orce(thrust). Lit occurs when air ows aster over the upper sur-

ace o the wing than it does over the lower surace; this allows

the bat to overcome gravity and stay in the air. Thrust countersthe eects o riction as the bat moves along. When a bat takes

ight, the wings are frst extended above its body and slightly


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BAT BASICS 13

Figure 6. The wing-beat cycle of a canyon bat (Parastrellus hesperus). (Photo-graph courtesy of Michael Durham, www.DurmPhoto.com.)

backwards. Next the wings move down and orward in a down-

stroke. Then the wings old slightly during an upstroke, where

they are again extended above the bats body and slightly back-

wards. Combined, this series o movements is called a wing-beatcycle. Bats y by repeating this cycle over and over again. This

link is to a video o a bat ying in a wind tunnel, where you

can observe its movements in detail: http://media.newscientist

.com/data/images/ns/av/dn11105V1.mpg.

Some bat species y much aster than others, depending on

the relationship between the area o the wing and the wing span

(length rom wing tip to wing tip), reerred to as the aspect ratio.

Bats with long, narrow wings are generally ast iers that eed inopen habitats, like the Brazilian ree-tailed bat (Tadarida brasil-

iensis). These bats y at an average speed o twenty-fve miles

per hour (orty kilometers per hour) but can approach speeds

o orty-seven miles per hour (about seventy-fve kilometers per

hour) in level ight, and with a tail wind they can reach amaz-

ing speedsover sixty miles per hour (over ninety-six kilome-

ters per hour). Bats with short, broad wings are slower iers,

typically maneuvering through vegetation or other cluttered en-vironments, plucking insects rom leaves or hovering to drink

nectar rom owers.

Image not available


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Question 12: How high do bats fly?Answer: Some bats y very low while oraging or ood, takinginsects or other prey directly rom the ground, like the pallid bat

(Antrozous pallidus), which ranges rom southwestern Canada to

central Mexico and Cuba. In contrast, the ast-ying Brazilian

ree-tailed bat (Tadarida brasiliensis) has been documented y-

ing at altitudes o nearly ten thousand eet (over three thousand

meters), higher than any other species.Researchers ound that the Brazilian ree-tailed bats eeding

activity was correlated with the northward ight o huge waves o

corn earworm moths (Helicoverpa zea), also known as cotton boll-

worm moths and tomato ruitworm moths. In the frst ew weeks

o June, these moths emerge rom the Lower Rio Grande Valley

o Mexico and rise to hundreds o eet above the ground, using

the winds to help them travel north to lay eggs on newly emerg-

ing crops. Three weeks ater the eggs are laid, the larvae hatchand eed on the crops in south Texas. In short order, they pu-

pate and then complete their growth cycle byeclosing(emerging

Figure 7. The pallid bat (Antrozous pallidus) is an agile flier with broad wings.(Photograph courtesy of Michael Durham, www.DurmPhoto.com.)

Image not available


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BAT BASICS 15

rom their pupae, having metamorphosed rom larvae into adult

moths) and ying urther north to lay their eggs. This cycle re-

peats with new generations o moths continually moving north-ward, ollowing the warm weather and the sprouting crops, and

ollowed by the bats. Corn earworms are pests on a tremendous

variety o crops including corn, cotton, tomato, artichoke, aspara-

gus, cabbage, cantaloupe, soybean, sugarcane, and many others.

Researchers at the Mexican border oated weather balloons

high among the moths, and radio microphones in the balloons

recorded bat calls at altitudes as high as thirty-nine hundred

eet (nearly twelve hundred meters), veriying that the bats wereying along with the moths. To confrm that the bats were in-

deed eeding on the moths, Gary McCrackens laboratory at the

University o Tennessee in Knoxville developed a DNA marker

that allowed them to identiy gene ragments rom these moths

in the bats eces. The results confrmed that the bats were in-

deed eeding on the moths.

Question 13: Are bats intelligent?Answer: Learning and memory are components o intelli-gence, as is the ability to use tools. Complex social behavior and

the ability to communicate are also associated with higher levels

o intelligence.

An important theory regarding the evolution o intelligence

relates eeding strategies to intellectual development. Extractive

oraging, or locating and processing embedded oods, is consid-ered evidence o a higher level o intelligence, and this behavior

is typically attributed to primates that use tools to accomplish

these tasks. According to Barbara King (College o William and

Mary in Virginia), some acts o extractive oraging by nonpri-

mates are equally sophisticated as those o primates. Peeling the

skin o a mango in order to prepare it to be eaten is described

by Natarajan Singaravelan (University o Haia at Oranim in Is-

rael) and Ganapathy Marimuthu (Madurai Kamaraj Universityin India) as a orm o extractive oraging, and they observed this

behavior in short-nosed ruit bats (Mangiera indica).


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Echolocating bats can adapt their calls to environmental cues,

varying the requency, duration, and bandwidth o pulses de-

pending on eedback rom obstacles and prey. This is evidenceo a more evolved technical intelligence in many species o

bats, according to Kamran Saf and colleagues at the University

o Zurich in Switzerland. Bats that have large, broad wings rela-

tive to the size o their body and that live in dense environments

with many obstacles tend to be highly maneuverable yers that

require a lot o energy to orage successully. I they are echo-

locators, they need good spatial memory and their hearing is

likely to be particularly acute. The brains o these bats tend tobe larger than the brains o species that orage in open spaces.

Bats that orage in open spaces tend to have smaller, narrower

wings relative to body mass, and they rely on speed rather than

maneuverability, so ying or them is more efcient and less

costly. Their sensory needs are reduced, and having a smaller

brain gives them the advantage o reduced weight, improved

aerodynamics, and lowered energy costs.

A variety o experiments have shown that pollinators canlearn to associate colors, visual images, and even sound with

ood sources. While these are neat experiments, they also have

important implications or higher-level unctioning in an envi-

ronment that is always changing. Butteries and bees as well as

bats can learn which owers are good nectar sources, and they

all eed more quickly and efciently on subsequent visits to the

same ower, even i it has a complex shape. Bats have spatial

memory, returning directly to a good nectar source without hav-ing to rediscover it each time they orageagain, evidence o a

relatively high level o unctioning in being able to retain inor-

mation o this complexity.

European ree-tailed bats (Tadarida teniotis) eed on moths and

other common garden insects that have some capacity to hear

the bats echolocation calls and avoid being captured. However,

Jens Rydell (University o Aberdeen in the United Kindgom)

and Raphael Arlettaz (University o Lausanne in Switzerland)ound evidence that when bats hunted or those insects, they

used echolocation calls that the insects were unable to hear be-


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BAT BASI CS 17

cause the requencies were above or below the insects hearing

range. The bats had adapted to the insects deenses.

Rachel Page and Michael Ryan at the University o Texas inAustin conducted experiments with ringe-lipped bats (Tra-

chops cirrhosus) and ound that the bats could learn by observing

their neighbors behavior. What is more interesting, they rap-

idly learned to eat in association with sounds that they would

normally avoid in the wild, indicating an impressive degree

o adaptability and exibility. These are bats that normally

eat rogs, and in the experiments the calls o toxic toads were

played or captured bats in large outdoor ight cages. Whenthey approached the loudspeaker that was playing the sounds,

they were rewarded with ood. They quickly learned to associ-

ate the sound o the toxic rog with ood, even though in the

wild that sound would warn them away rom the prey. When

newly captured bats were allowed to observe these bats, they

learned to associate the toxic toad call with ood ater observ-

ing the behavior an average o just fve times. Rachel Page in-

advertently recaptured an old and distinctive Trachopsbat thatshe had captured a year earlier and had used in another experi-

ment. Ater a one-year hiatus in the wild, the old bat remem-

bered the routine and repeatedly came to take small fsh rom

Pages hand when she made the clicking sound the bat had been

conditioned to the previous year.

There are experiments that indicate that bats can commu-

nicate with one another and can make group decisions, some-

times contrary to what experience would predict. Female greaterspear-nosed bats (Phyllostomus hastatus) live in colonies, and they

call to one another to coordinate group oraging. Gerald Kerth

at the University o Zurich in Switzerland conducted experi-

ments in which he gave wild Bechsteins bats (Myotis bechsteinii)

conicting inormation about the suitability o roosts in their

habitat in order to study how they make group decisions. The

bats live in small colonies in tree cavities and bat boxes (con-

structed bat houses placed in the habitat), and they changeroosts requently, apparently deciding at night where to roost

next. Forty-our bats were marked so that their behavior could


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be tracked, and a batch o new bat boxes was installed in the

habitat. Individual bats oten visited a new box several times be-

ore using it as a roost, and at frst the entrance to the roost waslet invitingly open so the bats could enter. Ater a ew bats rom

the colony had visited the box and departed, the experimenter

blocked the entrance to the box with wire mesh so the next visi-

tors could not enter and would fnd the same location unsuit-

able as a roost. Another experiment was designed to give some

bats an alarming experience at a roost that others had recently

experienced as sae. Waiting until some o the bats had emerged

uneventully at dusk rom a particular roost, the experimenterthen sought to alarm the remaining bats by making scratching

sounds on the outside o the box with aluminum oil attached

to a stick. The observers ound that each individual bats expe-

rience o a roost as suitable or unsuitable did not completely

predict where it would choose to roost. There were times when

the experience o a signifcant number o bats in the group led

to a group decision to use the roost, even i some o the bats

in the group had experienced it as unsuitable. At other times,when a group o bats had conicting inormation, they split into

smaller groups rather than acting together, but when the mem-

bers o a group were given the same inormation, the group

acted cohesively.

Amanda Lollar and Barbara Schmidt-French documented an

elaborate array o social calls within captive colonies o the gre-

garious Brazilian ree-tailed bat (Tadarida brasiliensis). Kirsten

Bohn, Ta-Sheng Ma, and associates at the George Pollak batlab at the University o Texas in Austin, together with Barbara

Schmidt-French, urther documented the assimilation o some

calls into more complex units that may demonstrate a simple

use o syntax, another indication o higher-level intelligence. So,

are bats smart? It does seem that they have an impressive capac-

ity to learn, an exquisite sensitivity to their environment, and

the ability to communicate with each other and to make group

decisions, all indications that they have a relatively high level ointelligence.


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BAT BASI CS 19

Question 14: Do bats drink blood?

Answer: Only three species o small bats actually drink blood.These are the true vampire bats, each weighing less than twoounces. They include the common vampire (Desmodus rotundus),

the hairy-legged vampire (Diphylla ecaudata), and the white-

winged vampire (Diaemus youngi), all native to Mexico, Central

and South America, and the Caribbean. The hairy-legged vam-

pire and the white-winged vampire eed mainly on blood rom

birds. Gerald Carter rom Cornell University used a noninvasive

method to investigate the diet o vampire bats that ed on birds.He extracted bird DNA rom the bats droppings and was able to

accurately determine the species o birds on which they preyed.

The common vampire eeds mainly on the blood o mammals

such as cattle, pigs, or goats. I a colony o common vampire bats

has been eeding on a large herd o cattle that is suddenly sold

o and moved, some o the bats may eed on humans i alterna-

tive ood sources are not available, but they choose individuals

to whom they have easy access, like people who sleep outdoorsor in homes with no screening on the windows.

Vampire bats use echolocation to orient themselves during

ight, but they probably rely on many actors, including smell

and spatial memory, when choosing individual prey, allowing

them to recall an environment and to return to the same eed-

ing location without extensive searching. Once a vampire bat

has chosen its prey, it typically lands on the back o the animal

or approaches it rom the ground, usually when the animal isasleep. Using heat-sensitive pits in its nose, the bat fnds a place

on the prey where there is a good blood supply just under the

skin and licks the spot or several minutes, sotening it beore

making a small cut with its razor-sharp incisors. Ater latching

onto its prey, an anticoagulant in the bats saliva is channeled

down a groove on the underside o the bats tongue and into the

wound. The bat then laps up the blood, which ows rom the

wound along a groove on the upper side o the bats tongue andinto its mouth (see color plate E).


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Researchers have explored some o the elements that attract

a vampire bat to its prey. In one experiment conducted by Udo

Grger and Lutz Wiegrebe (Ludwig Maximilians University inMunich, Germany), two vampire bats were each taught to associ-

ate a recording o a dierent person breathing with a particular

Bat Breath

Co-author Barbara Schmidt-French has cared or hundredso bats in her years as a bat rehabilitator and fnds that a bats

smell is sometimes helpul in diagnosing an illness. For exam-

ple, bad breath may indicate a dental inection. Scientists are

now paying attention to bat breath to determine what vam-

pire bats last ate.

Vampire bats in Costa Rica eed on rain-orest mammals

like tapirs and peccaries, but also eed on the blood o cattle.

The rain-orest mammals eed on dierent plants than thoseon which cattle eed, and the plants can be distinguished by

their carbon isotopes(chemical compounds). By analyzing the

isotopes in the carbon dioxide a bat exhales as it breathes,

scientists are able to determine the animal on which the vam-

pire bat recently ed.

When Christian Voigt and his colleagues analyzed the

breath o vampire bats in Costa Rica, they ound that the

last blood meal o most o them appeared to have originatedrom cattle, although some bats had ed on blood rom rain-

orest mammals. Scientists do not believe the bats preer the

blood o cattle, but rather that cattle are oten enced in open

pastures where they are easily accessible to the bats, while

rain-orest mammals are more likely to hide in dense vegeta-

tion. As rain orests are cleared or cattle ranching in Latin

America, common vampire bats (Desmodus rotundus) have be-

come more dependent on cattle than native orest animals or

blood meals. The conversion o rain orests to pasture landor cattle ranching has caused an increase in populations o

the common vampire bat in Latin America.


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BAT BASI CS 21

cattle blood dispenser that rewarded them with a blood meal.

The bats were then played short clips o the breathing, and they

went unerringly to the dispenser associated with the particularbreathing sound they had learned to identiy with ood, recog-

nizing the breathing whether it had been recorded when the

person was resting or ater exercise. Joseph Bahlman and Doug-

las Kelt (University o Caliornia at Davis) conducted what they

described as a modifed caeteria trial in which bats were o-

ered blood meals associated with the scent o ur or eces rom

cows and other meals that had no olactory cues (associated

smells). Bats showed a signifcant preerence or the blood as-sociated with the cows scents. These experiments suggest that,

along with spatial memory and vision, other sensory clues play

a role in the ability o vampire bats to return to the same prey

night ater night.

Blood is about 90 percent water, and what is let ater the wa-

ter is removed is all protein. Because their diet lacks ats and

carbohydrates, vampire bats are not able to store energy or very

long and they can starve to death i they go or only two nightswithout eeding. A vampire bat drinks about two tablespoons

(about thirty milliliters) o blood each night and will sometimes

share a blood meal with another vampire bat that did not have a

successul nights hunting by regurgitating blood into the hun-

gry bats mouth. The thin, stretchy walls o the vampire bats

stomach expand ater a blood meal, so the bat appears bloated

and is sometimes unable to y without resting or a while. Tiny

blood vessels surround the stretchy part o the stomach and a-cilitate rapid absorption o the blood protein and excretion o

large amounts o water in the orm o urine.

Common vampire bats have only twenty teeth, ewer than any

other species o bat. This is fne since they lap blood rather than

chew their ood. Their unique eeding habits make the spread

o rabies more likely, and the bite wounds they make in cattle

increase the likelihood o parasitic inections. Unortunately,

benefcial bat species are oten killed when cattle ranchers startfres in caves to try to eliminate vampire bats.


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TWO

Bat Bodies

Question 1: How are bats different from birds?Answer: Bats and birds are vertebrates, and many species havecomparable diets o insects or ruit, with plenty o exceptions,

o course. Most birds orage during the day, while most bats or-

age during the night, so they dont really compete directly or

ood. Although they both y, they are very dierent in many

ways. Birds have eathers and a beak with no teeth and they layeggs; bats have ur and teeth and they give birth to live young

that they nurse. Birds are in their own class, Aves, while bats are

in the class Mammalia, which includes a range o animals, rom

mice to elephants.

A birds wing is made up o a long upper arm (humerus), a

orearm (ulna and radius), and the wrist and fngers. The bones

o the wrist (carpals) and fngers (metacarpals) are used to-

gether, making the bird wing relatively rigid. The top and bot-tom surace o the bird wing is composed o eathers. The bat

wing also consists o an upper arm (humerus) and a orearm

(radius and reduced ulna), but the bones o the wrist and fn-

gers are not used as they are in the bird wing. Like the human

hand, the bat hand has our fngers and a thumb. The arms

and fngers are covered with a stretchy membrane made up o a

double layer o skin. Sandwiched between the layers o skin

are blood vessels, nerves, elastic fbers, and muscle strands.The many unused joints in the bat wing make it much more

exible than a bird wing. This allows a bat to easily change the


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BAT BODIE S 23

shape o its stretchy wings so it can change direction rapidly, us-

ing one wing independently o the other.

Like birds, many bats also have tails that are useul in ight.

Bats have a tail membrane (uropatagium or interemoral mem-

brane) that extends rom one oot to the other, enclosing the

tail. The tail membrane in some bat species is supported by a

spur o cartilage called a calcar that attaches to the oot. Some

bats do not have a tail.

Question 2: Why do bats hang upside down?Answer: Hanging head down rom a roost is an ideal positionrom which to take ight. Unlike birds, it is difcult or most

bats to launch themselves into the air rom the ground; they

need to drop rom a height in order to create enough lit. By

hanging upside down, they are in the best position to escapei necessary. When a bat is hibernating, it must use as little en-

ergy as possible in order to conserve its body at, and hanging

ulna

pinnae

tragus

knee

toes

humerus(upper arm)

radius(forearm)

thumb(first finger)

fourth finger

third finger

second finger

metacarpals

fifth finger

phalanges

phalanges

tail

calcar

lower leg(tibia and fibula)

Figure 8. Basic anatomy of a bat. (Drawing courtesy of David C. Chapman.)


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eortlessly upside down is an excellent way to conserve energy.

A bat hanging upside down rom the ceiling o a cave or the

branch o a tree is out o reach o many predators, and it caneasily watch or possible predators below. Microbats have modi-

fed cervical vertebrae that make the neck especially exible

so the bat can arch its head backwards, increasing its surveil-

lance area. I a bat detects a predatory snake approaching, it can

quickly escape by simply releasing its toes and dropping down

into the air to take ight. Hanging upside down by the toes also

leaves a bats wings (hands and arms) ree to do other things

like manipulate ood or hold a pup.A bats body is perectly constructed or an upside-down pos-

ture. Its legs are rotated 180 degrees so that its knees and eet

point backwards. The bat clings to its roost with the claws on its

toes. The weight o the bats body as it hangs head down pulls on

specialized tendons in the toes, keeping them locked in place

so that it requires no energy or a bat to hang in this position.

When the bat wants to release its grip, it exes muscles that pull

its toes open. Hanging in this way is so eortless that when a batdies while roosting, it will oten remain in place until something

knocks it down.

Bat in Different Languages

Abenaki madagenihlas

Algonquin nbhgan

Apache chabaanArabic watwt, Basque saguzar, gauenara

Blackoot mattsiipiitaa

Bulgarian

Caddo wakish

Cantonese ksy, isy

Cebuano kabog

Cherokee dlameha


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Cheyenne mosheshkanetsenoonaheChinese bin,

Chipewyan/Dene tsretanaze

Choctaw halambisha

Cree Apahkwaces

Croatian sismis

Czech netopyr

Dakota Sioux xupahuwakihdakena

Danish fagermusDutch vleermuis, knuppel

Eklektu sots

English bat

Esperanto vesperto

Estonian nahkhiir

Finnish lepakko, ylepakko

French chauve-souris

German federmausGreek nikhteridha,

Haida kaatsuu xaalaa

Hawaiian peapea, pea, peapea

Hebrew atale

Hindi camgdar

Hopi sawya

Indonesian kelelawar, kampret

Italian blocco, chirotteri

Japanese Kmori,Karelian uolapakko

Korean pakchwi

Lakota hupahuwakihdakena

Lappish girdisahpan, nahkkesoadji

Latin vespertilio

Latvian siksprnis

Lithuanian siksnys

(continued)


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Bat in Different Languages, continued

Maliseet- MotekoniyehsPassamaquoddy

Maori pekapeka, peka

Maya sootz

Mohawk yakohonhtariks

Mojave qampanyiq

Munsee Delaware peepiishlongwanaash

Muskogee Creek takvleleskv

Nahuatl quimichpatlanNavajo jaaaban

Nez Perce Uucuc

Norsk faggermus

Norwegian faggermusen

Ojibway/Chippewa Bapakwaanaajiinh

Olonetsian lepakko

Oneida Tsiklawistal

Osage TsebthaxePassamaquoddy motekoniyehs

Pima/ Tohono Oodham Nanakumal

Polish nietoperze

Portuguese morcego, basto

Potawatomi Mishaknekwi

Quechua mashu

Romanian lilieci

Russian letuchaya mysh,

Serbo-Croatian slepi misShawnee pithgath

Shoshone Honobichi

Slovakian netopierov

Spanish murcilago

Swahili popo

Swedish slagtr

Swiss German faedermus

Tagalog paniki, kabg


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BAT BODIE S 27


Taiwanese li bolThai khang-khaw

Tlingit Sigeideetan

Turkish yarasa

Vietnamese con doi

Welsch ystlum, slumyn

Yaqui Sochik

Yiklamu bami

Native American language translations by Laura Redish with

the nonproft organization Native Languages o the Americas,

www.native-languages.org.

Question 3: Do bats have teeth?

Answer: Like other mammals, bats have teeth or choppingtheir ood into smaller pieces so it can be more easily digested.Most bat pups are born with tiny, sharp, hooked milk teeth,

so-called because they press against a mothers teat as the pup

nurses. Within a ew weeks as the young bat grows, the milk

teeth all out and are replaced by a ull set o adult teeth. All

bats have our canines, two on the top and two on the bottom,

but the number o incisors, premolars, and molars varies among

species.The common vampire bat (Desmodus rotundus) has twenty

teeth, less than any other bat. The most teeth are ound in some

insect-eating bats that can have up to thirty-eight. The suraces

o the teeth in the upper jaw ft perectly together with the sur-

aces o the teeth in the lower jaw. These suraces are attened

in ruit-eating bats so that they can crush ruit, and in insect-

eaters they have sharp W-shaped ridges that are suitable or

tearing insects apart. Ater ood has been chopped up by theteeth, it moves rapidly through the digestive system, aided by

enzyme activity. Some bats have an enzyme called chitinase that


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digests the external covering on insects which is made o chi-

tin. Chitinase can even be at work in a bat during hibernation.

In the case o ruit-eating bats, enzyme activity acts on the seeds

in the ruits the bats eat, which helps the seeds to germinate whenthey all to the ground in the bats droppings (see chapter 7,

question 3: Are bats useul to plants?)

Question 4: Can bats walk?Answer: Bats are spectacular iers, but they can be vulnerableon the ground because they usually need to drop rom a perch

in order get enough lit to y. Many species o bats can movewell or short distances on the ground, crawling on their eet

and wrists, but other species are only able to hop awkwardly.

Among the most capable movers, New Zealand short-tailed bats

(Mystacina) have short, thick legs and talons on the claws o their

eet and thumbs, and they are able to run reely on the ground

and to climb smooth suraces. Sucker-ooted and disk-winged

bats (Myzopodaand Thyroptera) have disk-shaped suction cups on

their eet and at the base o their thumbs that help them clingto the smooth suraces o stems and palm leaves.

Figure 9. The teeth of an adult Brazilian free-tailed bat (Tadaridabrasiliensis).(Photograph courtesy of Bat World Sanctuary, www.batworld.org.)


44/179

BAT BODIE S 29

Perhaps the most accomplished walker is the common vam-

pire bat (Desmodus rotundus), which has very strong arms and

legs and is able to walk and jump well. In an experiment, DanielRiskin, John Hermanson, and Gerald Carter o Cornell Univer-

sity set up a treadmill to observe vampire bats as they walked;

videotapes revealed that the bats tucked their wings under their

orearms and used the power o their ront limbs, like a gorilla,

to run. As the treadmill speed was increased, they were observed

running at speeds o almost our eet (close to 1.2 meters) per

second. Since the treadmill could not be programmed to move

aster, this may not even represent the bats top speed. The evo-lution o the vampire bats superior walking ability remains an

interesting puzzle.

Question 5: How fast do bats grow?Answer: Bats o dierent species grow at dierent rates; but,in general, bats that live in temperate regions grow aster than

those that live in the tropics. Faster growth rates are essentialin temperate regions because young bats must reach maximum

growth and have sufcient at reserves prior to migration or hi-

bernation, when the cold weather sets in.

The amount o ood that is available to a lactating mother is

one o many actors that inuence the growth rate o her young.

For example, insect abundance can be aected by temperature

and precipitation, and during seasons when insects are less

abundant, pups grow more slowly than they do in years wheninsects are plentiul. Cold temperatures can cause mothers and

pups to spend more time in torpor, which also slows growth.

Bat pups are large at birth, weighing rom one-fth to one-

quarter o the mothers weight. Many are born naked, although

some, including the megabats, are born ully urred. Growth

rates vary between species, although most young are not able to

y until their wings have reached 90 percent o the adult wing

dimensions. Some young are weaned and ying within threeweeks, while others are not ready to y until the sixth or seventh


45/179


week ater birth; large megabats may not begin ying until they

are three months old. The common vampire bat (Desmodus rotun-

dus) has the slowest growth rate o all bats studied to date, andtheir young are not weaned until they are at least seven months

old. Although the reason or their slow growth is not known or

certain, it could be related to the act that they eed exclusively

on blood, which is defcient in carbohydrates and ats.

Question 6: Are bats blind?

Answer: Someone with poor vision is commonly called blindas a bat, but the expression is inappropriate since bats can ac-tually see quite well, with visual acuity varying rom one species

to another. Both megabats and microbats rely on vision dur-

ing social interactions with one another, to watch or predators,

and or navigating across landscapes. Megabats have large eyes

and depend on vision to orient themselves during ight and to

fnd ood. Most microbats use echolocation to navigate and fnd

ood, and they tend to have smaller eyes, although they, too,

Figure 10. Myotis velifer, the insect-eating cave myotis, is a microbat that hassmall eyes. (Photograph courtesy of Barbara A. Schmidt-French.)


46/179

BAT BODIES 31

use vision during their daily activities and to detect objects out-

side o the eective range o echolocation, which is about thirty-

three to sixty-six eet (ten to twenty meters). Some bats are alsocapable o visual pattern discrimination, which may assist ruit

or nectar bats in fnding ood.

The retinas o most bats consist mainly o rod cells that re-

quire very little light to be activated, thus all bats have night

vision in low light conditions. While not much color is visible in

dim light, the retinas o megabats also contain cones that, when

activated by brighter light, enable them to see some color. Until

recently, it was thought that only megabats have color vision,but new research suggests that some bats in the microbat amily

Phyllostomidae are able to make distinctions between red and

green.

Question 7: Why do bats have big ears?Answer: Not all bats have big ears; in act, the ears o megabats

are relatively small and simple. They use their acute hearing tolisten or predators and to communicate with one another, but

they rely mainly on vision and smell to fnd the ruit or nectar

that they eat. Echolocating microbats also rely on hearing to

detect predators and to communicate with one another, but in

addition they need to ampliy sound when they hunt or insects

or other prey using echolocation. Their ears are more promi-

nent and have a variety o tiny olds and notches that help to

collect returning echoes and sounds produced by small insectsor other prey (see chapter 4, question 1: How does echolocation

work?). Microbats that listen or the aint sounds made by prey

moving on the ground or on oliage have the largest ears o all

bats. With its exceptionally large ears, the Arican alse vampire

bat (Cardioderma cor) can hear the ootsteps o a beetle walking

in sand rom six eet away (1.2 meters).

The external part o each ear is called pinna, and bats can

rotate and tilt their pinnae to pick up sounds. Most microbatsalso have a eshy projection at the base o each pinna called a

tragus. The tragus is believed to assist echolocating bats in the


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localization o horizontal targets. Bats in the genera Corynorhi-nus, Idionycteris, and Eudermaare unusual in that they can roll

their long ears up on the sides o their heads when they are rest-

ing so that they resemble the curled horns on a rams head.

As in other mammals, the external ears direct sound waves

through the ear canal, causing the ear drum (tympanic mem-

brane) to vibrate. The vibrating ear drum then causes the vibra-

tion o three small bones (auditory ossicles) directly behind it

in the air-flled cavity o the middle ear. The three small bonesare named according to their shape, that is, the hammer (mal-

leus), the anvil (incus), and the stirrup (stapes). The movement

o these bones causes the vibration o a membrane-covered

opening between the middle ear and the inner ear. The vibrat-

ing membrane then transers the sound energy to the cochlea

o the inner ear, which is composed o three uid-flled tubes

embedded within a bony capsule. Movement o the uids in the

inner ear stimulates sound-sensitive hair cells that send signalsto the brain, where sound perception takes place.

Figure 11. Euderma maculatum, the insect-eating spotted bat, has largepink ears for the reception of echolocation calls. (Photograph courtesy of M. D.Tuttle, Bat Conservation International, www.batcon.org.)

Image not available


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BAT BODIES 33

Because some bats emit very loud echolocation calls, they

need a way to reduce their own sensitivity to the calls as they

make them. This is accomplished by the contraction o twomuscles o the inner ear, the tensor tympani and the stapedius.

Contracting these muscles decreases the transmission o sound

vibrations within the bats head by causing the stiening o the

small bones in the middle ear, which reduces the intensity o

certain requencies. By contracting these muscles a ew milli-

seconds ater producing each echolocation call, the bat is not

deaened by its own loud sounds (see chapter 4, question 1: How

does echolocation work?).


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THREE

Bat Life

Question 1: What do bats eat?Answer: Bats eat a surprising variety o oods. About 70 per-cent o bats are insectivorous, meaning they eat insects such as

moths, caterpillars, beetles, ies, grasshoppers, planthoppers,

leahoppers, crickets, termites, mosquitoes, and ying ants.

A single bat can eat more than one thousand small swarm-

ing insects, such as midges (Chironomidae), in an hour. Someinsect-eating bats, such as the pallid bat (Antrozous pallidus) and

species o slit-aced bats in the genus Nycteris, also include scor-

pions in their diet. In Bracken Cave in central Texas, a colony

o as many as twenty million Brazilian ree-tailed bats (Tadarida

brasiliensis) emerges in a huge cloud at dusk. Michael Novacek

described them as ying vacuum cleaners . . . with their large,

abby mouths opened wide . . . sweeping through clouds o in-

sects, consuming up to their own body weight in insects dur-ing the course o a night. This bat species is a valuable ally to

agricultural interests vital to human health. They consume vast

quantities o moths that lay eggs that develop into caterpillars,

including serious agricultural pests.

Researchers have used DNA analysis to identiy some species

o moths that are eaten by Brazilian ree-tailed bats, includ-

ing the corn earnworm or tomato ruit worm (Helicoverpa zea),

the tobacco budworm, (Heliothis virescens), the all armyworm(Spodoptera Frugiperda), and the beet armyworm (Spodoptera

Exigua). The larvae o these pests eed on an amazing variety


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BAT LI FE 35

Figure 12. Myotis yumanensis, a Yuma myotis, chases a moth. (Photographcourtesy of Michael Durham, www.DurmPhoto.com.)

o crops and ornamentals, including alala, apple, artichoke,

asparagus, avocado, barley, beet, Bermuda grass, broccoli, cab-

bage, cantaloupe, cauliower, celery, collard, cotton, corn, cow-

pea, cucumber, eggplant, ax, grape, lettuce, lima bean, melon,millet, oat, okra, onion, orange, papaya, pea, peach, pear, pea-

nut, pepper, plum, potato, pumpkin, radish, raspberry, rice, rye-

grass, saower, snap bean, sorghum, soybean, spinach, squash,

strawberry, sugarbeet, sugarcane, sunower, sweet potato, timo-

thy, tobacco, tomato, turnip, watermelon, and wheat.

About 80 percent o the diet o the big brown bat (Eptesicus

uscus) is oten agricultural pest insects. Both the big brown bat

and the evening bat (Nycticeius humeralis) have heavy jaws andinclude beetles in their diet. Many big-eared bats eed on moths.

Species oMyotisbats eat mainly dipterans (ies and midges),

Image not available


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small beetles, and small moths. Other bat species are general-

ists in their eeding behavior, eeding on a variety o insects.

Some insects that bats like to eat, such as termites, ants, andcaddis ies, are sporadic in occurrence, although numerous

when available. Since many insects are agricultural pests, bats

provide an enormously benefcial service at no cost to people or

the environment.

Figure 13. Micronycteris nicefori, Niceforos big-eared bat, captures a roach.

(Photograph courtesy of M. D. Tuttle, Bat Conservation International, www.batcon.org.)

Image not available


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BAT LI FE 37

Most o the remaining species are nectivorous (nectar-

drinkers), or they are rugivorous, meaning they are ruit-eaters,

sometimes also eating leaves or owers. Bats pluck ruit rom atree with their mouth, sometimes with the aid o their wings and

even their eet. I they carry the ruit away rom the tree to eat it,

they drop large seeds away rom the parent plant, and i they eat

ruit with small seeds, the seeds pass through their digestive sys-

tem, where enzymes help the seeds to germinate when they all

to the ground in the bats droppings. In these ways, bats help

spread the seeds rom mangos, peaches, fgs, dates, and many

other kinds o plants. By distributing seeds over large areas, batshelp renew vegetation and aid in the regrowth o rain orests.

Nectar-drinking bats eed on cactus owers and other plants

that bloom at night. Nectar bats have long snouts that ft neatly

inside the owers they preer, and many have tiny hairs on their

tongues that help them lap up the nectar rom inside the ow-

ers. While they are drinking, the bats aces become covered

with pollen that they carry to the next ower, helping to ertil-

ize the plant and enabling it to bear ruit. Bats pollinate agave,saguaro and organ pipe cactus, banana, eucalyptus, and many

other plants in this way (see color plate D).

Less than 1 percent o all bats eed on small vertebrates in

addition to insects. There are about eight species o fsh-eating

(piscivorous) bats ound in the genera Nycteris, Myotis, and Noc-

tilio. The fsherman bat (Noctilio leporinus) has particularly large

eet with strong claws that it uses to capture fsh swimming just

below the surace o the water, which it either eats in ight orcarries to a tree to east on. Piscivorous bats use echolocation to

detect ripples on the water rom a fsh swimming just beneath

the surace. The fsherman bat oten ollows pelicans as they

eed, catching the fsh that are disturbed as the pelicans dip

into the water.

In addition to fsh-eating bats, there are a ew carnivorous

bat species that eat other small vertebrates. In Europe, the gi-

ant noctule bat (Nyctalus lasiopterus) eats mostly insects but alsocatches and eats songbirds when the birds migrate annually


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during the spring and all. In Latin America, the ringe-lipped

bat (Trachops cirrhosus) eats small rogs (see color plate A) in ad-

dition to insects and lizards. There are also several species ocarnivorous alse vampire bats, including the Arican alse

vampire bat (Cardioderma cor), which eats beetles, centipedes,

scorpions, and sometimes other smaller bats. The carnivorous

Australian giant alse vampire bat (Macroderma gigas) eats mostly

mice, but also birds, reptiles, and other bats as well as insects.

This bat is known to drop rom its perch onto its prey, covering

it with the wings and biting the head or neck to kill it. The Asian

alse vampire bat (Megaderma lyra) eats insects, spiders, rodents,birds, rogs, fsh, and other bats as well. And there are three spe-

cies o vampire bats that are sanguivorous, eeding on the blood

o birds or mammals (see chapter 1, question 14: Do bats drink

blood?). Such dietary diversity among species speaks to the tre-

mendous adaptability o bats around the world.

Like other animals, bats require minerals in their diet, and

in caves they may acquire some minerals by licking deposits

on cave walls. Christian Voigt discovered that bats in the rainorest in Ecuador visit areas called salt licks, which are bod-

ies o mineral-rich water and clay. The bats caught in his mist

nets at the salt licks were mostly pregnant or lactating emales,

but outside the salt-lick zones he and his group caught a mix o

males and emales that were not pregnant or lactating. Voigt

suggests that pregnant or lactating emales may visit the salt

licks to obtain the additional minerals needed to enrich their

milk to promote optimal skeletal growth in their pups. This isparticularly important because the pups are not weaned until

they are almost adult size. The mineral-rich water and clay also

detoxiy the secondary plant compounds (such as natural pesti-

cides and other toxic chemicals) that the bats take in when they

eat ruit, compounds that can be damaging to their embryos or

pups. Because minerals have been depleted rom the soils and

crops in many tropical areas, some indigenous people in South

America and Arica also eat mineral-rich clay to supplementtheir diet.


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BAT LI FE 39

Bat Families of the World

MegachiropteraPteropodidae, Old World ruit bats

Microchiroptera

Craseonycteridae, hog-nosed bats

Emballonuridae, sheath-tailed bats, sac-winged bats, and

ghost bats

Furipteridae, thumbless bats and smoky bats

Megadermatidae, alse vampire bats and yellow-winged batsMolossidae, ree-tailed bats

Mormoopidae, naked-backed bats and mustached bats

Mystacinidae, New Zealand short-tailed bats

Myzopodidae, disk-winged bats

Natalidae, unnel-eared bats

Noctilionidae, bulldog bats

Nycteridae, slit-aced bats

Phyllostomidae, New World lea-nosed batsRhinolophidae, horseshoe bats

Rhinopomatidae, mouse-tailed bats

Thyropteridae, sucker-ooted bats

Vespertilionidae, vesper bats

Question 2: Where do bats live?Answer: Bats can be ound all around the world except in thepolar regions. In the vicinity o the Queen Charlotte Islands o

the northwest coast o British Columbia, Keens myotis (Myotis

keenii) raise their young alone, oten in geothermally heated rock

cavities. But most species live together in groups called colonies,

and species that orm large colonies oten live and raise their

young in caves. Small colonies sometimes roost in cavities in a

cave ceiling where heat is trapped. One o the largest coloniesever observed consists o as many as twenty million Brazilian


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ree-tailed bats (Tadarida brasiliensis) living and rearing their

young in Bracken Cave in central Texas. When the cave is oc-

cupied by the bats, their combined body heat can raise thetemperature by more than 20 degrees Fahrenheit (6.7 degrees

Celsius), providing the warmth needed or the young pups to

thrive. Brazilian ree-tailed bats are active year round. When

winter arrives, those in the southwestern United States migrate

south to warmer climates, while those in the southeastern

United States remain in the same region throughout the year.

Other bat species hibernate in caves or other secluded places

where temperatures are stable during the winter. Big brown bats(Eptesicus uscus) oten hibernate near cave entrances, where

they cluster together and wedge their bodies into crevices. In

the northeastern United States, big brown bats oten hibernate

in buildings. Tri-colored bats (Perimyotis subfavus) roost in some-

what warmer areas o caves than the big brown bats, and they

roost alone rather than clustering together like colonial species.

Indiana bats (Myotis sodalis) pack into dense clusters in a cave.

Canyon bats (Parastrellus hesperus) hibernate in deep crevices onthe sides o clis.

Some bats commonly live and raise their young in plants or

trees, roosting in leaves and branches, under bark or inside hol-

low tree trunks. Banana bats (Musonycteris harrisoni) live inside

urled banana leaves, and when the leaves unurl as they grow,

the bats move into new ones. Disk-winged bats (Thyroptera sp.)

roost in the curled leaves o plants such as Heliconia, using suc-

tion cups on their eet and wrists that allow them to hang head-up and to move in and out o the slippery leaves. The Honduran

white bats (Ectophylla alba) chew along the mid-rib oHeliconia

leaves, causing the sides to old down like a tent to shelter them

rom the elements (see color plate B). Other tent-making bats

modiy leaves in dierent ways to make roosts.

Fur color provides camouage or many bats (see chapter 6,

question 7: How do bats avoid predators?). Chocolate brown ur

with white tips and pale zigzag lines on the lower back helpsthe Latin American Proboscis bats (Rynchonycteris naso) blend

into the bark o mangrove trees where these bats oten roost


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BAT LI FE 41

in small groups, heads acing down, orming a vertical line on

the tree trunk. Flying oxes (Pteropus) live in tropical areas o

Asia, Arica, and Oceania and are grayish brown or black, otenwith yellowish ur between the shoulders. These bats wrap their

wings around their bodies and hang rom bare tree branches,

where they resemble large ruit pods. North American eastern

red bats (Lasiurus borealis) hang rom the stems o leaves or tree

branches, where they resemble dead leaves, while yellow bats

(Lasiurussp.) are well-camouaged in dead palm ronds or in

Spanish moss that hangs rom tree branches.

Shelters made by insects, birds, and other mammals are alsopopular roosts or some species. In the United States, big brown

bats (Eptesicus uscus) in the southwest sometimes roost in old

woodpecker holes in desert cacti, and cave myotis (Myotis velier)

may roost in abandoned cli swallow nests. In South Amer-

ica, round-eared bats (Tonatia silvicola) are known to roost in

cavities in the bottom o termite mounds suspended rom tree

branches, and in Asia, club-ooted bats (Tyloncterissp.) roost in

Figure 14. A hoary bat (Lasiurus cinereus) roosts inside a hole in a dead tree.(Photograph courtesy of Michael Durham, www.DurmPhoto.com.)


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bamboo stems, entering through small holes made by chryso-

melid beetles. In Arica, lea-nosed bats (Hipposideros ulvum)

sometimes roost in large-crested porcupine burrows, and slit-aced bats (Nycteris sp.) have been ound living in abandoned

aardvark burrows. Perhaps most interesting are Aricas wooly

bats (Kerivoulasp.), which can be ound living in the large webs

o colonial spiders.

Due to the loss o natural habitat, some bats now roost in shel-

ters made by people, including buildings, bridges, or abandoned

mines. In North America, insect-eating bats oten roost in barns

or in the attics or crawl spaces o homes. Big (Eptesicus uscus)and little brown bats (Myotis luciugus) commonly roost in build-

ings in the northeastern United States. Cave myotis (Myotis ve-

lier) sometimes roost in road culverts (water pipes), and Rafn-

esques big-eared bats (Corynorhinus ranesquii) have been ound

living in old cisterns or abandoned ammunition bunkers. In

Central America, long-legged bats (Macrophyllum macrophyllum)

have been seen roosting in irrigation tunnels. In Egypt, Tates

trident lea-nosed bats (Asellia tridens) roost in undergroundchannels at oases, and tomb bats (Taphozoussp.) sometimes roost

in old crypts and pyramids. Brazilian ree-tailed bats (Tadarida

Brasiliensis) readily roost in expansion joints under bridges, and

during the summer months, more than a million o these bats

live under the Congress Avenue Bridge in the middle o the city

o Austin in Texas. In what has become a major tourist attrac-

tion, crowds o people assemble every day at dusk during the

summer to watch a huge cloud o bats shoot out rom under thebridge as darkness settles in.

Question 3: Why do bats like caves?Answer: Caves provide good homes or bats in many ways. Be-cause caves are underground, the temperatures inside are gen-

erally stable and are not inuenced signifcantly by temperature

changes that take place above ground. Stable temperatures arenecessary or hibernating bats; i temperatures drop too low in


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BAT LI FE 43

a hibernation roost, the bats are at risk o reezing to death.

I the temperature becomes unseasonably high, the bats may

wake rom hibernation too soon, when there are still no insectsor them to eat. Stable temperatures are also important or ma-

ternity colonies, where mothers raise pups that require warmth

in order to grow. Caves are also oten inaccessible to animals

that might otherwise eed on the bats, and even in caves where

predators can enter, bats oten roost on the ceiling, high above

the ground where they cant be reached. Caves also tend to have

high humidity levels, and most bats require high humidity to

prevent dehydration or water loss. Some caves contain mineralslike calcium that bats can obtain by licking the walls where they

roost. But not all bats roost in caves; some bats roost under tree

bark or in hollows in trees, some hang in the oliage o trees or

other plants, and many live deep in rock crevices (see chapter 3:

question 2: Where do bats live?).

Question 4: Do bats only fly at night?Answer: Bats and birds coexist because, although they eat a loto the same things, in general they occupy dierent niches in

the environmentbirds oraging in the day, bats at night. Most

birds are dependent on their vision, so they are at a great dis-

advantage at night, although there are a ew exceptions. Owls,

or example, are nocturnal birds that are very nimble yers with

excellent night vision, and owls sometimes prey on bats. It is

unclear whether bats were nocturnal in their evolutionary past,but i so, perhaps some bats became diurnal because the ab-

sence o predators in their habitat allowed them to orage more

reely.

Two almost complete specimens o ossilized bats were recently

ound in Wyoming, representing a new species (Onychonycteris

nneyi), the oldest species yet discovered. They have provided

many interesting clues about early bats (see chapter 1, question 5:

When did bats evolve?), and one might expect this discovery toshed some light on whether early bats were nocturnal or diurnal.


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Unortunately, the upper part o the skulls were crushed and

their eye sockets could not be examined or clues as to the na-

ture o their vision, but analysis o their anatomy did indicatethat they were insect-eaters, capable o powered ight but not

o echolocation.

Most bats y and eed at night and return to their day roosts

by dawn. By ying at night, they avoid daytime predators and

take advantage o the ample supply o night-ying insects. Ex-

ceptions to this pattern are a ew species o megabats that y

and eed during the day. These bats are ound only on a small

number o islands that do not have the usual daytime preda-tors, such as hawks, making daytime activity relatively sae. It is

interesting to note that a species that orages during the day on

American Samoa, the Samoan ying ox (Pteropus samoensis), is

seen mostly at night on the island o Fiji, where there are preda-

do bats drink blood fascinating answers to questions about bats animal q amp a series

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