1. BAT FLIGHT AND ECHOLOCATION

2. Structure of bat wings

3. Comparative structure of vertebrate wings

4. Bat & Bird comparison

5. Mechanical efficiency

6. Origin of bat flight Gliding as an intermediate stage
Multiple independent origins among
living mammals
Marsupials – 1 Order, 3 Families
Placentals – 2 Orders, 3 Families

7. Dermoptera vs. Chiroptera – gliding membrane

8. Wing shape and flight dynamics
Wing aspect ratio
(length/width)
Artibeus
(low aspect ratio)
Eumops
(high aspect ratio)

9. Echolocation

10. Characteristics of sound
AMPLITUDE
(loudness)
20 dB – whisper
60 dB -- conversation
130 dB – pain threshold
Bat echolocation
60 – 120 dB
1400 Hz
(1.4 kHz)
FREQUENCY
Human hearing
0.02 – 20 kHz
Bat echolocation
9 – 200+ kHz

11. Characteristics of sound
ATTENUATION of sound
(rate of energy loss)
Increases with frequency
ECHO attenuation
Increases with frequency
HOWEVER
Higher frequencies produce
echoes from smaller objects.

12. Characteristics of sound in echolocation
High frequencies more effective in locating small targets but
have limited range
Low frequencies increase detection range but limit resolution
of target
Constant frequency (CF)allows for precise location via
doppler shift (i.e., returning sound has a shifted freqeuncy)
Multiple frequencies (broad band) provide more information
about target shape
Harmonics
Frequency modulation (FM) –frequecny sweep

13. Bat ear shapes

14. Bat facial structures Yinpterochiroroptera Yangochiroroptera
Cardioderma (Megadermatidae) Hipposideros (Hipposideridae)
Yangochiroroptera
Murina (Vespertilionidae) Lonchorhina (Phyllostomidae)

15. “ Tongue-clicking” echolocation Rousettus (Pteropodidae)
Does not involve larynx.
Sound pulses produced by
in mouth with tongue
Short duration pulses
with wide frequency range.
Effective for obstacle
avoidance inside cave roosts

16. Basic types of “microchiropteran” calls
Broad FM
(frequency
modulated
harmonics) FM
(frequency
modulated)
Initial CF
(“constant”
frequency)
Teriminal FM

17. Perch-hunters & “whispering” bats
Large ears for receiving low-frequency ambient sound from
prey. Large eyes (also use vision to locate prey)
Produce low amplitude FM “stealth” calls
Nycteris (Nycteridae) Macroderma (Megadermatidae)
harmonics
Plecotus (Vespertilionidae)

18. Low frequency FM bats Hunt in open habitat
Produce high amplitude calls at low frequencies
(some audible to humans)
Large ears “tuned” to low frequencies
Euderma maculatum (Vespertilionidae)

19. Broad frequency FM bats
Produce high amplitude calls with multiple harmonics over a
broad frequency range, with downward-sweeping FM.
Provide detailed information on shape and size of prey
Myotis ciliolabrum

20. High duty cycle bats
Fly in closed, cluttered habitat (forest interior).
Emit very high frequency constant frequency (CF) calls,
or CF and FM in combination, using Doppler shift to
determine location and movement of prey.
Elaborate nose involved in beaming calls and ear
shape “tuned” to receive narrow-band echoes
Rhinolophus (Rhinolophidae)
Hipposideros (Hipposideridae)

21. High duty cycle bats (Rhinolophidae)
Constant Frequency (CF)
Rhinolophus megaphyllus
Rhinolophus hipposideros

22. High duty cycle bats (Hipposideridae)
Constant Frequency + Frequency Modulated (CF/FM)
Hipposideros abae Hipposideros commersoni
CF component
FM component
Second harmonic
First harmonic

23. Insulation from “self-deafening”
Isolation of the
otic capsule from cranium
Dampening sound transmission through middle ear ossicles
Tensor tympani (increasing tension on tympanum)
Stapedius (regulates contact of stapes with cochlea)

24. Bat evolution:
flight first or echolocation first?

25. Comparative morphology
(size of cochlea) CF
CF/FM
fossils
FM no laryngeal
echolocation

26. “Microchiroptera” paraphyletic THE ABSENCE OF LARYNGEAL ECHOLOCATION
IN PTEROPODIDS
IS APPARENTLY
DERIVED
YINPTEROCHIROPTERA YANGOCHIREROPTERA