Echolocation and Bioacoustics in Orcinus orca

Echolocation & Bioacoustics
Orcinus orca

Rebecca Crawford

Introduction
• What Is Echolocation?
• Killer Whale Classification
• Orca Anatomy
• Killer Whales Up Close
• Whale called “Killer”

What is Echolocation?
 the sophisticated, biological, sonar-like system used by dolphins, bats

and other animals to detect and locate objects by emitting highpitched sounds that reflect off the object and return to the animal's
sensory receptors
 used in navigation, hunting and communication
 killer whales and other dolphins can determine the location, direction,
speed, size, shape and internal structure of another object or animal

Killer Whale Classification
KINGDOM:

Animalia

animals

PHYLUM:

Chordata

vertebrates

CLASS:

Mammalia

mammals

ORDER:

Cetacea

whales and dolphins

SUBORDER:

Odontoceti

toothed whales

FAMILY:

Delphinidae

oceanic dolphins

GENUS:

Orcinus

scientific name:

SPECIES:

orca

Orcinus orca

Killer Whales Up Close
 Largest member of the dolphin family
 Average Male: 8-10 tonnes, 7-10 metres, 50-60+ years
 Average Female: 4-6 tonnes, 6-8 metres, 80-90+ years

Average 1.8 metres







Average 0.9 metres

Extremely intelligent, social animals
General activities: foraging, socializing, travelling, resting
Found in all of the the world’s oceans
Top of the food chain
The most polluted animal on Earth
(PBTs such as PCBs and DDT bioaccumulate in an orca’s body)
 Status: some populations ENDANGERED, some THREATENED

Range

Most widely distributed animal among marine mammals!

Whale called “Killer”
 Efficient, deadly predators
 40-52 teeth: 3-5 inches long, 1 inch diameter
 Diet includes fish, birds, Cephalopods (octopi and squid), turtles, seals,
sea lions, sharks, whales, porpoises, dolphins, deer, moose
 A deliberate, fatal attack on a human by an orca in the wild has never been
documented
 Sleek, streamlined body ensures sheer speed (sometimes 45+ km/h)
 Known as the “Wolves of the Sea” because they hunt in packs called PODS
 Members of a pod stay together for life
 Individuals per pod ranges from 2-100+
 Two or more maternal groups may travel in SUBPODS
 Two or more pods with similar dialects may travel in CLANS
 Numerous pods have been spotted travelling in COMMUNITIES (500+)

Frequency Detection
Animal

Frequency (Hertz)
low

high

Humans

20

20 000

Whales/Dolphins

70

150 000

Seals/Sea Lions

200

55 000

Salmon/Fish

<1

380

POD CATEGORIES
Category I:
Residents

Category II:
Transients

Category III:
Offshore

Distinct Pod Categories
Resident

Transient

Offshore

General Vicinity

near shore, coastal
waters

off shore, coastal
waters

open ocean

Average Count

5-50+

2-7

30-60

Basic Diet

primarily fish

primarily marine
mammals

turtles, sharks, follow
migratory patterns of
salmon

Vocal Expression

frequent, loud

very silent,
single/cryptic clicks
instead of many clicks

frequent, loud

Leader

eldest female

dominant male

N/A

Genetics

unique from Transient

unique from Resident

some correspondence
to Southern Residents

Dorsal Fin

curved and tapering
tip

straight tip

rounded tip and
multiple nicks

Saddle Patch

five patterns

two patterns

N/A

PACIFIC COAST - COMMONLY SIGHTED RESIDENTS & TRANSIENTS
Resident

Transient

Pods

A, A5, D, D1,
AT1, O20
AB, AD05,
AD16, AE, AI,
AJ, AK, AN10,
AN20, I31, G1,
J, K, L

Clans

Northern:
A, G, R

N/A

Southern: J
Subpods

A1, A4, A5,
AB25
(occasionally
travels with
AJpod)

N/A

Sound
 SOUND is a compressed wave in a medium (air,

water).
 Sound waves are longitudinal waves.

In other words, the particles in the
medium vibrate parallel to the
direction of the motion of the
wave.

Wave
 A WAVE is a disturbance that transfers energy

through a medium.
 Waves are repeated over and over again.

Wavelength/Cycle
• A WAVELENGTH or CYCLE is the shortest
distance between any two points in the
medium that are in phase.
• A wavelength is measured from crest to
crest or trough to trough.

Pressure

wavelength

crest

trough

Time

Frequency





FREQUENCY is the number of complete wavelengths that
pass a point in a given amount of time.
Units: Hertz (Hz) or Kilohertz (kHz).
Pitch is perceived frequency.
The higher the frequency of the tone, the higher the audible pitch.

Tone I: low pitch

Tone II: high pitch

Converting Hertz to
Kilohertz and Vice Versa
Kilohertz = kHz
Hertz = Hz

1 Kilohertz = 1 000 Hertz
Therefore:

3.7
3 700 Hertz is _________ Kilohertz.

22 000
22 Kilohertz is _________ Hertz.

Amplitude
 The AMPLITUDE is the distance from the
rest position to the maximum point of the
crest or minimum point of the trough.
 The magnitude of a sound is associated

with the size of its amplitude.
Loud = high amplitude
Quiet = low amplitude

Decibels
 BELS and DECIBELS are a unit of sound

intensity.
 0.1 bel = 1.0 decibel
 The smallest increase in sound intensity level
that humans can distinguish is 1.0 decibel.
Therefore, we measure sound intensity in
decibels.

Spectrogram
 A SPECTROGRAM is a visual record of a

vocalization illustrating its power, frequency, and
timing per phrase.

Oscillogram
 An OSCILLOGRAM is a visual illustration of the

variations in a vocalization produced using an
oscilloscope.

 Clicks
 Pulsed Calls
 Tonal Sounds

Whistles (close-range motivational sounds)

The Blowhole
 The BLOWHOLE is the nostril located on the top of the

rostrum. The blowhole is closed by the nasal plug
when the orca dives underwater. When the orca
surfaces, the the nasal plug retracts, enabling the
whale to take a breath of air.

Sound Path
Blowhole.
Nasal sacs.

Oil-filled melon.
{OUTGOING} SOUND PATH.

{INCOMING} SOUND PATH.

Fat-filled cavity in lower jawbone.
Auditory bulla/middle ear bones.

The Orca & Echolocation
Killer whales do not possess vocal chords in the larynx.
Clicking sounds are produced by the movement of air
between the nasal passages and the blowhole. Some
whistles and calls are produced by the movement of air
in the larynx.

Located below the orca’s blowhole are nasal sacs which
produce clicks that are focused by the thick oil in the
melon. The melon is then shaped to form an acoustic
lens, which enables the orca to direct clicks towards a
particular object. Echoes then reflect off of the object
and are received through the lower jaw which focuses
the image and sends it to the middle ear bones. This
process allows the orca to form an acoustic image in its
brain of its surroundings.

Purpose
Is there a correlation between the
acoustics and behaviours of Orcinus orca?

Questions
 How is it possible to distinguish between orca pods by analyzing









their acoustics?
Is there a difference between the hunting vocalizations of Resident
and Transient orcas?
Do orcas possess a distinct vocabulary?
Do orca clans possess a distinct dialect?
How do acoustics play a role in maintaining the structure of a pod?
Is it possible to identify an individual orca by its acoustics?
Do male orcas produce different sounds than female orcas?
Are distinct sounds produced between a mother orca and her calf?
Do orcas produce a specific sound when pursuing their prey?

FOCUS
IS THERE A DIFFERENCE BETWEEN THE HUNTING
VOCALIZATIONS OF RESIDENT AND TRANSIENT ORCAS?

Variables
 Independent
*Hunting Vocalization Style
(Resident versus Transient)

 Dependent
*Frequency (kHz)
*Power (dB)
*Average Time per Whistle (s)
*Average Time Between
Whistles (s)
*Clicks (present or absent)

Hypothesis
I predict that Resident and
Transient orcas have unique
hunting vocalization styles.

Procedure
 Obtain digital-audio recordings of both Resident and







Transient orcas pursuing prey (source: internet).
Use software (Raven Lite 1.0 – source: Cornell
Laboratory of Ornithology, Cornell University, New
York) to create spectrograms and oscillograms.
Determine the frequency, power, and timing of the
vocalizations from the spectrograms and oscillograms.
Compare the observations to one another.
Analyze and explain the differences and similarities.
Draw conclusions and summarize.

The Hydrophone
 The digital-audio sounds were recorded by scientists

and researchers using a HYDROPHONE or
“underwater microphone”.

Echolocation and Bioacoustics in Orcinus orca

Vocalizations Of Transient Orcas

Communication Within A Pod

Maximum Frequency:

6800 Hz

Power Range:

85 dB – 115 dB

Timing:

0.5 – 1.0 s whistles separated by 3-5 s of silence


Foraging and Echolocating
Maximum Frequency:

17000 Hz

Power Range:

69 dB – 106 dB

Timing:

continuous, loud clicking and ten short whistles of
0.5 s, separated by 3 – 12 s of silence


Foraging and Echolocating … a sea lion has been located!
Maximum Frequency:

7000 Hz

Power Range:

54 dB – 100 dB

Timing:

quiet, continuous clicking, two rising phrases: each
2 – 3 s in length, separated by 15 s of clicking


Echolocating and Chasing Prey
Maximum Frequency:

8500 Hz

Power Range:

90 dB – 112 dB

Timing:

loud 1 – 2 s of tonal sounds separated by 3 – 5 s of
quiet clicking


Attacking and Killing Prey

Maximum Frequency:

9000 Hz

Power Range:

85 dB – 115 dB

Timing:

2 s whistles separated by 3 – 4 s of silence

Transient Data
Behaviour

Presence /
Absence of
Clicking Sounds

Maximum
Frequency

Minimum Power

Maximum Power

Average Length
of Whistles

Average Time
Between
Whistles

(P / A)

(kHz)

(dB)

(dB)

(s)

(s)

1
Communicating

A

6.8

85

115

0.8

4.0

2
Foraging/
Echolocating

P
(Loud)

17

65

106

0.5

7.5

3
Foraging/
Echolocating…
Prey Located

P
(Quiet)

7.0

54

100

2.5

15

4
Chasing Prey

P
(Quiet)

8.5

90

113

2.0

4.0

5
Attacking Prey

A

9.0

85

115

2.0

3.5

Transients - A Summary
 clicking sounds are present while orcas forage, when prey has been








located, and when orcas chase their prey
clicking sounds are absent while orcas communicate and when orcas
attack their prey
Foraging/Echolocating: high frequency (17 kHz)
Communicating/Prey Located/Attacking Prey: lower frequency (6.8 – 9.0
kHz)
Power is lower when orcas are foraging and when prey has been located
Power is higher when orcas are communicating or attacking prey
When communicating and foraging, the time per whistle is shorter and
the time interval between whistles is longer
When chasing prey and attacking prey, the time per whistle is longer and
the time interval between whistles is shorter

Vocalizations Of Resident Orcas

Communication Within A Pod
Maximum Frequency:

22000 Hz

Power Range:

97 dB – 120 dB

Timing:

constant pulsed calls, whistles and clicks

Vocalizations Of Resident Orcas: A1, A4, A5 Subpods

Foraging and Echolocating
Maximum Frequency:

3700 Hz

Power Range:

104 dB – 121 dB

Timing:

continuous whistles of 1.0 – 3.0 s, isolated and
infrequent clicking

Vocalizations Of Resident Orcas: A Clan

Foraging, Echolocating, and Feeding
Maximum Frequency:

9500 Hz

Power Range:

101 dB – 115 dB

Timing:

continuous 1.0 – 2.0 s whistles, isolated clicking

Vocalizations Of Resident Orcas: G Clan

Maximum Frequency:

8500 Hz

Power Range:

92 dB – 111 dB

Timing:

continuous whistles of 1.0 – 2.0 s

Vocalizations Of Resident Orcas: R Clan

Maximum Frequency:

9000 Hz

Power Range:

90 dB – 125 dB

Timing:

constant whistling of 1.0 – 3.0 s

Resident Data
Behaviour

Presence /
Absence of
Clicking Sounds

Maximum
Frequency

Minimum Power

Maximum Power

Average Length
of Whistles

Average Time
Between
Whistles

(P / A)

(kHz)

(dB)

(dB)

(s)

(s)

A

22

97

120

1.0

0.0
(Constant)

2
Foraging &
Echolocating

P
(Isolated and
Infrequent)

3.7

104

121

2.0

0.0
(Constant)

3 Foraging,
Echolocating,
and Feeding

P
(Isolated)

9.5

101

115

1.5

0.0
(Constant)

4 Foraging,
Echolocating,
and Feeding

A

8.5

92

111

1.5

0.0
(Constant)

5 Foraging,
Echolocating,
and Feeding

A

9.0

90

125

2.0

0.0
(Constant)

1
Communicating

Residents - A Summary


Clicking sounds are present while orcas forage/echolocate,
and occasionally when they feed



Communicating: high frequency (22 kHz)



Foraging/Echolocating/Feeding: lower frequency (3.7 – 9.5 kHz)



Power varies while orcas forage, use echolocation, and feed



Power is highest when orcas communicate





When communicating, whistling is constant and the the length of the
individual whistles is shorter
When foraging, echolocating, and feeding, whistling is constant and the
length of individual whistles is longest

Recall…
I hypothesize that Resident and Transient orcas have
unique hunting vocalization styles.

Presence and Absence of Clicking
RESIDENTS
 Absent: communication,
feeding
 Present: echolocation, foraging
(isolated and infrequent)

TRANSIENTS
 Absent: communication,
attacking/killing prey
 Present: echolocation, foraging (loud); chasing prey - (quiet)

OBSERVATION:
Both Resident and Transient orcas use echolocation to
locate their prey, whether it be a school of fish or a
humpback whale.
Resident clicking seems to be
infrequent whereas Transient clicking seems to be
abundant.

Frequency
RESIDENTS
 3700 – 22000 Hz
 highest when
communicating

TRANSIENTS
 6800 – 17000 Hz
 highest when foraging
and echolocating

EXPLANATION:
Resident orcas use frequencies beyond the detection
ability of their prey.
Transient orcas however use
frequencies at the low end of their prey’s frequency
detection range.

Average Length Of Whistles
RESIDENTS
 1.0 – 2.0 s

TRANSIENTS
 0.5 – 2.5 s

EXPLANATION:
The average time per whistle is very similar for both
Resident and Transient orcas. Resident and Transient killer
whales are the same species. Transient orcas however,
have adapted their behaviour and vocalizations due to their
different taste in prey. Their vocalizations are suited to
stalking their prey.

Comparing Average Time
Between Whistles
RESIDENTS
 0.0 s (Constant)
 Constant whistles and
calls.

TRANSIENTS
 3.5 – 15 s of silence
between individual
whistles.

EXPLANATION:
Resident orcas feed primarily on fish, whereas Transient orcas
feed primarily on marine mammals.
Fish have poor
underwater hearing compared to marine mammals. Thus, it
makes sense that Transient orcas restrict their echolocation
because their prey is extremely acoustically-sensitive.

Maximum Power
RESIDENTS
 Maximum Power:
111 – 125 dB

TRANSIENTS
 Maximum Power:
100 – 115 dB

EXPLANATION:
The maximum power is slightly higher for Resident
orcas than Transient orcas. Fish, the primary prey of
Resident orcas, have poor hearing. Therefore, the
power of the Resident whales’ whistles, clicks, and calls
do not affect their ability to locate their prey.

Minimum Power
RESIDENTS
 Minimum Power:
90 – 104 dB

TRANSIENTS
 Minimum Power:
54 – 90 dB

EXPLANATION:
The minimum power is distinctly lower for Transient orcas
than Resident orcas. Marine mammals, the primary prey
of Transient orcas, are extremely acoustically-sensitive.
Therefore, the Transient whales restrict the power of their
vocalizations to avoid being detected by their prey.

Frequency Detection
Animal

Frequency (Hertz)
low

high

Humans

20

20 000

Whales/Dolphins

70

150 000

Seals/Sea Lions

200

55 000

Salmon/Fish

<1

380

Transient Prey

Resident Prey

Conclusion
According to the observations, Resident orcas tend to be very
vocal. Whistling and pulsed calls are fairly constant throughout
their activities. Clicking is limited to low frequencies and used only
for echolocation. Transient orcas are less vocal and tend only to
produce short whistles and pulsed calls when attacking prey.
Cryptic clicks (single, short) are abundant and produced at
magnitudes at the low end of the frequency detection range of
marine mammals. Therefore, Transients make an effort to conceal
themselves. Due to the poor acoustic-sensitivity of the Residents’
prey, it is not necessary that they drastically modify their
vocalizations.
Therefore, Resident and Transient orcas have unique hunting
vocalization styles.

Current Research
RESIDENTS
 flamboyant vocalization

TRANSIENTS
 restricted vocalization

EXPLANATION:
Compared to current projects performed by scientists and
researchers, my analysis coincides. Resident killer whales
tend to be more vocal than Transient killer whales due to
the difference in the acoustic-sensitivity of their prey.

REFERENCES
Adobe Reader. “Introduction.” Photographic and Acoustic Monitoring of Killer Whales in Prince William Sound
and Kenai Fjords. 2001. 17 December 2006.
<http://www.evostc.state.ak.us/Store/Proposal_Documents/422.pdf>.
Adobe Reader. “Orca Natural History.” Current State of Our Orcas. 2000.
18 December 2006.
<http://flightline.highline.edu/MAST/Current%20State%20of%20Our%20Orcas_files/OrcasOutline.pdf>.
Cornell Lab of Ornithology. “Using Raven Lite.” Raven Lite 1.0 User’s Guide. 2006.
29 December 2006. <http://www.RavenSoundSoftware.com>.
Dick, Gregg et al. Physics 11. Toronto: McGraw-Hill Ryerson, 2001.
Russian Orcas Homepage. “Sound Production.” Killer Whale Acoustic Behaviour. 2007.
5 January 2007. <http://www.russianorca.com/Orcas/sounds_eng.htm>.
The Big Zoo. “Orcinus orca.” Killer Whale. 2007. 2 January 2007.
<http://www.thebigzoo.com/Animals/Killer_Whale.asp>.

REFERENCES
Vancouver Aquarium. “AquaFacts: British Columbia’s Killer Whales (Orcinus orca).” Vancouver Aquarium. 2000. 18
December 2006. <http://www.vanaqua.org/education/aquafacts/killerwhales.html>.
Whale Watch Telegraph Cove: Stubbs Island Whale Watching. “Stellar Sea Lion Attack.” Transients. 2006. 27
December 2006. <http://images.google.ca/imgres?imgurl=http://www.stubbsisland.com/images/orca/stories/stellar-04.jpg&imgrefurl=http://www.stubbsisland.com/english/orca/stories/trans_3.html&h=277&w=383&sz=23&hl=en&
start=1&tbnid=F4qdHX-tUmakXM:&tbnh=89&tbnw=123&prev=/images%3Fq%3Dtransient%2B%252
B%2Borcas%26svnum%3D10%26hl%3Den%26lr%3D%26sa%3DX>.
Woods Hole Oceanographic Institution. “Seeing Sounds: Dolphins, Killer Whales and False Killer Whales.”
Bioacoustics: Cetaceans and Seeing Sounds. 2004.
20 December 2006. <http://www.fathom.com/course/10701056/session3.html>.
Workshop on Applications of Signal Processing to Audio and Acoustics. “Introduction”. Classification of
Vocalizations of Killer Whales Using Dynamic Time Warping. 2005. 19 December 2006.
<http://72.14.203.104/search?q=cache:vvf1uxC8fesJ:web.media.mit.edu/~br
own/whaleclass2waspaa.ps+orca%2Bsounds%2Bmeaning&hl=en&gl=ca&ct=clnk&cd=16>.

Echolocation and Bioacoustics in Orcinus orca

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