Underwater vocalizations of Underwater vocalizations of Pacific Harbor Seals Pacific Harbor Seals

((Phoca vitulina richardiiPhoca vitulina richardii))

Mehgan M. ClarkMehgan M. Clark

OverviewOverview

• Harbor Seal Harbor Seal BackgroundBackground

• Research Research DevelopmentDevelopment

• Goals Goals

• MaterialsMaterials

• MethodsMethods

• ResultsResults

• ConclusionsConclusions

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Pinniped BackgroundPinniped Background

• Amphibious CarnivoreAmphibious Carnivore

• Varied Mating Systems Varied Mating Systems (Le Boeuf, 2001)(Le Boeuf, 2001)

• Highly vocal Highly vocal – Aerial and Underwater (Van Aerial and Underwater (Van

Parijs and Kovacs, 2002)Parijs and Kovacs, 2002)

• Evolutionary Relationship Evolutionary Relationship is Fuzzy (Arnason et al., is Fuzzy (Arnason et al., 2002)2002)– Order CarnivoraOrder Carnivora– Mustelids vs. UrsidsMustelids vs. Ursids

http://www.brookfieldzoo.org/pagegen/images/fix/sealcut.jpg

BackgroundBackgroundEcology (Riedman, 1990)Ecology (Riedman, 1990)

• Distribution Distribution (P.v.richardii)(P.v.richardii)– Alaska to MexicoAlaska to Mexico

• DietDiet– Fish, cephalopods, krillFish, cephalopods, krill

• Life SpanLife Span– 25 years in the wild25 years in the wild

• MaturityMaturity– Females: 3-7 yrsFemales: 3-7 yrs– Males: 2-7 yrsMales: 2-7 yrs

https://www.washington.edu/burkemuseum/collections/

mammalogy/mamwash/phvi.html

BackgroundBackgroundMating Behavior (Riedman, Mating Behavior (Riedman, 1990)1990)MalesMales• Dominance Dominance

HierarchyHierarchy• Aggressive BehaviorAggressive Behavior

– Flipper SlapsFlipper Slaps– Neck BitesNeck Bites

• TerritoryTerritory– VocalizeVocalize– Along travel corridorAlong travel corridor– Possible lek Possible lek (Van Parijs et al 1997)(Van Parijs et al 1997)

FemalesFemales• Post-Partum EstrusPost-Partum Estrus• Annually March-Annually March-

Sept.Sept.• Feeding tripsFeeding trips• Aquatic MatingAquatic Mating

– Exact method not Exact method not observedobserved

Background-Acoustic Background-Acoustic StudiesStudies• Started Started

– 1960s 1960s – Poulter and Poulter and

SchustermanSchusterman– California Sea LionsCalifornia Sea Lions

• EcholocationEcholocation– InvestigatedInvestigated– DebatedDebated

Photo By: Mehgan Clark

Background-Acoustic Background-Acoustic StudiesStudies• Females Females

– Mother-pup relations Mother-pup relations (Khan et al., 2006)(Khan et al., 2006)

• Males Males – Breeding season Breeding season

(Van Parijs et al., (Van Parijs et al., 1997; Hanggi and 1997; Hanggi and Schusterman, 1994)Schusterman, 1994)

– Announce breading Announce breading readiness and readiness and dominance hierarchy dominance hierarchy (Hayes et al., 2002)(Hayes et al., 2002)

Photo By: Mehgan Clark

Background-Harbor Seal Background-Harbor Seal AcousticsAcoustics• RoarsRoars

– Hanggi and Hanggi and Schusterman 1994Schusterman 1994• Mean 4.2 seconds Mean 4.2 seconds • Occasional Harmonics Occasional Harmonics

– Van Parijs et al. 1997 Van Parijs et al. 1997 • 1/min1/min• 1 roar underwater1 roar underwater• Mean = 665 HzMean = 665 Hz

– Van Parijs et a. 2003Van Parijs et a. 2003• Geographic variationGeographic variation

• Hearing Range Hearing Range (Renouf, 1991)(Renouf, 1991)– 1-50 kHz 1-50 kHz – Above 15 kHzAbove 15 kHz

• Perceived as same Perceived as same pitchpitch

– Above 60 kHz Above 60 kHz • Bone ConductanceBone Conductance

Sensory Systems and Sensory Systems and Communication (Renouf, 1991)Communication (Renouf, 1991)

• AcousticsAcoustics

• Spatial MemorySpatial Memory

• SmellSmell

• TactileTactile

• VisionVision

• VibrassaeVibrassae– Hydrodynamics Hydrodynamics

(Zimmer, 2001)(Zimmer, 2001)

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Research at a ZooResearch at a Zoo

• Zoos and aquaria Zoos and aquaria provide unique provide unique study sitestudy site– Control VariablesControl Variables

• Social StructureSocial Structure

• DietDiet

• VisibilityVisibility

• Etc.Etc.

– Animal HistoryAnimal HistoryPhoto By: Mehgan Clark

GoalsGoals

• To record underwater To record underwater sounds to look for sounds to look for ultrasonic components.ultrasonic components.

• Catalog all sounds as Catalog all sounds as part of the repertoire.part of the repertoire.

• Determine if the calls Determine if the calls types are truly types are truly different. different.

• Determine the number Determine the number of calls per minute.of calls per minute.

Photo By: Mehgan Clark

MaterialsMaterials

• Ithaco 605 HydrophoneIthaco 605 Hydrophone– Linear to 75 kHz Linear to 75 kHz

• DELL XPS M140 Laptop.DELL XPS M140 Laptop.– Linear to 96 kHzLinear to 96 kHz

• GoldwaveGoldwave sound sound analysis program and analysis program and recording software. recording software.

• SpectrogramSpectrogram sound sound analysis program. analysis program.

Photo By: Mehgan Clark

Software LimitationsSoftware Limitations

•Goldwave Goldwave – Great for:Great for:

• RecordingRecording

•Initial Analysis Initial Analysis

– Accuracy Accuracy ProblemsProblems

•SpectrogramSpectrogram– Great for:Great for:

•Accurate Accurate analysisanalysis

– Resolution Resolution IssuesIssues•±96 Hz±96 Hz

•209 Hz209 Hz

MethodsMethods

• Recordings Recordings – April and October 2006 April and October 2006 – 6-10AM6-10AM

• Behavioral Behavioral – Notes Taken as Notes Taken as

PossiblePossible– LimitedLimited

• StatsStats– Adapted from Potter Adapted from Potter

20052005 Photo By: Dr. Thomas

Legend

Hydrophone Recording Site

= Animal Shift Gates

N

West H

old

ing

:1

5’x

9’x

5’

505

0 g

allo

ns

East H

old

ing:

15’x

6’x

4’

270

0 g

allo

ns

Pool #1:38,000 gallons

Pool #2:135,000 gallons

Pool #3:125,000 gallons

Pool #4:32,000 gallons

Harbor Seals

Harbor Seals

Walrus

Sea Lion and Harbor Seals

Pinniped Point

Graphic Courtesy Brookfield Staff

Table 1. Animal Information

Species Name Age Sex Acquisition:

Wild vs. Captive Born

Notes

Phocavitulina

Scooter 9 M Captive Completely Blind

Darker Color

Phocavitulina

Banda 17 F Wild Crown on ForeheadPink Spots on Neck

Phocavitulina

Stirling 17 F Wild Black Spots on Stomach

Acoustical AnalysisAcoustical Analysis

Sonographic Sonographic analysis:analysis:

• FrequencyFrequency

• Sound Sound ComponentsComponents

• Harmonic Harmonic StructureStructure

• DurationDurationPhoto By: Mehgan Clark

Component One

Dominant Beginning Frequency

Dom. Max. Freq.

Dominant Minimum Frequency

Dominant Ending

Frequency

OscilogramSpectrogra

m

Total Duration

Study PhasesStudy Phases

• Pre-Mating SeasonPre-Mating Season– Female Only (66)Female Only (66)– Male Only (127)Male Only (127)

• Introduction of Introduction of Groups (105)Groups (105)

• Mating Season Mating Season (298)(298)

• Post-Mating Season Post-Mating Season (331)(331)

• 933 minutes Total933 minutes Total

Photo By: Mehgan Clark

Results-Call TypesResults-Call Types

• 3 Call Types (713 3 Call Types (713 calls)calls)– Growls Growls – Short Roars Short Roars – Long Roars Long Roars

• Rare Call TypesRare Call Types– GruntsGrunts– BuzzesBuzzes– HowlsHowls– CreaksCreaks– ClicksClicks

• Found only during Found only during the mating seasonthe mating season– June 25-28 2006June 25-28 2006– Probable startProbable start– End of behavior End of behavior

date unknown date unknown

• Associated with Associated with Phase 2 and 3Phase 2 and 3

Growl SpectrogramGrowl Spectrogram

Short Roar SpectrogramShort Roar Spectrogram

Long Roar SpectrogramLong Roar Spectrogram

Call Parameter Means and Standard Call Parameter Means and Standard DeviationsDeviations

Call Call TypeType

Dom. Dom. Beg.Beg.

Freq.Freq.

Dom. Dom. Ending Ending Freq.Freq.

Dom. Dom. Max. Max. Freq.Freq.

Dom. Dom. Min. Min. Freq. Freq.

CompComp..

Dur.Dur.

GrowGrowll

1026.11026.1

±315.1±315.11026.11026.1

±325.2±325.22060.22060.2

±566.6±566.6291.2291.2

±163.1±163.10.940.94

±0.5±0.555

Short Short RoarRoar

727.2727.2

±±133.7133.7797.2797.2

±210.2±210.21349.81349.8

±452.1±452.1336.5336.5

±148.1±148.11.841.84

±0.6±0.655

Long Long RoarRoar

611.3611.3

±98.8±98.8707.5707.5

±191.1±191.11329.31329.3

±319.8±319.8210.6210.6

±18.4±18.44.804.80

±1.7±1.777

GR

0 1000 2000 3000 4000 5000 6000DMAXFREQ

0

5

10

15

20

25

Co

un

tLR

0 1000 2000 3000 4000 5000 6000DMAXFREQ

0

10

20

30

40

50

60

Co

un

t

SR

0 1000 2000 3000 4000 5000 6000DMAXFREQ

0

10

20

30

40

50

Co

un

t

Dominant Maximum

Frequency in All Three Call

Types

GR

200 300 400 500 600 700 800 900DMINFREQ

0

10

20

30

40

50

60

70

80

90

Co

un

tLR

200 300 400 500 600 700 800 900DMINFREQ

0

50

100

150

Co

un

t

SR

200 300 400 500 600 700 800 900DMINFREQ

0

10

20

30

40

50

60

70

Co

un

t

Dominant Minimum

Frequency in All Three Call

Types

Results- Principle Component Results- Principle Component AnalysisAnalysis

• Components of Importance for Components of Importance for ClassificationClassification

• All Components UsedAll Components Used

Components Components in Seriesin Series

0.7120.712 0.5140.514 -0.199-0.199

Comp. Comp. AnalyzedAnalyzed

0.7580.758 0.4920.492 -0.213-0.213

Dom. Beg. Dom. Beg. FreqFreq

0.8110.811 -0.203-0.203 0.2630.263

Dom. End. Dom. End. FreqFreq

0.7010.701 -0.198-0.198 0.4410.441

Dom. Max. Dom. Max. FreqFreq

0.7470.747 0.0970.097 0.1430.143

Dom. Min. Dom. Min. Freq.Freq.

0.1500.150 --0.6210.621 0.3050.305

Component Component DurationDuration

--0.6530.653

0.5780.578 0.3620.362

Interval Interval DurationDuration

-0.189-0.189 -0.076-0.076 0.5790.579

Total DurationTotal Duration -0.062-0.062 0.8430.843 0.4240.424

Results- Principle Component Results- Principle Component AnalysisAnalysis

• No RotationsNo Rotations

• Frequency componentsFrequency components– Grouped together Grouped together – Factor 1Factor 1

Factor Loadings Plot

CIS

COMPANALYZED

DBFREQ

DEFREQ

DMAXFREQDMINFREQ

COMPDURATION

COMPINTERVALTOTDURATION

Results: Two Sample T-testsResults: Two Sample T-testsComparisons

DBF DEF DMAXF DMINF

SR vs. LR -7.891

-3.569 -0.417p= 0.667

-9.537

SR vs. GR 9.753 6.526 10.731 -2.221p=0.105

LR vs. GR 14.106

9.351 12.451 5.550p=0.000 unless noted df=254 df=235

Hierarchical ClusteringHierarchical Clustering

• Determines Correlations in dataDetermines Correlations in data

• Distance between call parametersDistance between call parameters

• DendrogramDendrogram

• Small branches = close relationshipsSmall branches = close relationships

Cluster Tree

0 1000 2000 3000 4000 5000Distances

CIS

COMPANALYZED

DBFREQ

DEFREQ

DMAXFREQ

DMINFREQ

HARMONICS

FIRSTHARMINT

HIHARMONIC

COMPDURATION

COMPINTERVAL

TOTDURATION

Results-Calls Per MinuteResults-Calls Per Minute

• Phase 1 Females Phase 1 Females OnlyOnly– 0.0000.000

• Phase 2 Male OnlyPhase 2 Male Only– 0.4500.450

• Phase 3 Phase 3 IntroductionsIntroductions– 0.3110.311

• Phase 4 Mating Phase 4 Mating SeasonSeason– 2.5952.595

• Phase 5 Post Phase 5 Post Mating SeasonMating Season– 0.0910.091

Average Calls per Minute Calculated for Each Average Calls per Minute Calculated for Each PhasePhase

Average Number of Calls Per Minute in Each Phase

0

0.5

1

1.5

2

2.5

3

1 2 3 4 5

Phase

Avera

ge N

umbe

r of C

alls

Series1

BehaviorsBehaviors

MaleMale• Loops-counter Loops-counter

clockwiseclockwise• Haul OutHaul Out• BottlingBottling• LobtailingLobtailing• VocalizingVocalizing• Neck BitingNeck Biting• Flipper SlapsFlipper Slaps• ChasingChasing

FemaleFemale• Loops-clockwiseLoops-clockwise• Haul OutHaul Out• SleepingSleeping• BottlingBottling• Flipper SlapsFlipper Slaps

Photo By: Mehgan Clark

ConclusionsConclusions

• Differences in 3 Differences in 3 Call types.Call types.– Statistically Statistically

SignificantSignificant– Support LiteratureSupport Literature– Frequency Frequency

Components Most Components Most ImportantImportant

Bandahttp://static.flickr.com/79/250184186_7397d1ee5f_m.jpg

ConclusionsConclusions

• Male vocalization Male vocalization – roar-associated with roar-associated with

mating behaviormating behavior– blowing bubblesblowing bubbles– selection by femaleselection by female

• No other malesNo other males• May rule out that it May rule out that it

is a competition is a competition callcall

• Females are very Females are very quietquiet

Photo By: Mehgan Clark

Future ResearchFuture Research

• Similar ResearchSimilar Research– Video RecordingsVideo Recordings– Simultaneous with acoustic recordingSimultaneous with acoustic recording– Surface intervalsSurface intervals– Number of roars per diveNumber of roars per dive– Behavioral ComponentsBehavioral Components

Literature CitedLiterature Cited• Hanggi, E. B. and Schusterman, R.J. 1994. Underwater acoustic displays and individual

variation in male Harbour Seals, Phoca vitulina. Animal Behavoiur 48: 1275-1283 • Hayes, S.A, A. Kumar, D.P. Costa, D.K Mellinger, J.T. Harvey, B. L. Southall, and B.J. Le

Boeuf. 2002. Evaluating the function of the male harbour seal, Phoca vitulina, roar through playback experiments. Animal Behaviour 67: 1133-1139

• Khan, C. B., H. Markowitz, and B. McCowan. 2006. Vocal development in captive harbor seal pups, Phoca vitulina richardii: Age, sex, and individual differences. J. Acoust. Soc. Am. 120 (3):1684-1694.

• Le Boeuf, B. J. Pinniped mating systems on land, ice and in the water: Emphasis on the Phocidae. in D. Renouf ed. Behavior of Pinnipeds. Chapman and Hall New York, NY.

• Poulter, T. C. 1963. Sonar Signals of the Sea Lion. Science 139: 753-754. • Riedman, M. 1990. The Pinnipeds: Seals, Sea Lions and Walruses. University of California

Press, Berkley, CA. • Schusterman et al. 2000. Why pinnipeds don’t echolocate. J. Acoust. Soc. Am. 107 (4):

2256- 2264• Van Parijs, S.M., P.M. Thompson,. D.J. Tollit and A. Mackay. 1997. Distribution and activity

of male harbour seals during the mating season. Animal Behavior 54: 35-43 • Van Parijs, S.M. et al. 2003. Patterns in the vocalizations of male Harbor Seals. J. Acoust.

Soc. Am. 113 (6): 3403-3410

• Van Parijs, S.M., G.D. Hastie, and P.M. Thompson. 2000. Individual and geographical variation in display behaviour of male harbour seals in Scotland. Animal

Behaviour 59: 559-568 • Zimmer, C. 2001. By a whisker, Harbor Seals catch their prey. Science 293 (5527): 29

AcknowledgmentsAcknowledgments

• Dr. Jeanette ThomasDr. Jeanette Thomas

• Jennifer McGee, Rita Stacey, Wendy Jennifer McGee, Rita Stacey, Wendy Komar, Brookfield Zoo StaffKomar, Brookfield Zoo Staff

• Dr. Musser and Dr. MeiersDr. Musser and Dr. Meiers

• Matthew ClarkMatthew Clark

• Fellow Graduate StudentsFellow Graduate Students

Questions?Questions?