Underwater Vocalizations Of Harbor Seals
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Underwater vocalizations of Underwater vocalizations of Pacific Harbor Seals Pacific Harbor Seals
((Phoca vitulina richardiiPhoca vitulina richardii))
Mehgan M. ClarkMehgan M. Clark
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OverviewOverview
• Harbor Seal Harbor Seal BackgroundBackground
• Research Research DevelopmentDevelopment
• Goals Goals
• MaterialsMaterials
• MethodsMethods
• ResultsResults
• ConclusionsConclusions
http://photos.aznightbuzz.com/gallery/view/1544
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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
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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
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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
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Background-Acoustic Background-Acoustic StudiesStudies• Started Started
– 1960s 1960s – Poulter and Poulter and
SchustermanSchusterman– California Sea LionsCalifornia Sea Lions
• EcholocationEcholocation– InvestigatedInvestigated– DebatedDebated
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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
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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
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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)
http://www.brookfieldzoo.org/pgpages/pagegen.278.aspx?shttplink=../pgpages/pagegen.278.aspx&nsection=2
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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
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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.
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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.
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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
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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
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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
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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
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Acoustical AnalysisAcoustical Analysis
Sonographic Sonographic analysis:analysis:
• FrequencyFrequency
• Sound Sound ComponentsComponents
• Harmonic Harmonic StructureStructure
• DurationDurationPhoto By: Mehgan Clark
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Component One
Dominant Beginning Frequency
Dom. Max. Freq.
Dominant Minimum Frequency
Dominant Ending
Frequency
OscilogramSpectrogra
m
Total Duration
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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
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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
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Growl SpectrogramGrowl Spectrogram
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Short Roar SpectrogramShort Roar Spectrogram
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Long Roar SpectrogramLong Roar Spectrogram
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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
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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
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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
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Results- Principle Component Results- Principle Component AnalysisAnalysis
• Components of Importance for Components of Importance for ClassificationClassification
• All Components UsedAll Components Used
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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
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Results- Principle Component Results- Principle Component AnalysisAnalysis
• No RotationsNo Rotations
• Frequency componentsFrequency components– Grouped together Grouped together – Factor 1Factor 1
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Factor Loadings Plot
CIS
COMPANALYZED
DBFREQ
DEFREQ
DMAXFREQDMINFREQ
COMPDURATION
COMPINTERVALTOTDURATION
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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
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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
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Cluster Tree
0 1000 2000 3000 4000 5000Distances
CIS
COMPANALYZED
DBFREQ
DEFREQ
DMAXFREQ
DMINFREQ
HARMONICS
FIRSTHARMINT
HIHARMONIC
COMPDURATION
COMPINTERVAL
TOTDURATION
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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
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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
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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
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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
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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
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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
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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
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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
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Questions?Questions?