Underwater vocalizations of a male Pacific harbor seal (Phoca vitulina richardii) during a

mating period at Brookfield Zoo, Chicago IL

Mehgan M. ClarkJeanette Thomas

Western Illinois University

BackgroundEcology (Riedman, 1990)

Distribution (P.v.richardii) Alaska to Mexico

Diet-Amphibious Carnivore Fish, cephalopods, krill

Life Span 25 years in the wild

Maturity Females: 3-7 yrs Males: 2-7 yrs

https://www.washington.edu/burkemuseum/collections/mammalogy/mamwash/p

hvi.html

BackgroundMating Behavior (Riedman, 1990)

Males Dominance Hierarchy Aggressive Behavior

Flipper Slaps Neck Bites

Territory Vocalize Along travel corridor Possible lek (Van Parijs et al 1997)

Females Post-Partum

Estrus Annually March-

Sept. Feeding trips Aquatic Mating

Exact method not observed

Background-Acoustic Studies

Females Mother-pup relations

(Khan et al., 2006)

Males Breeding season (Van

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

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

http://photos.aznightbuzz.com/gallery/view/1544

Background-Harbor Seal Acoustics

Roars Hanggi and

Schusterman 1994 Mean 4.2 seconds Occasional

Harmonics Van Parijs et al. 1997

1/min 1 roar underwater Mean = 665 Hz

Van Parijs et al. 2003 Geographic variation

Hearing Range (Fay 1988) Phocids have a greatest

sensitivity between about 1 and 60 kHz

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

Goals

Catalog all sounds as part of the repertoire.

Determine if the calls are different.

Determine the number of calls per minute.

Photo By: Mehgan Clark

Materials

Ithaco 605 Hydrophone Linear to 75 kHz

DELL XPS M140 Laptop. Linear to 48 kHz

Goldwave sound analysis program and recording software.

Spectrogram sound analysis program. Photo By: Mehgan Clark

Methods Recordings

April and October 2006

6-10AM Behavioral

Notes Taken as Possible

Limited Stats

Summary Stats PCA Hierarchical Cluster

Photo By: Dr. J. A. Thomas

Component One

Dominant Beginning Frequency Dominant

Minimum Frequency

Dominant Maximum Frequency

Dominant Ending

Frequency

Long Roar Short Roar

Growl

Results-Calls

3 Main Calls (n=713 calls) Growls Short Roars Long Roars

Found only during the mating period June 25-28 2006 Probable start End of behavior date

unknown Phase 4 of Study 2.5 Calls per Minute 98.6% of repertoire One-Way ANOVA

Dominant Maximum Frequency (p=0.377, df=93, alpha=0.05)

Call Parameter Means + Standard Deviations

1.84±0.65

336.5±148.1

1349.8±452.1

797.2±210.2

727.2±133.7

Short Roar

4.80±1.77

210.6±18.4

1329.3±319.8

707.5±191.1

611.3±98.8

Long Roar

0.94±0.55

291.2±163.1

2060.2±566.6

1026.1±325.2

1026.1±315.1

Growl

ComponentDuration(seconds)

Dom. Min. Freq. (Hz)

Dom. Max. Freq.(Hz)

Dom. Ending Freq.(Hz)

Dom. Beg.Freq.(Hz)

Call Type

Principal Component AnalysisComponent Loadings Factor 1 Factor 2 Factor 3Dominant Beginning Frequency -0.922 0.213 0.289Dominant Ending Frequency -0.916 0.225 0.287Dominant Maximum Frequency -0.865 0.177 0.285Dominant Minimum Frequency -0.602 0.122 0.067Component Duration 0.573 0.002 0.742Total Duration 0.566 -0.069 0.752Presence/Absence 0.216 0.849 -0.132of HarmonicsFirst Harmonic Interval 0.262 0.941 -0.001Highest Harmonic 0.252 0.93 -0.022

Variance Explained 3.627 2.635 1.385by Components

Percent of Total 40.297 29.281 15.393Variance Explained

0.000 Distances 5000.000

Hierarchical Clustering

Click

Short Roar

Grunt

Growl

Groan

Howl

Whistle

Long Roar

Creak

Conclusions

Differences in 3 Call types. Statistically Significant Support Literature Frequency Components

Most Important Male vocalization

roar-associated with mating behavior

blowing bubbles selection by female

No other males May rule-out that it is a

competition call

Photo By: Mehgan Clark

Future Research

Similar Research Video Recordings Simultaneous

with acoustic recording

Surface intervals Number of roars

per dive Behavioral

Components

Literature CitedHanggi, 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

Acknowledgments

Dr. Jeanette Thomas Jennifer McGee, Rita Stacey, Wendy

Komar, Brookfield Zoo Staff Dr. Musser and Dr. Meiers Matthew Clark Fellow Graduate Students

Questions?