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Localizing Vocalizations in fish-eating southern resident killer whales ( Orcinus orca)

This study examines the vocalizations of fish-eating Southern Resident Killer Whales (Orcinus orca) to understand their social arrangements, gender differences, and variations in call characteristics. The research used hydrophone arrays and acoustic analysis software to localize and analyze the calls. The findings suggest potential differences in calls based on gender and group composition. This knowledge is important for understanding individual recognition, social organization, and future studies on call variations.

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Localizing Vocalizations in fish-eating southern resident killer whales ( Orcinus orca)

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  1. Localizing Vocalizations in fish-eating southern resident killer whales (Orcinus orca) Peggy Foreman Beam Reach 2006 Marine Science and Sustainability School

  2. Social Arrangements • Pod- primary social unit of matrilineal groups • Subpods and matrilines (J, K, and L) • Communities- frequent associations with one or more pods, yet have different distributions with other communities (J + K + L) • Clans- acoustically related; shared vocal tradition (J clan)

  3. Vocal Clans • Complex repertoire of whistles, clicks, and calls • Calls are pulsed signals generated in high repetition rates and most fall into discrete categories • These discrete calls are the most common sound type when individuals are widely spread out (cohesion)

  4. Gender • 86 whales (~14 sexually mature males and ~23 reproductive females) • Sexual dimorphism • Predict lower frequency fundamental for males • May spatially segregate to some degree when foraging • Shorter duration of calls • Changes in harmonic frequency

  5. Questions • Are there any variations in calls in regards to gender? Call Characteristics: Call duration, Fundamental Frequency, and variations in the first harmonic of a call

  6. Materials * Towed linear 4 hydrophone array * National Instruments Board with 4 channels * PC computer: Ishmael software to localize calls Raven software to analyze calls * Clipboard: PDA/data sheets (behavioral data) * Binoculars * Range finder (research assistant) * Camera (research assistant)/ID guides

  7. Methods • Hydrophone array was deployed off the starboard steps • Continuous Acoustic Recording in Ishmael (sampling rate of 22050, DFT rate 512) • Behavior Data ( # focal animal/s, distance, bearing, and predominant group behavior state) • Opportunistic lone individuals or small groups (increase my success in localizing)

  8. Acoustic Analysis: ISHMAEL • Software designed to localize • Phone pair bearing, crossed-pair bearing, hyperbolic location, and beam forming • 0°, 180° can’t get a valid bearing (15°) • Dinghy experiment: accurate with in 17° and closer than 300m to the boat worked best • calculates two bearings

  9. Acoustic Analysis: ISHMAEL

  10. Raven Analysis: Call Characteristics • Duration • Fundamental • 1st Harmonic Analysis (low, high, and change in Frequency)

  11. Results: • Acoustic and surface behavior observations were recorded on 6 out of 19 field days • 19.5 hr of acoustical recordings and 16.95 hr of PDA data (1170 one minute files) • Looked through 115 one minute files • Localized 122 calls • 19 of those localized calls matched my bearing (avg 5.8° difference)

  12. Results: SD= slow directional

  13. Results: ANOVA: F[2,16]=2.4212, p= 0.1206 4 3 12 95% confidence intervals

  14. Results: ANOVA: F[2,16]=1.8183, p= 0.1943 4 3 12

  15. Results: 1st Harmonic ANOVA: F[2,16]=0.4785, p= 0.6283 4 3 12

  16. Results: 1st Harmonic ANOVA: F[2,16]=1.2457, p= 0.3142 4 3 12

  17. Results: 1st Harmonic ANOVA: F[2,16]=3.5752, p= 0.0521 12 4 3 4 3 12

  18. Discussion

  19. Discussion • Real differences between gender and mixed groups? • Analyzed calls: Different call types? • Males and Females could be using different calls • The frequency Modulation changes with mixed gender groups could that be due to group size? • Variations due to more than one pod together?

  20. Why is this important? • Localizing is only one piece of the larger picture • Who is speaking…is it the oldest matriarch • …is it the male on the periphery • scouting out “good” foraging areas • Acoustically recognize individuals • - especially in winter • - detect when additions or loss of individuals • occur in the population

  21. Future Studies • Full summer season to see if changes in calls change with location, behavior, different social organizations • Calling rate • Source level of calls • Call type vs. surface behavior • Do males and females use the same discrete calls (vary with age?)

  22. Acknowledgements • Huge thank you to the instructors of Beam Reach • (Jason Wood, Donna Hauser, Scott Veirs, and Val Veirs) • Beam Reach colleagues (Rena Escobedo, Emily Pierson, Erin Soucy, Colleen Barry, and Juliette Nash) • Todd, Mike, Glenn for the use and safe navigation of the Gato Verde • Puyallup Tribe of Indians for your financial support

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