Identifying Individual Variation in the Discrete Calls of the Killer Whale, Orcinus orca Sam Levinson October 27, 2007 Beam Reach Marine Science and Sustainability School beamreach.org/071

Why should there be variation? Every animal is different! Every animal is different! Size, shape of sound producing organs have an effect on voice Size, shape of sound producing organs have an effect on voice Subtle differences in size and shape make a big difference in the sounds we hear Subtle differences in size and shape make a big difference in the sounds we hear

Source-filter Theory Each sound must be produced (Source) Each sound must be produced (Source) Larynx, syrinx of terrestrial mammals and birds (“vocal chords”) Larynx, syrinx of terrestrial mammals and birds (“vocal chords”) Phonic lips of toothed whales and dolphins Phonic lips of toothed whales and dolphins Sounds are modified before leaving the animal (Filter) Sounds are modified before leaving the animal (Filter) Throat, nasal passages, mouth of terrestrial animals Throat, nasal passages, mouth of terrestrial animals Nasal passages, melon of killer whales Nasal passages, melon of killer whales Filtering creates formants Filtering creates formants

Formants Discrete calls have a a fundamental frequency and harmonics (multiples of fundamental) Discrete calls have a a fundamental frequency and harmonics (multiples of fundamental) Certain harmonics are amplified in the filtering process Certain harmonics are amplified in the filtering process Each set of amplified harmonics is called a formant Each set of amplified harmonics is called a formant

S3 Call from Adult and Calf See the difference in which harmonics are louder?

Formants of S3 Calls Those crazy red dots? Formants calculated by Praat

My Study Animals Three killer whales from J-pod Three killer whales from J-pod Two adults Two adults J-22 J-22 J-34, her son J-34, her son One calf - possibly J-38? One calf - possibly J-38? Calf approached the Gato Verde Calf approached the Gato Verde Adults stayed farther away Adults stayed farther away

Recording Sounds 4-hyrdophone array 4-hyrdophone array Hydrophones are approx. 10m apart Hydrophones are approx. 10m apart Sound arrives at each hydrophone at a different time Sound arrives at each hydrophone at a different time

Localizing Sounds Ishmael Ishmael Sound localization software Sound localization software Uses difference in arrival time to find sound of source Uses difference in arrival time to find sound of source Allows calculation of distance to source Allows calculation of distance to source

Matching Calls to Whales Used Ishmael to calculate distances to source of call Used Ishmael to calculate distances to source of call Personal observations Personal observations Calf came within 100m of Gato Verde Calf came within 100m of Gato Verde Adults stayed more than 100m from boat Adults stayed more than 100m from boat Calls from within 100m of boat came from calf Calls from within 100m of boat came from calf Calls from further than 100m from the boat came from either J-22 or J-34 Calls from further than 100m from the boat came from either J-22 or J-34

Comparing Adult and Calf Analyzed 4 call types: Analyzed 4 call types: S3: S7: S12: S19:

Call Analysis Used Praat (Institute of Phonetic Sciences) to extract formants Used Praat (Institute of Phonetic Sciences) to extract formants 27 variables per call! 27 variables per call! Duration of each of 3 syllables (as per Ford 1987) Duration of each of 3 syllables (as per Ford 1987) For each of 2 formants in each call: For each of 2 formants in each call: Start, end, maximum frequency Start, end, maximum frequency Proportion of syllable at which maximum frequency occurs Proportion of syllable at which maximum frequency occurs Compare all 27 variables between calf and adult Compare all 27 variables between calf and adult 4 call types x 27 variables = 108 comparisons 4 call types x 27 variables = 108 comparisons

My Findings Out of 108 comparisons, I found significant differences in... Out of 108 comparisons, I found significant differences in of them 11 of them 3 out of the 4 calls had variables that were different between adult and calf 3 out of the 4 calls had variables that were different between adult and calf No real pattern to which variables were significant No real pattern to which variables were significant Except that 8 out of the 11 significant variables were in the 1 st syllable Except that 8 out of the 11 significant variables were in the 1 st syllable

So... are the calls individually distinctive? Not according to my data Not according to my data Possible reasons for lack of difference: Possible reasons for lack of difference: Adult was probably either mother or brother to calf Adult was probably either mother or brother to calf Related individuals may sound similar? Related individuals may sound similar? Calf may have learned to mimic mom or brother Calf may have learned to mimic mom or brother Small sample size Small sample size Formant analysis may not be appropriate for whales Formant analysis may not be appropriate for whales

Acknowledgements Team VaTo: Team VaTo: Alex Kougentakis, Anne Harmann, Ashleigh Kemp, Tim Hunt Team JaMi Team JaMi Elise Chapman, Heather Hooper, Kenna Lehman, Liz Hetherington, Wessal Kenaio, Elise Chapman, Heather Hooper, Kenna Lehman, Liz Hetherington, Wessal Kenaio, Instructors Instructors Jason Wood, Mike Kramer, Scott Veirs, Shannon Fowler, Todd Shuster, Val Veirs Jason Wood, Mike Kramer, Scott Veirs, Shannon Fowler, Todd Shuster, Val Veirs My friends and family, who are too numerous to name on one slide My friends and family, who are too numerous to name on one slide