killer whale (orcinus orca) echolocation click rates during various behavioral states and ambient...
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Killer whale (Orcinus orca) echolocation click rates during various behavioral states and
ambient noise levels
Hana KazunasBeam Reach School of Marine Science and
BackgroundTransients
Marine-mammal eating
Less vocalSouthern Residents
Subpods: J, K, LFish-eatingHighly vocalEndangered species
Northern Residents
So what?
Inadequate nutritionDecline in prey
populationChronic Stress
Vessel impactsToxin buildup
Declining population size
EcholocationDirectional sounds with:
High amplitudeBroadband frequency structureShort duration
Single or train formation
Used for:NavigationPrey location
HypothesesClick rate will increase
as ambient noise increase
Click rates will change across behavior states; foraging and traveling will have the highest rates
Data CollectionAcoustic recordings made
using a hydrophone array and high-frequency hydrophone (CRT)
Record time, behavior state, whale orientation to boat, pod size, interesting notes
Behavior statesForaging, milling, resting,
socializing, traveling
Data AnalysisCount click rateCompare to ambient noise levels and behavior
state
Results: Ambient noise
85 90 95 100 105 110 115 120 1250
100
200
300
400
500
600
700
800
f(x) = 2.14905126660995 x − 147.934765560679R² = 0.038802885748415
Click Rates verus Ambient Noise Levels
Ambient noise level (dB)
Nu
mb
er
of
cli
ck
s/m
in
Results: Ambient noise
Preliminary trend of upper threshold at which click production or detection stops
116.5 117 117.5 118 118.5 119 119.5 120 120.5 121 121.50
20
40
60
80
100
120
140
Foraging
Traveling
Socializing
Resting
Milling
Upper threshold of click production
Ambient noise threshold (dB)
Cli
ck
Rate
at
hig
hest
back
gro
un
d l
evel
Results: Behavior States
Statistical significance: Foraging and resting, resting and socializing, and resting and traveling
Foraging Milling Resting Socializing Traveling -25
25
75
125
175
225
275Controlled Average Click Rates per Minute
Behavior State
Nu
mb
er
of
cli
ck
s p
er
Min
ute
Results: Behavior states
Significant: foraging and resting
Foraging Milling Resting Socializing Traveling0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9Controlled average number of click trains across behavior
Behavior State
Nu
mb
er
of
cli
ck
tra
ins/
min
ute
Discussion: Ambient Noise
Inherent difficulty studying masked clicks
Signal-to-Noise ratio
Whales click louder, not faster
Discussion: Behavior StatesWhy is foraging low?
Categorized by sporadic movement
Whales utilize other foraging techniques
Why is socializing high?Possible communicative
propertiesSmall sample size
Click trainsWhales zeroing in on targetDifferent meaning from
single clicks
Conclusions
Increased ambient noise levels pose a threat to whales
Different click rates serve different purposesMore significant results would allow for more
appropriate guidelines to be set to protect whales
ErrorMisidentification of behavior stateWhales not oriented towards hydrophonesDifficulty counting whalesError counting clicks
Future StudiesContinuation this studyAmbient noise thresholdEcholocation use at nightOther foraging strategiesEcholocation use in other
habitats
AcknowledgementsI would like to extend a big thanks to:
Dr. Jason Wood, Dr. Val Veirs, and Dr. Scott Veirs for continuous support and ever-open office doors
Captain Todd Shuster for keeping Beam Reach safe and sustainable on the water
Everyone who helped Beam Reach find the whales this term
Cat Peters, Megan Stoltzfus, Garrett Turner, Dave Cade and Vanessa Victoria for your cheer, effort and enthusiasm (and body heat)
The whales, just for being there
Questions?