does an increase of boats cause decreased vocalization rates in killer whales (orcinus orca)?
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Does an Increase of Boats Cause Decreased Vocalization Rates in Killer Whales (Orcinus orca)?. Matthew J. Williams Beam Reach Marine Science and Sustainability School June 4, 2009. Bioenergetics. Every action requires energy Energy is a limiting factor - PowerPoint PPT PresentationTRANSCRIPT
Does an Increase of Boats Cause Decreased Vocalization Rates in Killer
Whales (Orcinus orca)?
Matthew J. WilliamsBeam Reach Marine Science and Sustainability
SchoolJune 4, 2009
Bioenergetics
• Every action requires energy
• Energy is a limiting factor
• Do orcas limit vocalizations if they are unlikely to be heard?
Methods• Recorded:
– Vocalizations
– Behavioral state
– Number of boats within 1000 m
– Ambient noise levels
Key Questions
• Does an increase in boats correlate with an increase in ambient noise?
• Do call rates decline with an increase in ambient noise?
Does an increase in boats correlate with an increase in ambient noise?
Boat Noise in Relation to Ambient Noise Levels
y = 0.3201x + 124.7
R2 = 0.0447
0
20
40
60
80
100
120
140
160
0 2 4 6 8 10 12 14 16
Number of Boats
Am
bie
nt
No
ise
(dB
re
1 m
icro
Pa)
Linear (Boat Numbers in Relation toAmbient Noise)
P < .001
Sample Size: 1016
Do call rates decline with an increase in ambient noise?
Ambient Noise in Relation to Call Rates
y = -0.1464x + 19.686
R2 = 0.051
-5
0
5
10
15
20
25
30
100 105 110 115 120 125 130 135 140 145 150
Ambient Noise (dB re 1 micro Pa)
Cal
l Rat
e (C
alls
per
Min
)
Linear (Series1)
P < .001Sample Size: 1016
Call Rates
• Min: 0
• Max: 26
• Mean: 1.22
• Mode: 0
• Sample Size: 1016
• Very large proportion of data is 0 calls/min!
Supplementary Question
• Does the behavioral state influence the call rates?
• Important to limit a source of variance
Call Rates
Behavioral State
Min Max Mean Sample Size
Foraging 0 9 .53 134
Milling 0 1 .02 58
Playing 0 26 11.47 15
Resting 0 0 0 78
Traveling 0 18 1.37 731
Changes in Call Rates: ForagingForaging: Ambient Noise in Relation with Call Rate
y = -0.101x + 13.359
R2 = 0.0853
-2
0
2
4
6
8
10
115 120 125 130 135 140 145
Ambient Noise (dB re 1 micro Pa)
Cal
l Rat
e (C
alls
per
Min
)
Ambient Noise Level in Relation to Call Rate
Linear (Ambient Noise Level in Relation to CallRate)
P < .001Sample Size: 134
Changes in Call Rates: Traveling
Traveling: Ambient Noise Levels in Relation to Call Rates
y = -0.1148x + 15.78
R2 = 0.0349
-5
0
5
10
15
20
100 105 110 115 120 125 130 135 140 145 150
Ambient Noise (dB re 1 micro Pa)
Cal
l Rat
e (C
alls
per
Min
)
Series1
Linear (Series1)
P < .001Sample Size: 731
Questions?
• Acknowledgements:– Jason Wood– Scott Veirs– Val Veirs– Todd Shuster– Mike Kramer– Classmates