CHANGES IN RIGHT WHALE CALL BEHAVIOR: POTENTIAL EFFECTS OF OCEAN NOISE. By: Nilasha Sairandri Anika

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1 CHANGES IN RIGHT WHALE CALL BEHAVIOR: POTENTIAL EFFECTS OF OCEAN NOISE By: Nilasha Sairandri Anika

2 INTRODUCTION

3 Christopher W. Clark Cornell University

4 RIGHT ATLANTIC WHALES North and South Long-lived: up to 65 years North whales almost on the brink of extinction- more whaling and higher noise levels than South Scream call by focal female: possible mating call Up-call by males: communication call

5 WHY STUDY THIS ORGANISM? It is ENDANGERED! North vs. South o North has experienced a greater increase in noise pollution o Easier to compare and see extent of changes

6 PURPOSE To identify whether increased noise levels have resulted in any behavioral changes in sound production by North and South Atlantic right whales The paper uses 3 different analyses to see how right whales change their calling behavior in times of increased background noise: 1. Studies short term changes in behavior 2. North Atlantic vs South Atlantic 3. Present vs Historic recordings

7 COMPARISON 1 Method: Acoustic recordings made in Bay of Fundy, Canada of Surface Active Groups (SAGs)

8 Scream calls and up-calls were selected Noise levels in recordings classified: 1. Class 1 - no audible vessel noise 2. Class 2 - Noise from at least one distant vessel, moderate 3. Class 3 - Relatively continuous noise from vessels 1 mm from whales

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10 Analysis: Timing End and Start frequency Duration Increase in minimum frequency Decreased call rate Changes in duration significant but no clear trend with increasing noise

11 Conclusion Observed changes are: i. Increase in minimum frequency ii. Decrease in call rate iii. Significant changes in call duration seen but no clear trend Possible reason for decrease in call rate is increased effort or waiting for a temporary reduction background noise level Shortcomings- Doesn t allow for measurement of call amplitude as a function of short-term variability in noise level.

12 COMPARISON 2 Recordings Location Bay of Fundy, Canada Cape Cod Bay and the Great South Channel, MA

13 Recordings Location Golfo San Jose, Argentina 2000 Southern Right Whales

14 Results North Atlantic right whales call at a higher start and end frequency than southern right whales < SARW NARW North Atlantic right whale upcalls have a larger bandwidth than southern right whales

15 Start frequency differences between species and frequency differences over time for both species. Atlantic right whale call duration increased slightly through time, whereas southern right whale call duration decreased through time.

16 Limitations of the Study Unable to determine if observed changes were the result of a single individual changing its call or if a different individual was calling Unable to measure the intercall interval

17 COMPARISON 3 Method: North Atlantic right whales 1956 recordings vs recordings South Atlantic right whales 1977 recordings vs recordings

18 COMPARISON 3 Results: Measurement Start Frequency End Frequency Bandwidth Duration North Atlantic right whale Increased over time Greater difference in start frequency Increased over time No effect of time No interaction between species and time Increased slightly through time South Atlantic right whale Increased over time Increased over time No effect of time No interaction between species and time Decreased slightly through time

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21 Conclusion and Discussion: The observed change is: Significant increase in start and end frequency in recent recordings in both species. Shortcomings- Due to small sample size, it is unclear how representative the 1956 data are of the entire population at that time.

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23 ALTERNATE EXPLANATIONS Individual variation for observed shift of scream calls in SAGs Inherited species differences from random genetic drift or selective pressure for between-species differences Change in population demographics

24 RESULTS Right whales produce higher frequency sound and decrease their call rate in higher noise conditions. North Atlantic right whales have been more impacted due to increase in shipping in the northern hemisphere.

25 THANKS!