killer whales do it in the dark: nocturnal activity by transients at st. paul island kelly newman...

Killer Whales Do It In The Killer Whales Do It In The Dark: Nocturnal Activity By Dark: Nocturnal Activity By Transients At St. Paul IslandTransients At St. Paul Island

Killer Whales Do It In The Killer Whales Do It In The Dark: Nocturnal Activity By Dark: Nocturnal Activity By Transients At St. Paul IslandTransients At St. Paul Island

Kelly Newman Kelly Newman Alan SpringerAlan Springer

University of Alaska FairbanksUniversity of Alaska FairbanksSchool of Fisheries and Ocean SciencesSchool of Fisheries and Ocean Sciences

Kelly Newman Kelly Newman Alan SpringerAlan Springer

University of Alaska FairbanksUniversity of Alaska FairbanksSchool of Fisheries and Ocean SciencesSchool of Fisheries and Ocean Sciences

Photo: Bob Pittman

Why Study Killer Whales at St. Paul?

•Pinniped and sea otter collapses in Alaska•Fur seals declining on Pribilofs•Predation as a factor in population dynamics•St. Paul is a predation hot-spot

Problem of documentation

ExpensiveTime consumingLow probability of observing predationPoor field conditions

SolutionsSolutions

Work in predation hot-spots Use alternative techniques Acoustic monitoring

8x more effective than just visual for detecting marine mammals

Work in predation hot-spots Use alternative techniques Acoustic monitoring

8x more effective than just visual for detecting marine mammals

FUR SEAL ROOKERIES

From NMML website

Accepted TheoryAccepted Theory

Transients use stealth to hunt–quieter before kills

Transient killer whales are most vocal when feeding

Calling behavior can indicate feeding activity

Transients use stealth to hunt–quieter before kills

Transient killer whales are most vocal when feeding

Calling behavior can indicate feeding activity

Recording MethodsRecording Methods “Pop Up” Autonomous Recording Unit Continuous recording June 22-July 12,

2006 Frequency Range 0.5-16,000 Hz

“Pop Up” Autonomous Recording Unit Continuous recording June 22-July 12,

2006 Frequency Range 0.5-16,000 Hz

AnalysisAnalysis

Raven 1.3 Sound Analysis Software 512 point spectrograms were

visually and aurally inspected for killer whale calls and whistles

Sound files were fifteen minutes

Raven 1.3 Sound Analysis Software 512 point spectrograms were

visually and aurally inspected for killer whale calls and whistles

Sound files were fifteen minutes

Call DetectionCall Detection

Number of days recorded 22

Number of 24 days analyzed 20

Number of days killer whales detected

19

Number of hours analyzed 480

Number of 15 minute recording segments killer whales were detected

190 out of 1920

ResultsResults

0

2

4

6

8

10

12

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Nu

mb

er o

f d

ays

wit

h c

alls

in

eac

h h

ou

r

0

5

10

15

20

25

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Alaska Daylight Time

Nu

mb

er

of

15

min

ute

in

terv

als

w

ith

ca

lls

Killer Whale Vocal Frequency Over 24 hours

CT SR

CT SR

SS CT

SS CT

ST

Nu

mb

er o

f days w

ith

calls

Dete

ctio

ns

1 2 3

0

2

4

6

time

vox

More activity from midnight through morning

Kille

r Wh

ale

D

ete

ctio

ns

Time of Day P value<.0001

0000 through 0745 0800 through 1545 1600 through 2345

From Jeremy Sterling

Sunset Sunrise

Fur Seal Departure Times

KnownKnown

Only transients identified at St. Paul They have only been observed

eating fur seals at the islands Considered a “problem” in the past

Only transients identified at St. Paul They have only been observed

eating fur seals at the islands Considered a “problem” in the past

Abundance Persistence Group structure Predation rates

Abundance Persistence Group structure Predation rates

UnknownUnknown

From Heather Vukelic

ConclusionsConclusions St Paul is frequented by killer

whales on a daily basis Only transients have been

identified Potential predation rates can be

monitored at this hot-spot This is only one feeding area in the

Pribilof Islands

St Paul is frequented by killer whales on a daily basis

Only transients have been identified

Potential predation rates can be monitored at this hot-spot

This is only one feeding area in the Pribilof Islands

ImplicationsImplications

The observation window for killer whale activity needs to be expanded to include nocturnal activity.

Quantification of their ecological role is meaningless with limited observation power.

The observation window for killer whale activity needs to be expanded to include nocturnal activity.

Quantification of their ecological role is meaningless with limited observation power.

Phase II

Identify call typesCorrelate with visual observationsAcoustically “map” the Pribilof Islands for killer whale activity

AcknowledgementsAcknowledgements

Alaska Sea Grant John Melovidov and Crew of the

MarySea Greenpeace Jacob Merculief NPRB (COFFS)

Alaska Sea Grant John Melovidov and Crew of the

MarySea Greenpeace Jacob Merculief NPRB (COFFS)