Notes

MARINE MAMMAL SCIENCE, **(*): ***–*** (*** 2012)C© 2012 by the Society for Marine MammalogyDOI: 10.1111/j.1748-7692.2011.00557.x

Between-year synchrony in migratory timing of individual humpbackwhales, Megaptera novaeangliae

DANIEL BURNS1 and LYNDON BROOKS, Southern Cross University Whale ResearchGroup, Marine Ecology Research Centre, Southern Cross University, PO Box 157, Lismore,New South Wales 2480, Australia and South Pacific Whale Research Consortium, Avarua,Rarotonga, Cook Islands; PHIL CLAPHAM, National Marine Mammal Lab, Alaska FisheriesScience Center, 7600 Sand Point Way, NE, Seattle, Washington 98115, U.S.A. and SouthPacific Whale Research Consortium, Avarua, Rarotonga, Cook Islands; PETER HARRISON,Southern Cross University Whale Research Group, Marine Ecology Research Centre, SouthernCross University, PO Box 157, Lismore, New South Wales 2480, Australia and South PacificWhale Research Consortium, Avarua, Rarotonga, Cook Islands.

Humpback whales, Megaptera novaeangliae, undertake long annual migrations fromhigh-latitude summer feeding grounds to low-latitude winter mating and calvinggrounds (Mackintosh 1942, Dawbin 1966). Studies of migratory timing in thisspecies have been generally focused at the population level, or on age class cohortswithin a population, although the volume of information about individual migrationpatterns remains limited.

Using extensive whaling data from the 20th century, Dawbin (1966, 1997) de-scribed the temporal segregation of different age classes of humpback whales onmigration. On both directions of the migration, the earliest and last whales in eachcategory traveled approximately 6 wk before and after the central peak for thatcategory (Dawbin 1966).

Mattila et al. (2001) described the “temporal fidelity” of humpback whales ontheir West Indies breeding grounds, with individual females tending to be seen “onor about the same day (of the year)” in subsequent years. Consistency in the timing ofthree individual humpback whales off the coast of Ecuador has also been reported byFelix and Haase (2001), with intervals of 0, 7, and 21 d, respectively, between the dayof the year sighted for these whales. However, both historic whaling data (Dawbin1997) and more recent across-year sightings data of individual whales (Craig et al.

1Corresponding author (e-mail: daniel.burns@scu.edu.au).

1

2 MARINE MAMMAL SCIENCE, VOL. **, NO. **, 2012

Table 1. Survey effort and number of fluke photographs collected per season from 2003 to2005.

Number of days Number of flukeSurvey period (d) surveyed Hours surveyed IDs collected

1 September–6 November 2003 (65) 30 202 h 11 min 2001 September–1 November 2004 (60) 19 117 h 24 min 15217 August–4 November 2005 (77) 39 264 h 54 min 277Total (202) 88 584 h 29 min 629

2003) suggest that female humpbacks tend to arrive at and depart from the breedinggrounds earlier in years when they do not have a calf than in years when they givebirth. In this study, we report on the migratory timing of 22 individual humpbackwhales photographed in more than one year off the eastern coast of Australia from2003 to 2007.

Fieldwork for this project was based off the coast of Ballina (28◦52′S, 153◦35′E)in northern New South Wales, approximately 25 km south of Cape Byron, the mosteasterly point of the Australian mainland (Fig. 1). This location is approximately4,000 km north of the Antarctic feeding grounds and 1,000 km south of the generallydescribed breeding grounds for east coast Australian humpback whales (16◦–21◦S,Marsh et al. 1997, Chaloupka and Osmond 1999).

Fluke photographs were collected during vessel-based surveys of the southernmigration of humpback whales from 2003 to 2005 (Table 1). Annual surveys weretimed to encompass the major part of the southern migration, with only a smallpercentage of whales likely to pass Ballina on their journey south outside of thisperiod (Chittleborough 1965, Paterson 1991, Dawbin 1997). To obtain a represen-tative sample of the migrating population, fieldwork was conducted for 3–4 d/wkthroughout the survey period, weather and operational constraints permitting.

All photographs were reconciled both within and among seasons to compileresighting histories of individuals. Additional sighting information was obtained bycomparing the data set with a small number of photographs taken aboard a whalewatch vessel off Cape Byron during the humpback whale southern migration in 2006(data provided by A. Nichols and analyzed by P. Beeman, Southern Cross University).

Further information about consistency in migratory timing was assessed by com-paring sightings information for a hypo-pigmented whale, commonly known as“Migaloo,” that migrates along the eastern coast of Australia each year (Forestellet al. 2001). As Migaloo is readily recognizable and generates extensive public andmedia attention, sightings data for this whale are more readily available than for otherwhales. Migaloo was first sighted off Cape Byron in 1991 (Forestell et al. 2001), withgenetic evidence confirming that it is a male (Burns 2010), and probably an albino,although the latter has not been established definitively.

Information about sightings of Migaloo were collated from Forestell et al. (2001)and expanded upon with more recent data collected from personal observations bythe authors, as well as from other researchers, management authorities, newspaperreports, and photographs taken aboard whale watch operations. All sightings were

NOTES 3

Figure 1. Study site for vessel surveys. The study area extended from Brunswick Heads toEvans Head and offshore to 153◦53′E, however, most fieldwork was conducted within 10 kmof the coast.

assessed for reliability and classified as either “certain,” “likely,” or “anecdotal” as perForestell et al. (2001). Anecdotal sightings were excluded from the analyses. Migaloo’smean migration rate was calculated using the “certain” and “likely” sightings andestimated to be approximately 140 km/d on the migratory corridor. Estimates ofthe dates that Migaloo passed Cape Byron/Ballina on its northern and southern

4 MARINE MAMMAL SCIENCE, VOL. **, NO. **, 2012

migrations each year were calculated by extrapolating travel time from the nearestsighting location of this whale to Cape Byron and assuming a mean migration rateof 140 km/d. Estimates were not attempted for the 1998 season, as, in contrast to allother years when sightings occurred along the migratory corridor, the two sightingsfrom 1998 included one from the putative breeding grounds (Bait Reef; Paterson1991) and one at Hervey Bay, a location known to be a “temporary stopover” pointfor some whales early on their southern migration (Corkeron et al. 1994, Franklinet al. 2011). Any estimates of the dates that Migaloo passed Cape Byron in 1998would therefore have required assumptions to be made about how long this whaleremained in the sighting location before resuming his migration south. Instead theseestimates were excluded.

In total, 22 whales were photographed in more than one season of this study(Table 2). The interval between the day of the year sighted and the median dateof sighting was calculated for each resighted individual, including all confirmedsightings of Migaloo on his southern migration. Although sex and age class datawere lacking for many of the resighted individuals, only one whale (BA04027) wasidentified as a mother with calf on either sighting occasion. This whale was seen38 d later in 2005 than the date of the 2004 sighting and, because of its knownreproductive status as a mother, will be discussed separately from the other sightings.

Excluding BA04027, for the other 21 whales photographed in more than 1 yr ofthis study, the mean interval between the day of the year sighted from one year tothe next was 6.5 d (SD = 5.21), with a range of 0–18 d. There was a significantrelationship between initial and resight day of the year (Table 3, Fig. 2).

On its northward migration, Migaloo is estimated to have passed Cape Byronbetween 15 June and 16 July in each year for which at least one reliable reportexisted (Table 4). The median date on which it passed Cape Byron was 25 June, with

Figure 2. Linear regression of resight day of the year against initial sighting day of the yearfor 21 whales photographed in more than one year from 2003 to 2007 (excludes BA04027).

NOTES 5

Tabl

e2.

Inte

rsea

son

resi

ghti

ngs

ofin

divi

dual

hum

pbac

kw

hale

sph

otog

raph

edof

fthe

coas

tof

Bal

lina

2003

–200

7.

Ove

rall

Ove

rall

Inte

rval

betw

een

Sex

and

Dat

eof

Pod

dire

ctio

nD

ate

ofP

oddi

rect

ion

day

ofye

arsi

ghte

dm

etho

dW

hale

IDfir

stsi

ghti

ngco

mpo

siti

onof

trav

else

cond

sigh

ting

com

posi

tion

oftr

avel

and

resi

ghte

dof

sex

ID

BA

0303

313

-Sep

-03

6/0/

0S

6-Se

p-04

2/0/

0S

−7B

A03

049

14-S

ep-0

30/

0/3

SW20

-Sep

-05

2/0/

0S

6FG

PB

A03

055

15-S

ep-0

35/

0/0

–18

-Sep

-04

5/0/

0SS

E3

BA

0307

422

-Sep

-03

5/0/

0N

22-S

ep-0

49/

0/0

S0

BA

0308

75-

Oct

-03

4/0/

0S

26-S

ep-0

41/

0/0

E−9

BA

0308

96-

Oct

-03

2/0/

0N

12-O

ct-0

48/

0/0

S6

BA

0312

517

-Oct

-03

2/0/

0SW

7-O

ct-0

52/

0/0

–−1

0B

A03

133

17-O

ct-0

36/

1/0

S30

-Sep

-05

3/0/

0S

−18

BA

0313

617

-Oct

-03

3/0/

0SS

W12

-Oct

-04

2/0/

0SE

−5B

A03

148

20-O

ct-0

32/

0/0

N22

-Oct

-05

2/0/

0SS

W2

BA

0318

027

-Oct

-03

4/0/

0S

31-O

ct-0

44/

0/0

S4

BA

0318

631

-Oct

-03

3/0/

0S

30-O

ct-0

53/

0/0

S−1

BA

0320

45-

Nov

-03

1/0/

0S

31-O

ct-0

43/

0/0

S−5

BA

0321

36-

Nov

-03

3/1/

0N

2-N

ov-0

52/

0/0

S−4

MSS

BA

0401

04-

Sep-

043/

0/0

S16

-Sep

-05

8/0/

0S

12B

A04

022

6-Se

p-04

1/0/

0S

20-S

ep-0

52/

0/0

S14

BA

0402

76-

Sep-

042/

0/0

S13

-Oct

-05

4/2/

0SW

38FI

CB

A04

033

8-Se

p-04

2/0/

0S

12-S

ep-0

56/

0/0

SW4

BA

0408

318

-Sep

-04

4/0/

0S

17-S

ep-0

6aN

otre

cord

edS

−1B

A04

088

20-S

ep-0

41/

0/0

SE15

-Sep

-05

3/0/

0N

−5M

SSB

A04

124

2-O

ct-0

42/

0/0

S30

-Sep

-07b

Not

reco

rded

S−3

MSS

BA

0414

531

-Oct

-04

3/0/

0S

13-O

ct-0

54/

0/0

S−1

8

Not

e:P

odco

mpo

siti

ons

incl

ude

num

ber

of:

adul

tsan

dsu

badu

lts/

calv

es/u

nkno

wns

.Se

xid

enti

ficat

ion

met

hods

incl

ude:

FGP

=fe

mal

ege

nita

lph

otog

raph

;MSS

=m

ale

slou

ghed

skin

;FIC

=fe

mal

ein

ferr

edfr

ompr

esen

ceof

calf

.a P

hoto

grap

hed

byA

.Nic

hols

from

the

“Wha

leW

atch

ing

Byr

onB

ay”

vess

el.

b“M

igal

oo”

phot

ogra

phed

byC

.Syl

gefr

omth

e“W

hale

Wat

chin

gB

yron

Bay

”ve

ssel

.

6 MARINE MAMMAL SCIENCE, VOL. **, NO. **, 2012

Table 3. Regression of resight day of year on initial sighting day of year: estimates, standarderrors, P-values, and r2 for 21 whales (BA04027 excluded) and for all 22 whales.

Excluding BA04027 (n = 21) All whales (n = 22)Estimate SE P Estimate SE P

Intercept 53.67 21.29 0.021 79.71 27.48 0.009Day 1 0.80 0.08 0.000 0.713 0.01 0.000r2 0.85 0.72

Table 4. Sightings information, excluding anecdotal reports, for Migaloo on its migrationalong the eastern coast of Australia 1991–2009, plus estimated dates passing Cape Byron.

Migration Estimated date passingdirection Date Location Reliability Cape Byron

North 28 June 1991 Byron Bay Certain 28 June 1991North 10 June 1992 Gabo Island Likely 18 June 1992North 28 June 1993 Moreton Island Likely 27 June 1993North 16 July 1995 Byron Bay Certain 16 July 1995North 20 July 1998 Bait Reef Likely ?a

North 20 June 2000 Port Stephens Certain 24 June 2000North 22 June 2004 Byron Bay Certain 22 June 2004North 15 June 2005 Byron Bay Certain 15 June 2005North 26 June 2006 Byron Bay Certain 26 June 2006North 21 June 2007 N Stradbroke Island Certain 20 June 2007North 1 July 2009 Burleigh Heads Certain 30 June 2009South 6 October 1992 Tathra Likely 30 September 1992South 29 September 1993 Moreton Island Certain 30 September 1993South 14 October 1994 Montague Island Certain 7 September 1994South 2 October 1998 Hervey Bay Certain ?a

South 2 October 1999 N Stradbroke Island Likely 3 October 1999South 2 October 2004 Byron Bay Certain 2 October 2004South 12 October 2005 Byron Bay Likely 12 October 2005South 30 September 207 Byron Bay Certain 30 September 2007South 28 September 2009 Byron Bay Certain 28 September 2009

Note: Adapted and expanded upon from Forestell et al. (2001).aEstimates were not made for the 1998 season because of sightings being from locations

where residence, as well as travel times, would need to be estimated.

a mean interval of 5.8 d before or after that date. From the available records of itssouthern migration, Migaloo is estimated to have passed Cape Byron/Ballina between28 September and 12 October each year, with a median date of 1 October, and a meaninterval of 3.3 d from that date. By combining the 42 sightings of resighted whalesfrom this study with the 8 sightings of Migaloo on its southern migration, humpbackwhales were shown to pass Cape Byron/Ballina on their southern migration at a meaninterval of 3.7 d (SD = 4.07) from the median date of sighting for each whale.

The only whale photographed in more than 1 yr of this study that was identifiedas a mother with calf on either sighting occasion, BA04027, was seen migratingsouth with one other whale on 6 September 2004 and resighted as a mother with

NOTES 7

calf on 13 October 2005, a difference of 38 d between the date of sighting betweenyears. The migratory timing of this whale is consistent with suggestions by Dawbin(1997) and Craig et al. (2003), whereby female humpback whales are likely to arriveat, and depart from, the breeding grounds earlier in years when they are without acalf than in years with a calf. Craig et al. (2003) found 51 females that were identifiedboth with and without a calf in different years in Hawaii, with the mean date offirst identification earlier by 17.1 d (SD = 23.6) for years when these whales did nothave a calf compared with years with a calf. It is likely that newly pregnant femalesreturn to the feeding grounds as soon as possible to maximize feeding opportunitiesand build up blubber reserves in preparation for the increased energetic costs of lac-tation the following year (Dawbin 1966, 1997; Clapham 1996; Oftedal 1997; Craiget al. 2003). These females, therefore, would be expected to be seen on the migratorycorridor correspondingly earlier or later in the season according to their reproductivestate each year.

With the exception of BA04027, all other resighted whales in this study demon-strated a high level of consistency in the timing of their migration past Ballina fromone sighting year to the next. This pattern was further demonstrated by the sight-ings data for Migaloo, a known mature male for whom many more observations wereavailable. The migration patterns of Migaloo revealed a very high level of consistencyin the timing of this whale passing Cape Byron/Ballina during both the northwardand southward migrations each year.

Although the data collected in this study were biased to some degree by surveyeffort, the overall pattern observed suggested that the sightings correlations werenot simply a function of bias in data collection. For example, the sighting effortduring the 2004 vessel-based survey was restricted during the months of Octoberand early November, and the 2005 survey began 2 wk earlier in the year thanthe 2003 and 2004 surveys. Therefore, whales migrating past Ballina during lateAugust in 2003 and 2004, or after September in 2004, had a lower probability ofbeing photographed in more than one year of this study than individuals passingconsistently during the month of September each year from 2003 to 2005. However,of the 16 whales photographed in 2004 that were also sighted in 2003 or 2005, 6 werephotographed during October 2004 when survey effort was limited. Furthermore,despite the limited number of days surveyed during the latter half of 2004 season,the survey effort for all years of this study encompassed a long period covering themajority of the southern migration (at least 60 d each year) and included all ageclasses of whales. With the exception of BA04027, the widest resight interval of anyof the other resighted individuals (18 d) was considerably shorter than the surveyperiod each year (65, 60, and 77 d), suggesting that the timing of the resights werenonrandom. It is possible that this was a result of the temporal segregation of differentage classes on migration, with high densities of whales within an age class passing agiven location at one time. However, Dawbin (1966) suggested that the earliest andlast whales in each of the respective age class categories traveled approximately 6 wkbefore and after the central peak for that category. The resight intervals observed inthis study were therefore considerably smaller than the 12 wk period in which anentire age class would travel past a given location, suggesting individual consistency

8 MARINE MAMMAL SCIENCE, VOL. **, NO. **, 2012

in migratory timing. Furthermore, although the capture rates for this study werelow because of the large size of the migrating population, the observed numberof recaptures was in line with the number expected from random sampling. Thisfurther supports the suggestion that the observed pattern of consistency in individualmigratory timing was not simply a function of bias in data collection effort.

In summary, the timing of migration in humpback whales has been shown to beaffected by numerous factors, including age, sex, reproductive status, and migratorydestination (Dawbin 1966, 1997; Craig et al. 2003; Stevick et al. 2003). The resultspresented in this study demonstrate that, along with these factors, humpback whalesalso show some consistency in their migratory timing at an individual level.

ACKNOWLEDGMENTS

Southern Cross University and the International Fund for Animal Welfare provided fundingfor this project. Field surveys were conducted under scientific research permits issued by theAustralian Government Department of the Environment, Water, Heritage and the Arts andthe New South Wales National Parks and Wildlife Service (S10403). We thank AndrewNichols for contributing fluke photographs and Peta Beeman for analyzing the extra data.

LITERATURE CITED

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Chaloupka, M., and M. Osmond. 1999. Spatial and seasonal distribution of humpback whalesin the Great Barrier Reef. American Fisheries Society Symposium 23:89–106.

Chittleborough, R. G. 1965. Dynamics of two populations of the humpback whale, Megapteranovaeangliae (Borowski). Australian Journal of Marine and Freshwater Research 16:33–128.

Clapham, P. J. 1996. The social and reproductive biology of humpback whales: An ecologicalperspective. Mammal Review 26:27–49.

Corkeron, P. J., M. Brown, R. W. Slade and M. M. Bryden. 1994. Humpback whales,Megaptera novaeangliae (Cetacea: Balaenopteridae), in Hervey Bay, Queensland. WildlifeResearch 21:293–305.

Craig, A. S., L. M. Herman, C. M. Gabriele and A. A. Pack. 2003. Migratory timing ofhumpback whales (Megaptera novaeangliae) in the central North Pacific varies with age,sex and reproductive condition. Behaviour 140:981–1001.

Dawbin, W. H. 1966. The seasonal migratory cycle of humpback whales. Pages 145–171in K. S. Norris, ed. Whales, dolphins and porpoises. University of California Press,Berkeley, CA.

Dawbin, W. H. 1997. Temporal segregation of humpback whales during migration inSouthern Hemisphere waters. Memoirs of the Queensland Museum 42:105–138.

Felix, F., and B. Haase. 2001. The humpback whale off the coast of Ecuador, populationparameters and behavior. Revista de Biologıa Marina y Oceanografıa 36:61–74.

Forestell, P. H., D. A. Paton, P. Hodda and G. D. Kaufman. 2001. Observations of a hypo-pigmented humpback whale, Megaptera novaeangliae, off east coast Australia: 1991–2000.Memoirs of the Queensland Museum 47:437–450.

Franklin, T., W. Franklin, L. Brooks, P. Harrison, P. Baverstock and P. Clapham. 2011.Seasonal changes in pod characteristics of eastern Australian humpback whales (Megapteranovaeangliae), Hervey Bay 1992–2005. Marine Mammal Science 27:E134–E152.

Mackintosh, N. A. 1942. The southern stocks of whalebone whales. Discovery ReportsXXII:236–248.

NOTES 9

Marsh, H., P. Arnold, C. Limpus, et al. 1997. Endangered and charismatic megafauna.Proceedings of the Great Barrier Reef Science Use and Management 1:124–138.

Mattila, D., M. Berube, R. Bowman, et al. 2001. Humpback whale habitat use on theWest Indies breeding grounds. Report to the Scientific Committee of the InternationalWhaling Commission, Hammersmith, London, UK. SC/53/NAH3. Available uponrequest from the IWC Secretariat: Secretariat@IWCoffice.org.

Oftedal, O. T. 1997. Lactation in whales and dolphins: Evidence of divergence between baleen-and toothed-species. Journal of Mammary Gland Biology and Neoplasia 2:205–230.

Paterson, R. A. 1991. The migration of humpback whales Megaptera novaeangliae in eastAustralian waters. Memoirs of the Queensland Museum 30:333–341.

Stevick, P. T., J. Allen, M. Berube, et al. 2003. Segregation of migration by feeding groundorigin in North Atlantic humpback whales (Megaptera novaeangliae). Journal of Zoology259:231–237.

Received: 23 September 2010Accepted: 23 October 2011