GROWTH
OF THE
THE
WEDGE-TAILED
HAWAIIAN
SHEARWATER
IN
ISLANDS
TED N. PETTIT,• G. VERNON BYRD,2 G. CAUSEY WHITTOW, • AND
MICHAEL
P. SEKI I'3
•Department
of Physiology,
lohn A. BurnsSchoolof Medicine,Universityof Hawaii,
Honolulu,Hawaii 96822USA, and2U.S.Fishand WildlifeService,P.O. Box87,
Kilauea, Hawaii 96754 USA
ABSTRACT.--Growth
studiesof a tropical seabird,the Wedge-tailedShearwater(Puffinus
pacificus),
were conductedover 3 yr at three locationsin Hawaii. Basicgrowth patternsof
body dimensionsare described.The range of asymptotesand maximal recordedweights
suggeststhat feeding and the availability of food may influencegrowth from year to year
and in differentcolonieswithin the sameyear. Received
15September
1982,accepted
I September
1983.
GROWTHamong procellariiform chicks is
characterizedby slow development,a long and
flexible fledging period, large depositsof lipid
reserves, and achievement of a prefledging
weight well abovethe adult'sbody weight, followed by a prefledging weight loss. These
growth characteristicsare consideredto be adaptationsto meager,distant,or fluctuatingfood
resources (Lack 1967, 1968; Ricklefs 1968).
Few studies of tropical seabirds have addressed intraspecific variations in the growth
of nestlingsat different latitudesor in different
colonies.Nelson's(1978) studyof the Red-footed Booby (Sulasula)in the GalapagosIslands
just above sea level that comprise French Frigate
Shoals in the northwestern
Hawaiian
Islands.
Data
for body-weight gain in Wedge-tailed Shearwater
chicksfrom Manana Island, Oahu during 1972 (Shallenberger1973)have alsobeenanalyzedfor comparison. Morphological and developmental notes were
made throughoutthe growth period. Growth measurementswere obtainedby separatepartiesof observerson eachisland. A single personin eachparty
was responsiblefor making a single set of observations (body weight or body dimensions) to assure
uniform measurements.Fledging successin Wedgetailed Shearwatersaverages80% of hatched chicks
(Byrd, Moriarty, and Bradyunpubl.). The following
measurements
were
obtained
from
chicks of known
age(+ 1 day)that lived either beyond90 daysor were
and at Christmas Island, Indian Ocean is a noknown to have fledged successfully.
table exception.We present here the resultsof
(1) Bodyweight:chickswere weighed on an Ohaus
growth studiesof the Wedge-tailedShearwater triple-beambalanceto ñ0.1 g (MananaIsland)or with
(Puffinus
pacificus),
conductedover severalyears calibratedPesolaspring scalesto + ! g (Kilauea Point
at three different
locations
in the Hawaiian
Ar-
and Tern Island). Measurements were made either
1-3 times a week (Manana Island and Kilauea Point)
chipelago.
METHODS
Data were collected from three locations during
or daily (Tern Island).
(2) Culmenlength:the bill was measuredwith calipersor dividers (+0.5 ram) from the tip of the upper
mandible to the edge of the nasal skin covering the
1978-1980: Manana Island, Oahu (1978, 1979); Ki-
bill.
lauea Point, Kauai (1978, 1979, 1980); and Tern Is-
(3) Winglength:wings were measuredwith a tapemeasure(+2 ram) either with the wing straightened
and extendedperpendicularlyto the axisof the body,
from the most anterior point of the humerus at the
shoulderjoint to the tip of the phalanges(Manana
Island), or with the wing flattened, from the shoulder joint to the tip of the longestprimary or to feather sheathif primarieshad not erupted (Kilauea Point).
(4) Tarsuslength:the length of the tibia-fibula was
measuredwith calipers (+0.5 ram) from the distal
end of the tibiotarsusto the proximal end of the tibia
land, French FrigateShoals(1979). Manana (Rabbit)
Island (21ø30'N,157ø40'W)is a small island lying approximately 1 km off the southeasternshore of the
main island
of Oahu.
Kilauea
Point
(22ø15'N,
159ø30'W)is a peninsularising about45 m abovesea
level on the northwestern
coast of Kauai. Tern Island
(23ø52'N, 165ø18'W)is one of several small flat islands
• Present
address:
National
Marine
Fisheries
vice, Honolulu Laboratory, Hawaii 96822 USA.
Ser-
(Manana Island). The tarsometatarsuswas measured
on Kilauea Point accordingto Pettingill (1970).
103
The Auk 101: 103-109. January1984
104
PETTIT
ETAL.
[Auk,Vol.101
I,.- 3(30
-r
0
200
I00
10
20
30
40
50
60
70
80
90
I00
I10
AGE (days)
]Fig. 1. Growth in body weight of Wedge-tailed Shearwaterson Manana-Island, Oahu; Ki]auea Point,
Kauai; and Tern Island, French Frigate Shoalsin 1978, 1979,and 1980.
(5) Middle toelength:the middle toe was measured
with calipersor dividers (+_0.5mm) from the tip of
the claw (Manana Island) or from the tip of the toe
without the claw (Kilauea Point) to the proximal fold
in the webbing between the middle and lateral toe.
(6) Tail length:the tail featherswere measuredwith
dividers (+_2mm) from the tip of the longestrectrix
to the point betweenthe middle rectriceswhere they
emerge from the skin.
Each set of body-weight data was transferred to
computer cards. Body-weight data for chicks undergoing prefledging weight recession have been
omitted from computeranalysis.Logistic,Gompertz,
and yon Bertalanffy equationswere fitted to the data
TABLE1. Analysis of growth in the Wedge-tailedShearwater.a
KR
(100)/
Location
Manana
Manana
Manana
Kilauea
Kilauea
Kilauea
Tern Is.
Is.
Is.
Is.
Pt.
Pt.
Pt.
Year
n
x
K
b
A
4KA/9
1972
1978
1979
1978
1979
1980
1979
-11
13
37
16
23
14
65
120
145
393
175
346
621
0.038
0.052
0.051
0.045
0.059
0.049
0.043
0.591
0.574
0.579
0.588
0.597
0.583
0.595
499
424
456
440
477
454
503
8.43
9.80
10.34
8.80
12.51
9.89
9.61
t•o_9o A/w
Fw
A/Fw
0.444
59.2
43.3
44.1
50.0
38.1
45.9
52.3
-417
392
429
406
426
440
-1.02
1.16
1.03
1.17
1.07
1.14
-12.8
13.4
12.7
16.2
12.8
12.5
1.28
1.09
1.17
1.25
1.22
1.16
1.29
' The yon Bertalanffygrowth equationis W - [A(1 - be •r)]3,where W is mass(g), K is the growth constant(days •), e is the baseof the natural
logarithms,T is time (days),A is the asymptote(g), and b is a constantthat translatesthe time axis such that time (T) is equal to zero at the
inflection point. Other growth parametersare 4KA/9, the maximal amount of absolutegrowth (g.day •); t•0m (2.25/K), the amount of time
required to grow from 10%to 90% of the asymptoticweight; w, the mean adult weight (390 g); Fw, the fledging weight (g); KR(100)/0.444,the
maximalinstantaneousgrowth rate (asa percentageof adult weight), which occursat the inflection point of the growth curve.
January1984]
GrowthofShearwaters
105
4OO
300-
250
2OO
AGE (DAYS)
AGE (DAYS)
3OO
250
,o & •b •'o •o do •o do •o ,4o
AGE (DAYS)
•o •b •o •'o do do •o do ;o ,oo•-AGE (DAYS)
Fig. 2. Growth of body dimensionsof Wedge-tailed Shearwaterson Manana Island, Oahu in 1979.
by an iterative method and analyzed for goodnessof-fit by a FORTRAN program for nonlinear leastsquaresregression(Smond, Pettit, and Whittow unpubl.) implemented by an IBM 370/145 computer.
The yon Bertalanffyequation(Fabens1965)provided
the best fit in all cases.Summarystatisticsof growth
patternsare developedfor eachpopulationasa whole.
0.059/day, and the asymptotesranged from 424
g to 503 g.
Figure 2 presents the linear measurements
(culmen, wing, tibia-fibula, middle toe) of
Manana Island shearwaters in 1979. Figure 3
presents the linear measurementsof shearwatersat Kilauea Point in 1980.The linear body
dimensions cannot be compared directly (exRESULTS
cept for culmen length) due to differencesin
Growthanalysis.--Thefitted von Bertalanffy measurement techniques (see Methods). A
growth curvesfor shearwaterbody weight from summary of these data (Table 2) suggeststhat
Manana Island, Kilauea Point, and Tern Island
the asymptotefor leg growth (tarsometatarsus
are presented in Fig. 1. The smooth curves and tibia-fibula length) is reached about age
shown in Fig. 1 were generated by computer 50-60 days and before attainment of asymp(Fabens 1965), and they are extended to the totes for other measured body dimensions.
mean fledging period for the sample popula- Adult dimensionsof Wedge-tailed Shearwaters
tion. Thus, the smoothedgrowth curvesdo not (Shallenberger 1973) are presented for comparreflect the prefledging weight recessiondata, ison (Table 2).
Table 3 presentsthe mean maximal recorded
which were omitted from computer analysis.
Although the curves vary in slope and form, body weights of chicks and their correspondthey are grouped according to the major vari- ing mean ages,the mean fledging weights, and
ables, the growth rate constant (K) and the the mean fledging period for all sample popasymptotic weight (A). The von Bertalanffy ulations.Analysisof varianceindicated no stagrowth parametersare presentedin Table 1. tisticaldifferencesamong the fledging periods,
The mean K factor ranged from 0.038/day to but several significant differenceswere found
106
PETTITETAL.
[Auk, Vol. 101
5O 0
400
•
,z,,•
.';,.::',::...,
80
0
I00
I10
AGE (DAYS)
AGE (DAYS)
500
450
500
;•;:
;'?'
• so
• •o
;';"t:. - ' •,'i'•!t*?"'
.'"i
, •"i•'• ',
•o
,.•,-.
y,4':
:'/'!:;ß .;:,.•;.,...
,,1•,','
*',. ,,
,'o 2• •b 4'o •o 6'o 7• •
AGE
AGE (DAYS)
•'o ,60 ,',o
(DAYS)
Fig. 3. Growth of body dimensionsof Wedge-tailedShearwatersat Kilauea Point, Kauai in 1980.X = tail
length.
amongother growth characteristics
for the various populations(Table 4).
Development
of thechick.--Athatching,the feet
and the tarsi are flesh-colored,
and the bill is a
light slaty color.Hatchlings are able to support
themselves
and move about in the burrow
hatchling is initially fed stomachoil by regurgitation from the adult. The stomachoil of procellariiforms is high in energy content, averagingabout10 kcal/g (Warhamet al. 1976,Pettit
and Whittow unpubl.). During the first 3-4
nest-
chamber after the first day. The primary down
(protoptiles) may be quite variable but typical-
ly is a very light grey, unlike the dark grey of
the secondary down (mesoptiles), which appeared at a mean age of 22.6 days + 3.7 (SD)
(n = 23). Chicks are hatched with eyes closed,
but the eyesopen generallywithin the first 24
h. The egg tooth disappearedat an averageage
of 13.6 + 1.6 days (n = 22), and pin feathersof
the primary and secondaryflight feathersand
rectricesbegan to appear at a mean age of 34.9
days+ 3.7 (n = 15). Nestlingsare coveredwith
down until age 75-85 days. After 90 days of
age down may persist on the head, abdomen,
and neck. It is not uncommon for fledging
shearwatersto have down remaining on these
areasafter departure from the nesting colony.
Feeding and weight gain.--The shearwater
TABLE2. Asymptotic linear body dimensions and
corresponding ages of Wedge-tailed Shearwater
nestlings in Hawaii.
Measurement
Length
(ram)
Age
(days)
Tibia-Fibula
80 -85
50 -60
Tarsometatarsus
45-50
50-60
Culmen
35-40
60-70
Middle
Toe
With
claw
Without
50-60
60-70
claw
50-55
60-70
Point
275-300
100-110
310-325
80-90
100-130
100-110
Adulta
50
Wing
Kilauea
Manana
Tail
Island
Data from Shallenberger(1973).
297
138
January 1984]
107
Growthof Shearwaters
TABLE3. Growth characteristicsof Wedge-tailed Shearwaters.a
Population
Manana
Maximal weight
(g)
Year
Island
1978
497.0
Age
(days)
+ 33.0
Fledging weight
(g)
72.3 + 16.1
(11)
417.0
(11)
+ 87.9
Fledging age
(days)
+ 69.8
102.0 + 6.1
(8)
79.4 + 5.8
(8)
Manana
Island
1979
493.0
Kilauea
Point
1978
565.7 + 43.0
(37)
(37)
(33)
(33)
Kilauea
Point
1979
554.4 + 64.0
73.9 _+ 14.2
405.5 + 24.8
107.1 + 2.8
(16)
(16)
Kilauea
Point
1980
532.5 + 46.7
85.1 + 11.1
(23)
(23)
(23)
(23)
1979
573.9 + 51.3
68.4 _+ 11.8
439.6 + 32.5
104.4 + 4.8
(14)
(14)
(14)
(14)
(13)
Tern
Island
392.2 + 61.8
(13)
100.0 + 6.1
(10)
86.8 + 8.9
428.8
(10)
+ 54.1
109.2 + 3.2
(9)
(9)
426.1 + 51.9
106.2 _+ 4.6
Values are presentedas mean _+SD; (n) = sample size.
weighed approximatelyevery 12 h for a week
before fiedging and departure, feeding occurred on 66% of the days (1.3 days per feed-
days, the adult initiates the feeding processby
"actually picking up the chick'sbill" (Shallen-
berger 1973).Thereafter,the chick will peckat
the bill and throat of the parent and stimulate
ing + 0.4),andtheaverageweightgainfor each
feeding sessionwas 40.0 g + 11.4 (n=56).
Burger (1980) has summarizeddata showing
that a prefledgingweight lossamong procel-
regurgitation. Examination of regurgitated
stomach
contents
of the
chick
indicated
that
partially digested squid and stomachoil combined and then larger piecesof whole squid
lariiforms occurs both in species with and
without desertion periods. The 10-15% prefledging weight loss in the Wedge-tailed
Shearwateris similar to that of other speciesof
Puffinus(Warham 1958, Richdale 1963, Harris
1966). The absence of a desertion period has
also been reported for Audubon's Shearwater
(Puffinuslherminieri,Harris 1969).
and fish are fed to the chick.
Although the feeding intervals of some
shearwater chicks may be quite long and variable, judging by extended weight-lossperiods,
the daily weight measurementsof shearwater
nestlings on Tern Island (1979) indicated that
the mean feeding interval (the time between
recorded weight gains) was 1.7 days + 0.4
(range 1-11 days) for 432 observationsof 10
chicks. Some feedings are small and result in
no weight gain; therefore, this assessmentis
likely to be an underestimation.Among eight
DISCUSSION
Growth and geographicallocation.--Nelson
(1978) reported that growth in the Red-footed
Booby(Sulasula)is slower among chicksin the
shearwaters at Kilauea Point (1980), which were
TABLE4. Analysis of variance: comparisonof maximal recorded weight (a), age at maximal weight (b), and
fledging weight (c). S = significant difference (F-test, P < 0.05), NS = nonsignificant difference.
Manana
Manana
Kilauea
Kilauea
Kilauea
1978
1979
1978
1979
1980
Population
a
b
c
a
b
c
Manana 1978
Manana 1979
Kilauea 1978
Kilauea
1979
Kilauea 1980
Tern 1979
-S
S
S
S
S
-S
S
NS
NS
NS
-NS
NS
NS
NS
S
-NS
NS
S
S
-S
S
S
S
-NS
NS
NS
S
a
b
c
-NS
-S
NS
NS
-NS
--
--
--
NS
NS
NS
NS
NS
NS
NS
S
NS
NS
a
b
c
a
b
c
-NS
-NS
-S
108
PETTIT
ETAL.
[Auk,Vol. 101
ACKNOWLEDGMENTS
GalapagosIslandsthan at ChristmasIsland (Indian Ocean), and he attributed this difference
to climatic conditions and food supply. If
Data were collectedby severalemployeesand volunteers
with
the U.S. Fish and Wildlife
Service.
We
growthrateis a functionof foodavailability, greatly appreciatethe field effortsof S. Schulmeister,
then the variations in growth parametersmay
reveal differencesin foraging successand/or
prey species(energy content)among different
island breeding populations. In general, there
does not appear to be a simple correlation between growth parametersand geographicallocation. The analysisof shearwatergrowth (Tables 1, 3), however,suggeststhat nestlingsfrom
Kilauea Point and Tern Island achieved greater
maximal weights, fledging weights, asymptotic
weights, and longer fledging periods than did
those from Manana, although the differences
were not alwayssignificant(Table4). The fluctuation and variability of food resourcesare
R. Schulmeister,D. Moriarty, N. Reed, B. Brady, R.
Ittner, and H. Seshiki.We thank Roger Simond, Department of Physiology, University of Hawaii, for
help with computeranalysisof growth patterns.This
study was supported in part by a National Science
Foundation Grant (PCM 76-12351-A01) and Sea Grant
College Program (NOAA) Grant N1/R-14 administered by Dr. G. C. Whittow. We are grateful to the
Department of Land and Natural Resources,Division
of Forestryand Wildlife, State of Hawaii, for granting a permit to conductresearchon Manana Island.
LITERATURE CITED
BURGER,
J. 1980. The transition to independenceand
unknown for tropical Hawaiian waters, alpost-fledgingparental care in seabirds.Pp. 367though they are currently under investigation
447 in Biologyof marine animalsVol. 4 (J. Burg(see Grigg and Pfund 1980). Fish (Mullidae,
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Carangidae)and squid (Ommastrephidae)make
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A.J. 1965. Propertiesand fitting of the von
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rison and Hida 1980). The various feeding
groundsand distancesto shearwaterbreeding GRIGG,g. W., & g. T. PFUND(Eds.). 1980. Status of
colonies
resource investigations in the Northwestern
are unknown.
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waii Sea Grant College Prog.
shown that the average growth curves for the
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Manx Shearwater(P. puffinus)
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ShearwaterPuffinuspuffinus.
Ibis 108:27-33.
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1980) at Kilauea Point, however, display conIslands.Pp. 17-32 in Statusof resourceinvestisiderablevariation in the fitted growth curves
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rate occursat the inflection point of the growth
HU$$ELL,
D. J.T. 1972. Factorsaffectingclutch size
curve (Hussell 1972). It ranged from 12.7%in
in arctic passetines.Ecol. Mongr. 42: 317-364.
1978 to 16.2%in 1979 for growth data from KiLACK,D. 1967. Interrelationshipsin breeding adlauea Point. Thus, a 31% increasein this growth
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ß 1968. Ecologicaladaptationsfor breeding in
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Hawaiian
waters is not well understood, the
fluctuation in some prey fishes has been reported (see Grigg and Pfund 1980). Thus, variations in the observedgrowth patterns may be
related
to fluctuations
in food resources.
Some
NELSON,J. B. 1978. The Sulidae: gannetsand boobies. Oxford,
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PETTINGILL,
O. S. 1970. Ornithology in the laboratory and field. Minneapolis, Minnesota, Burgess
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RICHDALE,
R. E. 1963. Biology of the SootyShear-
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water. Proc. Zool. Soc. London 141: 1-117.
Wedge-tailed Shearwater, have apparently RICKLEES,
R. E. 1968. Patterns of growth in birds.
Ibis 110: 419-450.
evolved breeding patterns to fit the seasonal
abundance of juvenile fishes and fish larvae SHALLENBERGER,
g.J. 1973. Breedingbiology, hom(Harrison and Hida 1980).
ing behavior,and communicationpatternsof the
January
1984]
Growth
ofShearwaters
Wedge-tailed Shearwater Puffinuspacificuschlororhynchus.
Unpublished Ph.D. dissertation.Los
Angeles, Univ. California.
WARHAM,J. 1958. The nesting of the Shearwater
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109
, R. WATTS, •r R. J. DAINTY. 1976. The com-
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