The effect of renesting ability and nesting attempt on egg-size variation
in willow ptarmigan
BRETTK. SANDERCOCK'
A N D HANSCHR. PEDERSEN~
Department of Zoology, University of Alberta, Edmonton, AB T6G 2E9, Canada
Can. J. Zool. Downloaded from www.nrcresearchpress.com by KANSAS STATE UNIVERSITY on 10/30/15
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Received April 28, 1994
Accepted September 22, 1994
SANDERCOCK,
B.K., and PEDERSEN,
H.C. 1994. The effect of renesting ability and nesting attempt on egg-size variation in
willow ptarmigan. Can. J. Zool . 72: 2252 - 2255.
Interclutch variation in the size of free-living willow ptarmigan (Lagopus lagopus alexandrae) eggs was examined at Chilkat
Pass, British Columbia. Egg volume (19.9 f 0.1 cm3; mean f 1 SE) fell within the range reported for other populations
of ptarmigan. Most of the egg-size variation (56.0%) was explained by differences among females, but renesting ability and
nesting attempt were also important. The age-class of females and timing of nest loss had no effect on egg-size variation.
Females that laid replacement clutches produced eggs in their first nesting attempts (n = 12 females, 102 eggs) that were
4.6% (0.9 cm3) larger than the eggs of birds that did not renest (n = 12 females, 95 eggs). Clutch size decreased between
nesting attempts, and there was a 1.6% (0.3 cm" increase in egg size (n = 12 females, 65 eggs). We suggest that future
studies examining the influence of nesting attempt on egg size should also control for renesting ability.
SANDERCOCK,
B.K., et PEDERSEN,
H.C. 1994. The effect of renesting ability and nesting attempt on egg-size variation in
willow ptarmigan. Can. J. Zool. 72 : 2252-2255.
La variation de la taille des oeufs entre les couvCes a CtC CtudiCe chez des Lagopkdes des saules (Lagopus lagopus alexandrae)
en nature a Chilkat Pass, Colombie-Britannique. Le volume des oeufs (19,9 f 0,l cm" se situait a 1'intCrieur des limites
rencontrCes chez les autres populations de ce lagopkde. Une grande partie de la variation de taille (56,0%)pouvait s'expliquer
par des differences entre les femelles, mais la capacitC de nicher de nouveau et les tentatives de construire un nouveau nid
ont Cgalement leur importance. La classe d'ige a laquelle appartenait la femelle ou le moment de la perte d'un nid n'avaient
pas d'effet sur la variation de taille des oeufs. Les femelles qui ont Cventuellement pondu des couvCes de remplacement ont
produit, au cours de leur premikre tentative de nidification (n = 12 femelles, 102 oeufs), des oeufs 4,6% (0,9 cm3) plus
gros que les oeufs des oiseaux qui ne devaient pas nicher de nouveau (n = 12 femelles, 95 oeufs). Le nombre d'oeufs par
couvCe a diminuC d'une tentative de nidification a la suivante, mais il s'est produit une augmentation de 1,6% (0,3 cm3) de
la taille des oeufs (n = 12 femelles, 65 oeufs). I1 semble donc que les chercheurs qui Ctudient l'influence des tentatives de
nidification sur la taille des oeufs doivent aussi tenir compte de la capacitC des femelles a nicher de nouveau.
[Traduit par la Ridaction]
Introduction
Intraspecific variation in egg size has been well studied in
precocial birds, in part because it has been suggested that large
eggs produce larger chicks (for review see Williams 1994) that
have better survival than chicks from small eggs (Ankney
1980; Bolton 1991; Grant 1991). Egg size has a relatively
large heritable component (Lessells et al. 1989), but proximate
factors such as food supply (Duncan 1987; Martin 1987), age
of female (Gratto et al. 1983), and clutch size (Batt and Prince
1979; Flint and Sedinger 1992) also influence interclutch variation in egg size.
In this study we examined the influence of nesting attempt
on egg-size variation in willow ptarmigan (Lagopus lagopus
alexandrae). Female ptarmigan can produce a replacement
clutch (or renest) if the-first crutch is distroyed in early incubation by a predator (Robb et al. 1992), but raise only one brood
in a breeding season (Martin et al. 1989). The renest interval
ranges from 3 to 14 days (Parker 1981), and a female lays both
clutches on a breeding territory defended by the male (Schieck
and Hannon 1993). Nesting attempt could be related to eggsize variation if females differ in their ability to produce additional clutches of eggs, if conditions change as the breeding
'Present address: Department of Biological Sciences, Simon Fraser
University, Burnaby, BC V5A lS6, Canada.
2Present address: Norwegian Institute for Nature Research, Division of Terrestrial Ecology, Tungasletta 2, N-7005 Trondheim,
Norway.
Printed in Canada 1 Imprime au Canada
season progresses, or if females adjust egg size to give latehatching chicks a better chance of survival.
Previous studies of Scandinavian willow ptarmigan (L. 1. hgopus) have noted that eggs from replacement clutches are typically larger than eggs from first nests (Myrberget 1977;
Parker 1981; Erikstad et al. 1985). Large chicks are produced
from large eggs in both willow ptarmigan (Myrberget 1977)
and red grouse (L. 1. scoticus; Moss et al. 1981), and in aviary
conditions these large chicks have better survival than small
chicks (Moss et al. 1981). We used observations of radiocollared females to test whether egg size changes between
nesting attempts within a season because (i) females that lay
large eggs are more likely to renest, or (ii) females lay larger
eggs in replacement clutches.
Methods
Willow ptarmigan were studied at Chilkat Pass in northwest British
Columbia (590501N, 136O30 'W) during 1992. The features of this
study area and general methodology are described by Hannon (1984)
and Martin et al. (1989). Female ptarmigan were captured on territories prior to clutch initiation and uniquely marked with colour
bands and radio tags. Yearlings and adults were identified by the pigmentation patterns on the primary wing feathers (Bergerud et al.
1963). Willow ptarmigan lay their clutches in shallow scrapes on the
ground at the rate of about 1 egglday (Hannon et al. 1988; Sandercock 1993), and nests were found by locating birds with telemetry.
Newly laid eggs were measured each time a nest was visited. Eggs
were numbered on the blunt end with a felt marker; maximum length
(L) and breadth (B) were recorded with vernier calipers to the nearest
NOTES
TABLE1. Nesting data for female willow ptarmigan that either lost their first nest and did not renest, or laid
a replacement clutch after they lost their first nest
No. of days
incubated
before loss
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Q did not renest
Q renested
Egg volume
(cm3)
Clutch size
Nesting
attempt
Percentage of
yearlings
Mean f SE
Mean k SE
n
Mean f SE
n
First
First
Second
50.0
33.3
8.2k 1.5
2.3 f0.7
7.92f0.47
8.58k0.23
5.42k0.34
12
12
12
19.39k0.11
20.31 f 0.14
20.64k0.23
95
102
65
0.1 mm. Egg volume ( V ) was estimated using V = kLB* (Hoyt
1979), where k = 0.49 for willow ptarmigan (Myrberget 1977).
Incubating females on first nests were checked every 1-2 days to
determine if the nest was active or had been depredated. If a first nest
was destroyed before the eggs hatched, we continued to relocate the
female until we found the replacement clutch. We concluded that a
female had not renested if we did not find a replacement clutch within
20 days, or if the female had moved a long distance from her breeding
territory. Females that did not renest usually had pin feathers regrowing in their brood patch when we recaptured them to remove the radio
collar. Females that abandoned their first nest, were killed during
incubation, or had failed radio collars were not included in the study.
Eggs laid in the first nests of birds that renested were compared
with the eggs of those that did not renest to test whether renesting
ability is correlated with egg volume. A complication in studies of
egg size is that eggs within a clutch do not represent independent
observations. We addressed this problem by treating females as a
nested variable (Jover et al. 1993) in a general linear model (GLM
procedure, SAS Institute Inc. 1990). The VARCOMP procedure was
used to calculate the percent variation explained by each component
of our models.
Eggs in the two nesting attempts of birds that did renest were compared to test whether nesting attempt affects egg volume. It was not
possible to use conventional repeated-measures ANOVA because
clutch sizes in the two nesting attempts were not equal and egg
sequence was unknown. We used a randomization approach, where
one egg was selected at random from each nesting attempt. The difference in egg volume was calculated for each pair of eggs, and a
mean difference was calculated for all birds (n = 12). A distribution
of mean differences (analogous to a paired t test) was generated by
resampling the data for 500 repetitions.
Results
We observed 34 female willow ptarmigan that laid 343 eggs
in 46 nesting attempts. The overall volume of ptarmigan eggs
at Chilkat Pass was 19.9 f 0.1 cm3 (mean
1 SE). Birds
that successfully hatched their clutch were not included in further analyses because the renesting ability of these females was
unknown. There was no difference in clutch size between
birds that did or did not renest (Table 1; t = - 1.28, P =
0.22), but birds that did renest laid significantly fewer eggs in
the replacement nests (paired t test: t = 9.19, P < 0.001).
To examine variation in the volume of eggs laid in first
nests, we initially analysed the data with a saturated model that
included age of female, stage of loss, renesting ability, and
females (as a nested variable). The full factorial model was
reduced to a main effects model because no interaction term
was significant (P > 0.15, all terms). Age of female ( F =
0.32, P = 0.58) and stage of loss ( F = 0.74, P = 0.49) had
no significant effect on egg volume and were also removed.
The remaining variables, renesting ability (F = 4.19, P =
+
0.05) and differences among females ( F = 17.5, P < 0.001),
both had significant effects on egg volume. Differences among
females and within females and renesting ability explained,
56.0, 27.8, and 16.1%, respectively, of the total variation.
Birds that eventually laid a replacement clutch produced eggs
in their first nesting attempt that were 4.6% (0.9 cm3) larger
than the eggs of birds that did not renest (Table 1).
The differences in egg volume generated by resampling eggs
from first nests and renests were normally distributed
( W = 0.98, P = 0.46), and the difference (0.23 cm3 f 0.34;
mean f 1 SD) was significantly different from zero (t = - 15.5,
P < 0.001). Females that renested laid eggs in their renests
that were 1.6% larger than the eggs laid in their first nests
(Table 1).
Discussion
The range of mean egg sizes for willow ptarmigan in Chilkat
Pass, B.C. (19.4-20.6 cm3), was similar to values previously reported for ptarmigan from three locations in Norway
(19.2 cm3, Myrberget 1977; 19.6-20.6 cm3, Parker 1981;
18.0- 19.2 cm3, Erikstad et al. 1985). We found that most of
the variation in willow ptarmigan egg size could be attributed
to differences between females, which is consistent with
studies of egg-size variation in red grouse (heritability of egg
size (h*) = 0.66; Moss and Watson 1982), willow ptarmigan
(Erikstad et al. 1985), and other precocial birds (Vaisanen
et al. 1972; Alisauskas 1986; Hepp et al. 1987).
The ability of a female willow ptarmigan to renest was more
closely associated with egg-size variation than was nesting
attempt, after controlling for age of female and timing of nest
loss. We are aware of only one other study that has compared
egg sizes of birds that did and did not renest. Runde and
Barrett (1981) found that kittiwakes (Rissa tridactyla) that
replaced lost clutches did not lay larger eggs in their first nests
than birds that did not replace lost clutches. We do not infer
that egg size controls a female's ability to renest, rather we
expect that egg size is one of several correlated reproductive
traits. Hence, a good-quality female may lay big eggs, and
also may be more likely to renest. In this study, age-class was
not related to female quality.
We surveyed the literature for studies that tested whether
egg size changes between the nesting attempts of birds that do
renest. We used the ratio (r2/1)of the size (usually volume) of
eggs in replacement nests divided by the size of eggs in first
nests to show the relative change in egg size. Only birds that
were laying replacement clutches were included; a second
nesting attempt can also be a continuation clutch or a second
breeding attempt after young from the first nest have reached
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2254
CAN. J . ZOOL. VOL. 72, 1994
independence. We also discarded studies that pooled birds of
different renesting abilities, because it is clear from this study
of willow ptarmigan that egg size and renesting ability can
covary .
There did not appear to be any general pattern; egg-size in
replacement clutches either declined (kittiwakes: r2/, = 0.948,
Runde and Barrett 1981; American oystercatcher, Haernatopus palliatus: r2/ = 0.970, No1 et al. 1984; barnacle geese,
Branta leucopsis: r 2 / ~= 0.958, Owen and West 1988) or
increased (willow ptarmigan: r 2 / ~= 1.016, this study; r 2 / ~=
1.051, Parker 1981; northern pintail, Anas acuta: r 2 / ~=
1.037, Duncan 1987). Declines in egg size may be analogous
to the decline in clutch size with laying date that is commonly
observed in birds (Rohwer 1992).
There are several proximate reasons that may explain why
ptarmigan egg size increases between nesting attempts. For
example, conditions may improve as the breeding season progresses. Schuppli (1993) found that the metabolizable energy
in willow (Salix spp.), an important food for ptarmigan,
increased during the spring. In captive northern pintails,
improved food quality had a positive effect on the egg size of
replacement clutches (Duncan 1987). Alternatively, increases
in daily temperature may reduce the female's cost of thermoregulation and permit increased investment in the developing
follicles (Magrath 1992). Egg size could also increase if the
female's reproductive tract matures and expands as laying
progresses (Parsons 1976). It was not possible to evaluate this
latter idea without data on intraclutch egg-size variation in willow ptarmigan.
Egg size and clutch size are both components of a female's
reproductive effort and might be expected to covary. If food
quality or temperature improves during the breeding season,
it is unclear why females lay larger eggs but not more eggs in
replacement clutches. Batt and Prince (1979) suggested that an
increase in egg size may be an adaptive trade-off against a
reduction in clutch size, and many grouse lay fewer eggs in
renesting attempts (Milonoff 1989, 1991). In willow ptarmigan, however, a 1.6% increase in egg size could not compensate for the decrease in total clutch volume even if clutch size
was reduced by only one egg.
Replacement nests can make an important contribution to
net annual fecundity (Parker 1985; Martin et al. 1989), although
the return rates of young from replacement nests is lower than
from first nests (Martin and Hannon 1987). Females laying in
replacement nests face time constraints because their young
have only a short time period to grow and reach thermal independence before the onset of winter. It may be adaptive for
females to reduce clutch size in order to initiate incubation
3 -5 days earlier. Females may lay larger eggs in replacement
nests if larger chicks are able to cope better with inclement
weather or grow faster. Moss et al. (1981) found that an extra
gram of egg mass increased the survival of captive red grouse
young by 5-8%. The small increase in egg size (0.3 cm3)
that we observed may confer a survival advantage on freeliving willow ptarmigan young as well.
Future studies of egg-size variation in birds ,that compare
nesting attempts and control for renesting ability would be
valuable because only a small range of species have been
examined. The limited evidence currently available suggests
that there is no consistent pattern of egg-size variation between
nesting attempts. For willow ptarmigan, studying captive
birds may be the most effective technique for testing whether
such proximate factors as food or temperature influence eggand clutch-size variation.
Acknowledgements
The authors are grateful to D.H. Karlssen, R.C. Schoepf,
and J.R. Freeland for field assistance. E.G. Cooch contributed
useful statistical advice, and B. Ganter, S.J. Hannon, G.J.
Robertson, K. Martin, R. Moss, and T.D. Williams commented on the manuscript. B.K.S. and this project were
funded by a Natural Sciences and Engineering Research
Council of Canada (NSERC) grant to S.J. Hannon. H.C.P.
was supported by an NSERC International Research Fellowship. Ptarmigan were banded and radio marked under permits
from the British Columbia Fish and Wildlife Department and
the Department of Communications.
,
Alisauskas, R.T. 1986. Variation in the composition of the eggs and
chicks of American coots. Condor, 88: 84 -90.
Ankney, C.D. 1980. Egg weight, survival and growth of lesser snow
geese goslings. J. Wildl. Manage. 44: 174- 182.
Batt, B.D.J., and Prince, H.H. 1979. Laying dates, clutch size and
egg weight of captive mallards. Condor, 81: 35-41.
Bergerud, A.T., Peters, S.S., and McGrath, R. 1963. Determining
sex and age of willow ptarmigan in Newfoundland. J. Wildl.
Manage. 27: 700 - 7 11.
Bolton, M. 1991. Determinants of chick survival in the lesser blackbacked gull: relative contributions of egg size and parental quality.
J. Anim. Ecol. 60: 94.9-960.
Duncan, D.C. 1987. Variation and heritability in egg size of the
northern pintail. Can. J . Zool. 65: 992 -996.
Erikstad, K.E., Pedersen, H.C., and Steen, J.B. 1985. Clutch size
and egg size variation in willow grouse Lagopus 1. lagopus. Ornis
Scand. 16: 88-94.
Flint, P. L., and Sedinger, J .S. 1992. Reproductive implications of
egg-size variation in the black brant. Auk, 109: 896-903.
Grant, M.C. 1991. Relationships between egg size, chick size at
hatching, and chick survival in the whimbrel Numenius phaeopus.
Ibis, 133: 127-133.
Gratto, C.L., Cooke, F., and Morrison, R.I.G. 1983. Nesting success of yearling and older breeders in the semipalmated sandpiper,
Calidris pusilla. Can. J. Zool. 61: 1133- 1137.
Hannon, S.J. 1984. Factors limiting polygyny in the willow ptarmigan. Anim. Behav. 32: 153- 161.
Hannon, S.J., Martin, K., and Schieck, J.O. 1988. Timing of
reproduction in two populations of willow ptarmigan in northern
Canada. Auk, 105: 330-338.
Hepp, G.R., Stangohr, D.J., Baker, L.A., and Kennamer, R.A.
1987. Factors affecting variation in the egg and duckling components of wood ducks. Auk, 104: 435 -443.
Hoyt, D.F. 1979. Practical methods of estimating volume and fresh
weight of bird eggs. Auk, 96: 73-77.
Jover, L., Ruiz, X., and Gonzalez-Martin, M. 1993. Significance of
intraclutch egg size variation in the purple heron. Ornis Scand. 24:
127- 134.
Lessells, C .M., Cooke, F., and Rockwell, R.F. 1989. Is there a tradeoff between egg weight and clutch size in wild lesser snow geese
(Anser c. caerulescens)? J. Evol. Biol. 2: 457 -472.
Magrath, R.D. 1992. Seasonal changes in egg-mass within and
among clutches of birds: general explanations and a field study of
the blackbird Turdus merula. Ibis, 134: 171- 179.
Martin, K., and Hannon, S.J. 1987. Natal philopatry and recruitment
of willow ptarmigan in north central and northwestern Canada.
Oecologia, 71: 5 18-524.
Martin, K., Hannon, S.J., and Rockwell, R.F. 1989. Clutch size variation and patterns of attrition in fecundity of willow ptarmigan.
Ecology, 70: 1788- 1799.
Can. J. Zool. Downloaded from www.nrcresearchpress.com by KANSAS STATE UNIVERSITY on 10/30/15
For personal use only.
NOTES
Martin, T.E. 1987. Food as a limit on breeding birds: a life-history
perspective. Annu. Rev. Ecol. Syst. 18: 453 -487.
Milonoff, M. 1989. Can nest predation limit clutch size in precocial
birds? Oikos, 55: 424 -427.
Milonoff, M. 1991. Renesting ability and clutch size in precocial
birds. Oikos, 62: 189- 194.
Moss, R., and Watson, A. 1982. Heritability of egg size, hatch
weight, body weight, and viability in red grouse (Lagopus lagopus
scoticus). Auk, 99: 683 - 686.
Moss, R., Watson, A., Rothery, P., and Glennie, W.W. 1981. Clutch
size, egg size, hatch weight and laying date in relation to early
mortality in red grouse Lagopus lagopus scoticus chicks. Ibis, 123:
450 -462.
Myrberget, S. 1977. Size and shape of eggs of willow grouse Lagopus lagopus. Ornis Scand. 8: 39-46.
Nol, E., Baker, A.J., and Cadman, M.D. 1984. Clutch initiation
dates, clutch size, and egg size of the American oystercatcher in
Virginia. Auk, 101: 855 - 867.
Owen, M., and West, J. 1988. Variation in egg composition in semicaptive barnacle geese. Ornis Scand. 19: 58 -62.
Parker, H. 1981. Renesting biology of Norwegian willow ptarmigan.
J. Wildl. Manage. 45: 858-864.
Parker, H. 1985. Compensatory reproduction through renesting in
willow ptarmigan. J. Wildl. Manage. 49: 599-604.
Parsons, J. 1976. Factors determining the number and size of eggs
laid by the herring gull. Condor, 78: 481 -492.
Robb, L.A., Martin, K., and Hannon, S.J. 1992. Spring body condi-
2255
tion, fecundity and survival in female willow ptarmigan. J . Anim.
Ecol. 61: 215-223.
Rohwer, F.C. 1992. The evolution of reproductive patterns in waterfowl. In The ecology and management of breeding waterfowl.
Edited by B.D.J. Batt, A.D. Afton, M.G. Anderson, C.D.
Ankney , D.H. Johnston, J.A. Kadlec, and G.L. Krapu. University
of Minnesota Press, Minneapolis. pp. 486 - 539.
Runde, 0 . J., and Barrett, R.T. 198 1. Variations in egg size and incubation period of the kittiwake Rissa tridactyla in Norway. Ornis
Scand. 12: 80-86.
Sandercock, B .K. 1993. Free-living willow ptarmigan are determinate egg-layers. Condor, 95: 554 -558.
SAS Institute Inc. 1990. SAS user's guide, version 6 ed. SAS Institute Inc., Cary, N.C.
Schieck, J.O., and Hannon, S.J. 1993. Clutch predation, cover, and
the overdispersion of nests of the willow ptarmigan. Ecology, 74:
743 - 750.
Schuppli, C.A. 1993. Factors that influence the timing of reproduction in willow ptarmigan. M. Sc. thesis, University of Alberta,
Edmonton.
Vaisanen, R.A., Hildkn, O., Soikkeli, M., and Vuolanto, S. 1972.
Egg dimension variation in five wader species: the role of heredity.
Ornis Fenn. 49: 25 -40.
Williams, T.D. 1994. Intraspecific variation in egg size and egg composition in birds: effects on offspring fitness. Biol. Rev. Camb.
Philos. Soc. 68: 35 -59.
Le systhme expert << Nereis H des anndlides polychetes de France (ordre des
Phyllodocida, Amphinomida, Spintherida et Eunicida)
N. JUSSIEN,
V. VERGER,
Y. L'HOSPITALIER,
ET B. AUGEREAU
Institut de mathe'matiques applique'es, 3 , place Andre' Leroy, 49 008 Angers, France
P. GILLET
Laboratoire d'e'cologie anirnale, Institut d'e'cologie applique'e, Universite' catholique de I'Ouest, 3 , place Andre' Leroy,
49 008 Angers, France
Requ le 12 septembre 1994
Accept6 le 19 septembre 1994
JUSSIEN,N., VERGER,
V., L'HOSPITALIER,
Y., AUGEREAU,
B., et GILLET,P. 1994. Le systeme expert Nereis D des annClides
polychbes de France (ordre des Phyllodocida, Amphinomida, Spintherida et Eunicida). Can. J. Zool. 72 : 2255 -2260.
La Faune de France des annklides polychbes errantes de Fauvel (1923) ne comporte que 15 familles (Histriobdellidae et
Ichthyotomidae exclues). Actuellement, on compte 37 familles prksentes sur les c6tes de France; il a donc CtC nkcessaire de
rkviser la clC de dktermination des familles pour rkaliser un logiciel permettant un diagnostic rapide des taxa. Le gCnkrateur
utilisC, X,Plus, est Cditk par Syspertec.
Y., AUGEREAU,
B., and GILLET,P. 1994. Le systeme expert cc Nereis B des annklides
JUSSIEN,
N., VERGER,
V., L'HOSPITALIER,
polychetes de France (ordre des Phyllodocida, Amphinomida, Spintherida et Eunicida). Can. J. Zool. 72: 2255 -2260.
In his Faune de France volume on the errantiate polychaetous annelids, Fauvel (1923) listed only 15 families (not counting
the parasitic Histriobdellidae and Ichthyotomidae). There are presently 37 families found along the coast of France and it
was, therefore, necessary to revise the key to the families for a compterized systematics software program. The program
Nereis was developed by Syspertec using the language Xi Plus.
Introduction
Depuis plusieurs annkes, les systkmes experts ont permis
des applications dans des domaines aussi variks que la mkdePrinted in Canada I Imprirnt au Canada
cine, la botanique, la zoologie : un des premiers systkmes
experts, Mycin (Shortliffe et Buchanan 1975), a permis le
diagnostic des maladies infectieuses du sang (Fieschi 1984);