Table Of ContentMOULTIN BABBLERS (TURDOIDESspp.)1
V.J. Zacharias2 D.N. Mathew3 andK.V. Jayashree4
,
Key words: whiteheadedbabbler,junglebabbler, post-juvenalmoult, body feathers,
primaries, secondaries, rectries, breeding andmoult, duration.
ThejuvenileWhiteheaded Babbler Turdoidesaffinisandthe JungleBabblerTurdoidesstriatusundergo
partialmoultbeginningat3monthsafterfledging.Thismoultiscompleteonlyinthebirdsfledgedintheearlypart
oftheyear.Inothers,thelatedevelopingfeathersareretained.Theyundergoacompletemoultinthenextyear.In
boththespecies,thereisonlyoneannualmoult,andtheybreedandmoultsimultaneously.Thebodyfeathersstart
moultingfromMarchtoNovemberintheWhiteheadedBabblerandfromFebruaryto NovemberintheJungle
Babbler. Inbothspecies, moultofbodyfeathersproceedsataslowtempo.Primaries moultfromasinglefocus
fromlateApriltoOctober/Novemberinboththespecies.Inboththespeciessecondariesmoultfromtwofoci,the
tertiaries,irregularly,andtherectricescentrifugal.
Babblersofthegenus Turdoides live in groups repeatedly used for collection; we very frequently
and breed co-operatively. In the Calicut University changed sites ofcollection. Thesespecimenswere
Campus, thesebirdsbreedthroughouttheyearwith usedforthedoctoralthesesonecologyandbiology
alullin July, themonth ofheaviestrainfall (Gaston by thefirstauthor, legmyologyandpterylography
etal. 1979). They breed andmoult simultaneously. by Dr. K.V. Jayashree and for two M. Phil,
TheWhiteheadedBabblerTurdoidesaffinisandthe dissertationsoncomparativeappendicularmyology
Jungle Babbler T striatus co-exist in several parts by Elizabeth Stephen and Lija Thomas. The
ofSouth India. The former prefers open dry scrub remaining specimenswerepreservedcarefullyand
habitat, while the latter frequents woody areas. We usedforother studies as and when required. After
studied the biology of these species of babblers other studies were conducted they were dried in
(Zacharias and Mathew 1988) in the Calicut area the laboratory and the feather tracts examined
from 1974 to 1980. An account of their moult is carefully. Information on the state ofplumage in
givenhere. thebirdscollectedoverthreeyearsfrom1975-1977
was pooled. Data collected from the examination
Materials and Methods
oftheplumageofthebirdstrappedforringingand
SpecimensoftheWhiteheadedBabblerandthe those ringed as nestlings, were also used for
Jungle Babbler were collectedby shooting at arate studying themoult.
of 5-10 per month. The specimens collected for Details of moult were recorded on cards.
analysisofstomachcontentswerepreservedin 10% Moult in the body feathers was estimated by
formalin or 70% alcohol. All the specimens were counting thenumberofmoulting feathersoutofa
collected near the Chelannur area of Calicut and sample of 30 feathers each in all the body tracts
Thenhippalam village of Malappuram. These two everymonth. In the humeral, femoral and crural
areas had the same type of climate, physiographic tracts,whichhadveryfewfeatherstheentiretracts
conditionsandlayoutofcrops.Specimensofthetwo were examined to estimate the percentage of
babblerswerecollectedforstudying variousaspects feathers moulting. The system and symbols used
ofbiology by different workers over a period of 3 by Stressemann and Stressemann (1966) were
yearsfromavastareaofabout240sq.km.Particular followed fornumbering and naming the remiges
care was taken to seethatnogroupofbabblers was and rectrices.
Results
1AcceptedMarch 1994.
2TigerProject,PeriyarTigerReserve,Thekkady,India.
WHITEHEADEDBABBLER
3DepartmentofZoology, UniversityofCalicut,Kerala.
4Departmentof Zoology,ProvidenceCollege,Calicut. Post-juvenal moult: Thejuvenile undergoes
382 JOURNAL,BOMBAYNATURALHIST. SOCIETY, Vol. 91(1994)
apartial orcompletemoult ofitsfeathers starting thethirdprimary(H3)wasmoultingandendedafter
about three months after fledging. The post- H10hadbeenrenewed.Therewereexceptionalcases
juvenile moult begins in the frontal region of the of the secondary moult starting and ending earlier
capital tract or with the firstprimary. We did not than the beginning and end of primary moult
see any post-juvenile moult between October and respectively. Themoultoftertiaries startedin anyof
April. Inmanyjuveniles which fledgedlate in the its threequills (A7-9). Theymoultedbefore, during
year, the dormant papillae ofthe late developing oraftertherenewal oftheotherremiges.
feathers startedproliferatingjustbeforeor during Wing coverts: The upper greater primary
the post-juvenile moult. It is presumed that some coverts moulted in close coordination with their
of these were retained during the post-juvenile respective primaries. Moulting of several upper
moult, iftheymoultedin theyearofhatching, and secondary greatercoverts ahead ofthe renewal of
moulted completely if they moulted in the next the respective secondaries was a frequent
season. We have not examined a large sample of occurrence.
juvenilestodrawanydefiniteconclusion aboutthe Rectrices: Thereare12rectrices. Therectrices
above aspect. The feathercoat in both thespecies started moulting when H3 was growing and
ofbabblers never changes colour and there is no proceeded centrifugally. After the first pair had
sexual dimorphism. completed their growth, rectrices 2-6 moulted
Adultbodyfeathers: IntheCalicutarea,moult rapidly, sometimes asmany as 3 pairs ofrectrices
of the adult body feathers in the Whiteheaded grew simultaneously. In one third of the cases
Babbler started in March, beginning in the frontal examined(N=90)rectrixmoultwassymmetrical.
regionofthecapitaltract.Moultofthebodyfeathers The large numberofcases ofasymmetrical moult
wasmoreintensiveduring theperiod Septemberto ofrectriceswasprobablyduetotheaccidentalloss
October, butwas otherwise a slow and long drawn of these feathers. Moulting of rectrices was
process which endedin November. Thedorsal and completed either before the completion of the
ventral tractstookthe longestduration tocomplete primarymoult or along with H10, but in 10% of
renewal. AtnotimebetweenMarchandNovember the cases (N = 90), moulting of the tail feathers
were more than 50% ofthe feathers ofany of the continued after the completion of the primary
regions counted moulting. moult.
Primaries: There are ten primaries of which Alula: Thealulawasrenewedduring the span
the outermost is the smallest. The moult of the ofthemoultoftheprimaries. Alularquillsmoulted
primaries normally started in late April from the fromtheproximaltothedistalendandinanorderly
firstprimaryandproceededin theascendingorder. manner.
Growing oftwo primaries simultaneously was the Relationship betweenmoultandbreeding:
usual pattern. There were a few exceptional cases Eventhough a clearly marked breeding season
of3-4primariesgrowingsimultaneously;thesewere was absent in T. affinis, twopeak periods ofegg
notedtowards theendofthemoultingperiodofthe laying were identified in March/April and
primaries. Mostbirds had completedtheirprimary November/December (Gaston et al. 1979,
moultby the end ofOctober. Primary moult in the Zacharias and Mathew 1988). Females with
population thuscovered about6 months. developing eggs collected in May (2)5 August
,
Secondaries: There are nine secondaries, of (2), September (1) and October (1) were all
whichtheinnermostisthesmallest.Thesecondaries moulting their remiges.
moulted from two foci i.e., from A1 and A6. The
JUNGLE BABBLER
lattersometimesdroppedonlyafterA5hadmoulted.
Thesecondaries sometimesmoultedsimultaneously The moult of the Jungle Babbler was studied
frombothends.Secondarymoultusuallystartedwhen 5Numberoffemalescollectedineachmontharegiveninbrackets.
MOULTIN BABBLERS (TURDOIDES SPP.) 383
Tabi£ 1
COMMENCEMENTANDCOMPLETIONOFPRIMARYMOULTIN
T.affinisandT.striatus
StagesofPrimary Earliestrecordeddate Lastrecordeddate
Moult T.affinis T.striatus T.affinis T.striatus
Commencementof April26 April20-26 Junefirstweek June6
primarymoult (1) (6) (4) (1)
Completionof September28 August27 November November
primarymoult (1) (2) firstweek firstweek
(4) (4)
Thefiguresinbracketsshowthenumberofspecimensexamined.
by Naik and Andrews (1966) in Baroda (May to Alula: Thetailfeathersmoultedfromthecentre
October/November)andbyGaston in Delhi (June- to the periphery. Unilateral growing of the tail
November). In ourstudyareain Calicut T. striatus feathers ofone side was noticed in four out of72
started moulting its body feathers from February. cases ofrectrix moult. In the rest, the tail feathers
Thefrontal region ofthecapital tract was the first moulted symmetrically. Rectrices started moulting
tomoult.TheflightfeathersmoultedbetweenApril afterH3 in somecases,butin50% ofthecasesonly
and October. when H3 was moulting. The tail coverts appeared
Primaries: The primary moult was orderly, to moult symmetrically. The rectrices completed
regular and symmetrical. It began in April and moulting before thecompletion ofthemoultofthe
ended in November. Unilateral growth ofprimary primaries oralong with them.
featherssimultaneously,probablyduetoaccidental Moult in relation to breeding: In our study
loss of feathers of one wing and cases of 3-4 area the Jungle Babbler bred throughout the year.
primaries growing together were also noted There wererecordsofegg layingby thebirdsin all
occasionally. themonthsexceptJuneandJuly.Somoultoffeathers
Secondaries: The secondaries moulted from and breeding activity in this species were not
both proximal and the distal foci. The sixth temporarily separated. The midpoint ofthe moult
secondary and the tertiaries moulted at different coincidedwiththeperiodoflowestbreedinginJune
times. In 12outof29casesin whichthebeginning and July.
of the tertiary moult was recorded, A8 moulted Comparison of Moultinthe Whiteheaded and
aheadofA7 andA9. Ofthese29, A9moultedfirst theJungle Babbler
in 8specimensandA7 innine. Secondariesstarted
moulting simultaneously with the primaries in a The first complete moult: Both species
fewcasesbutusuallyonlyafterthe secondprimary undergo their first complete moult in their second
hadmoulted. Usually themoultofthe secondaries yearoflife.Patternofthismoultandallsubsequent
wasnotcompletedalongwiththatoftheprimaries. moults areidentical.
The tertiaries moulted before, during or after the Duration ofMoult: Table 1 gives the earliest
otherremiges wererenewed. and last cases of recorded commencement and
The upper greater wing coverts: The upper completionofprimarymoultintheWhiteheadedand
primary greater coverts moulted in co-ordination theJungleBabbler.Themoultoftheprimariesspans
withtheirrespectiveremiges.The secondaryupper almosttheentiremoultingperiod. Usingthemethod
greater coverts moulted in bunches as in the of Pimm (1976) the duration of primary moult at
WhiteheadedBabbler. individual level was crudely estimated to be 16-20
384 JOURNAL,BOMBAYNATURALHIST. SOCIETY, Vol. 91(1994)
weeksinboth thebabblers. Gaston (1981) described ofa decreasein the number offeathers growing at
a shorterduration ofprimarymoultin babblers and any one time or in theirrate ofgrowth (Snow and
some other birds in Delhi, the duration ofprimary Snow 1964, Newton 1966). Generally the pattern
moult in Baroda was not worked out. But at the ofmoult of flight feathers in these two species of
population level the primary moult in the Jungle babblersagreewiththegeneralpattern(Stressemann
Babbler began in May and ended in October/ and Stressemann, op. cit.) forpasserinebirds. The
November in Baroda (Naik and Andrews 1966). In renewaloftertiariesattimesdifferentfromthetimes
Delhi it was from June to October (Gaston pers. ofrenewaloftherestoftheremiges is an adaptive
comm.),whileinCalicutitwasfromApriltoOctober/ feature.AccordingtoStressemannandStressemann
November. In Sarawak, Fogden (1972)recordedthe (1966), H7-9 actasguard feathers whichcover the
duration ofprimary moultofindividual birds of 18 restofthewingfeathersin theclosedwing. Sothey
species, ranging from 17-20weeks. The duration of shouldnotbeweakenedbymoultingsimultaneously
moult in the Whiteheaded Babbler and the Jungle with the rest of the feathers. The simultaneous
Babbler in the study area were slow, compared to renewal of several upper secondary coverts also
temperate birds and some birds ofseasonal tropics should serve the same purpose. Howeverthe cases
(Delhi),butsimilartothedurationforspeciesofmoist oftertiary moult examined are too fewto establish
tropics. theirexactpatternofrenewal.
Varying degrees ofoverlap between breeding
Discussion and moulting activities were reported in many
species oftropical birds like the common Babbler
The pattern of moult of feathers of the T. caudatus (Gaston 1966), the Indian Myna
Whiteheaded and the Jungle Babbler were very Acridotherestristis theBankMynaA. ginginianus
, ,
similar in several respects but differed from that the Brahminy Myna Sturnus pagodarum (Naik
of many other passerine birds. Their pattern of 1970) and theHouseSwiftApus affinis(Naik and
moult is well adapted to their way of life in the Naik 1965).
study area. As they breed irregularly throughout
the year, they have no exclusive breeding and Acknowledgements
moulting seasons.
AtthepopulationleveltheprimariesintheJungle Oneofus (V.J.Z) is indebted to theBombay
Babbler moulted from April to October/November, Natural History Society for granting the S£lim
fromMaytoOctober/Novemberin Barodaandfrom Ali-LokeWan ThoOrnithologicalresearch fund
June to October in Delhi. The shorter duration of fellowship for carrying out the work. We are
primarymoultin—Delhimayberelatedtotheclimatic grateful to Dr. A.J. Gaston for his criticism and
conditionsthere theseveresummerandwinter. In suggestions. Our sincere thanks are due to the
Calicuttherearenosevereextremesofclimateexcept late Dr. Salim Ali and Sri J.C. Daniel for their
fortheheavyrainfallin June-July. encouragement. We record our thanks to Sri
As both breeding and moult of feathers are K.K. Ravindran whohelped us in collecting the
functions which demand much energy, it may be specimens. K.V.J. acknowledges with gratitude
advantageous torenew feathersataslow tempo, so the supportreceived from the UniversityGrants
that too much strain is not placed on the bird’s Commission. We record our gratitude to the
energy budget at any particular period. In birds spirit ofSwargiya Prof. Ramesh M. Naik forhis
which haveabreeding-moultoverlap, themoultof advice, encouragement and criticism of this
feathers may be considerably protracted by means paper.
MOULTIN BABBLERS (TURDOIDES SPP.) 385
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