<I>Calidris Canutus</I>

44 Population, status, moult, measurements,and subspeciesof Knot Calidris canutus wintering in south India S. Balachandran Balachandran,S. 1998. Population,status, moult, measurements, and subspeciesof Knot Calidris canutuswintering in southIndia. WaderStudy Group Bull. 86:44 - 47. The Knot Calidriscanutus is a regularwinter visitor to India; the samesubspecies rogersi winters both in India andAustralia. Winteringadults arrive with partialprimary moult in Octoberand complete moult by January.The weightobserved at departure time (March) is much less than that observedin Australia. Balachandran,S., BombayNatural History Society,Mumbai-400 023. India. Presentaddress: 11/100, Central Street,Agasteeswaram & P 0., KanyakumariDistrict. TamilNadu. S. India. 629701 INTRODUCTION arrivingin lateAugust, the nettingstarted from September The migrationand distributionof Knot Calidris canutusis onwards.Hence, each season commenced in Septemberand betterknown than that of any otherwader species (Piersma & endedin August. Thus, the 1985-86, 1986-87, 1987-88 Davidson 1992). However, the information from the Indian seasons are referred to as 'first' 'second and 'third seasons winteringgrounds is very scanty.This is evidentfrom the respectively. statusof rare vagrantgiven by Ali & Ripley (1983) andCramp & Simmons(1983) to Knot in India. Bird ringingcarried out STUDY AREA at the Gulf of Mannarbetween 1985-1988 by the Bombay Two coralislands, Manali and Hare island,a lagooncalled NaturalHistory Societyrevealed that this speciesis a regular Pillaimadamin the Gulf of Mannarnear Mandapam and winter visitorto the area,usually numbering a few hundred. Dhanushkodilagoon in the Rameswaramisland were the The specieswas alsoseen regularly during the early eightiesat majorstudy areas selected (Figure 1). GreatVedaranyam Swamp (Point Calimere Wildlife Sanctuary) and ten individualswere ringedbetween 1980 and 1981. Two individualswere alsoringed further north at PulicatLake near RESULTS Madrasduring 1990 (Mohapatra& Rao 1992). This paper Seasonal fluctuation providesinformation on the population,age structure, moult, The birdsstart arriving during the secondweek of Octoberand measurementsand subspecies of Knot winteringalong the the number increases until November after which there is a southIndian coastbased on the resultsof thesebird ringing declinein populationin Decemberbefore again increasing to a studies. maximumin March, prior to their returnjourney. Althoughthe birdsremain throughout the winter, the maximumnumbers counted in November and March indicate that a transient METHODS populationoccurs along with winteringindividuals, during The birdswere caughtwith meshnets and nooses, the inward andreturn migration (Figure 2). The sudden traditionalmethods used by professionalbird trappersof disappearancein certainmonths in 1985and1987 is dueto coastalregions. Birds caughtwere ringed,aged, measured, increasesin the waterlevel in the lagoon. The maximum weighedand examinedfor moult beforerelease. numbers were seen at the eastern end of the Dhanushkodi lagoon. The annualpopulation was around250 duringall the Birds were agedas 'adults'and 'first year' basedon the threeyears. charactersdescribed in the Prater et al. (1977). 'Adult' refers to birdsolder than first-year and included second-year birds Age composition from the first of Augustonwards. The term 'first year' refers The percentageof 'first year' birdscaught declined from 55% to birdshatched in the sameyear. (1985) to 27% in the secondyear. No 'first year' bird was caughtin the third year (1987). The absenceof first yearbirds Moult scoringwas carriedout following Snow(1967). Wing, from 1987/88catches may perhapsbe dueto breedingfailure bill and tarsuswere measured to the nearest millimetre, and duringthe previoussummer (1987). birdswere weighedto the nearestgram. Moult Monthly bird countswere carriedout to determinethe seasonal Adult Knot starttheir primary moult els where and complete it fluctuationin bird numbers.Although a few migrantsstarted at the Gulf of Mannarbefore leaving for the breedinggrounds. The earliestcaught adult (October 16) had a moultscore of 19, INDIA '• Devipattinam.• PALKBAY' Ramnad•'k• Kilakarai •.. Mannar • •' •., Island Figure 1. Studysites (it hadrenewed the innerthree primaries and the fourthwas whichcommences in January.Hence, further confirmation is aboutto be completed).Adults mainly complete their primary requiredas only a smallsample of first-yearbirds was moult in December,only a very few extendingit until January. obtained.An adultcaught on 17 Decemberwas observed in This is in contrast to the observation made at the Dutch secondmoult with all freshcompleted primaries except the 5th WaddenSea by Boere(1976), wherethey completetheir moult and6th growingprimaries which were about to complete. duringOctober, with an estimatedduration of 90100 days. All the threeadults caught in Octoberand November and a few Plumage changes caughtin Decemberand early January had growing primaries. Most adultbirds arrived with partialpostbreeding plumage All the adultscaught from mid December(except one in early duringOctober, and retained it until December.The birds January)to Marchhad completed primary moult. The seemto attaintheir partial prenuptial plumage in February,as completionperiod is six weekslater than the winteringKnots almostall theadults caught in Marchwere in partialprenuptial of north-west Australia and six weeks earlier than south-east breedingplumage. Some adults attain over 50% of the Australianwintering birds. No evidenceof suspendedmoult breedingplumage by March. One first-yearbird caughtin late wasdetected in the primaries.The differencesin timingof March had attainedpartial breeding plumage. primarymoult may be dueto the differencesin arrivaltime as suggestedby Barter(1992). All secondaryfeathers were Site fidelity to wintering sites renewedwhen the primarymoult was completed. Of the 11 birdsringed in the first season,one bird was retrappedin eachof the followingtwo seasons.This suggests First-yearbirds did not starttheir moult until Februaryand left that sitefidelity occursin Knots. The detailsof retrappingare for theirbreeding grounds with old moderatelyworn primaries. givenbelow: However,in AustraliaBarter et al. (1988b) observedthat many of the first-yearKnots undergo a partialor full primarymoult Ring No. Date of ringing Place of ringing Date ofrecapture Place of recapture B45632 4 Feb. 1986 Dhanuskodi 28 Mar. 1987 Dhanushkodi B45638 5 Feb. 1986 Dhanuskodi 12 Dec. 1987 Dhanushkodi The retraprate is thereforeover 18%. Biometrics Adult First-year Range Mean SD n Range Mean SD n Wing 153-175 165.6 4.69 28 151-165 159.6 4.97 9 Bill 30-36 32.9 1.79 30 30-33 32.2 0.92 9 Tarsus 29-34 31.7 1.27 30 29-33 31.7 1.33 9 The measurementsvaried from thosegiven in Ali & Ripley 1983. Adult measurementsare slightlyhigh comparedto those 50- ß ß ß ß ß ß ß ß ß ß ß of first-yearbirds as shownbelow. ß ß Measurement from other sources: 40- i) Ali & Ripley 1983 Wing 162 30. Bill 31.5.5 Tarsus 27.5 20' I I I I I I I I I I I I I ii) Barter et al. 1988a 16Oct10Nov12Dec15Dec3Jan 28Jan30Jan 4Feb 8Mar 12Mar13Mar14Mar28Mar Date Wing Bill Age Figure 3. Primarymoult scoreagainst date. Mean S.D. Mean S.D. 159.2 5.7 32.8 1.8 1 95-170 g for the adults.Apart from one adultcaught during 161.1 6.8 32.9 1.7 2 mid March which weighed170g, all birdsweighed less than 165.4 4.4 33.0 1.7 2+ 140g. As only a few birdswere caughtduring October and 165.2 4.5 32.8 1.7 3+ Novembermonthly mean weight was not calculatedfor these periods. However,the monthlymean weight of adultsshowed a steadyincrease from December(106g) to March (125g). The monthlymean weight for first year birdsvaried between 118g (December)and 123g(March). The meandeparture weight 3001 I 1985-86 (March) observedin southIndia is considerablyless than the meandeparture weight of 175 g. observedin rogersiwintering 250] • 1987-88 in north-westAustralia by Barteret al. (1988a). 2øø1 I I-I I 1986-871 150 DISCUSSION 100 The statusof 'rare vagrant'given in Ali & Ripley (1983) is not correct. The estimatedpopulation of 250 at Mandapamand the 50 ringing total of 39 birdsat Mandapamand 10 at Point Calimere o I a I 1 suggeststhat Knot is now a regularcommon winter visitor to October November December January February March the Indian subcontinent. The Knot at the Gulf of Mannar are month short-billed,which suggeststhat the race is rogersi(breeding Figure 2. Populationfluctuation of Knots. in eastSiberia and winteringin Australasia)not the nominate canutusas describedby Ali & Ripley (1983). The birdscaught Subspecies in breedingplumage had mfous fringeson the mantleand Among the morphometriccharecters described by Haymanet moderateareas of white on the rear belly, which match al. (1986) for the subspeciesrogersi (short-billed with medium characteristicsdescribed for rogersi. The measurementsof shadechesnut belly, moderatearea of white on rearbelly) wing andbill fall within the rangeof rogersigiven by Roselaar tallied with the Knotscaught at the Gulf of Mannar. In (1983). The meanwing andbill lengthsof adult andfirst-year addition,the measurementsof wing and bill lengthagree well birdsobserved in Australiaby Barter et al. (1988a) are almost with the biometricdata for rogersiwintering in Australia same as those observed in India. This also confirms that the obtainedby Barter et al. 1988b. subspecieswintering in India is rogersi,as in north-western Australia. TheseKnot may follow the flyway of the Great Knot Calidris tenuirostris which also breeds in eastern

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