Effects of a cyclone on waterbird populations at the Pichavaram , southern

KrishnamoorthyThiyagesan and RajarathinaveluNagarajan

Thiyagesan,K. and Nagarajan,R. 1997. Effectsof a cycloneon waterbirdpopulations at the Pichavaram mangroves,southern India. Wader Study Group Bull. 84:47-51 A severecyclone hit the Coramandalcoast of Tamilnadu,southern India on 4 December1993. The impactof this cyclone on the waterbirdpopulations of Pichavarammangrove forests was studied. Waterbirdnumbers and speciesrichness and speciesdiversity in 1994 were comparedwith censusdata collectedin 1993 and 1995 censusi.e. beforeand after the cycloneevent. The waterbirdpopulation in the area was 4,883 in January 1993, 3,060 in January 1994 and 5,091 in January 1995. The speciesrichness and speciesdiversity during 1994 was also lowerthan in the othertwo years. Althoughthe speciesrichness and speciesdiversity of these mangrovesreturned to normal after the cyclone,continuous monitoringof the bird populationsin this area is neededfor a few more years beforearriving at a definiteconclusion.

KdshnamoorthyThiyagesan, Division of IA41dlifeBiology, A. V.C. College, Mannampandal- 609 305, Tarnilnadu,India; RajarathinaveluNagaran, Divisionof IA41dlifeBiology, A. V.C. College, Mannarnpandal-609 305, Tarnilnadu,India. Present address:Department of Psychology, WashingtonSinger Laboratories, University of Exeter, Exeter-E)('44QG, UnitedK•hgdom

groundsattracting these birdsspecies (Nagarajan & INTRODUCTION Thiyagesan 1994).

Natural calamities such as floods. forest fires and Descriptionof the cyclone earthquakesare knownto result in bird mortality(Roberts 1932; Alexander 1948; Smith & Webster 1955; Merrill A severe cyclonehit the Coramandal coast of India on 4 196,1;Stout & Cornwell 1976; Higgins& Johnson 1978; December1993 causingunprecedented devastation. A Johnson 1979; Welty 1982; D'Cunha & Akhtar 1987; portionof Coramandalcoast sufferedthe impact of the Rammanohar& Rajasekaran1989). This paper describes cyclonethat crossedthe shore betweenNagapattinam the effects of the cyclone of 4 December 1993 on waterbird (10 ø46'N;79 ø53'E) and (11 '43'.N; 79' 53'E). populations at the Pichavarammangroves. southern The cyclonewas accompaniedby a torrentialdownpour India. and winds of up to 70 kmlhr, and it continuedfrom 0300 to 1145. Huge storm-waveswere generated by the Locationof the Pichavaram mangroves cyclonewhich caused major structuraldamage to the Pichavarammangroves. The brackishwaves and 150mm The Pichavarammangroves (11ø25'N; 74 ø47'E) are of rain inundatedseveral coastal areas and the nearby situated about 190 km south of Madras at the mouth of agriculturallands and settlementsfor three days. the Vellar, Coleroonand Uppanar riverson the southeast coast, knownas the Coramandalcoast (Bay of Bengal), of Waterbirdnumbers before and after the cyclone India(Figure 1). They are the only large area of mangroves, coveringan area of 11,000 ha, with 51 islets It was observedand reportedby the nearbyvillagers that separated by'a complex networkof creeks and channels many birdsat the Pichavarammangroves died becauseof (Figure 1). As Figure 1 shows, interspersedin this forest the cyclone,as many plantswere uprootedand/or their area, there are many types of wetland habitats such as branchesand canopyseverely damaged. Furthermore, swamps, marshy areas, estuaries,intertidal mudflats and the strong gale created panic and confusionamong the open waters (Wolstencroftet al. 1989), offeringa wide birdsand they were dashed againstthe trees and/or variety of roostingand nestingplaces and foraging adjoiningbuildings, as they were unableto controltheir groundsfor several migratoryand residentbird species flight. As a resultthe birds died.instantly or were badly (Nagarajan& Thiyagesan1996). The adjacentcroplands injured,fell intothe floodsand becameunable to escape, and abandonedfields also act as potentialforaging or were caughtby nomadicpeople and villagers. Some birdswere totallyemaciated and died becauseof exhaustion,fatigue and starvation.

47 In order to assess the impacts of the cycloneon the cinerea, Little Egret Egretta garzetta, Cattle Egret waterbirds of the Pichavram mangroves,waterbird counts Bubulcusibis, Painted Stork Mycterialeucocephala, Asian were made a month after the cyclone,in January 1994. Open-billedStork Anastomusosc/tans and Black-headed They were carried out using7x50 field binocularseither Ibis Threskiomismelanocephalus, it might also have from a boat or by walking along the edges of the wetlands. caused severe damage to their nests, eggs and young. The data collectedwere comparedwith censusdata from .• 1993 and 1995 for the same area, which we collected as The Pichavaram mangrovesare an importantwintering part of the Asian MidwinterWaterbird Census. Species area for many migratorybirds whose annual peak richness was measured as the number of waterbird occurrenceis usually during Novemberto January species recordedduring the census (Verner 1985). (Sampath & Krishinamurthy,1990, 1992; Nagarajan& Species diversitywas calculatedusing the Shannon- Thiyagesan 1994, 1996). Thus, it was feared that since Wiener index (Shannon & Wiener 1949). the cycloneoccurred during that period it might also have had significanteffects on the arian migration patterns on s this peninsula(Nagarajan & Thiyagesan1995). H'= -•.(pi)(Iog 2Pi) i=1 However, the birds seemed to have recovered from this event, as the species richnessand speciesdiversity as s = number of species well as the number of waterbirdsvisiting these pi = proportionof individualsof a given returnedto normal or even higher values during 1995. species However,continuous monitoring of the bird populationsin this area is neededfor a few more years, beforearriving at The differencesin the waterbird populationand species a definite conclusion. compositionbetween the years were analysed by the General Linear Model usingthe statisticalprogram MINITAB (Ryan et al. 1992) and a planned comparison test was done to comparethe mean populationof the ACKNOVVLEDGEMENTS cycloneyear with other years. We thank ProfessorStephen E.G. Lea, Departmentof Table 1 showsthe three years' censusdata groupedby Psychology,University of Exeter, Englandfor comments speciesi.e. herons& egrets;storks; shorebirds; and gulls and statistical advice, and R. Sivasankaran for field & terns. The estimatedtotal waterbirdpopulation in the assistance. area was 4,883 in January 1993, 3,060 in January 1994 and 5,091 in January 1995. The waterbirdspecies richnesswas 26 in January 1993, 24 in January 1994 and 29 duringJanuary 1995. Waterbird speciesdiversity (H') was 2.23, 2.02 and 2.38 duringJanuary 1993, 1994 and REFERENCES 1995 respectively(Table 1). There were significant variationsin the waterbirdpopulation between years Alexander,W.B. 1948. The indexof Heron population,1947. BritiSh (General linear model F=9.89, P<0.001)and species Birds 41: 146-1 48. (General linear model F=69.91, P<0.001). The mean Bailey,E.P. and Davenport,G.H.1972. Die-offof commonmuffes on waterbird populationin the year of the cyclonei.e. January the Alaska Peninsula and Unimak Island. Condor74:215-219. 1994 was significantlylower than the other two years (F=19.60, P<0.001; Planned comparison). D'Cunha,E.P.E. and Akhtar,A. 1987. Mortalityfrom a. hail storm at the KareraBustard sanctuary, Madhya Pradesh. J. Bombay nat. Hist. Soc., 83 (supplement):218-219. Fyfe, R.W. 1957. Hail damagein the June 17 storm. The BlueJay 15: 170-171.

DISCUSSION Higgins,K.F.and Johnson,M.A.1978. Avianmortality caused by a Septemberwind and hail storm.Prairie. Nat. 10: 43-48. Compared to 1993 and 1995 the populationsof all bird Hochbaum,H.A.1955. The travelsand traditionsof waterfowl. species and groupswere lower duringJanuary 1994 i.e. MinneapolisUniversity of MinnesotaPress. after the cyclone(Table 1). This may be due to large scale Johnson,D.H.1979. Effectsof a summerstorm on birdpopulation. mortalityof birds (Nagarajan& Thiyagesan1995) caused Prairie. Nat., 11: 78-82. by the cycloneand/or by movementof birdsto other areas to escape from the cyclone. Arian mortalityand other Jones,G. 1952. Hail damageto wildlifein southwestOklahoma. effectsof extremeweather conditionshave beenwidely WilsonBull., 64:166-167. reported and are summarised in Table 2. MerrilI,G.W. 1961. Loss of 1,000 lesser ssndhillcranes. Auk, 78: 641-642. Since high flood waters commonly result in the loss of Nagarajan,R., Neelanarayanan,Pand Kanakassbai,R. 1994. eggs and young of waterbirds(Welty 1982) and the Damagecaused by cycloneof December1993 to BarnOwl cycloneand its associatedflooding occurred during the (Tyroalba) nests in Tranquebartaluk, Tamilnadu. Cheeta133: breedingseason of Black-crownedNight Heron Nycticorax 42-44. nycticorax,Pond Heron Ardea grayii,Grey HeronArdea

48 Nagarajan,R. and Thiyagesan,K. 1994. Significanceof adjacent Sampath,K & Krishnamurthy,K. 1990. Shorebirds(Charadriiformes) croplandsto the Pichavarammangrove forests in attracting of the Pichavarammangroves, , IndiaßWader Study waterbirds.Proceedings of a NationalSymposium on Birdsin GroupBull. 58: 24-27. AgriculturalEcosystems, 1994, p38 (abstractsonly). Sampath,K & Krishnamurthy,K. 1993. Birdsof Pichavaram Nagarajan,R. and Thiyagesan,K. 1995. Avianmortality caused by a mangrovesand adjoining coastalenvirons. J. Ecol. cycloneat the Pichavarammangroves, southern India. Pavo Soc. 6: 23-38. 33:117-121. Shannon,C. E. & Wiener, W. 1949. The mathematicaltheory of Nagarajan,R. and Thiyagesa,K.. 1996. Waterbirdsand substrate communication.Urbana II1: Illinois University Press. qualityof the Pichavaramwetlands, southern India. Ibis 138: 71 O-721. Smith,A.G.1960. Hail:great destroyer of wildlife.Audubon Mag. 62: 170-171; 189. OrdaI,N.J.1964. A studyof ducknesting and productionas relatedto land use in Otter Tail Country,Minnesota. In: Ducksand land Smith,A.G. and Webster, H.R. 1955. Effects of hail storms on use in Minnesota.(J. B. Moyle,ed.) MinnesotaDept. Conserv. waterfowlpopulations in Alberta,Canada-1953. J. W'#d/. Tech. Bull. 8. Manage. 19: 368-374.

Rammanohar,B. and Rajasekaran,M. 1989. Additionalrecord on Stout,I.J. and ComwelI,G.W.1976. Non-huntingmortality of fledged mortalityfrom a hailstorm at Jaipur.J. Bombaynat. HistßSoc. NorthAmerican waterfowl. J. VtF#dl.Manage., 40: 681-693. 86: 461ß Vemer, J. 1985. Assessmentof countingtechniques. In Current Rate, H. 1957. Redheadskilled by a downdraft. Auk 74: 391. Ornithology,pp. 247-302. (Johnston,R.F. ed.). New York: Plenum Press. Ryan,F.B., Joiner,B.L. and Ryan,A.T. 1992. MINITAB Handbook. Boston: PWS- Weity,J.C. 1982. The life of birds.New York, Saunders College Publishing. KENT PublishingCompany. Wolstencroft,A.J., Hussain,S.A. & Varshney,C.K. 1989. Roberts,T.S.1932. The birdsof Minnesota.Minneapolis: University of Pichavarammangroves. In: A Directoryof AsianWetlands, pp. Minnesota 463-484. Gland,Switzerland and Cambridge,UK: International Union for the Conservation of Nature. Press. Wooten,W.H. 1954. Waterfowllosses in the suryalong the northern Californiacoast. J. W'#d/.Manage. 18:140-141.

.?

1 Km ','. '.: .' .... Co•er*O•r•EstuArY. ' .... ßß

Figure 1 Map of the studyarea, PichavaramMangroves, Southern India showingdifferent types of wetlands (CL=croplands;AF=Abandoned fields; MF=mudflats;SW=Swamps; MA=Marshyareas; OW=Open water; [] = waterbodies; 1'= mangrovevegetation

49 Table 1 Comparisonof waterbirdpopulation parameters (total counts,species richness and speciesdiversity) of Pichavaram mangrove forests during January 1993, 1994 and 1995.

HERONS & EGRETS Black-crownedNight Heron (Nycticoraxnycticorax 262 102 186 Pond Heron (Ardeola gray#) 1600 1100 1428 Little-greenHeron (Ardeolastdatus) 62 48 56 Grey Heron (Ardea cinema) 12 2 18 Purple Heron (Ardea purpurea) 4 0 8 Reef Heron ( Egretta gulads) 0 2 0 Little Egret ( Egretta garzetta) 1250 898 1300 Great Egret (Ardea alba) 182 58 162 Cattle Egret (Bubulcusibis) 150 128 210 GreatBiffern (Botaurus stellads) 0 0 12 Sub total 3522 2338 3380

STORKS Painted Stork ( Mycte#a leucocephala) 10 4 62 AsianOpen-billed Stork (Anastomus oscitans) 68 52 182 Sub total 78 56 244

IBISES & SPOONBILLS Black-headedIbis (Threskiornis melanocephalaus) 0 0 14 Sub total 0 0 14

SHOREBIRDS Black-wingedStilt (Himantopushimantopus) 280 32 168 RedwattledLapwing (Vane#us indicus) 128 102 212 Little Ringed Plover (Charaddusdubius) 220 180 316 Kentish Plover ( Charadrfusalexanddnus) 112 72 128 Greater Sand Plover (Charaddusleschenaultii) 12 0 18 LittleStint ( Caliddsminutus) 124 87 186 Common Sandpiper (Tdnga hypoleucos) 72 26 88 Marsh Sandpiper(Trfnga stagnat#is) 25 16 18 Green Sandpiper(Trfnga ochropupus) 64 48 58 Wood Sandpiper(Tdnga glareola) 16 8 10 Redshank (Trfnga totanus) 58 0 14 Common Snipe ( Gallinagogallinago) 26 11 32 Stone Curlew ( Burhinusoedicnemus) 0 4 0 AsiaticDowitcher (Umnodromus semipalmatus ) 0 0 2 Sub total 1137 586 1250

GULLS & TERNS Whiskered Tern ( Chlidoniashyb#da) 28 13 22 CaspianTern ( Hydroprogne caspia ) 42 18 47 LittleTern ( Sterna albifrons) 68 49 122 Gull-billedTern ( Gelochelidonnilotica ) 8 0 12 Sub total 146 80 203

Grand total 4883 3060 5091 Species Richness 26 24 29 Diversity (H') 2.2299 2.0231 2.3768

50 Table 2. Literature review of the impact of extreme weather conditionson birds.

Country/Place Weather Species Effect Source condition Western Iowa & Heavy snow Laplandlongspurs Killed Roberts 1932 Minnesota storm Calcarfuslaœponicus Britain Severe winter Grey herons Population Alexender1948 Ardea cinerea reduced Southwestern Hail storm & high Several species of Birds Killed Jones 1952 Oklahoma winds Northern Highwinds Waterfowls Killed Wooten1954 California Minnesota Torrential rain & Whistling Swans Killed Hochbaum 1955 hail storm O/or columbianus Canada Geeses Branta canadensis and Ducks Saskatchewan Hail storm Waterfowls Killed Fyfe 1957 America Highwinds Redheads Killed Rate 1957 Alberta Hail storm Waterfowls Killed Smith & Webster 1955; Smith 1960 NewMexico Hailstorm Severalspecies ofbirds Killed Merrill1961 Minnesota Severe hail storm Ducks Population Ordal 1964 declined Aleutian Island Storm Murres Killed Bailey & Devenport Udaaa/•e 1972 North America Hail storm Waterfowls Weather Stout & Cornwell caused 1976 deaths America High wind & hail Several species of birds Killed Higgins & Johnson storm 1978 America Summer storm Several species of birds Population Johnson 1979 declined India Hail storm Several speciesof birds Killed D'Cunha & Akhtar 1987; Rammanohar & Rajasekaran1989 India Cyclone Barn Owl Tyroalba Nests Nagarajanet. al., dama•led 1994 India Cyclone Several species of birds Killed Nagarajan & Thiyagesan1995

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