Research Article The Range of Prey Size of the Royal ...downloads.hindawi.com/archive/2013/351756.pdf · e tiger of Sundarbans is the World-renowned Royal Bengal Tiger ( Panthera

Hindawi Publishing CorporationJournal of EcosystemsVolume 2013 Article ID 351756 7 pageshttpdxdoiorg1011552013351756

Research ArticleThe Range of Prey Size of the Royal Bengal Tigerof Sundarbans

Subrat Mukherjee1 and Neera Sen Sarkar2

1 Sundarbans Tiger Reserve Institute of Environmental Studies and Wetland Management DD-24 Sector-I Salt Lake CityKolkata West Bengal 700 064 India

2Department of Botany University of Kalyani Nadia District Kalyani West Bengal 741235 India

Correspondence should be addressed to Neera Sen Sarkar neerashenyahoocoin

Received 25 May 2013 Revised 1 October 2013 Accepted 15 October 2013

Academic Editor Winn J Huang

Copyright copy 2013 S Mukherjee and N Sen Sarkar This is an open access article distributed under the Creative CommonsAttribution License which permits unrestricted use distribution and reproduction in any medium provided the original work isproperly cited

Relatively little is known about the feeding habit of the Royal Bengal Tiger of Sundarbans and the relative biomass of individualprey base species that the predator consumes during each kill This is the first attempt to collect such data from the study area Datasets of two phases have been used Identification of undigested remains of 214 tiger scat samples was carried out A comparisonwith Sundarbans tigers in zoo has been made In its natural habitat the tiger consumes more of spotted deer followed by wild boarrhesus monkey and water monitor Though the tiger consumes a relatively low proportion of small prey species to meet its dietaryrequirements it gains importance in the present perspective Significant increase is noted in the relative number of prey speciesconsumed in the second phase which correlates well with increased prey availability Hypotheses formulated to find the differencein prey biomass and relative number of prey consumed have been tested statistically A significant difference in terms of relativenumber of prey consumed only was derived which has been qualitatively correlated with the positive effect of increased vigilanceas revealed by secondary data on conserving tiger habitat vis-a-vis the increased prey availability in Sundarbans

1 Introduction

As with all other organisms the tigerrsquos diet is a fundamentalaspect of its ecological niche Quantifying diets has longbeen and continues to be one of the first steps in studyinga speciesrsquo basic ecology as discussed by Sih and Christensen[1] For the community ecologist forager diets potentiallyplay a central role in determining the predator-prey inter-actions and dynamics of competition between species [23] The availability and range of diet play a pivotal rolein determining the dynamics of competition at inter- andintraspecific levels predator-prey interactions and othercommunity interactions An understanding of diets andideally an ability to predict diet shifts in response to changesin prey biomass or prey availability are thus major issuesespecially in conservation and management affairs

The tiger is always found to be associatedwith largemam-malian herbivorous prey species in all its habitat ranges acrossthe globe These include wild buffalo (Bubalus bubalis) gaur

(Bos gaurus) nilgai (Boselaphus tragocamelus) swamp deer(Cervus duvaucelii) sambar (Rusa unicolor) barking deer(Muntiacus muntjak) spotted deer (Axis axis) and wild boar(Sus scrofa) [4ndash8] But according to Schaller [4] occasionallythey have been found to predate on other carnivores like leop-ards (Panthera pardus) sloth bears (Melursus ursinus) civetcats and small vertebrate species like frogs also The tigeris reported to have failed to survive in areas wherever thesekey prey species including large ungulates and primates havebeen exterminated [9] although it is known that most of thelarge mammals change their food habits according to theirphysiological as well as reproductive state Several hypotheseshave been proposed to explain prey selection by predatorsThese hypotheses at times take into account ultimate causalfactors such as energetic benefits and costs involved [10 11]and also proximate mechanisms of selection such as preyvulnerability [12ndash14] Tigers on an average like most othercats take more number of preys which are generally lessthan their own body size [15 16] but are also reported to

2 Journal of Ecosystems

consume prey species larger than themselves when large-sized preys are available in higher densities [8] Hence preyselection of tigers in any area is ultimately the cumulativeeffect of different ecological behavioral and habitat factorswhich delineates the availability and vulnerability of preyspecies at any particular time [17]

Studies have described systems where extinction of apexpredators has caused trophic cascades that have influencedcommunity structure and ecosystem [18 19] Because infer-ences are frequently drawn from food-habit studies of preda-tors to predict stability of an ecosystem with particular ref-erence to prey-predator dynamics it is important that resultsfrom such studies accurately describe the diet Faeces of wildanimals are the most evident and most easily recognizablesigns of their presence [20] Major carnivores are at anadvantage in this regard because they normally feed on suchanimals which are easily recognizable in their droppingswhich consist of partly digested material and undigestedparts of such animals and occasionally plants The fecalcomponents may include bones teeth claws scales feathersand plant tissues as well as mucus epithelial cells and asignificant amount of living and dead bacteria Because tigeris a specialized hunter its breeding success organization andland tenure system are affected by the availability composi-tion and distribution (temporally and spatially) of suitableprey Therefore emphasis is needed on understanding thepredator-prey relationship It is also important to study howthe tigers respond to the variable environments

The tiger of Sundarbans is the World-renowned RoyalBengal Tiger (Panthera tigris tigris) Sundarbans tiger isdifferent from any other tiger in the country and the worldbecause of its adaptability to the unique mangrove habitatTheir behaviour is largely individual specific and cannotbe generalized and is also not replicable from the studiesmade on other tigers of the world or the country evenin Sundarbans itself Much used word of ldquoaberrationsrdquo isactually its adaptation to a hostile land which renders itperpetually under stress Tigers in Sundarbans eat fish andcrabs can swim very fast in the big rivers even up to thespeed of 13 kmhr climb trees drink salty water take theirprey in broad daylight prey upon human beings and do nothave any common preying behaviour The tiger pugmarksare seen everywhere in the forest though the tiger itself isnot so visible These added with the hostile habitat makeSundarbans not an ideal place to study tigers The presentpaper deals with the study of food preferences availability ofprey and the effect that increased protection in the area bythe Department of Forest through its different measures overthe two phases of study has had on the Panthera tigris tigrisfrom the Sundarbans Tiger Reserve (STR)

2 Materials and Methods

21 Study Area The STR within 88∘421015840170310158401015840Endash89∘

61015840

3357310158401015840E and 22∘121015840543910158401015840Nndash21∘3310158401798610158401015840N is one of

the first tiger reserves amongst Indiarsquos nation-wide networkof 39 tiger reserves wherein Indiarsquos globally renownedconservation scheme ldquoProject Tigerrdquo was initiated on 23rd

December 1973 The initial demarcation of ldquoCore Areardquo wasdeclared as ldquonational parkrdquo since 1984 Under the presentdemarcation (since 2007) of this protected area an area of169962 sq km has been declared as ldquocore areardquo or ldquocriticaltiger habitatrdquo with a buffer area of 88527 sq Km (Figure 2)The adjoining forest area under the 24 Parganas (South)Division covering an area of 1500 sq km also acts as bufferarea to the STRWithin the buffer area the SajnekhaliWildlifeSanctuary is located covering an area of 36242 sq Km Theimportance of this area lies in the recognition of the area as aworld heritage siteproperty by the UNESCO Project Tigeris a comprehensive natural ecosystem conservation projectaiming to promote conservation of the natural ecosystemby mitigating man-induced limiting factors and to bring itas close to natural functioning as possible The region has atypical tropical climate with an average annual rainfall of192030mm and an average temperature range of 20∘C to34∘C round the year The expanse is also characterized by itshigh humidity the average humidity being just over 80 percent and more or less uniform throughout the year Duringthe months of January and February dense ground mistsoccur in the earlymorningThe area is characterized by densemangrove vegetation withAvicennia marina Forssk (Vierh)Avicennia alba Blume Avicennia officinalis L Sonneratiaapetala Buch-Ham Rhizophora mucronata Lam Bruguieragymnorhiza (L) Lam Excoecaria agallocha L Ceriopsdecandra (Griff) Ding Hou Xylocarpus granatum KoenigXyloarcarpus mekongensis Pierre Phoenix paludosa RoxbHeritiera fomes Buch-Ham Aegialitis rotundifolia RoxbAegiceras corniculatum (L) Blanco Nypa fruticans Wurmband a few others forming the major vegetation componentsThe entire area is covered by soft ill-consolidated slushy andsandy soil substratum with high salt and water content isregularly under the influence of tidal regimes the soil alsocharacterized by low oxygen content and abundant hydrogensulphide is comparatively young very fine grained andtypically semifluid some parts contain abundant humuswhereas some are rich in calcareous materials brought infrom the sea in the silt by the tides Only the upper layers ofthe soil in such areas are found to be well oxygenated

22 Methodology The tiger diet was reconstructed throughanalysis of the scat Tiger scats were collected wheneverencountered during the two phases of the study (1999ndash2001and 2008ndash2010) These scats were identified on the basis ofassociated signs and tracks and also size and appearanceTheexercise had its advantage as the habitat under study is nothome to any major same-trophic occupant competing forsimilar resources sampling could be done without confusionbut was extremely difficult in the hostile environmentalsituation of the study area While collecting all the availableboluses were collected as a single sample and mixed ran-domly Collected scats were washed with water followed by adilute acid Subsequently the undigested remains such as hairbones hooves quills nails and teeth of the prey consumedwere separated for prey base species identification The hairbones hooves quills nails and teeth were identified on thebasis of their general appearance like colour length width

Journal of Ecosystems 3

medullary structure and cuticle pattern Quantification ofthe diet was based on both frequency of occurrence (propor-tion of total scats in which each item was found) and percentof occurrence (number of times a specific item was found asa percentage of all items found)

23 Data Analysis and Interpretation The frequencies ofprey species remains which can be identified in scats donot usually give a representative picture of the consumedproportion of different prey species when the prey types varyin size to a considerable extent According to Floyd et aland Ackerman et al [21 22] smaller prey species havingmore hair per unit body weight produce more scats perunit prey weight consumed leading to an overestimationof smaller prey species in the carnivore diet Hence thecorrection factor developed by Ackerman et al [22] was usedto estimate the relative proportion of biomass of differentprey species consumed by tigers in the study area Theregression of biomass consumed per scat produced againstprey weight resulted in the linear relationship 119884 = 1980 +0035119883 [22] has been used in the present study where 119884 =kg of prey consumed per field collectible scat and 119883 =average weight of an individual of a particular prey typeSolving the equation for 119884 gave an estimate of biomassconsumed per collectible scat for each prey type Further therelative biomass consumed () and the relative number ofindividuals consumed () were calculated the data obtainedare represented in Tables 1 and 2

24 Study on the Diet of Captive Sundarbans Tigers A com-parative study on the dietary characteristics of Sundarbanstigers under captive situation that is within the premisesof Calcutta Zoo was also used to determine requirementsand habits with regards to food of the Sundarbans tigersThe environmental conditions under which the Zoo tigersreside are purely artificial and the diet provided is restrictedtoo Each tiger is provided with 7 kg of beef every day witha weekly fast So the weekly biomass consumed by an adulttiger under such condition amounts to 42 kg

3 Results

From the above data the mean biomass of each prey basespecies and percentage of relative biomass consumed in caseof each of the prey base species have been used to calculate theaverage weekly consumption of the tiger in the wild duringthe two phases (Table 3)The results highlight the fact that theweekly average dietary requirement of the Sundarbans tigerwhether in the wild or in captivity is similar

Based on the data in Tables 1 and 2 a comparative analysisof the relative number of prey individuals consumed duringphase 1 and phase 2 is graphically represented by a line plotin Figure 1

The range of peaks for each prey base species in Figure 1is indicative of difference in terms of the relative number ofindividuals consumedduring the two phases especially in thecases of the larger prey species-spotted deer wild boar andrhesus monkey A hypothesis H

01was formulated based on

30

25

20

15

10

5

0

Phase 1Phase 2

Variable

Spot

ted

deer

Wild

boa

r

Rhes

us m

onke

y

Fish

ing

cat

Wat

er m

onito

r

Fish

Bird

Turt

le

Crab

Relat

ive n

umbe

r of i

ndiv

idua

ls co

nsum

edFigure 1 Comparative account of relative number of prey individ-uals consumed during phase 1 and phase 2

the assumption that there is no significant difference betweenthe relative number of prey-base individuals consumed dur-ing the two phases A paired t test performed on the aboveassumption yields 119905 value = 254 and an associated 119875 value= 0035 at 120572 = 005 Thus H

01is rejected and a significant

difference is established between the relative number of prey-base individuals consumed by the Sundarbans tiger duringthe two phases over a temporal span of 10 years

A similar hypothesis H02

was formulated based on theassumption that there is no significant difference between therelative biomass consumed by the Sundarban tiger duringthe two phases of study A paired t-test performed onthis assumption establishes the null hypothesis and H

02is

accepted implying that there is no significant differencein the relative biomass consumed by the Sundarbans tigerduring the two phases of the study

4 Discussion

An examination of the 214 scats (113 (phase 1) + 101 (phase 2))led to the detection of 305 prey items in terms of occurrence(Tables 1 and 2) Spotted deermade up to 5379 (phase 1) and5251 (phase 2) of all the prey items detected but occurredin 6902ndash7227 of all scat samples Wild boar made upto 1931 (phase 1) and 3093 (phase 2) rhesus monkey689 (phase 1) and 719 (phase 2) andwatermonitor 965(phase 1) and 431 (phase 2) of all the items detected inthe collected scats Fish crab and birds together contributedto only 963 (phase 1) 502 (phase 2) of the detecteditems Fishing cats and turtles were detected only once in thescat of the tiger proving that they are not common dietarypreference of the Sundarbans tigers The leaves of Phoenixpaludosamdasha commonmangrove palm of the Sundarbans wasfound to occur commonly in the scats thatmdashare known to


Table 1 Frequency of occurrence estimated biomass consumed and estimated numbers of individuals consumed by tigers in STR based onthe contents of scats collected from 1999 to 2001 (119899 = 113)

Prey baseNo of

occurrence inscats119873

(occur)

Frequency ofoccurrence (A)

Percentoccurrence

Mean bodymassweight ofprey base (B)

Correctionfactor (kgscat)

(C)

Relative biomassconsumed ()

(D)

Relative no ofindividual

consumed () (E)Spotted deer 78 6902 5379 50 kg 373 6316 1362Wild Boar 28 2477 1931 45 kg 355 2157 529Rhesus monkey 10 884 689 8 kg 226 49 670Water monitor 14 1238 965 8 kg 226 685 920Fishing cat 1 088 068 20 kg 268 005 00002Fish 6 530 413 25 kg Not corrected 130 702Crab 7 619 482 02 kg Not corrected 108 537Turtle 1 088 068 15 kg 250 005 00003Phoenix paludosa 14 1238Total 159(i) Frequency of occurrence (proportion of total scats in which an item was found)Frequency of occurrence =119873

119894times 100119873

(occur)(ii) Percent of occurrence (number of times in which a specific item was found as a percentage of all food items found barring Phoenix which is not consideredas a conventional food item but is consumed by the tiger to regulate bowel movements)Percent occurrence =119873119894 times 100119873

(occur) minus 119873(119875ℎ119900119890119899119894119909 occur)(119873119894stands for number of times each species is found to occur in the scat samples)

Table 2 Frequency of occurrence estimated biomass consumed and estimated numbers of individuals consumed by tigers in STR basedon the contents of scats collected from 2008 to 2010 (119899 = 101)

Prey baseNo of


(occur)


Percentoccurrence



(C)


(D)


consumed () (E)Spotted deer 73 7227 5251 50 kg 373 5817 2624Wild Boar 43 4257 3093 45 kg 355 3261 1628Rhesus monkey 10 99 719 8 kg 226 482 1357Water monitor 06 594 431 8 kg 226 289 814Fish 04 396 287 25 kg Not corrected 085 769Bird 02 198 143 25 kg Not corrected 042 384Crab 01 099 072 02 kg Not corrected 021 375Phoenix paludosa 07 693Total 146(i) Frequency of occurrence (proportion of total scats in which an item was found)Frequency of occurrence =119873

119894times 100119873

(occur)(ii) Percent of occurrence (number of times a specific item was found as a percentage of all food items found barring Phoenix which is not considered as aconventional food item but is consumed by the tiger to regulate bowel movements)Percent occurrence =119873

119894times 100119873


be part of the tiger diet to help it regulate bowel movementsMost prey species that are common in the study area bothnocturnal and diurnal were represented in the diet A betterestimate of the numerical importance of the various preyitems in the diet could be calculated using a correctionfactor [22]This gave an estimate of the number of collectiblescats produced per animal consumed The results reveal thatthough spotted deer contributes to about 65ndash75 of the tigerdiet as biomass it is only 1362 (phase 1)mdash2664 (phase2) of the relative number of individuals of all the prey basespecies consumed by the tiger Interestingly it is the smaller

animals including the water monitors birds crabs and fishthat gain importance as part of the tiger diet than suggestedby the uncorrected sample and contribute 2159 (phase 1)mdash2342 (phase 2) of the individuals consumed by the tiger inthe wild Thus the ecological significance of the study lies inthat the Sundarbans tiger exploits a wider range of availableprey sizes to suit and fulfil its dietary requirements

Furthermore an analysis of the results obtained in the twodifferent phases highlights a significant difference in terms ofthe number of individual prey base species consumed by thetiger within the Protected Area of Sundarbans Tiger Reserve


Table 3 Average weekly contribution of different prey base species to tiger diet in the Sundarbans Tiger Reserve area during the two differentphases of study and weekly consumption of the Sundarbans tiger within zoo

Prey base(Kgweek) and contribution to tiger diet

Phase 1(Kgweek) and contribution to tiger diet

Phase 2Mean weeklyconsumption ofSundarban tiger in ZooBiomass (kgweek) Biomass Biomass (kgweek) Biomass

Spotted deer 315800 7469 290850 6549

7 kg of beef times 6 days + 1day fast

Wild Boar 97060 2295 146740 3304Rhesus monkey 03920 0927 03850 0866Water monitor 05480 1296 02310 0520Fishing cat 00100 0023 00000 0000Fish 00325 0076 00212 0047Crab 00021 0004 00004 00009Turtle 00075 0017 00000 0000Bird 00000 0000 00105 0033Total (kg) 4228 4441 42 00

India

West Bengal

N

E

S

W

Estuarine rivers

Buffer zone

Critical Tiger habitat

Basirhat range

National park (East) range

National park (West) range

Sajnekhali Wildlife Sanctuary (SWLS) range

0 4 8(km)

Bang

lade

sh

Figure 2 Sundarbans Tiger Reserve Area inWest Bengal India showing the critical tiger habitat Buffer area and different protection ranges


Estuarine riversBuffer zoneCritical Tiger habitat

Dobanki

Duttar

Chamta

Khatuajhuri

JhingekhaliBagna

JhillaPakhiralaya

Sudhanyakhali

Burirdabri

Harikhali

Haldibari

Kendo

Bagmara

N

E

S

WZone adjacent to fringe area

villages of Indian Sundarbans

Bang

lade

sh

0 4 8(km)

Camps present before initiation of this studyCamps established during 1st phase of studyCamps established during 2nd phase of study

Zone

adja

cent

to p

rote

cted

fore

st ar

ea o

f 24

Parg

anas

Sou

th D

ivisi

on

Wes

t Ben

gal

Indi

a

Bay of Bengal

Figure 3 Protection camp locations within Sundarbans Tiger Reserve before and during the study period

This implies an increased prey availability for the tiger whichcan be interpreted as a direct effect of increased protectionand vigilance initiatives implemented by the Departmentof Forest within the area The secondary data obtainedfrom the Annual Reports of the Sundarbans Tiger Reservevalidate such claims The initiatives include intensificationof management increase in patrolling regular monitoringprogrammes employment generation for fringe area pop-ulation specially in the ecotourism sector distribution ofadministrative units over large areas as compared to thepreviously existing units situated very near to fringe villagesincrease in number of land-based camps introduction offloating camps and check posts and stringency in issuance oftourist permits A summary of the directly related protectionactivities initiated and implemented in terms of protection

and vigilance during the two different phases of study ishighlighted in Figure 3 These initiatives clearly emphasizethe role that habitat protection has shownon the conservationof the Sundarbans tiger and its prey base

Acknowledgments

The authors acknowledge the support and cooperationextended to them by the officers and staff of the Directorateof Forests Government of West Bengal during both phasesof the present investigation The authors also acknowledgethe support and facilities extended to them by the NationalFellow Laboratory of the Central Inland Fisheries ResearchStation for undertaking the research during the first phase of


this present study Further the second author acknowledgesthe grant received from DST-PURSE to the University ofKalyani West Bengal India during the final tenure of thisstudy

References

[1] A Sih and B Christensen ldquoOptimal diet theory when does itwork and when and why does it failrdquo Animal Behaviour vol61 no 2 pp 379ndash390 2001

[2] A Sih P Crowley M McPeek J Petranka and K StrohmeierldquoPredation competition and prey communities a review offield experimentsrdquo Annual Review of Ecology and Systematicsvol 16 pp 269ndash311 1985

[3] E R Pianka ldquoCompetition and niche theoryrdquo in TheoreticalEcology R M May Ed pp 167ndash196 Blackwell ScientificOxford UK 2nd edition 1981

[4] G B Schaller The Deer and the Tiger A Study of Wildlife inIndia The University of Chicago Press Chicago Ill USA 1967

[5] A J T Johnsingh ldquoLarge mammalian prey-predators inBandipurrdquo Journal of the Bombay Natural History Society vol80 no 1 pp 1ndash57 1983

[6] A J T Johnsingh ldquoPrey selection in three large sympatriccarnivores in BandipurrdquoMammalia vol 56 no 4 pp 517ndash5261992

[7] M E Sunquist ldquoThe social organization of tigers (Pantheratigris) in Royal Chitwan National Park Nepalrdquo SmithsonianContribution To Zoology vol 336 pp 1ndash98 1981

[8] K U Karanth ldquoEstimating tiger Panthera tigris populationsfrom camera-trap data using capture-recapturemodelsrdquoBiolog-ical Conservation vol 71 no 3 pp 333ndash338 1995

[9] J Seidensticker S Christie and P Jackson Eds Riding theTiger Tiger Conservation in Human-Dominated LandscapesCambridge University Press Cambridge UK 1999

[10] D Griffiths ldquoPrey availability and the food of predatorsrdquoEcology vol 56 pp 1209ndash1214 1975

[11] D W Stephens and J R Krebs Foraging Theory PrincetonUniversity Press Princeton Mass USA 1987

[12] E CurioThe Ethology of Predation Zoophysiology and Ecologyvol 7 Spinger New York NY USA 1970

[13] R J Taylor ldquoValue of clumping to prey and the evolutionaryresponse of ambush predatorsrdquo American Naturalist vol 110pp 13ndash29 1976

[14] S A Temple ldquoDo predators always capture substandard indi-viduals disproportionately from prey populationsrdquo Ecology vol68 no 3 pp 669ndash674 1987

[15] C Packer ldquoThe ecology of sociability in felidsrdquo in EcologicalAspects of Social Evolution D I Rubenstein and R W Wrang-ham Eds pp 429ndash451 Princeton University Press 1986

[16] M E Sunquist and F Sunquist ldquoEcological constraints onpredation by large felidsrdquo in Carnivore Behaviour Ecology andEvolution J L Gittleman Ed pp 283ndash301 Cornell UniversityPress Ithaca New York USA 1989

[17] M V Shirbhate ldquoQuantification of predation and incidenceof parasitic infestation in Melghat Tiger Reserve with specialreference to leopards (Panthera pardus)rdquoTheBioscan vol 2 no1 pp 41ndash46 2007

[18] J A Estes D O Duggins and G B Rathbun ldquoThe ecology ofextinctions in kelp forest communitiesrdquo Conservation Biologyvol 3 no 3 pp 252ndash264 1989

[19] F Palomares P Gaona P Ferreras and M Delibes ldquoPositiveeffects on game species of top predators by controlling smallerpredator populations an example with lynx mongooses andrabbitsrdquo Conservation Biology vol 9 no 2 pp 295ndash305 1995

[20] L Liebenberg Tracks and Tracking in Southern Africa StruikCape Town South Africa 2000

[21] T J Floyd L D Mech and P J Jordan ldquoRelating wolf scatcontents to prey consumedrdquo Journal of Wildlife Managementvol 42 pp 528ndash532 1978

[22] B B Ackerman F G Lindzey and T P Hemker ldquoCougar foodhabits in southern Utahrdquo Journal of Wildlife Management vol48 no 1 pp 147ndash155 1984

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consume prey species larger than themselves when large-sized preys are available in higher densities [8] Hence preyselection of tigers in any area is ultimately the cumulativeeffect of different ecological behavioral and habitat factorswhich delineates the availability and vulnerability of preyspecies at any particular time [17]

Studies have described systems where extinction of apexpredators has caused trophic cascades that have influencedcommunity structure and ecosystem [18 19] Because infer-ences are frequently drawn from food-habit studies of preda-tors to predict stability of an ecosystem with particular ref-erence to prey-predator dynamics it is important that resultsfrom such studies accurately describe the diet Faeces of wildanimals are the most evident and most easily recognizablesigns of their presence [20] Major carnivores are at anadvantage in this regard because they normally feed on suchanimals which are easily recognizable in their droppingswhich consist of partly digested material and undigestedparts of such animals and occasionally plants The fecalcomponents may include bones teeth claws scales feathersand plant tissues as well as mucus epithelial cells and asignificant amount of living and dead bacteria Because tigeris a specialized hunter its breeding success organization andland tenure system are affected by the availability composi-tion and distribution (temporally and spatially) of suitableprey Therefore emphasis is needed on understanding thepredator-prey relationship It is also important to study howthe tigers respond to the variable environments

The tiger of Sundarbans is the World-renowned RoyalBengal Tiger (Panthera tigris tigris) Sundarbans tiger isdifferent from any other tiger in the country and the worldbecause of its adaptability to the unique mangrove habitatTheir behaviour is largely individual specific and cannotbe generalized and is also not replicable from the studiesmade on other tigers of the world or the country evenin Sundarbans itself Much used word of ldquoaberrationsrdquo isactually its adaptation to a hostile land which renders itperpetually under stress Tigers in Sundarbans eat fish andcrabs can swim very fast in the big rivers even up to thespeed of 13 kmhr climb trees drink salty water take theirprey in broad daylight prey upon human beings and do nothave any common preying behaviour The tiger pugmarksare seen everywhere in the forest though the tiger itself isnot so visible These added with the hostile habitat makeSundarbans not an ideal place to study tigers The presentpaper deals with the study of food preferences availability ofprey and the effect that increased protection in the area bythe Department of Forest through its different measures overthe two phases of study has had on the Panthera tigris tigrisfrom the Sundarbans Tiger Reserve (STR)

2 Materials and Methods

21 Study Area The STR within 88∘421015840170310158401015840Endash89∘

61015840

3357310158401015840E and 22∘121015840543910158401015840Nndash21∘3310158401798610158401015840N is one of

the first tiger reserves amongst Indiarsquos nation-wide networkof 39 tiger reserves wherein Indiarsquos globally renownedconservation scheme ldquoProject Tigerrdquo was initiated on 23rd

December 1973 The initial demarcation of ldquoCore Areardquo wasdeclared as ldquonational parkrdquo since 1984 Under the presentdemarcation (since 2007) of this protected area an area of169962 sq km has been declared as ldquocore areardquo or ldquocriticaltiger habitatrdquo with a buffer area of 88527 sq Km (Figure 2)The adjoining forest area under the 24 Parganas (South)Division covering an area of 1500 sq km also acts as bufferarea to the STRWithin the buffer area the SajnekhaliWildlifeSanctuary is located covering an area of 36242 sq Km Theimportance of this area lies in the recognition of the area as aworld heritage siteproperty by the UNESCO Project Tigeris a comprehensive natural ecosystem conservation projectaiming to promote conservation of the natural ecosystemby mitigating man-induced limiting factors and to bring itas close to natural functioning as possible The region has atypical tropical climate with an average annual rainfall of192030mm and an average temperature range of 20∘C to34∘C round the year The expanse is also characterized by itshigh humidity the average humidity being just over 80 percent and more or less uniform throughout the year Duringthe months of January and February dense ground mistsoccur in the earlymorningThe area is characterized by densemangrove vegetation withAvicennia marina Forssk (Vierh)Avicennia alba Blume Avicennia officinalis L Sonneratiaapetala Buch-Ham Rhizophora mucronata Lam Bruguieragymnorhiza (L) Lam Excoecaria agallocha L Ceriopsdecandra (Griff) Ding Hou Xylocarpus granatum KoenigXyloarcarpus mekongensis Pierre Phoenix paludosa RoxbHeritiera fomes Buch-Ham Aegialitis rotundifolia RoxbAegiceras corniculatum (L) Blanco Nypa fruticans Wurmband a few others forming the major vegetation componentsThe entire area is covered by soft ill-consolidated slushy andsandy soil substratum with high salt and water content isregularly under the influence of tidal regimes the soil alsocharacterized by low oxygen content and abundant hydrogensulphide is comparatively young very fine grained andtypically semifluid some parts contain abundant humuswhereas some are rich in calcareous materials brought infrom the sea in the silt by the tides Only the upper layers ofthe soil in such areas are found to be well oxygenated

22 Methodology The tiger diet was reconstructed throughanalysis of the scat Tiger scats were collected wheneverencountered during the two phases of the study (1999ndash2001and 2008ndash2010) These scats were identified on the basis ofassociated signs and tracks and also size and appearanceTheexercise had its advantage as the habitat under study is nothome to any major same-trophic occupant competing forsimilar resources sampling could be done without confusionbut was extremely difficult in the hostile environmentalsituation of the study area While collecting all the availableboluses were collected as a single sample and mixed ran-domly Collected scats were washed with water followed by adilute acid Subsequently the undigested remains such as hairbones hooves quills nails and teeth of the prey consumedwere separated for prey base species identification The hairbones hooves quills nails and teeth were identified on thebasis of their general appearance like colour length width





3 Results





30

25

20

15

10

5

0

Phase 1Phase 2

Variable

Spot

ted

deer

Wild

boa

r

Rhes

us m

onke

y

Fish

ing

cat

Wat

er m

onito

r

Fish

Bird

Turt

le

Crab

Relat

ive n

umbe

r of i

ndiv

idua

ls co

nsum







02is


4 Discussion




Prey baseNo of


(occur)


Percentoccurrence



(C)


(D)



119894times 100119873




Prey baseNo of


(occur)


Percentoccurrence



(C)


(D)



119894times 100119873


119894times 100119873










Spotted deer 315800 7469 290850 6549



India

West Bengal

N

E

S

W

Estuarine rivers

Buffer zone


Basirhat range




0 4 8(km)

Bang

lade

sh




Dobanki

Duttar

Chamta

Khatuajhuri

JhingekhaliBagna

JhillaPakhiralaya

Sudhanyakhali

Burirdabri

Harikhali

Haldibari

Kendo

Bagmara

N

E

S



Bang

lade

sh

0 4 8(km)


Zone

adja

cent

to p

rote

cted

fore

st ar

ea o

f 24

Parg

anas

Sou

th D

ivisi

on

Wes

t Ben

gal

Indi

a

Bay of Bengal




Acknowledgments




References



























Journal of












Volume 2014

Advances in









Geophysics


















3 Results





30

25

20

15

10

5

0

Phase 1Phase 2

Variable

Spot

ted

deer

Wild

boa

r

Rhes

us m

onke

y

Fish

ing

cat

Wat

er m

onito

r

Fish

Bird

Turt

le

Crab

Relat

ive n

umbe

r of i

ndiv

idua

ls co

nsum







02is


4 Discussion




Prey baseNo of


(occur)


Percentoccurrence



(C)


(D)



119894times 100119873




Prey baseNo of


(occur)


Percentoccurrence



(C)


(D)



119894times 100119873


119894times 100119873










Spotted deer 315800 7469 290850 6549



India

West Bengal

N

E

S

W

Estuarine rivers

Buffer zone


Basirhat range




0 4 8(km)

Bang

lade

sh




Dobanki

Duttar

Chamta

Khatuajhuri

JhingekhaliBagna

JhillaPakhiralaya

Sudhanyakhali

Burirdabri

Harikhali

Haldibari

Kendo

Bagmara

N

E

S



Bang

lade

sh

0 4 8(km)


Zone

adja

cent

to p

rote

cted

fore

st ar

ea o

f 24

Parg

anas

Sou

th D

ivisi

on

Wes

t Ben

gal

Indi

a

Bay of Bengal




Acknowledgments




References



























Journal of












Volume 2014

Advances in









Geophysics
















Prey baseNo of


(occur)


Percentoccurrence



(C)


(D)



119894times 100119873




Prey baseNo of


(occur)


Percentoccurrence



(C)


(D)



119894times 100119873


119894times 100119873










Spotted deer 315800 7469 290850 6549



India

West Bengal

N

E

S

W

Estuarine rivers

Buffer zone


Basirhat range




0 4 8(km)

Bang

lade

sh




Dobanki

Duttar

Chamta

Khatuajhuri

JhingekhaliBagna

JhillaPakhiralaya

Sudhanyakhali

Burirdabri

Harikhali

Haldibari

Kendo

Bagmara

N

E

S



Bang

lade

sh

0 4 8(km)


Zone

adja

cent

to p

rote

cted

fore

st ar

ea o

f 24

Parg

anas

Sou

th D

ivisi

on

Wes

t Ben

gal

Indi

a

Bay of Bengal




Acknowledgments




References



























Journal of












Volume 2014

Advances in









Geophysics



















Spotted deer 315800 7469 290850 6549



India

West Bengal

N

E

S

W

Estuarine rivers

Buffer zone


Basirhat range




0 4 8(km)

Bang

lade

sh




Dobanki

Duttar

Chamta

Khatuajhuri

JhingekhaliBagna

JhillaPakhiralaya

Sudhanyakhali

Burirdabri

Harikhali

Haldibari

Kendo

Bagmara

N

E

S



Bang

lade

sh

0 4 8(km)


Zone

adja

cent

to p

rote

cted

fore

st ar

ea o

f 24

Parg

anas

Sou

th D

ivisi

on

Wes

t Ben

gal

Indi

a

Bay of Bengal




Acknowledgments




References



























Journal of












Volume 2014

Advances in









Geophysics
















Dobanki

Duttar

Chamta

Khatuajhuri

JhingekhaliBagna

JhillaPakhiralaya

Sudhanyakhali

Burirdabri

Harikhali

Haldibari

Kendo

Bagmara

N

E

S



Bang

lade

sh

0 4 8(km)


Zone

adja

cent

to p

rote

cted

fore

st ar

ea o

f 24

Parg

anas

Sou

th D

ivisi

on

Wes

t Ben

gal

Indi

a

Bay of Bengal




Acknowledgments




References



























Journal of












Volume 2014

Advances in









Geophysics
















References



























Journal of












Volume 2014

Advances in









Geophysics


















Journal of












Volume 2014

Advances in









Geophysics














Documents

Research Article The Range of Prey Size of the Royal ...downloads.hindawi.com/archive/2013/351756.pdf · e tiger of Sundarbans is the World-renowned Royal Bengal Tiger ( Panthera