Status, distribution and conservation of crocodiles in Sri Lanka

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  • Status, distribution and conservation of crocodiles in Sri Lanka

    Charles Santiapillai *, Mangala de Silva

    Department of Zoology, University of Peradeniya, Sri Lanka

    Received 20 January 1999; received in revised form 7 July 2000; accepted 25 July 2000

    Abstract

    Two species of crocodile occur in Sri Lanka, namely the marsh crocodile (Crocodylus palustris) and the estuarine crocodile(Crocodylus porosus), confined largely to the low-country in the first peneplain. Both species have declined in range and numbersince the turn of the century, mainly through over-hunting for hide and meat in the past, and conversion of their habitat to other

    land-uses by man at present. They have been completely extirpated from the Jana peninsula in the north. The study on the statusand distribution of crocodiles was carried out from 1991 to 1996 during which crocodiles were recorded from 113 localities, 105 ofwhich were inhabited by the marsh crocodile (C. palustris), while 33 localities harboured the estuarine crocodile (C. porosus). The

    two species were sympatric in 25 localities. Of the 105 localities from which C. palustris were recorded, it was considered rare in 62,common in 35, abundant in five, and perhaps extinct recently in three. Of the 41 large river systems, 32 were found to supportcrocodiles. Both species of crocodile are particularly abundant and secure in the countrys two premier conservation areas: the

    Ruhuna National Park in the south-east and the Wilpattu National Park in the north-west. It is estimated that there could be atleast 1220 marsh crocodiles, and perhaps no more than 300 estuarine crocodiles in Sri Lanka. Crocodiles are being threatened byindiscriminate destruction of the islands mangroves and marsh vegetation for human habitation and prawn farming. In Sri Lanka,the marsh crocodile is known to tolerate concentrations of salt higher than that in sea water for a long time. The estuarine crocodile

    is known to move a considerable distance in land from the coast. The strong territorial behaviour among the male estuarine cro-codiles may perhaps help space the individuals. Crocodiles have a poor image in Sri Lanka. Most rural people consider them aserious and potentially dangerous pest and so do not regret their disappearance from their neighbourhood. Marsh crocodiles can be

    ranched, but the concept of sustainable utilization of wildlife in general is still anathema to a large segment of the population in SriLanka. On the other hand, if crocodiles could benefit people, they are not likely to become extinct.# 2000 Elsevier Science Ltd. Allrights reserved.

    Keywords: Marsh crocodile Crocodylus palustris; Estuarine crocodile C. porosus; Poaching; Ranching; Conservation; Sri Lanka

    1. Introduction

    The family Crocodylidae is represented by 23 species(King and Burke, 1989), of which two are found in SriLanka, Crocodylus palustris, the freshwater (freshy),marsh, mugger, or swamp crocodile, and C. porosus, thesaltwater (salty) or estuarine crocodile. Both are listedin Appendix I of CITES (Convention on InternationalTrade in Endangered Species of Wild Fauna and Flora).According to the current IUCN listing given by Baillieand Groombridge (1996), C. palustris is classified asvulnerable but C. porosus is no longer consideredthreatened and so may be included in the lower

    risk category. However, within Sri Lanka, both C.porosus and C. palustris would meet the IUCN criteriafor being critically endangered and endangeredrespectively. Although the two species have been pro-tected legally in Sri Lanka under the Fauna and FloraProtection Ordinance of 1938, they can still be huntedon a special licence (Klemm and Navid, 1989). Identifi-cation with unaided eye at a distance or when the twospecies are in water is often dicult. When lying on theground, the estuarine crocodile, being more solitary,seldom basks in groups unlike the marsh crocodile(Whitaker and Whitaker, 1977). However, in Sri Lankait has been observed basking with marsh crocodiles.Dierences in the structure, habitat preferences, andbreeding of the two species of crocodile in Sri Lanka aregiven in Table 1.

    0006-3207/00/$ - see front matter # 2000 Elsevier Science Ltd. All rights reserved.PI I : S0006-3207(00 )00126-9

    Biological Conservation 97 (2001) 305318

    www.elsevier.com/locate/biocon

    * Corresponding author. Tel.: +94-8-224-784; fax: +94-8-232-343.

    E-mail address: csanti@slt.ik (C. Santiapillai).

  • In Sri Lanka, the number and geographical range ofcrocodiles in general, and of the marsh crocodile inparticular, seem to have been aected by the growthand spread of the human population. As there are nonatural lakes in Sri Lanka, the construction of thousandsof irrigation reservoirs or tanks by the ancient kings inthe low country Dry Zone, greatly enhanced the spreadand survival of the marsh crocodile. At the same time,given the inherent economic value of their skins, croco-diles were also subjected to illegal hunting. As a keystonespecies, crocodiles are said to help maintain ecosystemstructure and function through predation on fish, recy-cling of nutrients, and maintenance of water refugiaduring droughts (King, 1988). Most people living in therural areas in Sri Lanka regard crocodiles as dangerousanimals, and would gladly have them removed fromtheir neighbourhood or killed, even though judgingfrom press reports, incidences of crocodiles killing peopleor domestic animals today are not common as they werein the past. According to Whitaker and Whitaker(1977), in Sri Lanka more people are killed by bualoesand cows than crocodiles. According to Groombridge(1982), crocodiles are threatened throughout their rangeprimarily by illegal hunting for their hide and meat, andto a lesser extent by habitat destruction. If this is so,once illegal hunting is eliminated, crocodile populationsshould be able to recover, provided their habitats arenot destroyed (Webb and Manolis, 1989). This isborne out by the fact that although many crocodilepopulations have declined in range and size, no speciesof crocodile has yet been driven to extinction. Be that asit may, in Sri Lanka conversion of habitat in generaland the draining of the wetlands in particular seem to

    undermine seriously the long-term survival of croco-diles.Crocodiles have been poorly studied in Sri Lanka

    since Deraniyagalas (1953) pioneering work, and thesurvey carried out by Whitaker and Whitaker (1977,1979). No scientific research had been carried out oncrocodiles, until the preliminary study by Santiapillai etal. (2000) in the Ruhuna National Park from 1991 to1994. More recently, Porej (1997) identified and asses-sed the status of crocodiles from 20 wetland sites in SriLanka. Whitaker and Whitaker (1979) recommendedfurther, detailed survey to map the exact distributionand status of the crocodiles in Sri Lanka, and followingtheir suggestion, this paper re-examines as much aspossible, the distribution and status of the two species.

    2. Methods

    The study on the distribution and status of crocodilesin Sri Lanka was carried out from 1991 to 1996, andwas based on (i) already published information, (ii)direct evidence from surveys of water-holes and rivers,in the so called safe areas of the island, (iii) indirectevidence obtained from interviewing refugees from theunsafe areas, and (iv) results of a workshop on cro-codile conservation and management that the authorsconducted for the rangers of the Department of WildlifeConservation in 1993. Our own ecological study of thecrocodiles was carried out in the Ruhuna National Parkbetween 1991 and 1994 (Santiapillai et al., 2000), whereall observations on the crocodiles were made from avehicle, using 742 binoculars, from 0600 to 1900

    Table 1

    Characteristics of Sri Lankas crocodiles species

    Marsh crocodile (C. palustris) Estuarine crocodile (C. porosus)

    Skull Broad-snouted Snout not so broad

    Post-occipital scutes Present Vestigial or absent

    Skin Olive-green Brassy yellow

    Osteoderms Rectangular Ellipsoid

    Maximum size

    Males 4.0 m 6.4 m

    Females 3.0 m 5.5 m

    Size at maturity

    Males 2.7 m 2.7 m

    Females 1.6 m 1.7 m

    Habitat Rivers, marshes and irrigation reservoirs River estuaries and coastal lagoons

    Breeding

    Mating November April

    Nesting FebruaryMarch JuneAugust

    Hatching MayJune SeptemberOctober

    Nest type Hole Mound

    Clutch size 1030 2070

    Hatchling size 2025 cm 2530 cm

    Temperament Aggressive Very aggressive

    306 C. Santiapillai, M. de Silva / Biological Conservation 97 (2001) 305318

  • hours, during which time, most water holes in the parkwere visited. At every sighting of crocodiles, their number,location, habitat and behaviour were noted. Wheneverpossible, the species was identified based on field criteriasuch as the shape of the dorsal osteoderms (Table 1).This is often dicult, as Daniel (1983) pointed out, thetwo species are dicult to distinguish in the field, espe-cially smaller individuals. Wherever possible, the lengthof the animals was estimated visually. Four categorieswere recognized: hatchlings (2 m). It wasnot possible to determine the sex of the individuals inthe field. Marsh crocodiles were assigned to the follow-ing categories based on their number: (i) rare (30 animals), and (iv) probably extinct (when therewere no recent records, but crocodiles were known tohave occurred in the past). Estuarine crocodiles weremuch rarer wherever they occurred, except at the salineKokkarai villu in the Wilpattu National Park.

    3. Results and discussion

    Crocodiles have been reported from 113 localities(Table 2), two of which are the Wilpattu National Park(WNP) in the north-west and the Yala Protected-AreaComplex (YPC) in the south-east. All the localities aredrained by rivers (Fig. 1). Crocodiles were found to berare in 67 (59.3%), common in 37 (33%), abundant in 5(4.5%), and probably extinct in 4 (3.6%). Of the 111localities (excluding the WNP and YPC), C. palustriswas recorded from 100, C. porosus from 31 (Fig. 2), andthe species coexisted in 20 (Table 3). Of the 103 riverbasins found in Sri Lanka, C. palustris occurred in 45,and C. porosus in 27. Of the 41 large river systems wherethe discharge of water into the sea exceeds 100 millionm3/year, crocodiles were recorded from 32. Theremaining 9 river systems (Table 4) represent eitherareas from where there has been no recent informationon crocodiles, or areas that could not be visited forsecurity reasons. In both WNP and YPC, crocodilesoccur in almost all water holes. Fig. 2 shows the presentdistribution of the two species.The location no. 1 of the single specimen of C. palus-

    tris (Table 2) is a canal in the southern part of the city ofColombo. This crocodile had apparently come from thereservoir and stream to the east of the city in the presentcapital of Sri Jayewardenepura or Kotte. This city wasthe capital of Sri Lanka during the Portuguese andDutch colonial periods too, at which time, the streamand the lake were modified into a moat to protect thecity. Crocodiles were kept in the moat, and a few des-cendants still remain. This area does not lie in anymajor river basin.

    Whitaker and Whitaker (1979) recorded crocodilesfrom 32 river systems, and Porej (1997) found them in16 river systems (Table 5). The former researchersrecordedC. palustris from 12 river systems, andC. porosusfrom 17 river systems, and Porej (1997) recorded thetwo species from 9 and 10 river systems, respectively.These findings agree with the present data except that,in our study, crocodiles were not recorded from six riverbasins (nos 3, 10, 14, 37, 65 and 97) in three of which Whi-taker and Whitaker (1977) had recorded their presence. C.porosus was recorded by them from the estuaries of (no.3) Kalu ganga, (no. 10) Koggala oya, and (no. 97)Kalagamu oya. While it is possible that individuals ofthis species may still occur in the estuaries of Kaluganga and Kalagamu oya, the species is already extinctin Koggala oya.

    3.1. Range, distribution and habitat of crocodiles

    3.1.1. Marsh crocodileThe historical range of the marsh crocodile extended

    from Iran in the west to Bangladesh in the east, and thepresent geographic distribution extends throughout theIndian subcontinent from Baluchistan in the west toAssam in the east, and from Nepal in the north to SriLanka in the south. It has also been recorded from Iranand Myanmar (Daniel, 1983). However, within thisrange, the species has become locally extinct over largeareas, and today viable populations occur mostly withinprotected areas. According to Whitaker and Whitaker(1989), in Iran, Pakistan, Nepal and Bangladesh, thereare very few crocodiles left; their long-term survivalprospects outside the protected areas appear grim.In Sri Lanka, prior to the large-scale conversion of

    forests and the expansion of the human population, themarsh crocodile was widely distributed across much ofthe low-country Dry Zone. According to Clark (1901),all the tanks, rivers and forest pools swarm withthem. Tennent (1859) referred to the still waters andtanks of the northern provinces literally teeming withcrocodiles. The marsh crocodile was once common evenin the Jana peninsula (Ferguson, 1877) where it nolonger occurs. Today its range is almost confined to thefirst peneplain in the low country, below an altitude of100 m, where it is still widely distributed and is particu-larly common in large irrigation tanks built by the ancientkings (Table 2). The highest elevation from which themarsh crocodile has been recorded in Sri Lanka in recenttimes is 230 m a.s.l, in Randenigala reservoir built acrossthe Mahaweli river, at a distance of about 160 km fromthe delta. In India, it has been recorded from an altitudeof 420 m in the Corbett National Park (Whitaker andWhitaker, 1984).The distribution of the marsh crocodile in Sri Lanka is

    still extensive (Fig. 2). It is interesting to note that in allthe river systems where C. porosus occurs, C. palustris is

    C. Santiapillai, M. de Silva / Biological Conservation 97 (2001) 305318 307

  • Table 2

    Recent records of crocodiles in Sri Lankaa

    No. Location Categoryc Reserved C. palustrise C. porosuse Statusb River basinf NRBb

    1 Wellawatta Canal C + R (minor basin)

    2 Bellanwila-Attidiya Marsh M SA + C Bolgoda Lake 2

    3 Bolgoda Lake E + X Bolgoda Lake 2

    4 Panadura Ganga E/R + X Bolgoda Lake 2

    5 Anguruwathota Ganga R + R Kalu Ganga 3

    6 Athruwela Wewa T + + C Benthara Ganga 4

    7 Bentota River E/R + + R Benthara Ganga 4

    8 Dedduwa Wewa T + + R Benthara Ganga 4

    9 Indigaha Thotupola R + + C Benthara Ganga 4

    10 Indirilla Ganga R + + X Benthara Ganga 4

    11 Kaluwamodera Ganga E + R Madu Ganga 5

    12 Madu Ganga E + + R Madu Ganga 5

    13 Madampe Oya E + + R Madampe Oya 6

    14 Molapu Oya E SA + + R Molapu Oya 7

    15 Gin Ganga E + + R Gin Ganga 9

    16 Koggala Estuary E + X Koggala Ganga 10

    17 Nilwala Ganga E/R + + R Nilwala Ganga 12

    18 Rekawa Lagoon L + R Rekawa Oya 15

    19 Muruthawela Wewa T + + C Urubokke Oya 16

    20 Buruthagolla Wewa T NP + C Walawe Ganga 18

    21 Uda Walawe Wewa T NP + R Walawe Ganga 18

    22 Chandrika Wewa T + R Walawe Ganga 18

    23 Ridiyagama Wewa T + R Walawe Ganga 18

    24 Walawe Ganga R + + C Walawe Ganga 18

    25 Badagiriya Wewa T + + A Malala Oya 20

    26 Kalametiya-Lunama Lagoon L SA + + R Malala Oya 20

    27 Bundala Lagoon L NP + + C Kirindi Oya 22

    28 Wirawila Wewa T SA + + R Kirindi Oya 22

    29 Handapanagala Wewa T + R Kirindi Oya 22

    30 Lunugamvehera Wewa T NP + R Kirindi Oya 22

    31 Tissamaharama Wewa T + C Kirindi Oya 22

    32 Yoda Kandiya Wewa T + R Kirindi Oya 22

    33 Gode Lagoon L + + A Bambawa Ara 23

    34 Yala Protected Area Complex L/R/E/T NP/SA + + C

    35 Panama Wewa T + A Wila Oya 35

    36 Heda Oya R + R Heda Oya 36

    37 Lahugala Wewa T NP + C Heda Oya 36

    38 Gal Oya R + R Gal Oya 44

    39 Ekagal Aru Wewa T + C Gal Oya 44

    40 Senanayake Samudra T SA + C Gal Oya 44

    41 Inginiyagala Wewa T + A Gal Oya 44

    42 Namal Oya Wewa T + R Gal Oya 44

    43 Jayanthi Wewa T + R Gal Oya 44

    44 Kondawattavan Kulam T + C Gal Oya 44

    45 Irakhamam Kulam T + R Gal Oya 44

    46 Sammanthurei Wewa T + + R Gal Oya 44

    47 Batticaloa Lagoon L + Gal Oya 44

    48 Rugam Wewa T + R Mundeni Aru 52

    49 Kitul Wewa L + R Mundeni Aru 52

    50 Chenkaldi Aru S + R Mundeni Aru 52

    51 Maduru Oya R/T NP + R Maduru Oya 54

    52 Henanegala Wewa T + C Maduru Oya 54

    53 Pimburettewa Wewa T + R Maduru Oya 54

    54 Punani T + C Maduru Oya 54

    55 Randenigala T SA + R Mahaweli Ganga 60

    56 Minipe C + R Mahaweli Ganga 60

    57 Weragantota R + C Mahaweli Ganga 60

    58 Ulhitiya Wewa T NP + C Mahaweli Ganga 60

    59 Nilgala T + C Mahaweli Ganga 60

    60 Wasgamuwa T/R NP + C Mahaweli Ganga 60

    61 Elahera R + C Mahaweli Ganga 60

    62 Anganmedilla C + C Mahaweli Ganga 60

    63 Diyabeduma C + C Mahaweli Ganga 60

    64 Nelum Wewa T + R Mahaweli Ganga 60

    65 Parakrama Samudra T + C Mahaweli Ganga 60

    (continued on next page)

    308 C. Santiapillai, M. de Silva / Biological Conservation 97 (2001) 305318

  • Table 2 (continued)

    No. Location Categoryc Reserved C. palustrise C. porosuse Statusb River basinf NRBb

    66 Giritale Wewa T SA + C Mahaweli Ganga 60

    67 Minneriya Wewa T SA + C Mahaweli Ganga 60

    68 Habarana Wewa T + C Yan Oya 67

    69 Kaudulla Wewa T + R Mahaweli Ganga 60

    70 Somawathiya R NP + + C Mahaweli Ganga 60

    71 Allai Wewa T + R Mahaweli Ganga 60

    72 Thrikonamadu R SA + R Mahaweli Ganga 60

    73 Mahaweli Delta E + + R Mahaweli Ganga 60

    74 Trincomalee Lagoon L + Mahaweli Ganga 60

    75 Kantale Wewa T + R Kantale Oya 61

    76 Paravipanchan Wewa T + C Per Aru 75

    77 Periya Kulam T + R Pan Oya 63

    78 Irakkakandi Lagoon L + Pan Oya 63

    79 Mora Wewa T + R Pankulam Aru 64

    80 Horowpothana Wewa T + R Yan Oya 67

    81 Wahalkada Wewa T + R Yan Oya 67

    82 Padewiya Wewa T SA + A Ma Oya 69

    83 Kokilai Lagoon L SA + + C Ma Oya 69

    84 Kalvakerny Kulam T + R Per Aru 75

    85 Per Aru R + R Per Aru 75

    86 Chundikulam Lagoon L SA + R Kanakarayan Aru 81

    87 Iranamadu Wewa T + R Kanakarayan Aru 81

    88 Vavuni Kulam T + R Pali Aru 86

    89 Mamaduwa Wewa T + R Parangi Aru 88

    90 Nachchaduwa Wewa T + R Malwathu Oya 90

    91 Tissa Wewa T SA + R Malwathu Oya 90

    92 Nuwara Wewa T SA + R Malwathu Oya 90

    93 Mahakandarawa Wewa T SA + R Malwathu Oya 90

    94 Pavat Kulam T + R Malwathu Oya 90

    95 Thanthirimale Wewa T + R Malwathu Oya 90

    96 Giants Reservoir T SA + R Malwathu Oya 90

    97 Kuda Wilachchiya Wewa T + C Moderagam Aru 92

    98 Mahawilachcchiya Wewa T + C Moderagam Aru 92

    99 Dutch Bay L + Kala Oya 93

    100 Wilpattu National Park R/E/T NP + + C

    101 Kala Wewa & Balalu Wewa T SA + C Kala Oya 93

    102 Giribawa Wewa T + C Kala Oya 93

    103 Rajanganaya Wewa T + R Kala Oya 93

    104 Portugal Bay L + Kala Oya 93

    105 Thabbowa Wewa T + R Mi Oya 95

    106 Mi Oya E/R + R Mi Oya 95

    107 Puttalam Lagoon L + + R Mi Oya 95

    108 Mundel Lake L + R Kalagamu Oya 97

    109 Anaiwilunda Wewa T + C Rathambala Oya 98

    110 Magalle Wewa T + R Deduru Oya 99

    111 Chilaw Estuary E/R + Deduru Oya 99

    112 Negombo Lagoon L + Attanagalu Oya 103

    113 Muthurajawela Marsh M SA + + R Attanagalu Oya 103

    Wilpattu National Park

    1 Mulli Kulam T + + C Moderagam Aru 92

    2 Moderagam Aru E/R + C Moderagam Aru 92

    3 Marai Villu W + C Moderagam Aru 92

    4 Kali Villu W + C Moderagam Aru 92

    5 Mana Wila W + C Moderagam Aru 92

    6 Manikkapola Uttu W + A Moderagam Aru 92

    7 Maha Pelessa Wila W + C Kala Oya 93

    8 Thimbiri Wila W + C Kala Oya 93

    9 Borupan Wila W + A Kala Oya 93

    10 Kumbuk Wila W + C Kala Oya 93

    11 Kokkarai Villu W + C Kala Oya 93

    12 Nelum Wila W + C Kala Oya 93

    13 Panikkar Villu W + C Moderagam Aru 92

    14 Thala Wila W + C Kala Oya 93

    15 Maradanmaduwa Wewa T + C Kala Oya 93

    16 Pomparippu T + + C Kala Oya 93

    (continued on next page)

    C. Santiapillai, M. de Silva / Biological Conservation 97 (2001) 305318 309

  • Table 2 (continued)

    No. Location Categoryc Reserved C. palustrise C. porosuse Statusb River basinf NRBb

    Yala Protected Area Complex

    1 Bambawa Wewa T NP + R Bembawa Ara 23

    2 Bandu Wewa T NP + A Bambawa Ara 23

    3 Palatupana Wewa T NP + + A Bembawa Ara 23

    4 Pattiya Wala T NP + + C Mahaseelawa Ara 24

    5 Mahaseelawa Wewa T NP + C Mahaseelawa Ara 24

    6 Jamburagala Wewa T NP + A Mahaseelawa Ara 24

    7 Mahaseelawa Podi Wewa T NP + + A Mahaseelawa Ara 24

    8 Vilapala Wewa T NP + + A Mahaseelawa Ara 24

    9 Heen Wewa T NP + C Buthuwa Ara 25

    10 Gonagala Wewa T NP + C Buthuwa Ara 25

    11 Galketa Wala T NP + C Buthuwa Ara 25

    12 Debaragas Wewa T NP + + C Buthuwa Ara 25

    13 Lolugas Wala T NP + C Buthuwa Ara 25

    14 Palugas Wewa T NP + C Buthuwa Ara 25

    15 Kohombagas Wala 1 T NP + C Buthuwa Ara 25

    16 Siyambalagas Wala W NP + C Buthuwa Ara 25

    17 Kohombagas Wala 2 T NP + C Buthuwa Ara 25

    18 Karaugas Wala T NP + C Buthuwa Ara 25

    19 Uraniya Lagoon L NP + + C Buthuwa Ara 25

    20 Uraniya Wewa T NP + + A Buthuwa Ara 25

    21 Buthuwa Lagoon L NP + + C Buthuwa Ara 25

    22 Buthuwa Wewa T NP + + A Buthuwa Ara 25

    23 Meynert Wewa T NP + + A Buthuwa Ara 25

    24 Ruk Wila T NP + C Menik Ganga 26

    25 Patanangala Wewa T NP + + A Buthuwa Ara 25

    26 Kimbulagala Wewa T NP + C Menik Ganga 26

    27 Kohomba Pelessa Wewa T NP + C Menik Ganga 26

    28 Ihala Sugandinan Ara Wewa T NP + C Menik Ganga 26

    29 Pahala Sugandinan Ara Wewa T NP + C Menik Ganga 26

    30 Dambakote Wewa T NP + C Menik Ganga 26

    31 Indigolla Wewa T NP + C Menik Ganga 26

    32 Thalakola Wewa T NP + C Menik Ganga 26

    33 Uralu Wewa T NP + C Menik Ganga 26

    34 Katagamuwa Wewa T SA + + A Menik Ganga 26

    35 Halmilla Wewa T NP + C Menik Ganga 26

    36 Korawak Wewa T NP + C Menik Ganga 26

    37 Moderagala Wewa T NP + C Menik Ganga 26

    38 Kotabendi Wewa T NP + C Menik Ganga 26

    39 Koma Wewa T NP + + A Menik Ganga 26

    40 Andunoruwa Wewa T NP + C Menik Ganga 26

    41 Gonalahaba Wewa T NP + C Menik Ganga 26

    42 Digan Wala T NP + + A Menik Ganga 26

    43 Gonalahaba Lagoon L NP + + A Menik Ganga 26

    44 Rakina Wala T NP + C Menik Ganga 26

    45 Menik Ganga E/R NP + + C Menik Ganga 26

    46 Agara Ara S NP + + C Katupila Ara 27

    47 Katupila Ara S NP + + C Katupila Ara 27

    48 Keta Gal Wala T NP + C Kurunde Ara 28

    49 Athuru Mithuru Wewa T SN + C Nabadagas Ara 29

    50 Mahirawa Lagoon L NP + + C Namadagas Ara 29

    51 Maha Gajabawa Lagoon L NP + + C Kumbukkan Oya 31

    52 Kumana Wewa T NP + A Kumbukkan Oya 31

    53 Kumana Villu W NP + + A Kumbukkan Oya 31

    54 Kumbukkan Oya E/R NP + + C Kumbukkan Oya 31

    55 Okanda Wewa T NP + C Kumbukkan Oya 31

    a NRB, Number of river basin.b Status (applies to C. palustris): A, abundant, C, common, R, rare, X, probably extinct.c Category: C, irrigation canal, E, estuary, L, lagoon, M, marsh, R, river, S, stream, T-reservoir, W-Natural waterhole.d Reserve: NP, national park, SA, sanctuary, SN, strict natural reserve.e +denotes the presence of a species.f Following local names apply to dierent types of water bodies. Ara=seasonal river or stream (Sinhala), Aru=river and sometimes stream (Tamil), Gang-

    a=river (Sinhala), Kulam=irrigation reservoir (Tamil), Oya=river, sometimes stram (Sinhala), Samudra= large irrigation reservoir (Samudra means sea in

    Sinhala), Thotupola=ford (Sinhala), Villu=natural waterhole (Tamil), Wala=waterhole, sometimes very small irrigation reservoir (Sinhala), Wewa=irigation

    reservoir (Sinhala), Wila (natural waterhole (Sinhala).

    310 C. Santiapillai, M. de Silva / Biological Conservation 97 (2001) 305318

  • Fig. 1. Map of Sri Lanka showing the 113 localities from where crocodiles were recorded. The names of the localities are given in Table 2. The

    numbers within circles refer to major river basins. Shaded areas refer to the Wilpattu National Park in the north-west and the Ruhuna National

    Park in the south-east.

    C. Santiapillai, M. de Silva / Biological Conservation 97 (2001) 305318 311

  • Fig. 2. Geographic distribution of the two species of crocodile in Sri Lanka in relation to the 100 and 500 m contours:*marsh crocodile (Crocodyluspalustris), ~: estuarine crocodile (C. porosus).

    312 C. Santiapillai, M. de Silva / Biological Conservation 97 (2001) 305318

  • found also. According to Whitaker and Whitaker(1979), the numerous literature references to crocodilesfrom the salt pans in Sri Lanka are to marsh crocodiles,as they are able to tolerate concentrations of salt higherthan that in sea water for long periods. Crocodiles areattracted when fish die in large numbers in the shallowsalt lakes as a result of increased salinity during thedrought. In India, they are known to eat carrion(Champion, 1934), as has also been observed in theYPC. The roots of large kumbuk (Terminalia arjuna)trees provide ideal hiding places for crocodiles along theriver banks. The two most important conservation areasfor both species in Sri Lanka are (i) the WNP and (ii)the YPC, where viable populations capable of long-termsurvival occur. Over 100 marsh crocodiles were recordedfrom the Katagamuwa tank alone, situated adjacent tothe Block I of Ruhuna National Park (Santiapillai et al.,2000), where they were also seen herding fish attimes (Fauna International Trust, 1993). The survey byWhitaker and Whitaker in SeptemberOctober 1977represented the first attempt to estimate the total numberof marsh crocodiles in the island. They counted 300marsh crocodiles and estimated the total population tobe about 3000 animals (Whitaker and Daniel, 1978).Using the average values in the categories adopted duringthe present survey, there could be a minimum of 1220marsh crocodiles in Sri Lanka. There appears to have

    been a 60% decline in the number of marsh crocodilesduring the past 20 years.

    3.2. Estuarine crocodile

    The estuarine crocodile is the largest of all living cro-codile, and perhaps the largest living reptile (Webb andManolis, 1989). Adults reach a maximum length of 56m, and weigh over 1 tonne. In Sri Lanka, the largestspecimen measured 6.4 m. C. porosus has the widestpresent day range of any crocodilian, owing to its abilityto swim long distances in the open seaan ability thathelped colonize almost the whole of tropical coastalAsia besides many inland areas (Whitaker and Whi-taker, 1989). Its distribution once included the Sey-chelles and the Mauritius in the west, but it is nowextinct on these islands, and its distribution extendsfrom South India and Sri Lanka in the west to theCaroline Islands in the east, from Myanmar andSoutheast Asia in the north to Australia in the south. InSouth India, its distribution extends as far north asCochin on the west coast, and to the north of the Bay ofBengal along the east coast (Deraniyagala, 1953).In the past, the estuarine crocodile was very common

    along the western and southern coastal areas of SriLanka. During the 17th century, it was so common inthe vicinity of Colombo and Negombo, that the Portu-guese used to hurl native captives into the moat to beeaten. These animals were so used to eating human fleshthat they would crowd round with gaping expectantjaws upon hearing a whistle (Deraniyagala, 1953). Themoat of the then capital city of Sri Lanka, Sri Jaye-wardenepura near Colombo, contained crocodiles ofboth species. There is still a remnant population of C.palustris there, while it is highly likely that C. porosusknown locally as the man-eater, also would have beenstocked there. That they were once abundant even closeto the city of Colombo can be inferred today by suchplace names as Kimbula wala(= crocodile pool) andKaymans gate, now parts of suburban Colombo.Although the estuarine crocodile is generally confined

    to the coastal region of the first peneplain, it is also

    Table 3

    Occurrence of crocodiles in dierent types of water body in Sri Lanka

    Type of water body Number of locations Frequency (%)

    C. palustris C. porosus

    River 12 83 25

    Estuary 8 100 62

    River and estuary 5 60 80

    Lagoon 15 60 73

    Irrigation reservoir 63 98 11

    Irrigation canal 3 100 0

    River and reservoir 2 100 0

    Marsh 2 100 50

    Total 110 90 28

    Table 4

    Larger river systems (annual discharge over 100 m3106) from which crocodiles were absent or could not be recordedRiver basin

    no.

    River system Annual discharge

    (m3106)Probable

    status

    Reasons for the absence/unavailability of recent records

    1 Kelani Ganga 5474 Extinct Urbanization, proximity to the city of Colombo

    11 Polwatta Oya 299 Extinct Dense human population

    42 Pannela Oya 129 Present Survey not possible because of security situation

    45 Andella Oya 286 Present Survey not possible because of security situation

    51 Magalavatavan Ara 290 Present Survey not possible because of security situation

    53 Miyangolla Ela 118 Present Survey not possible because of security situation

    89 Nai Aru 123 Present Survey not possible because of security situation

    100 Karambalan Oya 251 Extinct Urbanization, proximity to the city of Chillaw

    102 Maha Oya 1608 Extinct Urbanization, proximity to the city of Negombo

    C. Santiapillai, M. de Silva / Biological Conservation 97 (2001) 305318 313

  • known to move far up rivers. It has been recorded in theKalu ganga as far inland as Ratnapura, while a large deadanimal was found 160 km inland from Aluthnuwara onthe banks of the Mahaweli river (Dernaniyagala, 1953).(Deraniyagala might have referred to the village ofAluthnuwara along theMaha oya in the Kegalle District.)It has been recorded from 31 sites excluding the YPCand WNP, along the western, southern and south-easterncoasts of Sri Lanka (Fig. 2), where it frequents riverdeltas and mangrove swamps, and at times moves alongrivers and invades man-made reservoirs. The estuarinecrocodile is known to tolerate salinities up to 5.6%which is about 1.8 times the salinity of sea water (Wells,1979). It is particularly abundant in the saline waters ofthe Kokkarai villu in the WNP where over 30 animalshave been recorded. It prefers brackish water to sea

    water, and occurs in the estuaries of large rivers. Despiteits name, it is not strictly confined to estuaries or salt-waters and can survive in tidal and freshwater rivers andswamps. Males are essentially solitary and territorial,and dominant individuals advertise their large size byswimming boldly at the surface (Lang, 1989). Along thewestern and southern coasts of Sri Lanka its distribu-tion was once closely linked to that of the flag plantsLagenandra ovata and L. praetermissa (known locally asketela), which provide shelter. Destruction of theseplants along the coast led to the local disappearance ofcrocodiles in many places (Dernaniyagala, 1953). AsWebb et al. (1977) pointed out, females may live inregions where fresh water is available throughout theyear. Therefore their main nesting areas are freshwaterswamps. The loss of these habitats greatly reduces thenesting ability ofC. porosus, and this is an important causefor the local reduction or disappearance of the crocodile inSri Lanka. No firm data are available on the number ofestuarine crocodiles in Sri Lanka, but it is likely that thetotal population numbers no more than 300 animals.

    4. The decline of crocodiles

    Although once very numerous, both species began todecline in number as a result of indiscriminate huntingfor skins and meat. Between 1920 and 1940, numbersdeclined with increased export of raw skins (Nicholas,1956; Whitaker and Whitaker, 1977; Uragoda, 1994).By 1946, concerned by the increased persecution of thecrocodiles, the Department of Wild Life (now theDepartment of Wildlife Conservation) placed the twospecies on schedule IV of the Fauna and Flora ProtectionOrdinance, which prohibits killing except on a speciallicence. Nevertheless, given that reservoirs inhabited bycrocodiles, outside the protected areas, come under theIrrigation Department and not the Department ofWildlife Conservation, the crocodiles are vulnerable topoaching. Today, crocodiles are no longer found in theJana peninsula. Act 1 of the Customs Gazette of 1969prohibits the export of crocodile skins.

    4.1. Poaching for skin

    The skin of the estuarine crocodile is the most prizedof all crocodilian skins for fashion leather (Webb andManolis, 1989). The skins were often smuggled out ofthe island to India in sailing vessels. In 1974, the IndianExcise Department seized 86 raw salted crocodile skinssmuggled out of Sri Lanka on the ferry (Whitaker andWhitaker, 1977).

    4.2. Poaching for meat

    Crocodile meat resembles shark flesh in taste andtexture so much that it is sometimes sold as shark meat

    Table 5

    River basins in which crocodiles were recorded by Whitaker and

    Whitaker (1979) (WW) and Porej (1999) (DP) (L, C. palustris, R,

    C. porosus, X, unidentified)

    NRB River basin WW DP

    2 Bolgoda Lake X

    3 Kalu Ganga R

    4 Benthara Ganga R LR

    6 Madampe Oya X

    7 Molapu Oya X

    9 Gin Ganga R

    10 Koggala Ganga R

    12 Nilwala Ganga R

    14 Kirama Oya X

    16 Urubokka Oya X

    18 Walawe Ganga X L

    20 Malala Oya R

    22 Kirindi Oya LR LR

    23 Bambawa Ara X R

    26 Menik Ganga LR LR

    35 Wila Oya L

    36 Heda Oya L

    37 Karanda Oya X

    44 Gal Oya L L

    52 Mundeni Aru X

    54 Maduru Oya L

    60 Mahaweli Ganga X LR

    61 Kantale Oya X

    63 Pan Oya X

    65 Kunchukumban Aru X

    67 Yan Oya X

    69 Ma Oya X

    75 Per Aru L

    81 Kanakarayan Aru L

    88 Parangi Aru L

    90 Malwathu Oya L L

    92 Moderagam Aru L

    93 Kala Oya L X

    95 Mi Oya LR

    97 Kalagamu Oya R R

    98 Rathambala Oya

    99 Deduru Oya R

    103 Attanagalu Oya LR R

    314 C. Santiapillai, M. de Silva / Biological Conservation 97 (2001) 305318

  • in Sri Lanka (Whitaker and Whitaker, 1977). Somepeople living in coastal areas have a definite preferencefor crocodile meat. The fact that even donkey and dogmeat in dried form has been sold as crocodile meat incoastal areas, points to its demand. Crocodiles areusually slaughtered for meat during the dry season,when the medium sized tanks in which they live shrinkto the size of ponds (Uragoda, 1994). According toWhitaker and Whitaker (1989), itinerant fishermen inSri Lanka also kill crocodiles for meat, sometimes asmany as 20 in a day. But slaughter of crocodiles on sucha scale must have been an exception and not the rule.More recently, in 1996 a crocodile was killed for meat inthe Wasgomuwa National Park (S. Wijeyamohan, pers.comm.).

    4.3. Competition with inland fisheries

    Intensive inland fishing in some areas has also led todecline in crocodile numbers, through the reduction in theavailability of food and accidental drowning of crocodilesentangled in the nets cast by fishermen. The problem isfurther exacerbated by the use of synthetic fibre gill netsin which crocodiles get entangled and drown. Fishermenmay also deliberately kill large numbers of crocodiles inreservoirs, because they compete for fish (Uragoda,1994). One such reservoir is Badagiriya (no. 25 in Fig. 1)in the south, which has a surface area of 484 ha at FullSupply Level (FSL) and an annual fish yield of about475 kg per ha. The catch consists almost entirely (95%)of tilapia (Oreochromis mossambicus). Apart from tila-pia, there are smaller fish, mostly minor cyprinids whichalso form a substantial fish biomass. Fishermen killcrocodiles whenever they can, although the fact is rarelyacknowledged. Crocodiles could in fact be beneficial tothe reservoir fishery. Contrary to general opinion, cro-codiles do not eat enormous quantities of fish. Rela-tively few fish are eaten except in the middle years of acrocodiles life. A beneficial role of crocodiles in fish-eries stems from the fact that young crocodiles usuallyprey extensively on many invertebrate predators of fish-fry such as water bugs, water beetles, and crabs. Theyare known to control a number of avian predators offish such as storks, darters and pelicans which consumesubstantial amounts of fish. For instance, in the Para-krama Samudra in Sri Lanka, cormorants (Phalacro-corax spp.) annually consume 112168 kg of fish per ha(Winkler, 1983). This irrigation reservoir, which is oneof the largest ancient tanks (surface area 2529 ha atFSL), has a high annual fish productivity of 317 kg perha. Thus loss of fish yield owing to the consumption bythe cormorants alone could be as high as 50%. Fur-thermore, cormorants consume mainly tilapia which isthe main commercial fish and forms 8090% of thecatch (De Silva, 1988). On a visit to Block I of RNP, inSeptember 1998, in just one water hole (Meynert wewa),

    there were 40 Grey pelicans (Pelecanus philippensis) and62 Painted storks (Mycteria leucocephala), but only fourmarsh crocodiles. Pelicans are known to consume anequivalent of their body weight in three days, whilecrocodiles take 125160 days to consume food equal totheir body weight (Cott, 1961). Taking the loss of fishyield in the Parakrama Samudra from predation bycormorants as 380 metric tonnes per year (150 kg peryear), and assuming that fish makes up only about 40%of the diet of crocodiles, and a crocodile may take 5months to consume an amount of food equal to itsown body weight, a rough calculation shows that itwould take 528 crocodiles of average weight (750 kg) toconsume the amount of fish that is eaten by the cor-morants in the reservoir concerned. In India, aquaticsystems have suered and fisheries declined as a resultof removal of crocodiles (Whitaker and Whitaker,1977).

    4.4. Habitat destruction

    As crocodiles grow from hatchling to adult stage theyincrease in size through several orders of magnitude.This necessitates relatively large and diverse areas ofundisturbed wetlands for the maintenance of largepopulations (Ross, 1998). Such large areas are becomingincreasingly dicult to be set aside in Sri Lanka. Of thetwo species, the estuarine crocodile that has suered themost from habitat destruction. Much of the crocodileshabitat has been destroyed through reclamation ofswamps, draining of coastal wetlands, conversion ofmangroves to prawn farms, and the removal of riverineand littoral forests for human settlements, agricultureand aquaculture. Mangroves occupy only about 87 km2

    in Sri Lanka (Legg and Jewell, 1995), but they are beingrapidly and indiscriminately destroyed along the coastthrough the proliferation of prawn farms, especiallyalong the coast from Negombo to Kalpitiya a stretchof about 300 km (de Silva and de Silva, 1998). One ofthe lesser known causes for the decline of crocodiles isincreased soil erosion and consequent floods whichdestroy both crocodile nests and eggs. Mangroves areespecially important for the protection of hatchlings,which seek shelter among the prop roots of Rhizophoraspp., where birds such as storks which prey on hatchlingcrocodiles, cannot reach their prey.

    5. Conservation of crocodiles

    Sri Lanka has made considerable progress in estab-lishing protected areas which cover over 12% of theland area, but the system of protected areas as far ascrocodiles are concerned, is not comprehensive. Thecoverage in the western, south-western and southern

    C. Santiapillai, M. de Silva / Biological Conservation 97 (2001) 305318 315

  • areas remains inadequate. Crocodiles became legallyprotected in Sri Lanka in 1938, but law enforcement isineective if it is against public opinion. This is especiallytrue of large predators such as the crocodile, leopard, orlarge dominant herbivores such as the elephant, whichseriously compete with human livelihood. According toCustoms Ocials, Sri Lanka has become a transit pointin global tracking of endangered species because ofthe poor enforcement of laws to punish oenders. Inci-dences of smugglers using the island as an entrepot fortransport of endangered and rare animals and plants toEuropean destinations have increased lately. Severallocal as well as foreign travellers were caught smug-gling endangered species of wild fauna and florathrough the international airport in Colombo in 1998.Nevertheless, the illegal trade in wildlife in Sri Lanka isnowhere as serious as it is in some countries in south-east Asia.

    5.1. Conservation education

    Crocodiles are considered dangerous by those peoplewho share their land and waterways with them. Localpeople have no reason to regret the disappearance of thecrocodile from their neighbourhood, and in fact it mayeven provide a psychological relief for the people. Giventhis situation, the management of crocodiles must bebacked by a strong programme of conservation educa-tion and public awareness campaigns on the importanceof the animals in the ecology and economy of thecountry. There is considerable confusion in the minds ofpeople about the role of crocodiles in wetland ecosys-tems. Through ignorance, crocodiles are often treated asserious pests of inland fisheries and exterminated. Peo-ple must be made aware of the useful role crocodilesplay as natural predators and scavengers in the aquaticecosystem.There are no detailed studies on the food habits of

    crocodiles in Sri Lanka. However, the classical paper byCott (1961) on the Nile crocodile (C. niloticus) providesgreat insight into many aspects of the ecology of croco-diles. Given that the habits of the marsh crocodileare very similar to those of the Nile crocodile, Cottsfindings could be of enormous importance in theconservation and management of the Sri Lankanspecies, and the education of people regarding theusefulness of crocodiles. In addition to educating thepeople on the role of crocodiles in nature, it is alsoimportant that the Department of Wildlife Conserva-tion, as the custodian of all wildlife, mitigate thehumancrocodile conflict wherever it occurs. If thereare problem crocodiles in conflict with people, theyshould be captured and released into a protected areaor used in a carefully controlled captive crocodile-breeding programme.

    5.2. Farming and ranching crocodiles

    Farming refers to the closed-cycle breeding of croco-diles in captivity. The twomain activities seen in crocodilefarms are breeding and raising stock from hatchlings toslaughter size (Webb and Manolis, 1989). Adult breedingstock, many of which represent problem animals, isusually taken from the wild. Although farming oers anumber of advantages from a commercial standpoint,including the ability to exploit CITES Appendix I spe-cies, since it excludes wild populations from manage-ment practices, it has no direct benefit to conservation(Thorbjarnarson, 1992, 1999). But ranching is a mod-ified cropping programme involving the captive rearingof crocodiles collected from the wild as eggs or juve-niles. Since crocodiles suer very high mortalities in theegg/hatchling stages, the impact of the removal of a fewyoung from the wild to a captive facility would beminimal. The animals are reared to a commercial size(usually 12 m), slaughtered, and the skins and meatsold commercially. Ranching is by far the most desir-able form of farming crocodiles, as it depends on themaintenance of a healthy, viable crocodile population inthe wild (Webb and Manolis, 1989). For ranching to besuccessful, nests and nesting habitat have to be pro-tected. These are ultimately what need to be safe-guarded to ensure the survival of crocodiles in the wild.As David (1994) points out, ranching if carried outunder strict guidelines and regulations via such interna-tional treaties as CITES, may become a managementpractice with potentially high conservation benefitsand relatively little risks to population status.Giving an economic value to wildlife would ensure

    that local communities will want to conserve it. In theabsence of economic incentives, no amount of legisla-tion will ensure the long-term survival of wildlife out-side the protected areas in Sri Lanka (Wikremasingheand Santiapillai, 1999). Unfortunately, in Sri Lanka, theidea of breeding any wildlife in captivity and sustainablyutilizing them is anathema to the purists, preserva-tionists and the politically powerful Buddhist clergy.Any programme designed to commercially utilize cro-codiles in Sri Lanka will be met with considerableopposition. But in the absence of economic incentivesfor crocodile conservation, there is also a danger thatcrocodiles may disappear from many areas outside thesystem of protected areas in Sri Lanka in the future.One way of making the crocodile economically valuableto local communities is through the development ofprogrammes that rely on non-consumptive uses suchas eco-tourism. It is important that we understandthe economics and behaviour associated with theinteraction between people and their environment inthe tropics, where wildlife species are particularlyvulnerable to overharvest (Robinson and Bodmer,1999) and therefore as Thorbjarnarson (1999) cautions,

    316 C. Santiapillai, M. de Silva / Biological Conservation 97 (2001) 305318

  • crocodile conservation programmes based solely onthe sustainable utilization of its skin would becomesubject to the vagaries of the exotic reptile leathermarket.

    6. Conclusion

    As in most tropical countries, wildlife species are rarelymanaged within conservation areas in Sri Lanka. This isespecially the case as far as the crocodiles are concerned.So far the policy has been to allow nature to follow itscourse within these areas. Such a policy however, asLamprey (1974) argued, seems to have operatedadvantageously in most national parks in the past andcontinues in many at present. The management of cro-codiles has been aimed primarily at preservation. Butoutside protected areas, some form of management isnecessary in the light of the changes in human demo-graphy and the increasing conflict between man andwildlife. In Zimbabwe, crocodiles that were once regar-ded as dangerous animals are now contributing tohuman welfare. Illegal trade is minimal and wild popu-lations are increasing (Child, 1995). It has finally broughtconservationists and landholders together as allies andnot as adversaries, as they were in the past. As Child(1995) suggested, if wildlife conservation is to succeed,it must avoid the double standards borne of the con-flict between emotions and pragmatism. As conserva-tionists, our role is to either prevent or delay the processof species extinction, even if this means domesticatingthe species or maintaining them in a zoo. The marshcrocodile is an ideal animal for ranching: it has a clas-sic hide valuable on the international market (Andrewsand McEachern, 1994). In India, there are well over12,000 marsh or mugger crocodiles in captivity, with apotential for 500010,000 hatchlings per year. Thereforethe species is not globally endangered and can be sus-tainably utilized (Andrews and McEachern, 1994).As Child (1995) argued, if wildlife is permitted to con-

    tribute meaningfully to their welfare, people will not beable to aord to lose it in their battle for survival. If wild-life does not contribute significantly to their wellbeing,people will not be able to aord to preserve it, except as atourist curiosity in a few protected areas. Any conserva-tion programme in developing countries designed toenhance the long-term survival of a species, must be justi-fiable in terms of its value in tangible benefits to people atthe local level. Crocodiles are a valuable renewable nat-ural resource, whose prudent utilization should be regar-ded as a form of land-use that can compete eectively oneconomic terms with agriculture. In addition, increasingattention must be given to the development and imple-mentation of programmes such as eco-tourism that wouldpromote the non-consumptive use of crocodiles. Croco-diles have a poor image, and hence as Gorzula (1987)

    pointed out, their long-term survival in the wild willdepend on the attitude and tolerance of the local people.

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