Download pdf - Status, distribution and conservation of crocodiles in Sri Lanka

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), con®ned largely to the low-country in the ®rst 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 Ja�na 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 ®ve, 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 country's 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 island's 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 bene®t 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 classi®ed as``vulnerable'' but C. porosus is no longer considered``threatened'' 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 `èndangered''respectively. 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). Identi®-cation with unaided eye at a distance or when the twospecies are in water is often di�cult. 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.Di�erences 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) 305±318

www.elsevier.com/locate/biocon

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

E-mail address: [email protected] (C. Santiapillai).

In Sri Lanka, the number and geographical range ofcrocodiles in general, and of the marsh crocodile inparticular, seem to have been a�ected 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 ®sh, 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 bu�aloesand 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 Deraniyagala's (1953) pioneering work, and thesurvey carried out by Whitaker and Whitaker (1977,1979). No scienti®c 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) identi®ed 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 the`ùnsafe'' 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 7�42 binoculars, from 0600 to 1900

Table 1

Characteristics of Sri Lanka's 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 February±March June±August

Hatching May±June September±October

Nest type Hole Mound

Clutch size 10±30 20±70

Hatchling size 20±25 cm 25±30 cm

Temperament Aggressive Very aggressive

306 C. Santiapillai, M. de Silva / Biological Conservation 97 (2001) 305±318

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 identi®ed based on ®eld criteriasuch as the shape of the dorsal osteoderms (Table 1).This is often di�cult, as Daniel (1983) pointed out, thetwo species are di�cult to distinguish in the ®eld, espe-cially smaller individuals. Wherever possible, the lengthof the animals was estimated visually. Four categorieswere recognized: hatchlings (<0.5 m), juveniles (0.5±1.0m), subadults (1.1±2.0 m), and adults (>2 m). It wasnot possible to determine the sex of the individuals inthe ®eld. Marsh crocodiles were assigned to the follow-ing categories based on their number: (i) rare (<10animals); (ii) common (10±30 animals); (iii) abundant(>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 modi®ed 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 ®ndings 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),`àll 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 Ja�na peninsula (Ferguson, 1877) where it nolonger occurs. Today its range is almost con®ned to the®rst 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) 305±318 307

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)


Table 2 (continued)


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)


Table 2 (continued)


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 di�erent 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).


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.


Fig. 2. Geographic distribution of the two species of crocodile in Sri Lanka in relation to the 100 and 500 m contours:*marsh crocodile (Crocodylus

palustris), ~: estuarine crocodile (C. porosus).


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 ®sh 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'' ®sh attimes (Fauna International Trust, 1993). The survey byWhitaker and Whitaker in September±October 1977represented the ®rst 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 5±6m, 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 seaÐan 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 ¯eshthat 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) and``Kayman's gate'', now parts of suburban Colombo.Although the estuarine crocodile is generally con®ned

to the coastal region of the ®rst peneplain, it is also

Table 3

Occurrence of crocodiles in di�erent 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 m3�106) from which crocodiles were absent or could not be recorded

River basin

no.

River system Annual discharge

(m3�106)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


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 con®ned 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 ¯ag 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 ®rm 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 theJa�na 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 ¯esh 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, unidenti®ed)

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


in Sri Lanka (Whitaker and Whitaker, 1977). Somepeople living in coastal areas have a de®nite 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 ®shermen 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 ®sheries

Intensive inland ®shing 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 ®shermen. The problem isfurther exacerbated by the use of synthetic ®bre gill netsin which crocodiles get entangled and drown. Fishermenmay also deliberately kill large numbers of crocodiles inreservoirs, because they compete for ®sh (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 ®sh yield of about475 kg per ha. The catch consists almost entirely (95%)of tilapia (Oreochromis mossambicus). Apart from tila-pia, there are smaller ®sh, mostly minor cyprinids whichalso form a substantial ®sh biomass. Fishermen killcrocodiles whenever they can, although the fact is rarelyacknowledged. Crocodiles could in fact be bene®cial tothe reservoir ®shery. Contrary to general opinion, cro-codiles do not eat enormous quantities of ®sh. Rela-tively few ®sh are eaten except in the middle years of acrocodile's life. A bene®cial role of crocodiles in ®sh-eries stems from the fact that young crocodiles usuallyprey extensively on many invertebrate predators of ®sh-fry such as water bugs, water beetles, and crabs. Theyare known to control a number of avian predators of®sh such as storks, darters and pelicans which consumesubstantial amounts of ®sh. For instance, in the Para-krama Samudra in Sri Lanka, cormorants (Phalacro-corax spp.) annually consume 112±168 kg of ®sh per ha(Winkler, 1983). This irrigation reservoir, which is oneof the largest ancient tanks (surface area 2529 ha atFSL), has a high annual ®sh productivity of 317 kg perha. Thus loss of ®sh yield owing to the consumption bythe cormorants alone could be as high as 50%. Fur-thermore, cormorants consume mainly tilapia which isthe main commercial ®sh and forms 80±90% 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 125±160 days to consume food equal totheir body weight (Cott, 1961). Taking the loss of ®shyield in the Parakrama Samudra from predation bycormorants as 380 metric tonnes per year (150 kg peryear), and assuming that ®sh 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 ®sh that is eaten by the cor-morants in the reservoir concerned. In India, aquaticsystems have su�ered and ®sheries 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 di�cult to be set aside in Sri Lanka. Of thetwo species, the estuarine crocodile that has su�ered themost from habitat destruction. Much of the crocodile'shabitat 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 Ð 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 ¯oods 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


areas remains inadequate. Crocodiles became legallyprotected in Sri Lanka in 1938, but law enforcement isine�ective 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 O�cials, Sri Lanka has become a transit pointin global tra�cking of endangered species because ofthe poor enforcement of laws to punish o�enders. Inci-dences of smugglers using the island as an entrepoÃ t 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 ¯orathrough 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 ®sheries 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, Cott's®ndings 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 thehuman±crocodile con¯ict wherever it occurs. If thereare problem crocodiles in con¯ict 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 o�ers 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 bene®t to conservation(Thorbjarnarson, 1992, 1999). But ranching is a mod-i®ed cropping programme involving the captive rearingof crocodiles collected from the wild as eggs or juve-niles. Since crocodiles su�er 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 1±2 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 bene®tsand 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,


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 `òperatedadvantageously 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 con¯ict 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 ®nally 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,`ìt must avoid the double standards borne of the con-¯ict 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 5000±10,000 hatchlings per year. Thereforethe species is not globally endangered and can be sus-tainably utilized (Andrews and McEachern, 1994).As Child (1995) argued, `ìf wildlife is permitted to con-

tribute meaningfully to their welfare, people will not beable to a�ord to lose it in their battle for survival. If wild-life does not contribute signi®cantly to their wellbeing,people will not be able to a�ord 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-®able in terms of its value in tangible bene®ts 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 e�ectively 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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