Observations on Burrows Dug by Mugger Crocodiles (Crocodylus Palustris) in Bundala National Park, Sri Lanka

2007·2.9 MB·

by  Rom Whitaker

MISCELLANEOUS NOTES
Moreover,sightingsweremorein2000and2004asthe
census was carried out in March. During this time, the river
bank area was more exposed and the temperature was 20° -
30° C, which was suitable for Muggersighting. The release
figure(Table 1)revealsthatthepopulationinsideSimilipalis
not related to the release ofthe Muggerin the wild.
From Table 4 it is seen that during the 2004 census,
33Muggerswithinabodylengthof1.5to2.0m,and8Muggers
YEARS ofmorethan 2 mbody length indicatethat47% are adult. In
mWESTDEO BEASTDEO SKHAIRI 3BUDHABALANGA KHADKEI
TamilNadu,thewildmuggerpopulationis465 withanadult
Fig.2: DistributionofMuggersintheriversystems population of 52% (Andrews 1999), and in Gujarat, the
ofSimilipalTigerReserve population is 492, with an adult population of 88%
(Vijayakumaretal. 1990).InSimilipal,therecentsurveyshows
disturbance,bioticinterference,thepresenceofdarahs(deep that the population is 83 with an adult population of 47%.
waterarea), andadequatebasking sites. Though East Deois However, the census shows that the mugger population is
also situated in the core area, there are fewer darahs and stableinsidetheSimilipalTigerReserve.
basking places. In Budhabalanga, the riverbank is steep and
ACKNOWLEDGEMENTS
rocky, the availability of basking places lower, and biotic
interferencegreater. In Khairi, the populationoftheMugger
is higher from Jenabil to Jadi darah in the Jenabil to Ransa We specially thank L.A.K. Singh, Senior Research
route. Here, theirnumberis lowerincomparisontothe West Officer, Office of the Chief Wildlife Warden, Orissa,
Deoastheriverbedisrocky,providingasmallerareaforthe Bhubaneswarforproviding information andguidance in the
basking. But a detailed systematic study has to be made field. We also thank the field staff of the Orissa Forest
seasonally in order to study the seasonal behaviour and the Department fortheirhelp during the survey. We are grateful
ecologyoftheMuggerintheSimilipalTigerReservebecause toallthestudentsofthePostGraduateDepartmentofWildlife
thecrocodileplaysthevitalecologicalroleofamasterpredator andConservation Biology,NorthOrissaUniversity,Baripada
in the aquatic habitat where it lives (Whitaker andAndrews forassistanceinfielddatacollection.
2003).
REFERENCES
Andrews, H.V. (1999): Statusanddistributionofmuggercrocodile in Crocodile Specialist GroupNewsletter. January 2000 - March
Tamil Nadu. ENVIS(Wildlife & ProtectedAreas)2(1): 44-57. 2000 19(1): 7-9.
Anon. (1999): Crocodile-Research: Conservation. Based on the Vijayakumar,V.,R.Vyas&B.C.Choudhury(1999):StatusofMugger
compilationbyS.S.SrivastavaandL.A.K.Singh.SimilipalTiger and its conservation problems in Gujarat. ENVIS (Wildlife &
Reserve. Baripada,Orissa21 pp. ProtectedAreas) 2(1): 69-76.
Singh, L.A.K. (1999):AprofileofIndianCrocodiles. ENVIS(Wildlife Whitaker,R.&H.V.Andrews(2003):Crocodileconservation.Western
& ProtectedAreas) 2(1): 1-4. Asia region: an update. J. BombayNat. Hist. Soc. 100 (2&S):
Singh,L.A.K.(2000):InterpretingvisualsignsoftheIndianCrocodile. 432-445.
OBSERVATIONS ON BURROWS DUG BY MUGGER CROCODILES
16.
(CROCODYLUS PALUSTRIS) IN BUNDALA NATIONAL PARK, SRI LANKA1
RomWhitaker2 Brady Barr3 AnslemdeSilva4andPradeepRatnasiri5
, ,
'Accepted December 19, 2005
:P.O. Box 21, Chengalpattu 603 001, Tamil Nadu. Email: [email protected]
34 Fetter Lane, Severna Park, Maryland, USA.
415/1 Dolosbage Road, Gampola, Sri Lanka.
"Department of Wildlife Conservation, Uda Walawe National Park, Uda Walawe, Sri Lanka.
During abriefvisit to Bundala National Park (Fig. 1), and mapped, and temperatures recorded, both inside and
May7-10,2002,theauthorscaught,measuredandsexedtwo outside the burrows, for 48 hrs. Atotal of38 burrows were
muggercrocodilesinburrows.Theseburrowsweremeasured seen, which ranged from 3.05 m to over 6.0 m in length.
J. Bombay Nat. Hist. Soc., 104 (2), May-Aug 2007 217
MISCELLANEOUS NOTES
Entranceswere45.72cmto 137.16cminwidthand27.94cmto describes the U-shaped mugger burrow found in riverbanks
60.96 cm in height. Temperatures outside the burrows in Sri Lankaoften undertherootsofthetypical ripariantree
fluctuatedfrom28°Cto46°Cwhileburrowinteriorsremained giant, Terminaliaarjuna. McCann (1940) mentions mugger
virtuallystaticat29°C. burrowsattheSindsaltlakes(nowPakistan).Whitaker(1977)
It is likely that most of the world’s crocodilians dig describesfindingsixteenmuggerburrowsintheHiranLake,
burrowsortunnelstohideinandtotideoverextremeweather GirLionSanctuaryinGujaratwith“flattened,ovalentrance”
conditions(Guggisberg 1972; Steel 1989;Chenetal. 1990). averaging80cmwidthand4to5mdeep.Therewasacrocin
Crocodilian species found in the tropics presumably rely on nearly every tunnel at the end of May 1975 and outside
burrows to survive the effects ofdrought and extreme heat; temperatureswerereaching46°Cintheshade.Whitakerand
however, the two species ofalligator (A. misissipiensis and Whitaker (1984) referred to mugger burrows in Sri Lanka,
A. sinensis) that range above 30° N where temperatures fall Gujarat, South India and noted that yearling, subadult and
belowfreezing,digand utilize burrowsasrefugesfromcold adult mugger all dig burrows. They briefly describe the
winter temperatures. The mugger crocodile (Crocodylus tunnelling, the crocodile using its front feet to dig and push
palustris) foundthroughout the Indian subcontinent, as well earthbacktothehindfeetwhichscrapethedirtbacktowhere
asSriLanka,isanotedburrowdigger.Thisspeciespresumably thetailpropelsitawayintothewater.GuptaandSrihari(1990)
utilizes the burrows as an effective refuge from the hot studiedmuggerburrowsatBhorsaindan Sanctuary,Haryana
daytime ambienttemperatures found in Bundala, Sri Lanka, andfoundthatburrowutilizationwasgreaterinwintermonths
thesouthernmostrangeofC.palustris.Crocodilianshavean whentemperaturesdroppedto 1 1°C. Shekar(1993)reported
optimum body temperature of30-35° C, and ifsubjected to two to six muggers in the same burrow in winter months at
temperatures below 5°orabove 38°C forextendedperiods, this Sanctuary. Vijaykumar (1997) enumerated 114 mugger
theyareindangerofdying(Lang 1987). Burrowsmayplaya burrowsindifferentpartsofGujarat.Mostburrowswerefrom
critical role in the survival of crocodiles living in harsh 0.6mto2.6mindepth,thoughtwoinGirSanctuarywereover
environments, such as southern Sri Lanka. 6 m. He mentions that the temperature inside a 3 m burrow
There are numerous references to mugger burrows in remained constant at 19.2 to 19.8° C while the outside
the literature, a few of which follow; Deraniyagala (1936) temperaturefluctuatedfrom 12to43°C.Hegivesnodatebut
218 J. Bombay Nat. Hist. Soc., 104 (2), May-Aug 2007
MISCELLANEOUS NOTES
judgingfrom thetemperatureandthe factthat most burrows
were empty it was probably in February, before the serious
dry season sets in.
Methods
With the permission of the Department of Wildlife
Conservation,SriLankaandhelpfromtheBundalaNational
ParkWarden andstaffwe visitedthree main burrow sitesby
a4-wheeldrivevehicleandonfoot(Fig. 2). Severalburrows
weremeasuredfromtheburrowmouth,andtwoofthelarger
ones were entered and mapped. These two large tunnels
contained crocodiles which were caught, measured, sexed,
markedandreleasedonsite.Twootherfreeswimmingcrocodiles
werecaughtwithswivel-lockwirenoosestodemonstratesafe Fig.2:Detailofstudysite,BundalaNationalPark
capture, sexing, marking and release techniques to the NP
staff.Dataloggers(StowawayTidbitloggers.OnsetComputer west.Waterandchannel20mwideand 1 to 1.5 mdeep,fresh.
Corporation) recorded temperature simultaneously at 30- Vegetation:sameasSite 1 withPhoenixsp.(dwarfdatepalms).
minute intervals for 48 hours and were placed inside and Burrows: 10burrows, 1 occupiedplus4crocodiles 1.5
outside burrows andin the waterclose tothe tunnel mouths. to2.5 mintheadjacentwater. Burrowentrancesweremostly
Sexing wasdonebydigital probingofthecloaca. abovepresentwaterlineandrangedfrom20-40cminheight
and28-135cm inwidth. Depthofonewasmorethan6m.
m
Results Crocodilepulledoutofthisburrowwasa2.35 female
Site 1: Localname: Sudugala withamangled4thsinglecaudal whorl(forI.D.).Temperature
Description:raised50mlongembankmentofsandand loggers were placed in the water and on the substrate
black soil about a metre above present water level (it had (unshaded)outside the burrow andat threedepthsinsidethe
rainedafewdaysearlier),facingsouthwest.Waterchannelin burrow. Resultsaregiven inFigs4and5.
front ofembankment 12 m wide and 25-50 cm deep, fresh. Site3: LocalName: CampsiteTuduna(point)
Vegetation: Prosopisjitliflora(mesquite),Salvadorapersica
, Mapping of sample burrow
reeds (dry now) and small bushes. (No. 2from North end under Phoenixpalm - Fig. 3)
Mapping of sample burrow (No. 1 at North end) Height (cm) Width (cm)
Height(cm) Width (cm) Entrance 40.0 135.0
Entrance 37.5 70.0(2.5mfromwater'sedge) 2 metres in 42.0 77.5
3 metres in 27.5 72.5
2 metres in 32.5 90.0 5 metres in (chamber) 82.0 114.0 (partly caved in)
4 metres in 37.0 105.0 (chamber)
Burrows: Five burrows, three were occupied and two Description: Raised 160 m embankment ofsand and
crocodiles about 2 m length were observed in the adjacent dark soil 1.5 to 2 m above present water level facing west-
water. Burrowentrancesrangedfrom25-40cminheightand south-west. Water channel about 25 m wide and 1 m deep,
35-70 cm in width. Two ofthe burrows were at water level, slightly brackish. Vegetation: mainly Prosopis and small
threeweredry. bushes.
Crocodilepulledoutofthisburrowwasa2.70mfemale Burrows: 23burrows,3occupied,2crocodilesc. 2min
missingabout 15cmofitstailendandclippedbyusonthe6th water. All entrances were above the present water level.
dorsalcaudal whorl on the left. Entrance height ranged from 23 cm to 60 cm, widths from
Crocodile caught in adjacent waterwas also afemale, 28cmto77cm.Burrowdepths3-5m.
2.40minlengthandclippedonthe8thdorsalcaudalwhorlon Other animal life observed in the burrows: Gecko,
left. centipedes, mosquitoes, cockroaches, and ants.
Site2:LocalName:Campsite
Description: Raised 75 m long embankment of sand Discussion
and black soil 2 m above present water level facing north- Muggerdigburrows ofsometimes more than 6.0m in
J. Bombay Nat. Hist. Soc., 104 (2), May-Aug 2007 219
MISCELLANEOUS NOTES
ISGcjn
BURROWENTRANCE
Fig.3: Burrow2(site2)interiormap(nottoscale)
ai-i
30.5 1 8 metersinside
—
5metersinside
x 0.6 metersinside
30-
C
?
Temperature
27
00:00:00 12:00:00
05407/0212:38:00 DateandTime 05/09/0210:35:00
Fig.4: Burrow2(site2)temperaturereadingsinsideburrow
220 J. Bombay Nat. Hist. Soc., 104 (2), May-Aug 2007
!
MISCELLANEOUS NOTES
Fig.5: Burrow2(site2)bihourlytemperaturereadings
length to escape the heat and desiccation ofsometimes very their tunnel, a strategy that can optimize nest and hatchling
long and harsh dry seasons in South Asia. The burrows survival.
observed in this study were clean with no smell and with The graphs showingthe datafrom the loggers (Figs4
varying degrees of dampness. Few of them were occupied and5)areself-explanatory.Thetwothingsthatstandoutare
which is likely to be because ofthe recent rains and lower (a)theamazingconsistencyoftemperaturesdeepwithinthe
temperatures. Most burrows showed signs of recent burrows(notcoincidentally,optimumforacrocodilian)and
occupationandsomeofrecentdigging.Invariablythedeeper (b) a sudden small rise in temperature nearmidnight in one
burrows sloped downward attheend, with alargerchamber burrow, which could have been the entry ofa crocodile.
upto double the widthofthe tunnel forthe crocodile to turn A behavioural observation ofconsiderable interest is
around and comfortably lie in. Very often deeper burrows that when we approached adult muggers in shallow water
turned so that the end was not visible. One characteristic of they would first attempt to swim away, but failing to find
mosttunnelentrancesistheraisedcentral moundofearthor deep water they would leave the water to enter a nearby
sand. This is formed as the crocodile enters the tunnel and tunnelorifnotunnelwaspresenttheywouldsimplywalkup
digswithfrontandhindlimbs,asitgoesin.Diggingseemsto intotheforestforshelter,morelikeabiglizardthanacrocodile
be a continuous process and it is likely that some burrows In one case a large female got herself entangled in some
took several years to dig and may be in use for decades or bushesandwewereabletoascertainhersexwithoutcatching
more.Itissurmisedthattunnelsareusedasoccasionalrefuges orrestrainingher.
atthistimeofyearwiththemorepermanentresidentsmoving Some burrows were observed to have unstable roofs
in at the July-October period of peak hot weather. Several in danger of collapse. Numerous collapsed burrows were
observers(Shekar 1993;Vijaykumar 1997;Whitaker/'/? lift.) seen (mostly old) probably due to heavy rains. One ofthe
notedthatfemale muggerwill lay theireggs at the mouth of authors (Pradeep) has counted over 90 mugger burrows in
J. Bombay Nat. Hist. Soc., 104 (2), May-Aug 2007 221
MISCELLANEOUS NOTES
BundalaNPandanother(Whitaker)enumeratedburrowsin are a vital refuge. Protection of the embankments in the
theMenikGanga(YalaNP)andLunugumveheraNP.These Park is important for the long-term conservation of the
observations and the results of this small study point to a species.
fascinating and important behaviour by mugger which
deserves systematic study. A comprehensive investigation ACKNOWLEDGEMENTS
focussing on the role of burrows in relation to the thermal
ecologyofcrocodiliansissorelylackingandSriLankaoffers We wishtothankthe Director,DepartmentofWildlife
a unique opportunity. The muggercannot survive extended Conservation,SriLanka,theParkWardenandstaffatBundala
dry seasons without being able to regulate its temperature National Park for their help in making this study possible.
withinsafelimits.Inahot,dryarealikeBundalatheirburrows Thanks are alsodue to Harry V. Andrewsforhis inputs.
REFT NCES
Chen, Bihui, Wang Chaolin & Lian Baodong (1990): Observation Limited, 1987, pp. 301-317.
on the Burrow ofChineseAlligator. In: Crocodiles, Proceedings McCann, C. (1940): A reptile and amphibian miscellany. J. Bombay
ofthe 10th Working Meeting ofthe Crocodile Specialist Group, Nat. Hist. Soc. Vol. 41: 742
IUCN - World Conservation Union, 1: 47-53. IUCN. Gland, Shekar, Chander (1993): Ecological studies on Indian mugger
Switzerland. (Crocodyluspalustris)atBhorsaindanCrocodileSanctuary.Unpubl.
Deraniyagala,P.E.P.(1936):AnewcrocodilefromCeylon.TheCeylon Ph.D. Thesis, Kurukshetra University, India.
J. ofSci.; Section B 19(3): 279-286. Steel, Rodney (1989): Crocodiles. Pp. 14. Christopher Helm.
Guggisberg,C.A.W.(1972):CrocodilestheirNaturalHistory,Folklore Vijaykumar,V.(1997):Evaluationofrestockedmuggercrocodilesand
and Conservation. Pp. 105-108. David and Charles Limited. its implications in long term conservation and management of
Gupta, R.C. & P. Srihari (1990): On the burrow utilization by the thespeciesinGujarat,India.ReportNo.95/5/4ofGujaratInstitute
Indian marsh crocodile (Crocodvlus palustris) at Borsaindan ofDesertEcology,Bhuj,Gujarat. India.
Crocodile Sanctuary, Haryana. J. Environ. Biol. 11(2): 169-178. Whitaker, R. (1977): Note onthe statusofGircrocodiles.J. Bombay
Lang, J. (1987): Crocodilian thermal selection. In: Wildlife Nat. Hist. Soc. Vol. 75(1): 224-227.
Management: CrocodilesandAlligators, Ed. By GrahameWebb, Whitaker,R.&Z.Whitaker(1984):ReproductiveBiologyofMugger.
S.C. Manolis, and P.J. Whitehead, Surrey Beatty and Sons Pty J. Bombay Nat. Hist. Soc. 81(2): pp. 119-127.
17. A REPORT OF GECKOELLA NEBULOSA (BEDDOME, 1870)
FROM SEONI DISTRICT, MADHYA PRADESH
1
ISHAN AGARWAL2
1 Accepted June 13, 2005
25/44, Hira, K.C. Road, Mumbai 400050, Maharashtra, India. Email: [email protected]
OnOctober30,2003afreshlykilledGeckoellanebulosa Other reptiles seen in the same area were Sitana
(Das2003)wasseennearapileofrocks,closetoaroadnear ponticeriana Psammophilus blanfordanus Hemidactylus
, ,
Seoni(22.06°N,79.35°E),justoutsidePenchNationalPark. brookii, Calotes versicolour, Mabuya carinata (visual
The specimen was collected and deposited in the identification) andashedskin ofPtyasmucosus.
collections of the Bombay Natural History Society (Regn. Thisgeckowasoriginallydescribedas Gymnodactylus
No.: BNHS 1598).TheforesttypeinSeonidistrictisTropical nebulosafromGolcondaHills(AndhraPradesh)byBeddome
Dry Deciduous and Tropical Moist Deciduous, largely in 1870.Furtherdistributionalrecordsareasfollows:Nelambo,
dominated by Tectona grandis (Champion and Seth 1968). South India (= Andhra Pradesh): Annandale 1913), Smith
(
Theareainwhichthegeckowasfoundwasashady,forested (1935),TikaderandSharma(1992);GorgeHills,Godaveryand
patch,withlittleundergrowth,dominatedby Tectonagrandis. Russelconda inAndhra Pradesh: Smith (1935), Tikader and
The lizard measured 37.3 mm snout-vent length, and Sharma (1992); Mandla district, Madhya Pradesh (adjacent
mm
27.2 taillength.ThespecimenagreeswithSmith’s(1935) toSeonidistrict):Sharma(1976),TikaderandSharma(1992);
description - 10 supralabials on both sides, 38 midventrals, Kerala (Nilambur, Malappuram district) and Tamil Nadu
back with small granularscales interspersed with numerous (Saidapetdistrict):TikaderandSharma(1992);Koraputdistrict,
larger rounded tubercles. A notable discrepancy is that the Orissa:Sanyal (1993);Puridistrict,Orissa: Dutta(1997).Das
specimen has 8 infralabials on each side, as against 10 in (2002) gives the distribution of this species from Puri and
Smith(1935).ThecolorationisalsothesameasSmith(1935), Koraput district in Orissa, to Gorge, Golconda and other
exceptthe tailtipwasbrightorange. isolatedhillsinAndhraPradesh.TheUniversityofMichigan
222 J. Bombay Nat. Hist. Soc., 104 (2), May-Aug 2007