POPULATION DENSITY OF BENGAL MONITOR(Varanus bengalensis) AT DIFFERENT HABITATS OFDISTRICT SWABI, KHYBER PAKHTUNKHWA, PAKISTANGul Zada*, Muhammad Rais, Iftikhar Hussain, Tariq Mehmood and Maqsood AnwarDepartment of Wildlife Management, PMAS Arid Agriculture University Rawalpind*Presenter; Paper emanated from M.Sc Research Report
INTRODUCTIONBengal Lizard (Order: Squamata; Family: Varanidae; Genus:VARANUS; Species: BENGALENSIS) is a well-known large-sizedlizard species in Pakistan.73 species of Genus Varanus in Africa, Australia and Asia; Nine inAsia; Four in South Asia (reptile-database.org).The Genus Varanus is represented by three species in Pakistan(Khan 2006).Conservation Status: Least Concern ( as per IUCN redlist.orgaccessed 18/04/2011).Listed in Schedule III (Protected Animals) of KPK Wildlife Act(1975) and KPK Wildlife Rule (1977) (Shafique, 2005).
Easily identifiable: Juveniles colorful with a series of yellow spots anddark transverse bars on dorsal side. Adults have light brown or grey colorwith dark spots.Males have flaps near the vent that is formed by clusters of scales.(Auffenberg, 1994 and Khan, 2006).Lives in burrows/ crevices; DiurnalFeeds on invertebrates such as, arthropods; also prey upon smallbirds and their eggs, rats, frogs, fish and rotten flesh (Smith, 1930;Murthy, 1978; Auffenberg, 1979 and Tikader, 1983).Widely distributed in Pakistan in various habitats, but moreabundant in agricultural areas (Auffenberg et al. 1991 and Khan,2006).Hunted for pelt used in various products such as shoes and bags etc; eaten,
OBJECTIVE To estimate density (number of individuals and burrows) ofBengal Lizard at various habitat types viz. agriculture lands,stream banks and muddy houses near human habitations.OUTCOMES Quantitative data on population will be gathered that could beused to assess conservation status of lizards of Pakistan ingeneral and varanids in particular. Baseline data will help design detailed ecological studies.
Study Area Gangodher Village, Tehsil and District Swabi (34 7 12" Latitude North,72 28 20" Longitude East), Khyber Pakhtunkhwa Province, Pakistan Three sampling units were selected:1. Zahir Shah Aratt,2. PalosiKhwar and3. Gangodher Kaly An area of 20 square kilometer were surveyed within each sampling units. Each sampling unit represented three distinct habitats viz. agricultural fields(Wheat, Maize, Tobacco and Vegetables) , stream banks and muddy houses(human habitations). Population and Burrow Density was calculated by dividing number ofindividuals/ burrows with the area.Study Period: Eight months; March to November 2010.Study Parameters: Population density andBurrow DensityMATERIALS AND METHODS
Agriculture Fields Stream BankMuddy House (Human Habitations)
Population Density: Fixed-width Line TransectNumber of individuals of Bengal Lizard were recorded along a line ofpredetermined length and width viz. 400 meters and 25 meters (on eitherside), respectively (Sutherland, 1996).Area of Transect= Length X 2 Width= 400 X 2 (25)= 20000 meter square= 20 square kilometerBurrow CountNumber of active and passive burrows were counted along the transects.To differentiate passive from active burrows, openings of burrows werecovered with dry vegetation in the evening and were checked in thesubsequent morning.Presence of foot prints, tail trails and removed vegetation indicated theburrow was active.SURVEY TECHNIQUE
Agriculture Fields Stream Banks Muddy House(Human Habitations)TotalNumber PopulationDensityNumber PopulationDensityNumber PopulationDensityNumber PopulationDensityMarch 1 0.05 2 0.1 1 0.05 1.33 0.06April 2 0.1 4 0.2 1 0.05 2.33 0.116May 2 0.1 5 0.25 2 0.1 3 0.15June 2 0.1 4 0.2 3 0.15 3 0.15July 5 0.25 8 0.4 4 0.2 5.66 0.28August 0 0 1 0.05 2 0.1 1 0.05September 4 0.2 3 0.15 4 0.2 3.66 0.18October 3 0.15 3 0.15 4 0.2 3.33 0.167November 3 0.15 3 0.15 4 0.2 3.33 0.167Total 2.4 0.122 3.37 0.183 2.78 0.139 2.96 0.149Table 1: Number and Population Density of Bengal Lizard recorded from differenthabitats during March, 2010 and November, 2010 from Zahir Shah Aratt , District Swabi
Muddy Houses Agriculture Fields StreamBanksTotalZahir Shah Aratt 0.38* 0.12* 0.18 0.14Palosi Khwar 0.07* 0.13* 0.14 0.119Gangodher Kaly 0.06* 0.16* 0.1 0.11District Swabi 0.50±0.43 0.13±0.01 0.14±0.02 0.123±0.008Table 7: Population Density (Mean ± SE) of Bengal Lizard recorded from different habitatsof the selected sampling units of District Swabi from March, 2010 to November, 2010.Agriculture Fields Stream BanksTotalActive Passive Active Passive Active PassiveZahir Shah Aratt 5.22 4.11* 7.22 6.22* 6.22 5.16Palosi Khwar 5.55* 4.44 7.8* 6 6.72 5.6Gangodher Kaly 5.11 5.66 5.33 7.33 5.22 6.49District Swabi 3.62± 0.13 3.63± 0.47 4.80±0.74 4.68± 0.41 4.23± 0.44 4.25± 0.39Table 8: Burrow Densities (Mean ± SE) of Bengal Lizard recorded from different habitats ofthe selected sampling units of District Swabi from March, 2010 to November, 2010.Pair of values marked with * in a row shows significant difference i.e. P<0.05Population Density= Number of individuals per square kilometer
DISCUSSION•No previous study on population status of the species in Pakistan.•Large lizards account for over 50% of all lizards considered threatened(IUCN, 1990).•Bengal lizard (Varanusbengalensis) is quite predominant and occursthroughout the Indian subcontinent (Smith, 1935; Murthy, 1978 and 1985;Tikader, 1983;Auffenberg, 1986)•Many populations of monitor lizards are threatened due to habitatdestruction and fragmentation (Pianka, 1969; Auffenberg, 1988; Branch,1991).•Members of genus Varanus, the monitor lizards are considered particularlyVulnerable with all 37 species categorized as threatened or endangered by theUS Fish and Wildlife Service.
CONCLUSION•Bengal Monitor (Varanus bengalensis) is a widespread and wellknown large-sized lizard species in Pakistan.•Using Fixed-width Line Transect Method density (number ofindividuals and burrows) of Bengal Monitor at different habitatsviz. agriculture fields, bank streams and muddy houses nearhuman habitations in District Swabi, Khyber PakhtunKhwa wererecorded from March, 2010 to November, 2010.•Average population densities (per square kilometer) recordedfrom agriculture fields, bank streams and muddy houses were0.13±0.01, 0.14±0.01 and 0.50±0.43 respectively.
•Densities of active burrows (per square kilometer) were3.62 0.13 and 4.80 0.79 in agriculture fields and bank streamsrespectively.•Densities of passive burrows were 3.63 0.47 and 4.68 0.32 inagriculture fields and bank streams respectively.•Higher density of lizard and burrows along bank streams andmuddy houses reflected lizard’s habitat preference.•Trapping of lizards and persecution by locals were recorded asmain threats to the species in the area.