Amphibians and reptiles (herpetiles) are cold-blooded animals. Mostly lay eggs, fertilization is external in amphibians and internal in reptiles. Amphibians undergo metamorphosis to reduce competition between larval (usually aquatic) and adult (terrestrial) stage. The reptiles are found in a variety of habitats throughout the world except some isolated islands. Diversity and abundance of herpetiles is dependent on climate and geographic position of any region and is also directly linked with some avian and mammalian species. Amphibians and reptiles are important bio-indicators of climate change and the survival of both taxa is under continuous threat due to deforestation, habitat loss, fragmentation, urbanization and pollution. Data on local distribution patterns is helpful in regional conservation planning (Petrov 2004).
Herpetiles are the important members of environment and have important position in pyramids. They control the population of many insects and pests, and themselves are source of food for many predators. Amphibians and many reptiles transfer nutrients from aquatic to terrestrial ecosystems and if they are removed from any ecosystem, the algae communities, invertebrate populations, predator dynamics, leaf litter decompositions and nutrient cycling can be affected (Baig 2006 ).
Pakistan has the world’s rarest animals and plants but these are now in danger due to habitat loss, overuse and anthropogenic activities. The herpetofauna of Pakistan is represented by 219 species; 24 species of amphibians and 195 species of reptiles out of these 9 species of amphibians and 13 species of reptiles are endemic to Pakistan (Khan 2004). The herpetiles received less attention of scientific community hence these taxa remained unexplored in Pakistan. There is extreme scarcity of data on the distribution of various amphibian and reptilian species in the country (Khan 2006). The only authentic source of information till so far on herptiles in this region is the data collected and compiled by Daniel and Khan (2002, 2006).
In Pakistan arid to semi-arid climatic conditions prevail that make it, an amphibian poor country however, humid riparian conditions in the Indus Valley, streams in the northern Himalayan sub-mountainous region and water channels in the western Baluchistan highland are home to some 24 amphibians, that belong to four families viz. Bufonidae, Megophryidae, Microhylidae and Ranidae (Khan 2011). The reptilian fauna of Pakistan is represented by 195 species belonging to 23 families viz. Cheloniidae, Dermochelyidae, Emydidae, Testudinidae, Trionychidae, Crocodylidae, Gavialidae, Agamidae, Chameleonidae, Eublepharidae, Gekkonidae, Lacertidae, Scincidae, Uromastycidae, Varanidae, Leptotyphlopidae, Typhlopidae, Boidae, Colubridae, Elapidae, Hydrophiidae, Viperidae and Crotalidae (Khan 2004).
In Pakistan, due to over hunting the marsh crocodile is in danger and nearly extinct. Now this species only occur in small numbers in Sindh and a few areas in Balochistan. The gharial is now few in numbers and found only between the Sukkur and Guddu barrages. In addition monitor species are heavily hunted for their skins. 72 snake species found in Pakistan and out of these, 14 marine and 12 terrestrial snake species are poisonous; most well-known are the Indian cobra, common krait, saw-scaled viper and Russel's viper. The snake venom is a complex mixture of enzymes including the pro-coagulant, non-enzyme proteins, peptides, carbohydrates, amines, lipids and metal ions. The venom exertsneuro-toxic, cytotoxic and hemotoxic effects. Genus monospecific Teratolepsis and Eristicophis is endemicto Pakistan. The Chagai Desert is of particular interest for reptiles, with six species of reptiles including five lizards and one snake are endemic to Pakistan and a further six species found only here and along the border of Iran. Important populations of marine turtles nest on Pakistan's southern beaches. The internationally threatened species of reptiles in Pakistan are Green and olive turtle, mugger, gharial, central Asian monitor, Indian python, central Asian cobra (Groombridge 1988).
District Kasur is located between two rivers of the Punjab province, namely river Ravi and Sutlej. This district is bounded by India from east, Okara from south, Sheikhupura from north-west and Lahore covers its north side. District Kasur is administratively divided in to four Tehsils i.e. Kasur, Chunian, Pattoki and KotRadhaKishan. The district lies 150 to 200 m above sea level and experiences extreme hot weather during summer (April -September) to severe cold in winter (November to February). The difference between day and night temperatures is considerable. Average annual rainfall is 500 mm. Water logging and salinity has affected large area of the district making underground water brackish (Anwar 2012).
Reptiles and amphibians have historically taken less concern as components of many ecosystems. Many ecosystems support high densities of herpetofaunaas compared to endothermic vertebrates because they make efficient use of energy (Pough 1980).Moreover, high densities of reptiles and amphibians presentin many ecosystems provide major role for the trophic transfer of energy and matter except one study that shows high amphibian densities affect ecosystem processes (Wyman 1998). Moreover, the high rate of herpetofauna decline increase the interest in scientific communities for documenting the abundance and status of amphibians on a global scale (Collins and Storfer 2003).
Despite the high densities of herpetiles present in many ecosystems, it is difficult to sample them quantitatively because many snakes and several species of amphibians and lizards live in burrows making their capture difficult (Conant and Collins 1998). Furthermore, the cryptic nature of herpetiles, hibernation in winter, climatic factors affects the activity and the presence or abundance of amphibians and reptiles species (Zug et al 2001).As a result, many methods have been developed to sample herpetofauna such as drift fences with pitfall and funnel traps are a good way to maximize the number of individuals and number of herpetofauna species captured (Gibbons and Semlitsch, 1982; Enge 2001). On the other hand, drift fence surveys can be time-intensive and inappropriate applications can result in low capture rates of some species or high mortality of captured animals. Moreover, documenting the presence of all species occurring in a given area is difficult, if not impossible, and can be particularly time-intensive in systems with many rare species (Dodd 1991).
Herpetological studies carried out in Pakistan are outdated and are mainly limited to Sind and Baluchistan provinces (Minton 1966; Mertens 1969). There is paucity of data on herpetiles of Punjab, densely populated province of the country. There is dire need to explore herpetofauna of the province in general and the district kasur is specific due to geographic location and climatic condition. Present study was therefore planned to explore herpetofauna diversity and distribution patterns of various amphibians and reptiles inhabiting district Kasur.