An island in the Indian ocean, Sri Lanka is located in between 5°55' - 9°50'N and 79°42' - 81°53'E, southward to the Indian main sub continent.
Separated by the Indian subcontinent by shallow sea, it harbors all the tropical eco system types, except deserts and volcanic mountains. Sri Lanka belongs to the oriental region. The island has total land area of 65525 km2 together with the internal waters of 1570 km2. Being the higher elevations at southern centre of the island, it gradually sloping down to foot hills and then into low lying coastal region.The Highest peak is the Piduruthalagala which is 2524 m above mean sea level. There are four mountain regions in this central massif namely Piduruthalagala, Samanala, Namunukula and Dumbara (knuckles). Slopes are steeper in eastern and southern part of this massif. Apart from the central massif there are another two mountainous regions, known as Rakwana and Uva. Coastal region is wider at North Western and it is narrower at South Western part of the island.
Sri Lanka has two distinct rainy seasons which are known as South Western monsoonal rains (from March to May) and North Eastern monsoonal rains (from October to January), according to the wind direction. Both these winds are condensated by up lifting it by central highlands, giving rains to the country. Latter wind is having less water than the former and its time period can be shrinking. Hence, Western slopes and low lands have more rainfall than other parts, naming it as ‘wet zone’. This zone bares higher amount of bio diversity. South Eastern and North Western parts of the island get least rainfall. Apart from these monsoonal rains, there are two other inter-monsoonal rainy seasons, which add fewer rains. 103 major river basins drain the runoff from central hills to the sea.
Since Sri Lanka is located near the equator, seasonal temperature variation is minimum. Maximum temperature recorded in the months of April, May and June, while minimum is in December, January and February. Central massif is having cold temperatures due to its elevation. Average temperature at lowlands is around 27 oc, while it is 16 oc at Nuwara-Eliya.
According to afro mentioned variations, there are many types of forests in Sri Lanka. Montain forests, Sub-montain forests, Lowland wet zone forests, Dry monsoon forests, Riverine dry forests and Mangrove forests. There are some minor habitat types such as coastal sand dunes, grass land, scrub lands, plantations, parks and home gardens as well.
Apart from the geoclimatic zonation, many of the butterflies in Sri Lanka are found with a wide distribution whereas the microhabitat features are favorable. Some species prefer wet zone while there are a number of species that favor the coastal region and some prefer the mountain region. Yet we can encounter certain species only at extreme climates; there are butterflies restricted to extreme dry areas in the far north and the north western coastal belt, in distribution.