For a small island of about 65,000 sq.km. Sri Lanka has an extensive terrestrial mammalian fauna. There are 90 indigenous species, of which 14 species are endemic to Sri Lanka (Table 1). Another 12 species have been introduced.
The mammals are extensively distributed in the country according to the available information. The wide climatic, vegetation, altitudinal and geographic history of the island have all contributed to a very interesting distribution of the mammalian fauna. The overall influence of these factors on the mammalian fauna has been to create:
- high endemism and restricted species in the hill country-wet zone (D),
- a fauna more akin to the Indian sub continent in the low country dry zone (Al, B and C), and
- a high degree of variation resulting in numerous sub species.
Over the years various methods have been applied to indicate the distribution of the fauna in the country. In the case of mammals it has been done with the use of the climatic regions and most recently in line with the major vegetation distribution patterns as shown by Muller-Dombois (1968). Phillips (1935, 80-81, 84) considered the mammalian distribution on the lines of the major climatic zones while, Eisenberg and Mckay (1970) has adopted the 'pattern of vegetation distribution' described by Muller-Dombois (1968) as they observed that "mammalian faunal diversity parallels floral diversity".
The country, according to Eisenberg and Mckay is divided into 4 major zones, A, B, C, D and 5 minor zones. Zone A and D are divided into the following minor zones Al, A2 and Dl, D2, D3 respectively. Figure 1 indicates these zones. The distribution according to the bioclimatic zones published in Wijesinghe et al. 1993, (Figure 2) was adapted by Weerakoon et al. In IUCN Sri Lanka 2000.
The 14 endemic species have an interesting distribution. Eight are confined entirely to the wet zone, especially to the zones of D2 and D3. The endemic genus is also confined to these zones (Table 2). One mice is confined to the dry zone, while the two pri mates are found widely distributed with numerous sub species in each zone.
The highest diversity of species is seen in zone Dl (Table 3). The highest number of species confined to a given zone is in D3 in which there are 3 species. Dl has one species confined to it. There are no mammals confined to any other zone. Of the total number, 75 species are found in zones Dl, D2 and D3; 20 of them are confined to this area (D) (Table 2), 68 species are found in zones A, B and C of which 12 are confined to this area.
In the non endemic species, the most prominent feature is the closeness shown to the Indian sub continent. Many species found in India are represented in Sri Lanka by the same species eg. Pangolin (Manis crassicaudata), Palm squirrel (Funambulus palmarum), Porcupine (Hystrix indica), Indian house mouse (Mus musculus) etc. while some are represented by local sub species eg. Grey langur (Semenopithecus priam theristes), Gerbil (Tatera indica ceylonica), Mole rat (Bandicota bengalensis gracilis), the Black naped hare (Lepus nigricollis singhala), Ring-tailed civet (Viverricula indica mayori), Spotted deer
(Axis axis ceylonensis) etc.
The closeness in the fauna is further substantiated by the presence of many sub species eg. Grey slender loris (Loris lydekkerianus), Bush rat (Golunda ellioti), Brown mongoose (Herpestes brachyurus) etc. Some species are represented in the world by two sub species, one in Sri Lanka and the other in Southern India - these are the Small flying squirrel (Petinomys fuscocapillus), and the Dusky striped jungle squirrel (Funambulus sublineatus).
Many more examples that show this sub continental relationship are available among the numerous bats and other species too.
In this short introduction one cannot forget to mention the fossil mammals of the island. During the Pleistocene period Sri Lanka has had a very rich mammalian fauna related to the Indian forms - among these were porcupines (Hystrix species), the red dog (Cuon javanicus), a tiger (Panthera led), different genera of elephants (Hypselephas, Palaeoloxodon), two species of rhinocerous (Rhinocerous sp.), a pig (Sus sp.), a hippopotamus (Hexaprotodon sp.), another deer (Muva sp), a gaur (Bibos gaurus) and a further small bovine ( Gona sp.); ( Hill 1980).