In the animal kingdom, the group that is considered as "highly" developed are the mammals. There are many aspects of their structure and activities that set them apart from other organisms. One of these mam­mals is man.

The mammals form a distinct group of ani­mals identified today by the possession of hair. Thus the Duck-billed platypus from Australia is considered as a mammal even though its internal structure and egg lay­ing show many similarities to reptiles and a bill like a bird.

Mammals are the most fully adapted for land. Some have adapted to water and there the largest animal - the Sperm whale, is a mammal that breathes air.

The mammalian organization has enabled it to live in very difficult conditions. With a waterproof body it has been able to ex­ploit the harsh desert eg. Camel. The abil­ity to maintain body temperature enabled them to stay either in very cold situations or very hot conditions. With the ability to feed throughout the day they have been able to expand and increase in numbers,thus enabling them to establish themselves in many terrains very quickly. With re­markable mix of habits mammalian life styles are very interesting to study.

The mammals of today belong to three broad groups. The first group are those that are considered as "living fossil" forms. Among them are the Monotremes- found in the Australasian region. The Spiny ant-eaters of Australia and New Guinea and the Duck-billed platypus of Australia rep­resent this group. They posses many fea­tures of reptiles, but due to the presence of hair and mammary glands along with some other structural features they are con­sidered mammalian.

The second group are the pouched mam­mals, represented by about 250 species of which most (172) are found in Australasia. The balance is seen in North and South America and Madagascar. As the group is commonly called the "pouch bearers" they carry their infants in a pouch. The sight of infants jumping out and in of the pouch have always made these animals very in­teresting.

The third group are the advance members referred to as the "placentals". Young are attached to the mother via a placenta which is internal in the womb. The new born in­fant may be active like that of a cow or horse or totally dependent on the mother like that of human species. The unique "mother-child" attachment and parental care seen among mammals is highly de­veloped. In terms of evolution it is consid­ered today that placental mammals are the most evolved group.

Sri Lanka is blessed with 102 terrestrial mammals. This book is to provide an ini­tial introduction to the identification of the most common types. In this quest no at­tempt has been made to provide detail eco­logical and biological information. The checklist at the end gives all species iden­tified for Sri Lanka.

MAMMALS OF SRI LANKA: AN INTRODUCTION

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.

DISTRIBUTION
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.

ENDEMICS
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.

DIVERSITY
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.

NON-ENDEMICS
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).

List of Sinhala generic names of the terrestrial mammals in Sri Lanka

  Download Checklist of the terrestrial mammals in Sri Lanka