CHAPTER VII
FAUNA OF THE ANDAMANS AND NICOBARS
Previous to entering into any details of the fauna of the Andamans and Nicobars, a glance at the depths of the surrounding ocean is interesting, and to a great extent explanatory of the peculiarities occurring in both groups: it is well known that the soundings of the adjacent seas clearly indicate the extent of time during which masses of land have been isolated, and the facts of this case seem to fully explain the variation and numerous peculiarities of the local fauna.
Preparis Island is situated at the tail of a 100-fathom (to be more particular, 50-fathom) bank projecting from the Arakan Yoma Peninsula. It is continental in its fauna, and possesses monkeys and squirrels.
Between it and the Cocos Islands is a depth of 150 fathoms.
The Andaman group, from Cocos to Little Andaman (except the South Sentinel, which is isolated), all stand on a 100-fathom bank (actually 50 fathoms).
All these are connected by a 200-fathom line with the Arakan Yoma Peninsula.
Narkondam and Barren Island both rise from a sea approaching 1000 fathoms in depth.
The Andamans and Nicobars are separated by a channel with depths of 600 fathoms.
Soundings about the Nicobars are at present very incomplete, but the Archipelago seems capable of division into two groups, each standing on a 100-fathom bank.
The northern of these consists of the compactly-situated central islands, and possibly Kar Nicobar, and is separated from the southern (Great and Little Nicobar and the adjacent islets, all perhaps surrounded by a 50-fathom line) by a channel with approximate depths of 200 fathoms.
The Nicobars stand at the termination of a 1000-fathom bank, projecting from the Arakan Yoma Peninsula, and from thence also curving east and south towards Sumatra, thus enclosing a long tongue of deep sea, over 1000 fathoms deep, that is connected with the Indian Ocean by the channel separating them from Sumatra.
This deep sea that surrounds the islands everywhere but on the north, shows that, so far as need be taken into account for present purposes, they have never been connected with the Malay Peninsula or Sumatra—a condition that is further shown by the almost total absence of any members of the Malayan fauna—although they may at one time have been a prolongation of the Arakan Hills.
"It cannot, however, be asserted that this latter theory of connection derives, primâ facie, much support from a consideration of their fauna; and if they ever were in uninterrupted communication with the Arakan Hills it must apparently have been at an immensely distant period, for not only are all the most characteristic species of the Arakan Hills, as we now find them, absent from the islands, but the latter exhibit a great number of distinct and peculiar forms, constituting, where the ornis is concerned, considerably more than one-third the number known."—Hume, Stray Feathers, vol. ii.
From the above details, it is to be inferred that not only have the Nicobars—if ever in connection with the mainland—been longest separated, but that they have also been disconnected among themselves for a great extent of time. At a later period the Andamans were cut off from the continent, and the process by which they have been broken up into islands is—except in the cases of Narkondam and Barren Island—comparatively recent. This theory is fully borne out by the greatly localised nature of the fauna, nearly every island possessing its own peculiar species of terrestrial mammals.
Mammals.
The mammalian fauna of the Andamans and Nicobars is now known to consist of 35 positively identified species, 1 sub-species, and 4 others whose status is still doubtful.
Of this total of 40 animals, 19 are found in the former (if we leave out a dugong, which, though at present reported from the Andamans, will certainly be found to occur in the Nicobars), 22 in the latter. Only two species are common to both groups, and both these are bats—Pteropus nicobaricus, a wide-flying species found also in the Malay Peninsula and Java, and P. vampyrus—of which further knowledge will doubtless show that each group possesses its own variety.
To the Andamans 12 species are peculiar, the others being Mus musculus; Felis chaus, whose identification is doubtful; 4 bats; and a monkey, Macacus coininus, in all probability introduced.
The Nicobars possess 14 peculiar species and 1 sub-species, and the remaining members are Mus alexandrinus, and 6 bats.
Not only is the peculiarity marked among the terrestrial, but among the winged animals, which form so large a part of the fauna; also, of the 7 bats occurring in the Andamans, 3 are endemic, while the same is the case with 5 of the 11 in the Nicobars.
Thus it is to be noted that in the Andamans all the 11 terrestrial mammals—except M. musculus, M. coininus (introduced?) and the doubtful F. chaus—are peculiar, and also 3 out of 7 bats; while in the Nicobars, only 1 species—M. alexandrinus—of 10 terrestrial is other than endemic, and of the 11 bats 5 (nearly half) are peculiar. Remarkable as is the state of things with regard to the terrestrial, it is equally notable where the flying mammals are concerned.
The most noteworthy features of the fauna are the preponderance of bats (16 species) and rats (13 species)—which together constitute nearly three-fourths of the total number of mammals known to occur in the islands—and the absence of practically all representatives of the ungulates, squirrels, carnivores, and flying lemurs, which are characteristic of the surrounding regions and abound on other islands at equal distance from the mainland. From the Malayan islands where these occur they differ in that "they are surrounded by water of relatively great depth, while the others lie within the 50-fathom line. This paucity of mammalian life cannot be regarded as due to an unfavourable environment, since all the natural conditions on both Andamans and Nicobars are perfectly suited to the support of a rich and varied fauna"; yet so great is it that it appears safe to assume that these, "contrary to the case with the shallow-water islands, were isolated at a time when the mammals now characteristic of the mainland did not exist there." In fact, we are almost driven to conclude that they never were at any time a portion of the continent, but were formerly only far nearer to it, far larger and far more compactly situated—a hypothesis that is further supported by an investigation of the birds appertaining to them.
"As yet no species have been discovered whose origin may be referred to the remote period of a land connection: such mammals as are now known are evidently of very recent origin, as in scarcely an instance has their differentiation progressed further than in the case of members of the same genera found on islands lying in shallow water. The question at once arises, therefore, as to the means by which they have arrived where they now are. Flights from the mainland would readily account for the distribution of the bats; but the presence of the other mammals seems impossible to explain otherwise than through the agency of man. With the single exception of Tupai nicobarica,[219] all are types well known to be closely associated with man throughout the Malayan region. Moreover, the period of time necessary to the development of the peculiarities of the native Andamanese would undoubtedly be ample to allow the formation of any of the species known from either group of islands, since in a biologic sense it has been vastly longer to the smaller, more rapidly breeding, animals than to man. The introduction, intentional or otherwise, of a pig, a monkey, a palm-civet, two or three species of rats, a shrew, and perhaps also a tree-shrew, at about the time when the various islands were peopled by their present human inhabitants, would amply account for the existence of the present mammal fauna with its striking peculiarities."
The following tabular summary shows the distribution of the fauna among the islands. (The letter A indicates material obtained by Dr Abbott, the letter R a previous record; an asterisk denotes occurrence beyond the Andamans and Nicobars; doubtful species have a note of interrogation placed against them; and those in italics have been described as new from the collections made during the cruise of the Terrapin):—
Synopsis of the Mammalian Fauna of the Andaman and Nicobar Islands.[220]
| Name. | Andaman Islands. | Nicobar Islands. | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| South Andaman. | Rutland Island. | Little Andaman. | Henry Lawrence Island. | Little Jolly Boy. | Barren Island. | No island specified. | Kar Nicobar. | Tilanchong Island. | Trinkat Island. | Kamorta Island. | Nankauri Island. | Kachal Island. | Little Nicobar. | Great Nicobar. | No island specified. | ||
| *Dugong dugon | R | ||||||||||||||||
| Sus andamanensis | R | RA | |||||||||||||||
| Sus nicobaricus | A | R | |||||||||||||||
| *Mus musculus | R | ||||||||||||||||
| Mus palmarum | R | ||||||||||||||||
| Mus bowersi(?) | R | ||||||||||||||||
| Mus stoicus | A | ||||||||||||||||
| Mus taciturnus | A | ||||||||||||||||
| Mus flebilis | A | ||||||||||||||||
| Mus andamanensis | RA | ||||||||||||||||
| Mus pulliventer | A | ||||||||||||||||
| Mus atratus | A | ||||||||||||||||
| Mus burrus | A | ||||||||||||||||
| Mus burrulus | A | ||||||||||||||||
| Mus burrescens | A | ||||||||||||||||
| *Mus alexandrinus | A | ||||||||||||||||
| Paradoxurus tytleri | RA | ||||||||||||||||
| *Felis chaus(?) | R | ||||||||||||||||
| Tupaia nicobarica nicobarica | RA | ||||||||||||||||
| Tupaia nicobarica surda | A | ||||||||||||||||
| Crocidura nicobarica | A | ||||||||||||||||
| Crocidura andamanensis | A | ||||||||||||||||
| *Scotophelus temminchii | R | ||||||||||||||||
| *Tylonycteris pachypus | R | ||||||||||||||||
| *Pipistrellus tichelli | R | ||||||||||||||||
| *Pipistrellus tenuis(?) | R | ||||||||||||||||
| Pipistrellus camortæ | A | ||||||||||||||||
| *Miniopterus pusillus | R | ||||||||||||||||
| Rhinolophus andamanensis | R | ||||||||||||||||
| Hipposideros nicobaricus | R | ||||||||||||||||
| Hipposideros nicobarulæ | A | R | |||||||||||||||
| *Hipposideros murinus(?) | R | ||||||||||||||||
| *Pteropus nicobarus | R | R | R | A | A | R | |||||||||||
| Pteropus faunulus | A | ||||||||||||||||
| *Pteropus rampyrus | R | R | |||||||||||||||
| Cynopterus brachyotis | R | ||||||||||||||||
| Cynopterus brachysoma | R | ||||||||||||||||
| Cynopterus scherzeri | RA | ||||||||||||||||
| *Macacus coininus | R | ||||||||||||||||
| Macacus umbrosus | A | A | A | R | |||||||||||||
Birds.
The birds of the Andamans and Nicobars have always been better known than the mammals, particularly since Mr A. O. Hume, with a number of collectors, made a cruise round the islands in a steamer in 1873, which resulted in the discovery of many new species, and a careful analysis of the avifauna.
In spite of what is to be expected from their position, the islands derive the bulk of their species from the distant Indian region, while the Indo-Burmese and Indo-Malayan regions are represented to a far less degree.
One of the most striking features is the extreme paucity of rasorial birds—peafowl, junglefowl, pheasants, partridges, or any of the natural genera into which these divide, and which are all well represented in the Arakan Hills. The next point is the highly specialised character of the ornis, for, excluding waders and swimmers, more than a third of the species are peculiar to the islands; while still more remarkable is the extent to which it is localised in the several groups between which is nowhere a break of more than 80 miles. Even more noteworthy are the details: for instance, the Andaman Hypothymis, which, as a rule, is a very distinct form, is replaced in the Nicobars by one which, although not precisely identical with the Indian form, is far more closely allied to this than the Andaman Tytleri. Each group has its distinct harrier eagle, red-cheeked paroquet, oriole, sunbird, and bulbul. Two woodpeckers are peculiar to the Andamans, but neither extends to the Cocos or Nicobars. The latter group possesses three distinct but closely allied species of Astur, each confined to separate islands.
So far as the species not peculiar to the islands are concerned, the influence of the Indian sub-region has vastly predominated; and if we look to the genera the preponderance is still more marked, and thus it seems difficult to avoid the conclusion that the ornis has altogether a very far stronger affinity with that of the Indian region than with those of either the Indo-Burmese or the Indo-Malayan. Yet this involves great difficulties, for if we take Port Blair as a centre we shall find that its average distance in all directions north and east from Tenasserim (where the Indo-Malayan fauna predominates), and north of this from the Indo-Burmese sub-region, is less than half its distance from the nearest point of the Indian sub-region.
That so many of the characteristic birds of the Arakan Hills, especially the Rasores, should be entirely wanting, we may partly account for by the supposition that the mountains and the chain of islands never were continuous, and that the same agency that raised the Arakan Hills only raised portions of their continuation above the sea-level, so that, therefore, the islands have never been connected with Pegu. If, however, the groups first appeared and have ever since remained as detached islands, it is inconceivable how the great bulk of the work of colonisation should have gone on from a region so distant while so little should have been done from others less than half as far away.
Colonisation in no ordinary sense, however, can explain these facts. But the case of Sumatra, which, although only 80 miles distant from Great Nicobar, and itself the first link of a great chain, teems right up to Acheen Head with species unknown to the Nicobars, is perfectly comprehensible in the light of our knowledge of the deep sea existing between it and these latter islands.[221]
If we conclude that the avifauna of the islands of the Bengal Sea is essentially Indian and not Indo-Burmese and Indo-Malayan, we must accept the fact with the qualification that we find it here in a most imperfect and mutilated form, lacking more or less entirely a large proportion of its characteristic genera, many of which are the strongest and most widely distributed, and to which the climate would appear in every way congenial.[222]
List of Birds occurring in the Andamans and Nicobars.[223]
(A. denotes occurrence in the Andamans, N. in the Nicobars.)
The following new additions should now be made to the above to complete the known list of Andaman and Nicobar avifauna:—
| Zosterops sp. | Kar Nicobar. |
| Sturnia sp. | Kachal, Nicobars. |
| Rhinomyias sp. | Great and Little Nicobar. |
| Arachnechthra sp. | Nicobars. |
| Pitta sp. | Great and Little Nicobar. |
| Ninox sp. | Little Nicobar. |
| Spilornis sp. | Great Nicobar. |
| Astur sp. | Kachal, Nicobars. |
| Osmotreron sp. | South Andaman. |
| Excalfactoria sp. | Trinkat, Nicobars. |