DISTRIBUTION OF MAMMALS 177 marsupials, as did some of the bats. The dingo was brought there by the early men who came near the end of the Pleistocene period. The dingo, very much like the earliest known domestic dogs, has no other near relatives in southeastern Asia. The Papuan Subregion lacks a number of the distinctively Australian mammals. Of the archaic Australian fauna only wallabies, tree kangaroos, phalangers or possums, flying phalangers, bandicoots, marsupial cats, marsupial mice, and the spiny anteater are found there — a much less varied assemblage than on the continent. Of these the cuscus phalangers alone extend much beyond New Guinea. Of the bats, many are species characteristic of this subregion, but more frequently they are local forms of widely ranging bats, found in tropical Australia as well as in the islands east and west. The rats are, with a number of exceptions, closely related to Malaysian types, but even the most peculiar are rat-like and belong in the same family. The mammals which extend westward have been discussed under the Australo-Oriental Subregion. Cuscus phalangers reach the Solomon Islands, as do the giant and mosaic-tailed rats. Tubenosed fruit bats {Nyctimene) and spinal-winged bats {Dobsonia) are other Papuan forms that reach these islands. Several genera of bats and rats, found only on the Solomons, are either relicts of ancient types or local developments. Bandicoots and a spotted cuscus are found on the Admiralties ; these with wallabies are the chief land mammals of the Bismarck group. Water rats extend northeast to New Britain ; they are also found on the Aru and Kei Islands to the west. The other mammals of these last islands are much like those of southern New Guinea, but less varied.
New Guinea, the only large land mass of the Papuan Subregion, contains many more native species of mammals than the outlying islands. The bandicoots include four genera, two of them restricted to New Guinea and one chiefly Australian but found in southern and southeastern Papua. Marsupial mice are represented by several primitive forms, marsupial cats by a
178 MAMMALS OF THE PACIFIC WORLD single species. Phalangers or possums are both common and varied, while the characteristic tree kangaroos are found elsewhere only on Great Kei Island and Cape York, Australia. The New Guinea gazelle-faced wallabies (Dorcopsis) are a distinctive group ; the island has also several distinct species of wallabies related closely to those of the continent. The feather-tailed phalanger, the striped phalangers (also on Aru) and several species of ring-tailed phalangers are typical of the Papuan fauna.
Close ties between southeastern New Guinea and northern Australia are shown by the presence on the island of the sand wallaby (Wallahia agilis), one of the short-nosed bandicoots (Jsoodon), and dormouse phalangers. The common flying or gliding possums (Petaurus) belong to distinct species in the two subregions. Spinal-winged and tube-nosed bats, tree kangaroos, cuscuses, and mosaic-tailed rats represent New Guinea types that have reached the continent.
The Pacific islands north and east of the Australian Region, as restricted here, are extremely poor in mammals. Pigs, house rats, and mice have been carried to virtually all these islands from the East Indies by various human migrants, in many cases hundreds or thousands of years ago. Black rats, roof rats, and Norway rats have been taken to the more important islands by the vessels of white traders and explorers. These more aggressive forms often have driven from the villages the Polynesian rat, taken there much earlier by native travelers, and on some islands may have caused its extinction. Bats have been carried by storm, or have wandered, to many of the islands. The Micronesian Islands have one or two species of flying foxes and a sheath-tailed insectivorous bat (Emballonura) in addition to rats and mice. In the Carolines there is also a longtailed fruit bat (Notopteris), a primitive type known elsewhere only from the New Hebrides, New Caledonia, and Fiji. No bats are recorded from the Gilbert group, and only the sheath-tailed
DISTRIBUTION OF MAMMALS 179 bat is reported from the Marshall Islands. Absence of records may indicate either incomplete collecting or actual absence; such small islands offer few of the necessities of life, even for bats.
The Melanesia!! Islands (leaving out the Solomons and the Bismarck Archipelago, which have been discussed with New Guinea) harbor flying foxes, long-tailed fruit bats, and sheathtailed bats. New Caledonia, the largest of these islands, has in addition one of the bent-winged bats and an insectivorous bat (Chalinolohus) related to Australian forms. The New Hebrides and Santa Cruz Islands have Chalinolohus and a leaf-nosed bat (Hipposideros), New Zealand has a very interesting invertebrate and bird fauna, but its land mammals are restricted to two kinds of bats and introduced species of deer, elk, and various others. One of the two bats (Mystacops), placed in a family by itself, is perhaps a relict of the primitive group which gave rise to the freetailed bats of the tropics and warmer zones of both hemispheres. The other is a common bat {Chalinolohus) related to those found in Australia and New Caledonia.
The Polynesian Islands, roughly definable as those east of the International Date Line, are inhabited for the most part only by introduced rats and mice. Samoa and the Tonga Islands, however, mark the eastward limits of the Australo-Oriental bats ; and Hawaii is the home of a species of hoary bat (Lasiurus) derived from an American stock. Samoa, perhaps because its fauna has been better studied, is known to have two species of flying fox bats, a common bat {Myotis) of a genus almost world-wide in distribution, and a sheath-tailed bat (Emballonura). From the Tongas, several hundred miles farther east, only the flying fox is known.
The Juan Fernandez Islands were originally without native land mammals. Their aquatic mammals include sea lions, fur seals, and some true seals. Rats and mice have been introduced by whalers and sealers, and goats were turned loose and in-
180 MAMMALS OF THE PACIFIC WORLD creased enormously. For a while dogs lived on the island but they have disappeared.
The Galapagos Islands, situated more than five hundred miles from the coast of Ecuador and separated from it by water more than a thousand fathoms deep, have probably never been in contact with the continent. Yet they are inhabited by several rats of a tropical American group related to our rice rats {Oryzomys). Although these rats have been isolated from one another on the various islands for a long enough period of time to allow a number of races and species to develop, they have not diverged enough from the mainland forms to be considered a separate genus. A bat (Lasiurus) closely related to the red bats of the Americas and the Hawaiian bat, is also found on the islands. Some species of this genus normally make long migratory flights ; of all the American bats they are the most likely ones to be carried far out of their usual range. The ships of whalers and sealers used to put in at the Galapagos and for many years a penal colony was located there. As a result house rats and mice have invaded the islands. Liberated pigs, cattle, and goats have gone wild, doing much injury to the native vegetation.
The Pacific islands from the Solomons and the Northern Micronesian group to Hawaii, the Galapagos, and Juan Fernandez are all truly oceanic. On a basis of their mammals they cannot be related closely to the faunal regions used here. The Galapagos and Juan Fernandez Islands may be considered Neotropical or South American.
Conservation of Mammals The animals that live on these Pacific islands and others should be allowed to persist almost indefinitely in order to provide interest, information, sport, and even a means of livelihood for the present and future generations, but they may be destroyed in a few years by thoughtless and wasteful hunting, NEED FOR PRESERVATION Island mammals are in a difficult situation for survival, even when no human beings are present. The number of individuals of any species is limited by the area of the island; a limited number can find food or shelter necessary to life. Related or similar species may be present to compete for minimal requirements, a condition which still further limits the number of individuals of the first mammal. If natives are present, the land they cultivate reduces the area available for the animals, and the natives eke out their food supply by hunting and trapping. A few species are actually benefited by the presence of man; several rodents make their homes with him and feed parasitically on the food he grows and stores. The natives are usually neither numerous enough nor well enough supplied with modern guns to effect great changes in the anima^ population, but they may exterminate large, slow-breeding mammals if the wild island population of a species is small enough to be at a critical point. For example, although the only banting now found in Bali are domesticated, wild banting may very well have occurred there formerly. This may also explain why the elephant, which was 181
182 MAMMALS OF THE PACIFIC WORLD in Java during the Pleistocene, is not found there today. Hunters with modern rifles and shotguns can all too easily exterminate most of the game animals in a short time on the smaller islands and can seriously reduce those on the larger islands. Many mammals found on islands are different from those that occur elsewhere; sometimes this difference is only slight, but in other cases it is obvious and important. To a biologist or one interested in nature it is one of the greatest crimes against science to destroy any form of wild life completely. A species is a unique thing — the product of natural forces and circumstances through the ages — and if once exterminated it cannot be replaced. Some of the island mammals are remnants of ancient groups that have survived until the present, thanks to their isolation and protection from competition with more modern mammals by the barriers of sea straits. These living fossils are often less adaptable to changing conditions than more upto-date mammals ; often clearing the jungle for plantations is enough to destroy them. The Luchu and Sumatran rabbits, the long-tailed fruit bats of the Melanesian Islands, the New Zealand bat, the babirusa, anoa, macaque, and black ape of Celebes, a small deer on the Bawean Islands near Java, the tapir of Sumatra and the Malay Peninsula, the two Malaysian rhinoceroses, many of the marsupials, and a number of inconspicuous mammals of other groups are in need of sanctuary. Every effort should be made to protect these rare and scientifically invaluable animals.
COLLECTING AND STUDY OF SPECIMENS Those persons who have free time on their hands and find themselves in areas poorly known zoologically, and those who find mammals they cannot identify from the descriptions in this handbook or mammals out of their known range, can do a great deal for natural science by preserving specimens. Skins with skulls, and complete specimens properly preserved and accom-
CONSERVATION OF MAMMALS 183 panied by notes on the exact locality or origin would add much to our knowledge and would be of the greatest interest to scientists and institutions. A field catalogue with this information and numbers corresponding to the data attached to the specimens would serve to keep this important material for future reference. Collecting can be both interesting and worthwhile, but of course should not be done if a species is so near extinction that this will increase the jeopardy.
In the tropics the heat and humidity cause the hair to "slip" or come off with the epidermis of the skin unless the mammal is skinned shortly after death. Larger mammals should be slit from the breast to the end of the tail ; other cuts are made from the sole of the feet or just above the hoofs to meet the median cut. Horned mammals require an additional cut from the neck to between the horns and then a cut from this line, on each side, to the horns and around them. For best results the ear cartilage must be skinned out and the toe-bones as far as the claw or hoof, and the flesh that is closely attached to the skin should be cut away. Salt should then be thoroughly rubbed into the skin on the flesh side and the skin rolled up overnight. It should then be spread out in the shade to dry. In very wet weather and climates the salt will keep taking up water from the air and the skin will not dry ; in this case, after a second thorough rubbing with salt and leaving over a second night, wash the skin in fresh water and dry under shelter. A fire may help, but scorching the skin must be avoided.
The skull should be carefully disjointed from the neck, the flesh roughly trimmed off and the brain removed through the hole at the rear end (J or amen magnum). The skull should be dried as thoroughly as possible. Smoking, salting, or covering it with pepper may help keep maggots out ; they injure the bone, especially of small skulls. Skins and skulls of the same individual should have identical numbers.
Smaller mammals may be cased, that is, cut from heel to heel across the underside and the skin turned inside out like a glove,
184 MAMMALS OF THE PACIFIC WOELD leaving the feet attached, as most commercial furs are fixed in the United States. Or a cut may be made from the breast to between the hind legs, and the legs cut off the body at the knee, the skin worked off the rump and then off the rest of the body. The tail can usually be pulled out by holding the tail loosely in a V-shaped stick and pulling on the vertebrae. A little crumpled paper, tow or straw put inside the hairy pocket formed by the inside-out skin, to keep the fur surfaces apart and a straw splinter of bamboo pushed to the end of the tail will permit the skin to dry safely in all except the worst weather. Arsenical soap or a mixture of arsenic powder and alum, half and half, will preserve the skin.
Bats and some other small mammals are easily preserved in a formalin solution: one part commercial formalin to ten parts water, or one part to forty parts saturated salt solution. The abdomen should be opened to let the solution penetrate the intestines, which may otherwise spoil.
Skulls can be saved when the skin is spoiled or when a dead carcass is found in the wilds. The teeth and measurements of such skulls are very interesting scientifically if the locality from which they come is known. Various museums will identify such skulls for any curious finder.
A booklet giving the details of collecting and preparing specimens may be obtained from the American Museum of Natural History, New York 24, New York.