The Neglected Ape

Edited by R. Nadler, B. Galdikas, L. Sheeran, and N. Rosen. Plenum Press, New York. 1995. ISBN: 0306-45213-8 £68

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It is not the view of the editors of this book that the orang-utan has been 'neglected' from the standpoint of scientific research. After all, there have been a creditable number of field studies conducted on the orang-utan (e.g. by Galdikas, Horr, MacKinnon, Mitani, Rijksen, Rodman and Schurmann) and several books devoted to its biology (e.g. DeBoer, 1982; Schwartz, 1987; 1988). Rather, it is the comparative neglect of the orang-utan by the international conservation organizations which frustrates Rijksen and some of the other contributors to this interesting volume. Species such as the giant panda, mountain gorilla, African elephant and various of the larger whales have become the focus of campaigns to prevent the extermination of rare species and to conserve their natural habitats. Rijksen comments that 'after more than 20 years following the fate of the orang-utan, I have come to the conclusion that what the red ape most seriously needs is to be neglected by the majority of mankind. After all, most of the contacts with humans during its evolution have meant untimely death'. Since this book was published, large scale (man-made) forest fires have devastated huge areas of the remaining habitat of orang-utans in Borneo and Sumatra, so that its chances of survival seem worse than ever.

There are 5 sections in the book and a total of 27 short papers dealing with conservation, population biology, behaviour, reproduction and captive management. Smits et al. describe a new approach to the rehabilitation and reintroduction of orang-utans to the wild in Indonesia. Confiscated animals are trained to feed on naturally occurring foods and human contacts are discouraged in order to prepare them for eventual release. The animals are screened medically to minimise the risks of introducing human diseases into the wild and they are transferred to forest areas where there are no existing resident orang-utans. By 1994, 38 out of 40 animals released had 'adapted well to the new forest environment'. This study interested me because articles about the 'rehabilitation' of captive orang-utans are often short of objective data on success/failure of the procedures used. The section on population biology contains an interesting account, by Faust, Tilson and Seal, of the status of the orang-utan in the Gunung Leuser National Park in North Sumatra. This huge park provides the best chance for the survival of orange in Sumatra. Two sub-populations occur in the park, totalling approximately 9,200 individuals. These are reasonably secure, provided that land use, involving destruction of forest surrounding the park or on the lower slopes within its boundaries, can be contained. In Borneo, as Rijksen et al. point out, the situation is somewhat different. There were estimated to be somewhere between 10,282-15,546 orange living in 8 separate populations and occupying a total of 22,360 km2 of rainforest. These populations were considered to be in 'serious decline', however, even before the recent fires which have destroyed millions of hectares of habitat.

The section on social and cognitive behaviour contains reviews on the social organization and reproductive strategies of orang-utans (van Hooff), the reproductive behaviour of adolescent females (Galdikas), the effects of male 'take-overs' on social organization (Utami and Setia) and tool use (Russon and Galdikas). The final section, dealing with 'Basic science and captive maintenance' consists of short articles on ovarian physiology (Asa et al.), sexual behaviour (Nadler), social behaviour (Zucker and Thibaut), morphological development (Winkler), genetics (Muir et al.), reproduction (Markham) and captive management (Mallinson and Carroll).

Although many of the individual contributions can be found, in more detailed form, in the published literature, it is useful to have them collected into a single volume. There are a few serious errors in the book. Hiong et al., in calculating doses of drugs for immobilization of free-ranging orang-utans provide a bizarre average of 33.4kg for the body weight of adult males (Table I, page 54), whereas a healthy adult male weighs more than twice this amount. Some of the data on reproduction in females in the wild, such as the implication that females do not reproduce until 12-15 years of age, may not be entirely sound. In reality, the exact ages of wild females are rarely known, in relation to their reproductive histories.

This book is quite expensive and very specialised in its content. Plenum Press has done a reasonable job as regards the quality of the text and its lay-out, but this may be a volume which is destined to be purchased by libraries rather than by individual primatologists with limited budgets.