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Source: Human Ecology: An Interdisciplinary Journal
Publication Date: 01-AUG-04
Author: Gausset, Quentin
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Chronicle of a foreseeable tragedy: birds’ nests management in the Niah caves (Sarawak).
COPYRIGHT 2004 Springer
INTRODUCTION
The exploitation of birds’ nests as food has a long history, dating back to the sixteenth century. Its trade from Borneo to China was already in existence when Dutch merchants began operating in the Malaysian and Indonesian region (Cranbrook, 1984, p. 150; Koon and Cranbrook, 2002, pp. 64-65). The nests are made out of the saliva and feathers of swiftlets. Once processed to remove the feathers, the nests are consumed in soups that are believed by many people (mainly Chinese) to have rejuvenating and cosmetic virtues. In Malaysia there are two main species of birds that produce edible nests: Aerodramus fuciphagus (producing the highly valued white nests) and Aerodramus maximus (producing black nests) (Koon and Cranbrook, 2002, pp. 2-16). They inhabit limestone caves, such as the Niah caves, which are the object of this study. In the Niah cave, the exploitation of black nests began fairly recently, less than 200 years ago (Harrisson and Jamuh, 1956; Koon and Cranbrook, 2002, p. 68; Medway, 1958). It soon became a major center of black nest production, which peaked at 18,500 kg per year in 1931 (i.e., 70% of the total production of black nests in the state of Sarawak; Cranbrook, 1984, p. 155). The fame of the Niah cave owes a lot to this huge production of nests, and also to the archeological discovery of the oldest human remains in South-East Asia (Harrisson, 1958). To protect this unique archeological site, the caves were made into a national heritage site under the authority of the Sarawak Museum, and later into a national park under the authority of the National Parks’ administration. Recently, the swiftlets have become a protected species.
The exploitation of birds’ nests in the Niah cave sustains the livelihoods of hundreds of people, and has been one of backbones of economic development of Niah town. However, for several reasons, the number of swiftlets and nests has sharply declined during the past 15 years (it is estimated to be between 5 and 10% of what it was 70 years ago). It is widely believed that one of the causes of this decline is the overexploitation of the nests. This is very unfortunate, as birds’ nests are a renewable resource which could very well be managed sustainably. Since the Aerodramus maximus has three breeding periods per year (Koon and Cranbrook, 2002, pp. 37-39), it would suffice to practice selective harvesting and refrain from harvesting the nests until the young chicks can fly away, to have a sustainable management of the resource combined with a high yield. Yet, today, nests are generally harvested as soon as they are big enough to be sold, regardless of whether they hold eggs or immature chicks. The aim of this paper is to review the causes of the overexploitation, and to discuss the way in which the present management system relates to the model of the “tragedy of the commons” developed by Hardin (1968).
EVIDENCE OF BIRDS’ NEST DECLINE
It is difficult to know exactly the number of birds living inside the cave, and how this number has evolved over the course of time. Estimates of Birds’ Nest Management in Niah Caves (Sarawak) birds’ nests numbers have been made for the past 70 years, and show a reduction of 90% of the original population. (3) But these estimates are questionable because they are based on different methods, ranging from eyeballing to systematic counting. Even counting birds flying in and out of the cave has been problematic, as it sometimes concentrated only on the main mouths of the caves, which left many birds unaccounted for. Moreover, the counting has been based on the assumption that each bird comes in and out of the cave twice per day, and that the number of swiftlets constitutes 70% of the total population of birds in the Niah cave. Yet, despite the inprecision of the data, everyone in Niah recognizes that there has been a drastic decline. People remember that not so long ago (10-15 years), they would not visit the cave without a plastic bag on their head and shoulders to prevent bird droppings from falling on their hair and clothes. People would be white with droppings when leaving the cave. The noise made by the birds prevented people from talking to each other if they were some dozen meters apart. Tourist guides praised the extraordinary sight of millions of birds and bats flying in and out of the cave. Today, all of this is gone. The caves look empty and are quiet. So despite the fact that the exact number of birds is difficult to establish, everybody agrees that there has been a major decline.
Establishing the causes of bird decline has proved equally problematic. Various hypotheses have been proposed. It has been suggested that the collection of guano in the cave was disturbing the cave ecosystem and reducing the population of insects on which birds feed (Leh and Hall, 1996, pp. 25-26). But the collection of “fossil” guano has been forbidden since 1985, mainly to protect the archaeological potential of the cave, and there has been no increase in the population of birds. It has also been suggested that the use of pesticides has had a negative impact on the bird population (Vardon, in Sim, 1997, p. 91). However, DDT-type pesticides have now been forbidden formany years, and this argument too is losing its relevance. Many local people suspect that the use of insecticides has both reduced the amount of insects on which birds feed, and poisoned the birds who ate those insects. This seems to be confirmed by the finding of insecticide residues in swiftlets from Niah cave (Cranbrook, 1984, p. 160). This argument is often linked to the fact that most of Niah area has been transformed into oil palm plantations in the past decade, which is likely to have had a significant impact on the ecosystem of insects and birds (Koon and Cranbrook, 2002, p. 135). Moreover, many people claim to have witnessed a major drop in the bird population due to the forest fires and haze which hit the region in 1997 (El Nino). Some also blame smoke for the drop in bird numbers in the big mouth of the cave after a house standing there burnt down and the smoke killed thousands of birds. Finally, a recent invasion of green algae is also blamed for spoiling the reproduction grounds of swiftlets (Sim, 1997, p. 91; Leh, 2001, personal communication).
Apart from these “physical” causes of decline, most people agree that humans have also had a negative impact on the population of birds. Some believe that the noise made by people in the cave, the smoke of their cooking fires or petroleum lamps, and the fact that they wave torchlight at the birds at night in order to deter thieves from stealing the nests, disturb the birds, who fly away and look for quieter caves. This seems to be supported by the observation that new caves have indeed been recently colonized by swiftlets (Leh, 2001, personal communication), although there are no good data describing this change and the influence of climate and other physical factors might play a role. Finally, most actors involved recognize that the overexploitation of nests is partly responsible for birds’ decline.
This article will focus on the issue of overexploitation, but it is important to keep in mind that it is not the sole factor responsible for the decline, and that physical aspects do have an impact on the bird population. This can be seen in the fact that the populations of bats and of mossy swiftlets have also fallen dramatically, despite the fact that the reproduction of these species is not disrupted (mossy nests are not harvested). Big clouds of bats used to be seen coming out of the cave at dawn, but this is no longer the case, as the bats are no longer so numerous. The production of guano, which comes not only from edible nest swiftlets but also from mossy swiftlets and bats, has declined so sharply (Leh and Hall, 1996) that the extent of the decline cannot be accounted for only by the decline in edible-nest swiftlets, but implies also a decline in the bat and mossy swiftlet populations. Although mossy swiftlets and some species of bats are occasionally eaten by people staying inside the cave, especially when their access is easy, this can probably not account for a major drop in their populations. The decline in mossy swiftlets and bats therefore requires explanation in terms of physical causes. Moreover, it should be noted that in 1978 (i.e., before the serious overexploitation of nests began), people exploiting the nests were already complaining about…
