Due to a belief in the high medicinal value of bird's nest soup, heavy Chinese demand for swiftlet nests has resulted in a multibillion-dollar industry that may be endangering the bird.

There are three species of commercially important swiftlets in Southeast and South Asia: the edible-nest swiftlet (Collocalia fuciphaga); Germain's swiftlet (C. germani); and the black-nest swiftlet (C. maxima). The biggest supplier of nests is Indonesia, with other exporting countries including Thailand, Vietnam, Singapore, Myanmar, Malaysia, India and Sri Lanka.

Chinese for centuries have eaten the nests of edible-nest swiftlets in soup or in jelly mixed with spices or sweets. It is traditionally believed that the nests contain aphrodisiac properties and, if consumed, may prolong life. Chemically, however, the nests have been shown to be made primarily of proteins (50-60 percent). While there is a water-soluble glyco-protein in the swiftlet nest that can promote cell division in the immune system, it may be lost during the cleaning process prior to eating, meaning the nests may have minimal medicinal properties.

Still, demand has been continuously increasing. From the 1960s to the 1980s, trade of swiftlet nests has increased by more than 30-fold in Southeast Asia. Today, a top-quality swiftlet nest can sell for between $2,500 and $4,000 per kilogram.

Male swiftlets weave thin, gelatinous strands secreted from their salivary glands into half-cup nests that glue high on the inside of cave walls. Harvesting these nests can therefore be a dangerous activity, but their economic importance to the poverty-stricken areas where they are found has made nest-collecting a tradition in many local communities.

Because the nests sell for half the price of their weight in gold, nest collection is also a lucrative avenue for poachers. In many cases during harvesting -- both by so-called traditional methods and by poachers -- eggs and young are tossed down to the cave floor to die. It is estimated that in one cave system in Sabah, Malaysia, alone, over half a million eggs or nestlings perish each year.

Poaching is difficult to control because of the remote location of caves and is suspected to account for a substantial proportion of the swiftlet-nest trade. Because of overexploitation, as well as the loss of foraging habitats, swiftlet populations are coming under increasing pressure. While concrete data on the status of edible-nest swiftlets are lacking, studies suggest that some populations of the species have been severely depleted, with extinction likely in certain areas. And while there is legislation to regulate the harvesting, poaching, selling and importing and exporting of swiftlet nests, enforcement is weak in remote areas and little is known of the full extent of the trade and its effect swiftlet populations.

To address the situation, nest harvesters in Indonesia have started to "farm" swiftlets. The uniform swiftlet (C. vanikorensis) nests in old houses, whereas the more commercially valuable edible-nest swiftlet is more fussy about where it nests. Swiftlet farmers therefore buy old houses with colonies of uniform swiftlets, and use them as foster parents for edible-nest swiftlets. They hope that the fledgling edible-nest swiftlets will return to nest in the houses when they are adults.

It is claimed that one-third of exported swiftlet nests from Indonesia now come from farmed swiftlets, but this claim is difficult to verify. There also is the danger of inter-species hybridization in swiftlet farming having spillover effects on wild populations.

Italy in 1994 proposed the listing of edible-nest swiftlets on Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). Such a move would require regulation of swiftlet trade and verification that it is not detrimental to wild populations. The proposal, however, was rejected due to vigorous opposition from Asian countries.

Working toward the conservation of edible-nest swiftlets, the Association of Southeast Asian Nations has established a task force mandated with ensuring sustainable harvesting of swiftlets within the region.

There is evidence that strict management can help increase the population of edible-nest swiftlets. In south-central Vietnam, strict sustainable nest-harvesting by a state-owned company has resulted in an increase of 3 percent of nest production per annum. The nests are harvested in two phases. The first phase occurs when 10-15 percent of nests have eggs, as early harvesting like this means most pairs can build a new nest. The second phase occurs after 160 days, when almost all the nestlings have fledged. This system minimizes the disruptive effect of harvesting on the swiftlet population.

The company is also implementing criteria such as strict selection of field personnel. By involving police and a network of informants, the company has largely prevented external poaching. However, this apparent success story may be an anomaly in the swiftlet nest-harvesting scenario in Southeast Asia.