Mar 19, 2018 Last Updated 7:10 AM, Mar 17, 2018

Bird’s nest boom

Bird’s nest boom
Published: Apr 18, 2014

Craig Thorburn

Some nest houses are attractive, others are ugly, but all affect humans and birds alike Nick Long

Indonesia is a major supplier of exotic ingredients for Chinese connoisseurs, the best known being sea cucumber, shark fin and edible bird’s nest. Edible bird’s nest, made from the hardened saliva of cave-dwelling swiftlets, is one of the most expensive animal products consumed by humans, sometimes referred to as ‘the caviar of the East’.

Swiftlets - a type of small swift - are native to the Indo-Pacific region, reaching their greatest diversity in Southeast Asia. All swiftlet species use saliva cement secreted from glands under their tongue as binding material to build their nests. White-nest swiftlets of the genus Aerodramus construct their nests entirely of saliva, and it is these nests that are the most highly prized. Indonesia is home to an estimated 80 per cent of the global population of wild edible-nest swiftlets.

The international trade in bird’s nest dates back to at least the 16th century, possibly much earlier.
Demand has soared since the 1980s, generated by the burgeoning middle and wealthy classes in China. While demand was met previously by harvesting from cave nesting sites, the rising market has led to a new practice of raising the birds in purpose-built ‘nesting houses’, often multi-story windowless buildings with small openings through which the swiftlets enter to make their nests. These nesting houses, often built in urban areas, are controversial because of the noise they generate and their potential to spread disease.

The ‘caviar of the East’

Bird’s nest soup is not especially appetising, requiring the addition of chicken broth or sugar to give it at least a little appeal. As with many other Chinese delicacies, however, it is not the flavour that generates consumer demand, but rather its purported health benefits. The elixir is reputed to possess medicinal properties that nourish and vitalise the organ systems of the body, help to increase energy and metabolism, dissolve phlegm, improve the voice, relieve gastric problems, aid kidney function, enhance complexion, alleviate asthma, suppress cough, cure tuberculosis, strengthen the immune system and improve concentration.

Whether these health benefits are real or imagined, edible bird’s nest is a very expensive commodity. A single bowl of soup sells for as much as A$30 and a kilogram of well-formed white nests fetches between A$2000 and A$3000. Prices surged upward in the mid-1980s, due to declining nest supplies from traditional sources and the rising affluence of an emerging consumer society in China. The international trade in bird’s nest is estimated to exceed 210 tons per annum, worth upwards of A$1.6 billion. Around three quarters of nests traded come from Indonesia.

Harvesting the nests

Harvesting swiftlet nests from traditional nesting sites is a dangerous occupation. Collectors scale flimsy bamboo scaffolding to heights in excess of 60 metres to scrape the nests from the rock face using simple tools, while their partners wait below to collect the nests as they fall. In some locations, such as the famous Niah and Gomantong Caves in Borneo, intricate property rights systems, enforced by government statutes, regulate the harvest of nests. In East Java, the location of nest-bearing caves is a closely guarded secret.

Despite efforts to manage the harvest, over-exploitation has occurred in many locations, leading ecologists to worry that the trade will cause the extinction of some swiftlet populations. A few such cases have been documented, such as in the Andaman and Nicobar islands in the Bay of Bengal, where endemic swiftlet colonies are either extinct or critically endangered. Commenting on the decline of swiftlet populations in the Niah caves in Sarawak, an environmental anthropologist noted that as recently as the 1990s people visiting the caves would cover themselves with a plastic bag to prevent bird droppings from soiling their hair and clothes. The plastic bags would be white with droppings when they left the cave. The birds’ noise prevented people from talking to each other even if they were only a few metres apart. Today, however, the caves appear empty and quiet.

In 1994, concern over the consequences of over-harvesting led Italy to propose adding edible-nest swiftlets to Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora. An Appendix II listing does not prevent international trade, but does require its regulation and verification that the trade is not detrimental to wild populations. The proposal was withdrawn in the face of opposition from Indonesia and other Southeast Asian nations, and a technical workshop was organised instead.

House farming

By that time, a new form of production was making its appearance. The business of raising swiftlets in purpose-built buildings that mimic cave conditions is booming across Southeast Asia, transforming the skyline of towns and cities across the region. In Indonesia, towns such as Kisaran in North Sumatra, Kumai in Central Kalimantan and Sungai Liat in Banka Belitung have become known as ‘swiftlet cities’, with whole neighbourhoods dominated by blocky windowless three and four-storey ‘swiftlet houses’. The din of amplified birdcalls broadcast from the entrances of these buildings can be deafening.

The practice of rearing swiftlets in buildings is thought to have begun in the village of Sedayu near Malang, East Java, in the 1980s. Sedayu is located near limestone cliffs that are dotted with caves. Given the swiftlets’ propensity to nest in rock shelters or caves, it is not surprising that some birds build nests in man-made structures such as culverts, go-downs or even houses. When this occurred, it was considered good fortune, or a blessing, and little was done to improve the conditions of the buildings to attract or suit the needs of the birds.

thorburn 2Tiny birds' nests such as this one are a valuable commodity  Glenn Hurowitz

Some time later, entrepreneurs in Java began to alter buildings and even construct special structures to induce swiftlets to nest. Swiftlets have a high degree of nest site fidelity; breeding pairs return to the same site to build new nests, and chicks often return to the cave where they were fledged to make their own nests. At some point, growers discovered that the more common Glossy or Cave Swiftlets made good ‘foster parents’, and would hatch and rear chicks from eggs of house-farmed swiftlets placed in their nests. This hastened the establishment of new self-sustaining colonies of white-nest swiftlets.

The house-farming business really boomed in the 1990s and 2000s and spread rapidly from Java to Sumatra and Kalimantan, as well as to Malaysia, southern Thailand and Vietnam. A lively trade in associated products and services developed. Farmers used amplified broadcasts of recorded swiftlet calls to attract birds to their buildings. The internet was soon crowded with sites advertising CDs of birdcalls; custom sound systems; building location, design and refitting services; and an array of scents, bio-agents and appliances designed to induce the birds to choose your building as their nesting place. A trade in white-nest swiftlet eggs also developed at this time, giving rise to concern among ecologists that the Javan subspecies could replace native populations in other regions.

Numerous factors contributed to the industry’s rapid growth in Indonesia. Plunging exchange rates made export commodities much more lucrative. The economic collapse of 1997-98 left thousands of newly-constructed shops and residential estates vacant; many of these were converted to swiftlet houses with only minor modifications. When President Suharto stepped down, many monopolies held by family members – including trade in swiftlet nests – were terminated, thereby rendering the enterprises immediately more profitable for producers.

But ecological factors were also at work. Practitioners on both sides of the Straits of Malacca claim that flocks of birds began appearing after the catastrophic fires of 1997-98 that consumed over eight million hectares of forest in Kalimantan and Sumatra, suggesting habitat destruction was driving the birds out in search of new homes. But whether or not this is the best explanation for the migration, it is important to recognise the swiftlets’ own role in driving the expansion. House-farmed swiftlets have lower nest site fidelity compared to their wild progenitors, allowing populations to disperse more quickly and colonise new areas.

Regulating the nest trade

To date, the house-nest industry has been fairly unregulated. Some towns – more in Malaysia than in Indonesia – have instituted noise and aesthetic regulations. In 2010, the Malaysian Ministry of Agriculture issued national guidelines on swiftlet farming known as 1GP, stipulating a minimum distance of swiftlet houses from residential premises, and basic standards for sanitation and ventilation, much like national regulations on poultry farming. Indonesia, to date, has no such regulations.

The biggest regulatory shock to the industry has come from China, the ultimate destination of most nests. Perhaps prompted by health concerns related to the consumption of tainted nests, in August 2011 China banned the import of swiftlet nests from Malaysia and Indonesia. Prices for raw nests plummeted by as much as 70 per cent, causing huge losses for many new investors. In the ensuing negotiations, the Chinese government has insisted that exporting countries put in place enforceable standards on the nitrate content of nests, establish registered quarantine facilities routinely inspected by Chinese government agents, and institute sophisticated tracking systems that allow Chinese inspectors and consumers to know the provenance and processing history of each individual nest. Both the Indonesian and Malaysian governments have signed Memoranda of Understanding with the Chinese aimed at restoring the lucrative trade. To date, only a handful of Malaysian firms have succeeded in passing the certification process to begin legally exporting to China. No Indonesian companies have yet been successful.

Meanwhile, producers are scrambling to develop new products and markets to offset the downturn in exports to China. Various ready-to-drink health tonics are appearing in supermarkets across the region, and the benefits of swiftlet nests are increasingly being promoted to domestic consumers. As a result, the ‘caviar of the East’, once an exclusive delicacy enjoyed only by royalty and the very wealthy, is becoming a mass-produced tonic of Asia’s growing middle class.

Domestication and speciation

But it is not just the industry and the market that are transforming. The growth of the house farming industry may also be leading to the emergence of an entirely new species of swiftlet.

Swiftlets hatched in buildings, it seems, will build their own nests in buildings. There are no confirmed instances of domestic house-farmed swiftlets establishing colonies in caves – even in areas where there are an abundance of natural caves where house-farms have been established. Contrary to the notion that wild populations are fleeing habitat destruction and moving into nest-houses, it appears that we are witnessing the expansion of a new sub-type: the house-farmed swiftlet. In areas where the practice of house farming has only recently been established, researchers are finding that the occupants of house farms are phenotypically and genetically similar to house-farmed birds from Java, Sumatra or peninsular Malaysia, as opposed to native populations living in nearby caves or islands. It is still unclear whether cross-breeding is taking place between wild and house-farmed populations. But some biologists are proposing that the house-farmed swiftlets represent a new species based on their behaviour of nesting only in buildings, the high degree of morphological similarity between them, and the fact that house-farmed and native swiftlet populations rarely mix, even in common activity spaces.

In other words, we are witnessing the latest episode of domestication. The relationship between house-farmed swiftlets and humans is somewhat different than our relationship with the family dog or farm animals, as the swiftlets still range freely and seek their own food. But as with other forms of domestication, human partners have increasingly managed the target species to acquire particular use values, increased security and predictability of access. The domesticate, in turn, gains increased reproductive fitness and range expansion. As with so many other examples from the history of domestication, the question remains, ‘Who is domesticating whom?’ Ever since pioneering populations of white-nest swiftlets first trained humans to construct excellent caves and keep them free of predators, their population and range has expanded dramatically. Whereas the desirability and high price of the nests once threatened the reproductive success of individual breeding pairs and endangered some colonies, this new co-evolutionary partnership is producing benefits for bird and human alike.

Craig Thorburn ( is a Senior Lecturer in the School of Geography and Environmental Science, Monash University.

Inside Indonesia 116: Apr-Jun 2014


#3 +1 Creighton Connolly 2014-05-26 04:17
Actually Ben, it's not only China that is driving global demand for these products, but other countries in the region like Vietnam, Japan, Hong Kong, etc. As well as some parts of the Middle East. In fact, most of these countries have actually made considerable progress in reducing their consumption of such products in recent years. China is one of the most notable examples, where there are now widespread public media campaigns which use celebrities like Yao Ming and Zhang Zi Yi to sway the public away from such habits of 'conspicuous consumption'. Even the government has banned the consumption of these products at official banquets and events to set an example for the rest of the populace.
#2 -2 Creighton Connolly 2014-05-26 04:13
Actually Ben, it's not only Chinese demand for these products, but also other southeast countries like (especially) Vietnam, Japan, Hong Kong, Taiwan, etc. However, most of these countries - including China - are actually starting to create awareness about the detrimental effects of consuming these products. For instance, in China there is now a widespread campaign using celebrities like Yao Ming and Zhang Zi Yi to sway the public away from such trends of 'conspicuous consumption'. Even the government has banned dishes like bird's nest from official banquets to set an example for the rest of the population.
#1 +4 Ben Miler 2014-04-21 04:49
Interesting. The only disagreement I have is with the author's use of the word "connoisseur" in the first sentence - let's be politically incorrect, and state what's true: the Chinese demand for such products as shark fin (manta ray gills, tiger bones, and more, much more) will drive these animals to extinction. They're not "connoisseurs" any more than is a pig in a pen - they're the rapists of the Earth.

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