Sea-swallow nests are an original Southeast Asian resource and their collection is a traditional occupation. Thanh Chau, Hoi An, Vietnam, is one example of areas inhabited by sea-swallows. Studies of the bird and this occupation, which have been a source of income for the local people, are quite necessary and interesting, and have attracted for a long time the attention of researchers, traders and missionaries at home and abroad. This paper presents a brief outline of the collection of the sea- swallow nests in Thanh Chau as an independent traditional occupation. It was casually formed, has existed and developed for nearly 400 years and is an example of the creative labour of the Hoi An population. In the first place, a brief introduction should be made on the lithe bird and the reasons for its appearance in the cluster of Cham Islets.

Yen Hang (Collocaliafuciphaga germaini Outstalet) is a particular bird of subspecies "Swiftlets," species "Collocalia," family "Apodidae" and order "Apodiformens," with a small stature akin to a sparrow, grey belly and sides, brownish-black body, long pointed wings (115 - 125 mm), a short forked tail, a short fine beak that can open wide, a short legs with sharp claws. It is called "Huyen dieu," "Du ba dieu" or "Hai yen" in Chinese, "Sea-swallow" in English, "Salangane" and "Hirondelle de mer" in French and simply "Chim yen" in Vietnamese. It lives on such insects as ants, termites, flies, mosquitoes, bugs, stink-bugs, spiders, and dragon-flies and hunts at the foot of mountains and hills. Sea-swallows fly in flocks at night and in the daytime, catching insects in the air for 12 - 18 hours running during a flight of hundreds of kilometers. What is particular about the sea-swallow is that it makes its nests with its own saliva and affixes it to high cliffs or in grottoes on islands or peninsulas. It gives birth once a year, to 2 eggs that are incubated and raised by both the father and the mother. Over a year later, the little swallow comes of age, capable of reproduction, building a nest of its own like its parents. An environment fit for the sea-swallow must have these conditions: dry cliffs, airy grottoes, with waves lapping against the rocks, a high humidity of 80 - 90%, few natural enemies, and an abundance of food. The cluster of Cham Islets with such grottoes are Kho, Tai, Ca, and To Vo 15 km from the shore satisfy the above conditions and have for centuries been one of the ideal habitats for the sea- swallows to come in ever larger numbers. The presence of the sea- swallows on the islands has given rise to the occupation of collecting sea-swallow nests in Thanh Chau.

According to written records by researchers, traders and missionaries home and abroad and to local lore (i.e. tales, theories on stone slabs, family annals ... ), apparently the first man to have discovered the sea-swallow in the cluster of Cham Islets (To Vo grotto - Lao Isle) was a fisherman from Thanh Chau came into being as an occupation early in the 17th century. We think that Ho Van Hoa was never the initiator of the occupation nor the son-in-law of the Tran Family, as concluded by a few researchers. To conclude who was, whether Mr. Tran Tien or another, the initiator of the occupation is really a Herculean task that calls for in-depth study. As a matter of fact, the Thanh Chau people have, for generations, managed directly and exploited this resource. Like all other traditional occupations in Vietnam, the collection of sea- swallow nests in Thanh Chau has been subject to the vagaries of history. At the beginning, under the Nguyen Lords' reigns, the Thanh Chau villagers collected sea-swallow nests in a spontaneous manner, and then the feudal state set up "Thanh Chau Brigade," entrusting the local people with the exploitation of the resource and making them pay annual taxes. In the late 19th century, also under the Nguyen Dynasty, the royal court formed the "Thanh Chau Brigade" along military lines, nominating "Ngu Truong" and "Ho Truong," both from Thanh Chau village, to take charge of the management of the collection of s ea- swallow nests in the three provinces of Quang Nam, Binh Dinh, and Khanh Hoa, Mr. Ho Van Hoa was a very first manager of the under- taking (under Gia Long's rule), and his office (as well as all other important functions) was inherited by his descendants for nearly a century. However, the sea-swallow nest collectors were still entitled to the exploitation apart from their payment of taxes to the feudal administration, and they even had the right to sell their surplus products to traders. Under the colonial rules (from the early 20th century to 1974) the Thanh Chau people were deprived of their right to exploit s ea- swallow nests, which was transferred to merchants and company-
contractors. For a term of 3 - 5 years, the contractors enjoyed a monopoly of exploitation and consumption, and the collectors were mere wage-earners for their employers. Since 1975, the revolutionary government has taken up the exploitation and consumption of the resource, and the Hoi A n sea-swallow nest collecting Brigade has come into operation on the basis of the development of the traditions of Thanh Chau village.

Different times see different procedures in exploitation and processing (in equipment, instruments...), but t he traditional experience has been applied from generation to generation. As usual, early in the season, careful preparations are made in terms of workforce (10 - 15 people), facilities (boats, baskets ... ), instruments (bamboo poles, forks, hand-nets, cords and ropes, bags and water-bottles ... ) and food. By mid-April, they set off the Cham Islets to undertake the first harvest of the year. To obtain the nests, the collectors must abide strictly by the procedures that have been summed up from generations of experience. The construction of sea-folding, checking, spraying of water and collection of the nests represent very hard and dangerous work in which laborers must work on hanging cliffs or in deep grottoes. They must be very flexible in coping with various circumstances: gently crawling through the narrow gill between rocks, diving and swimming into the cave, or climbing down a rope from the mountain top to the bottom of the grotto. They must do all this with great care, without overlooking any nests. T hey work on, from grotto to grotto, and it often takes them 4 months to complete a harvest.

The crude nests must be processed before they can be consumed. This work is undertaken by women, since men have done the hard job in the fields. As a matter of fact, processing the nests is quite simple: one must pick off all the bird feathers, feces, or dry leaves stuck in the nests with a sharp knife or little clippers, i.e. clean the nests. This job may be completed in a couple of days by 10 - 15 women. After processing, the nests are classified into categories (including huyet, hong, quan, thien, bai, dia, vun) on the basis of their size, colour, volume, etc., then packed in half a kilo each (before 1975) or 1 kilo (after 1975), and stored under good conditions before they sold to traders.

Inheriting the fine traditions be quested by their ancestors, the Thanh Chau people have constantly improved the procedures and instruments in exploitation and processing. Thanks to the annual cleaning-up before their production season, the birds enjoy a whole- some environment in which to build their nests. This insures the high quality of the products. The concrete barriers held the sea waves off the entrance of the caves so that fewer nests fall from the cliff-walls due to high breakers. The application of cement on the cracks and ruptures in the cave-walls can prevent leaking water from wetting the birds and their nests. The erection of artificial cave walls with bricks and cement has provided more room for the birds to build their nests. In addition, the use of motor-boats in the place of sail-boats, torch-lights instead of oil-lanterns, 2 harvests instead of 3 harvests a year, all have contributed to increasing economic efficiency: maximum collection of nests and increase in the number of flocks in future years. This has contributed to a quick annual growth of Hoi An sea-swallow nests at a rate of 10 - 30% and promises great potential.

For nearly 400 years, the sea-swallow nest has brought about immense resources for the Hoi An people in many respects. First of all, it is a type of food of superior quality, with a high nutritional value (with 36 - 52% protein); it is also a medicinal material that may cure various fatal diseases (e.g. tuberculosis, asthma, inflammation of arm and leg-bones, anus inflammation, and some others), and in this way, it is a precious and very expensive commodity. The Hoi An sea- swallow nest has a higher value and price than its counterparts from Binh Dinh, Khanh Hoa or Singapore. If, four centuries ago, it was one of the 6 key exports of Hoi An-Faifo commercial port, today it is the export number one, accounting for nearly 20% of the total income of the town, with billions of dong per year.

Unlike Kim Bong carpentry and Thanh Ha ceramics, which have inherited the traditions of the Vietnamese people from the Northern Delta, the collection of Thanh Chau sea-swallow nests came into being from the creativity of the Hoi An population. Therefore, the key point is that the Hoi An population has created an original occupation compatible with its living environment, in accordance with the potential for exploitation. The collection of Thanh Chau sea-swallow nests has not only brought a considerable source of income but also created a rational division of work in society, among the collectors themselves and in the socio-economic life of the community as well. It is ready an original economic Endeavour: collection and exploitation of natural products with investment and awareness. Thanh Chau with its-sea- swallow nest collection as a cradle of this occupation in Central Vietnam has seen its further expansion to Binh Dinh, Khanh Hoa.