Bird Nest Soup and Swiftlet Nesting Houses

Jul 14, 2011
John Blatchford

Swiftlet Nesting House - Alexander Heitkamp - Wikimedia Commons

Nests were once collected from natural caves, but new buildings persuade the birds to nest in towns. This new technique is causing some concern.

The Edible-nest Swiftlet (Aerodramus fuciphagus) has been the source of nests for bird nest soup for centuries. Traditionally these nests were collected from the caves where the birds chose to breed – but recent techniques have changed all that. Now special 'nesting houses' lure the birds into towns.

Edible Nest Swiftlet

Aerodramus fuciphagus is found in South-east Asia where it breeds in deep caves.

The nests are small, and made of hardened saliva – presumably something that evolved to compensate for the lack of building material in the caves, and the difficulty of bringing anything suitable from outside.

Edible nest swiftlets breed in large colonies and have a variety of calls, including one which is thought to be used for echo-location in the dark caves. The calls of birds already nesting successfully seems to attract new recruits.

Bird Nest Soup

In China the soup (yan wo) is made by dissolving the nests in water, and it is considered to have high medicinal value as well as being pleasant to drink.

'Edible bird's nest is one of the widely used health foods in Chinese communities' (Shun Wan Chan, 2004), and clean nests are worth a lot of money.

National Geographic estimated that over one hundred tons were imported into Hong Kong in 2002 – worth around twenty million U.S. dollars.

The huge popularity of the soup, together with the limited supply of nests, has led to bird nest soup becoming one of the most expensive animal products consumed by humans.

Swiftlet Nesting Houses

BBC News (2011) reports that: 'drab concrete buildings have sprouted up all across Kumai' in Borneo, and The New York Times (2011) says that a similar thing is happening in Sukadana, also in Borneo.

The nesting houses have holes that allow air to circulate. Misters to keep them cool, and open water tanks encourage the birds to drink and bathe inside the houses.

Once these comfortable houses have been built recordings of swiftlet calls are played to attract the birds.

The technique seems very successful in terms of increasing the production of nests for the Chinese market, but there are a few concerns.

Concerns About Nesting Houses

As with any novel technique involving the natural world there are many possible impacts:

favouring just one species of insect-eating bird might reduce populations of its competitors

drinking (bathing) water in the houses might be expected to increase mosquito populations – dengue fever and malaria are tropical diseases of particular concern in Borneo

greater numbers of swiftlets in towns might affect the incidence of H5N1 (avian flu) – the toll in Indonesia is already the highest in the world, according to the World Health Organization.

It should be stressed that these are only a few of the 'concerns' – and that none of them have yet come to pass. It should also be noted that there are undisputed economic advantages to the use of nesting houses. Nevertheless the situation needs careful monitoring.

Sources: