About swallow birds or Swifts and their Nests

South East Asia Swallow birds or Swifts (Collocalia Family) are very unique birds. They have short bills, wide mouths, very small with crescent –shaped wings. They are about the same size as sparrows, but their wingspan is wider than that of a pigeon. These swallow birds or swifts have a very strong ability and endurance to fly; being the fastest fliers and capable of flying 40 hours non-stop. They never perch or rest except when they are sleeping, building their nests, or feeding their chicks. The monogamous parents lay 2 eggs, incubated by both parents for 21 to 29 days. The chicks remain inside the nest for 43 days, before they are fully independent from their parents. The average longevity of the bird varies from 10 to 20 years.

Consumption of Swallow’s nest first appeared in Gu Ming’s guidelines on Diet (circa 1350) of the Yuan Dynasty in China. In the Jin Ping Mei Tsz Hua (1617) of the Ming Dynasty, it was clearly stated that swallow’s nest and sharkfin were the food of the rich. According to many classical Chinese books about health food, swallow’s nests were imported into China from South East Asian region since Tang Dynasty (A.D 618 – 907). Numerous citations of ancient texts have also confirmed swallow’s nest as a highly-prized delicacy of the rich as they consider it as one of the most precious tonic food. Similarly, the article “Yan Wo Kao” (The Investigation on Swallow’s Nest) in Mingpao Monthly Vol. 231 (May 1985), Prof. Y. C. Kong and Prof. P. S. Kwan of the Chinese University of Hong Kong reported on their research that swallow’s nest contains a ‘cell division inducing hormone’ and an ‘epidermal growth factor’ that can stimulate growth and division of cells, thereby enhancing metabolism, cellular regeneration and cell-mediated immunity in humans.

Edible nests built by swallow or swiftlet are found in caves, cliffs in offshore islands of North Borneo, Indonesia, Malaysia, Thailand, Vietnam and the Philippines. Small colonies of swiflets are also found in some remote areas of Hainan and Fujian of China. In addition to cave swallows, there are also house swallows farmed in these areas; largely in Indonesia and Malaysia. Indonesian swallow bird’s nest is one of the finest qualities in the world.

Types of Birdnest

There are basically two categories of bird nests namely; cave bird nest and house bird nest. Cave bird nest is usually found in dangerous and hard to reach areas such as coastal caves, cliffs and overhanging crags. Sarawak (eastern part of Malaysia), Indonesia, Thailand and Vietnam are the major bird nest origination countries. Cave bird nest comes usually in red, yellow/orange or white colour, due to perhaps the effect of sunshine, water or mineral content of the limestone caves and the food ate by the swallows or swiftlets. Owing to the harsh natural climate and environment, the nest is firm, hard and deep in colour. It is not as well shaped as house nest and containss higher impurities. Cave nest is crunchy with a low swelling capacity that lengthens the time for it swell when preparing. House bird nest refers to nest which the swiftlets build in a house. ‘House Farming’ of bird nest is getting popular in many parts of South East Asia especially in Indonesia and Malaysia. The birds leave farmhouse to find food in the wild during the early morning and return in the evening. House bird nests are much cleaner with less impurities and feathers. They have an intact cup shape and have a high swelling capacity. They are usually of very good quality and mostly white in colour with some in red or yellow/orange colour due to different types of food the swallows or swiftlets ate. Generally, bird nests or `yen-ou' are differentiated based on its appearance i.e. the natural whole nest cup, nest strips, nest pieces. The whole nest cup, mostly comes from house nests, has the highest nutritional value and hence, is the most expensive. During processing, some nest cups are broken into strips and pieces and they are then sold as such. Their swelling capacity and prices are lower but the nutritional value is the same as that of nest cups.

In the case of cave nests, they contain more impurities and feathers, the nests may be required to be broken during processing in order to remove dirt and feathers. Due to extensive cleaning process, the nest may be sold in nest strips and nest pieces, or molded into the shape of nest cake. These nests generally contain less nest-cement and are of less nutritional value.

The world’s major producers of bird nests are Indonesia, Malaysia and Thailand. Indonesia produces about 80% of the world population. Most of the product is exported to Hong Kong (China), Taiwan, Singapore and even Canada.

Harvest of bird nests

Bird nests are harvested thrice yearly. These nests look like a cupped hand, a hollow quarter-ball shape, with a 3 – 5” diameter. One side is stuck to a cave wall (wild nests) or wooden base (house nests) and the other side of the nest is a place for them to perch. In the hollow nest are either their eggs or their chicks. Right after the swallows or swiftlets mated, they regurgitate long, thin gelatinous strands from their salivary glands under their tongues. These strands play an important role in making their nests.

Bird nests are of best quality during the period from November to March. Rainfall is particularly substantial and hence, provides an excellent environment for the growth of tiny insects and plants. Swiftlets during this period grow well and strong thereby produce copious amount of saliva and the nests constructed are big and thick, containing fewer impurities.

The period between April and June is a dry season. Due to decrease in food supply for the swiflets, the bird nests produce are thin and nest threads are thick. The shape and the swelling capacity are poorer.