In natural environment, swiftlets build nests as a breeding habitat for its next generations. However, not all bird's nest has medicinal value. 'Bird's Nest' usually refers to those that contain medicinal and nutritional values. The bird's nest is built as a breeding bed for young swiftlets and it is made by swiftlets' saliva secretion.
Bird's nests are categorized into 2 main groups, one being built by swiflets living in caves and another built in bird's houses.
Many people often have the misconception that house nests swiftlets were rared while cave swiftlets were wild. In fact, swiftlets consider both habitual and living in natural ecology. Swiflets leave their nests before sunrise for food and return in the evening. An average adult swiftlet has body width(including feather) of about 4cm, and length of about 10cm, its length with wings fully spreaded is about 22cm, and weighs about 15g, it has short flat tail, and short but soft legs. Swiftlet, unlike most birds living on the ground or walk on wires, it only uses its four tiny toes to hook and hang on walls or cliffs. It can live up to is 2,800 metres above sea level. Swiftlets spend 10-11 hours daily in food hunting for itself and would sometimes return to its nest on an hourly basis to feed its baby swiftlets. Swiftlets' foraging activities are mainly during flying, and feed on flying insects or small organisms in the rain water and by the pond.
This illustrates the special physiological structure of the swiftlet, and therefore, swiftlets are not farmed. We are only able to provide the swiftlets with suitable living environment, others such as diet, growth and scope of activities, etc., are not controllable by human beings. Swiftlets are treated as precious treasure by the swiftlet farmers. They provide the best living environment as possible to the swiftlets for its better breeding process. The swiftlet farmers will wait until the baby swiftlets are able to leave the nest before any harvesting since the nest could not be recycled. Therefore, bird's nest collected from the bird's houses are environmental friendly, accordance to human's act and of higher quality.