Aerodramus

Aerodramus

Languages: English

Overview

Brief Summary

Aerodramus cave swiftlets are best known as contributors of the key ingredient in bird’s nest soup, which is a coveted delicacy in many parts of Asia--the “caviar of the East”.  True bird’s nest soup is made from the nests of any of several species of colonial Asian Aerodramus cave swiftlets, especially the Edible-nest Swiftlet (A. fuciphagus) and the Black-nest Swiftlet (A. maximus) of southeast Asia. These are swallow-like birds (although, like other members of the swift family, they are actually more closely related to hummingbirds) which are able to navigate through dark caves using echolocation, like bats.  Their small cup-shaped nests, typically placed on the walls of caves, often quite high up, are composed largely or entirely of the hardened saliva of the male swiftlet.

Although they apparently hunt their insect prey relying mainly on vision, Aerodramus swiftlets are among the very few bird species to use echolocation to find their way, although, in contrast to typical echolocating bats, swiftlets appear not to use frequency modulation but rather rely only on temporal information (Fullard et al. 1993; Price et al. 2004; Price et al. 2005; Thomassen and Povel 2006). As a group, Aerodramus swiftlets are distributed very broadly, with species occurring in southern Asia, in Australasia, and on islands in the South Pacific and Indian Oceans (Chantler 1999).

Traditionally, swiftlet nests were harvested from natural populations in caves, the locations of which were often carefully guarded secrets. During the past couple of decades, demand for these nests, which command a very high price, has taken a severe toll on many swiftlet populations (e.g., Sankaran 2001; Gausset 2004; Hobbs 2004) and in some areas this high demand has even generated a criminal enterprise.  On the brighter side, market demand has also stimulated the development of a successful cave swiftlet farming industry utilizing newly developed swiftlet husbandry methods and specially designed nesting structures situated largely in urban areas. In the meantime, some restaurants offer an imitation bird’s nest soup that uses noodles shaped like a bird’s nest in lieu of the real thing.

In some cases, counterfeit (or adulterated) edible bird's nests are marketed, either nests of other species or nest-shaped materials molded with fried pork skin, Tremella fungus, karaya gum from Sterculia trees, or red seaweed. Some of these versions are easy to distinguish from authentic nests of A. fuciphagus and A. maximus, but distinguishing the nests of other swifts can be another matter. Lin et al. (2009) investigated and discussed the effectiveness and limitations of a simple genetic analysis that could be an important tool in discriminating authentic and counterfeit edible bird's nests. (Marcone 2005; Lin et al. 2009)  Marcone (2005) investigated the chemical composition of edible bird's nests. According to Goh et al. (1999), in a study of food allergens inducing anaphylactic allergic reactions in children seen at a general hospital in Singapore, bird's nest soup topped the list.

As swiftlet ranching has become big business, the marketing of information and equipment to individuals hoping to get in on the profits has itself become a business, as is apparent from the following sampling of links (note that inclusion of these links here in no way implies any sort of endorsement or determination of legitimacy!):

www.swiftletonline.com

www.swiftletecopark.com

nesttech.com.my

www.swiftletfarming.com.my

Author(s): Shapiro, Leo
Rights holder(s): Shapiro, Leo

Comprehensive Description

Aerodramus cave swiftlets are best known as contributors of the key ingredient in bird’s nest soup, which is a coveted delicacy in many parts of Asia--the “caviar of the East”.  True bird’s nest soup is made from the nests of any of several species of colonial Asian Aerodramus cave swiftlets, especially the Edible-nest Swiftlet (A. fuciphagus) and the Black-nest Swiftlet (A. maximus) of southeast Asia. These are swallow-like birds (although, like other members of the swift family, they are actually more closely related to hummingbirds) which are able to navigate through dark caves using echolocation, like bats.  Their small cup-shaped nests, typically placed on the walls of caves, often quite high up, are composed largely or entirely of the hardened saliva of the male swiftlet.

From a taxonomic perspective, the swifts are among the most challenging of bird families and, within this family, species boundaries and relationships among the swiftlets have proved to be among the most difficult to work out. At one time, all the swiftlets were placed together in the genus Collocalia, but based on a range of evidence ornithologists now divide these species among several genera--although some controversy remains regarding the composition of these genera (Chantler 1999; Price et al. 2004; Price et al. 2005; Thomassen et al. 2005). Although they apparently hunt their insect prey relying mainly on vision, Aerodramus swiftlets are among the very few bird species to use echolocation to find their way, although, in contrast to typical echolocating bats, swiftlets appear not to use frequency modulation but rather rely only on temporal information (Fullard et al. 1993; Price et al. 2004; Price et al. 2005; Thomassen and Povel 2006). As a group, Aerodramus swiftlets are distributed very broadly, with species occurring in southern Asia, in Australasia, and on islands in the South Pacific and Indian Oceans (Chantler 1999).

Traditionally, swiftlet nests were harvested from natural populations in caves, the locations of which were often carefully guarded secrets. Diverse (and dubious) health and aphrodisiac properties are often attributed to swiftlet nests and, despite their odd texture and lack of much taste, they are also prized for their culinary value, prepared in a variety of both sweet and savory dishes. During the past couple of decades, demand for these nests, which command a very high price, has taken a severe toll on many swiftlet populations (e.g., Sankaran 2001; Gausset 2004; Hobbs 2004) and in some areas this high demand has even generated a criminal enterprise.  On the brighter side, market demand has also stimulated the development of a successful cave swiftlet farming industry utilizing newly developed swiftlet husbandry methods and specially designed nesting structures situated largely in urban areas. It remains to be seen whether these farming efforts will be sufficient to relieve the unsustainable pressure on wild populations (or have unforeseen negative environmental impacts). In the meantime, some restaurants offer an imitation bird’s nest soup that uses noodles shaped like a bird’s nest in lieu of the real thing.

In some cases, counterfeit (or adulterated) edible bird's nests are marketed, either nests of other species or nest-shaped materials molded with fried pork skin, Tremella fungus, karaya gum from Sterculia trees, or red seaweed. Some of these versions are easy to distinguish from authentic nests of A. fuciphagus and A. maximus, but distinguishing the nests of other swifts can be another matter. Lin et al. (2009) investigated and discussed the effectiveness and limitations of a simple genetic analysis that could be an important tool in discriminating authentic and counterfeit edible bird's nests. (Marcone 2005; Lin et al. 2009)  Marcone (2005) investigated the chemical composition of edible bird's nests. According to Goh et al. (1999), in a study of food allergens inducing anaphylactic allergic reactions in children seen at a general hospital in Singapore, bird's nest soup topped the list.

Langham (1980) reviewed the breeding biology of A. fuciphagus. Kang et al. (1991) investigated the impact of nest harvesting on nest construction and egg-laying in A. fuciphagus and A. maximus in Singapore and made recommendations on sustainable harvest frequency.

As swiftlet ranching has become big business, the marketing of information and equipment to individuals hoping to get in on the profits has itself become a business, as is apparent from the following sampling of links (note that inclusion of these links here in no way implies any sort of endorsement or determination of legitimacy!):

www.swiftletonline.com

www.swiftletecopark.com

nesttech.com.my

www.swiftletfarming.com.my

Author(s): Shapiro, Leo
Rights holder(s): Shapiro, Leo

References

Chantler, P. (1999).  Family Apodidae (Swifts). (delHoyoJ., ElliottA., TargatalJ., Ed.).Handbook of the Birds of the World. 5, 388-466. Barcelona, Spain: Lynx Edicions.
Fullard, J. H., Barclay R. M. R., & Thomas D. W. (1993).  Echolocation in free-flying Atiu Swiftlets (Aerodramus sawtelli). Biotropica. 25, 334-339.
Gausset, Q. (2004).  Chronicle of a Foreseeable Tragedy: Birds' Nests Management in the Niah Caves (Sarawak). Human Ecology. 32(4), 487 - 507.
Hobbs, J. J. (2004).  Problems in the harvest of edible birds' nests in Sarawak and Sabah, Malaysian Borneo. Biodiversity and Conservation. 13(12), 2209 - 2226.
KANG, N., HAILS C. J., & SIGURDSSON J. B. (1991).  Nest construction and egg-laying in Edible-nest Swiftlets Aerodramus spp. and the implications for harvesting. Ibis. 133(2), 170 - 177.
Langham, N. (1980).  BREEDING BIOLOGY OF THE EDIBLE-NEST SWIFTLET AERODRAMUS FUCIPHAGUS. Ibis. 122(4), 447 - 461.
Lin, J-R., Zhou H., Lai X-P., Hou Y., Xian X-M., Chen J-N., et al. (2009).  Genetic identification of edible birds’ nest based on mitochondrial DNA sequences. Food Research International. 42(8), 1053 - 1061.
MARCONE, M. (2005).  Characterization of the edible bird’s nest the “Caviar of the East”. Food Research International. 38(10), 1125 - 1134.
Price, J. J., Johnson K. P., & Clayton D. H. (2004).  The evolution of echolocation in swiftlets. Journal of Avian Biology. 35, 135-143.
PRICE, JORDAN. J., JOHNSON KEVIN. P., BUSH SARAH. E., & CLAYTON DALE. H. (2005).  Phylogenetic relationships of the Papuan Swiftlet Aerodramus papuensis and implications for the evolution of avian echolocation. Ibis. 147(4), 790 - 796.
Sankaran, R. (2001).  The status and conservation of the Edible-nest Swiftlet (Collocalia fuciphaga) in the Andaman and Nicobar Islands. Biological Conservation. 97(3), 283 - 294.
THOMASSEN, H. A., & POVEL G. D. E. (2006).  Comparative and phylogenetic analysis of the echo clicks and social vocalizations of swiftlets (Aves: Apodidae). Biological Journal of the Linnean Society. 88(4), 631 - 643.