The Society finch (Lonchura striata domestica), also known as the Bengali finch or Bengalese finch, is a domesticated subspecies of estrildid finch. It became a popular cage and trade bird after appearing in European zoos in the 1860s through being imported from Japan, though it was domesticated in China. Coloration and behavior were modified through centuries of selection in Asia, then later in Europe and North America. Another aspect of the Bengali finch that evolved throughout the centuries is song production. Extensive research has been done and continues to be done on the different ways Bengali finch songs are produced, how they are processed in the brain, what characteristics of the songs are preferred by females, and how their songs compare to the also commonly studied zebra finch.
Evolution and origin Although the English language literature on aviculture called these birds as Bengali finch, the German aviculturist Karl Russ called them in 1871 as Japanese mövchen (or mew, an old word for gull, possibly related to Chinese mövchen, a pigeon breed named in France and introduced to Germany around the same time for their resemblance to gulls). The birds are members of the estrildid finch family and most authorities consider them a domestic form of the white-rumped munia (known in aviculture as the striated finch) most likely derived from the subspecies Lonchura striata swinhoei although some have suggested a hybrid origin.
Behavior
Bengali finches are well adapted to captivity and the company of humans. They breed well and are good foster parents for other finch-like birds. While two males may not get along without other company, it has been found the best "pairing" for fostering is to use two males, this works better than either two females or a male and female pairing. Two males will usually accept eggs or even partly grown young without any hesitation. These birds like to be close together and tend to all roost in one nest if kept in a group. In an aviary they lay eggs and crowd into a single nest, interfering with incubation (which is performed by the female and lasts 16 days) or damaging the eggs. Thus they breed better if kept as single pairs in individual breeding boxes. This sociability is also responsible for their American name of "society finch." Bengali finches are quite easy to look after. They are also quite easy to breed provided they are properly sexed. Obtaining a female-male pair can present a difficulty because both sexes look similar. However, it is possible to determine gender by behavior since males tend to display to females. One method to sex a Bengali finch is to place one bird in a small cage completely isolated it from its own kind (both sight and hearing) and then introduce another Bengali to the cage after several hours. If the first bird is a male, it will immediately display to the newcomer. However, this does not necessarily mean the introduced bird is a female, but if the first bird does not display then it is almost certainly female. Society finches can be housed with other finches including other societies, Zebra finches, Gouldian finches, and Spice finches.
Diet They are generally given a diet of seeds, such as millets and canary seed, and greens. They will not usually take live-foods, but it has been found they will often accept housefly pupae, which they crack like seeds. This is particularly useful if they are being used to foster species that require a high protein component to be successfully reared.
Song production
Syrinx Bird species produce some of the most complex sounds compared to any other animal. Singing is a learned behavior that has similarities with human speech. Birds breathe in oxygen past the throat and into the trachea where air splits off into either bronchial tube to reach the lungs. At the point where the trachea divides is where the sound producing organ called the syrinx lies. This avian song-producing organ is double-barrelled having two potential sound sources that are each under unilateral, ipsilateral neural control. Different songbird species vary with their lateralized song production and rapid switching between left and right song production motor control. Even when birds are rapidly switching between the left and right sides of the syrinx, or producing songs unilaterally, the respiratory muscles on both sides are acting equally, making song production require symmetrical respiratory motor control and asymmetrical syrinx motor control. Respiratory air pressure can be used to identify the syllables of songs and control acoustic phonology when syringeal gating of airflow and motor control is compromised. Since the Bengalese finch has the ability to rapidly change the acoustic structure of their songs in response to deafening and experimental modulations of auditory feedback, they have gained considerable attention regarding the workings of their syrinx. The Secora et al. (2012) study worked to characterize how the two sides of the Bengalese finch syrinx work to produce songs. With the use of syringeal denervation in a large sample group and air pressure recordings before and after unilateral nerve resection in a smaller sample group, data from this study provided evidence of syringeal specialization of acoustic control and rapid switching of motor control during Bengalese song production. It was discovered that the left side of the species' syrinx produces louder, higher frequency sounds above 2.2 kHz while the right side produces quieter, lower frequency sounds below 2.2 kHz. It was also found that higher peak frequency syllables are created by active motor control of the left side and they do not require active motor control from the right side of the syrinx. Thus, separate roles were discovered for the song production between the left and right sources of the Bengalese finch's syrinx.
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