Small town songbirds develop unique local styles
The musical repertoire of birds in Israel has become much richer, thanks to the rapid development of rural communities over the past 100 years. Researchers from Tel Aviv University have discovered that one of the prominent songbirds in Israel, the Palestine Sunbird, has developed unique song styles after nesting in newly-settled areas.
In each of the dozens of locales in which the Sunbird's songs were recorded and analyzed, the birds have developed their own unique "dialect," characteristic of each specific area, and even for different neighborhoods in the same town that had been built at different times.
Song is an important component in communication between birds, and is used for various purposes such as protecting territory, communication between mates and warnings against predators. Among Sunbirds, which weigh all of 6 to 8 grams, the male is usually the singer, and sings mostly during the mating season. A male who sings well improves both his status and chances of finding a mate.
Kineret Yoktan of Tel Aviv University has been researching the Sunbird's songs in various locations. Under the guidance of Prof. Yoram Yom-Tov and Dr. Noam Leader, Yoktan recorded the Sunbird's songs in many locales from the eastern Upper Galilee to the Jordan Valley.
The Sunbird used to be common only in areas where there were nectar-producing flowers - the bird's food source. With the expansion of Jewish settlement and the establishment of flower gardens, the Sunbird population grew and spread accordingly, and the researchers wanted to examine how this influenced the birds' songs. Yoktan found a different dialect of song in each locale, and in Yesod Hama'ala, an Upper Galilee community with three distinct neighborhoods, the Sunbirds in each neighborhood had their own dialect. "This town was founded in 1883, and there is a perfect correlation between the stages of building and the locations of the Sunbird populations," writes Yoktan in her research.
In seven rural communities in the Beit She'an Valley, the Sunbirds sing without their characteristic trill. Yoktan's research found that a few "founding fathers" came to each new community, and the younger Sunbirds that joined them in each area learned the local songs in order to become integrated into the bird community. "The Sunbirds developed their different song dialects as they adapted to their surroundings," explains Yom-Tov. "In the Arava region, for example, the birds' territories are larger, and they sing at a lower frequency so that their songs carry over greater distances. Another type of adaptation is the mimicking of other birds, to enrich their vocal repertoire and attract more females."
"The Zionist resettlement has influenced the composition of the animal kingdom in Israel," concludes Yom-Tov. "This study proves that the animals' behavior has also been affected."