Annual bird census data reveals Singapore as the global stronghold of endangered songbird.
Wild populations of many bird species are in rapid decline across Southeast Asia as a result of unsustainable hunting for the pet-bird trade, especially in Indonesia. Sought by bird hobbyists for its powerful and rich song, the globally endangered Straw-headed Bulbul (Pycnonotus zeylanicus) is one of the world’s most threatened songbirds due to soaring demand for the pet trade. Across much of Southeast Asia, the Straw-headed Bulbul has been relentlessly trapped from the wild to be later sold in the bird markets of Java, Kalimantan, Sumatra and Peninsular Malaysia. The species has now gone extinct from Thailand and most parts of Indonesia where it used to be found, including the whole island of Java. There are also no recent records from Sumatra.
In a recent study published in the journal Bird Conservation International led by members of the Nature Society (Singapore) Bird Group, wild populations of the Straw-headed Bulbul in Singapore was found to have steadily risen over the last 15 years, and may now be the largest in its entire distribution. Using data gathered from more than 15 years of the Annual Bird Census, the study found that populations on the island of Pulau Ubin have increased at nearly 4% per year. It is estimated that at least 110 individuals of the Straw-headed Bulbul now survives on Ubin, making the island a global stronghold for the species. On the other hand, trends in mainland Singapore were less clear, appearing to remain unchanged over the study period.
The population of the Straw-headed Bulbul in Singapore is estimated to be at least 202 individuals based on existing data. However this estimate is likely to be conservative since the Western Catchment area was not comprehensively surveyed. Moreover, new sites for the bulbul, including remnant pockets of woodland like Burgundy woods has been discovered very recently and these were not captured in the Annual Bird Census. Given that the global population of the species is now estimated at 600-1,700 individuals, Singapore may easily hold 12-34% of the world’s remaining wild Straw-headed Bulbuls.
To effectively conserve the Straw-headed Bulbul, there will be a need to conserve small pockets of woodland such as Bukit Brown and Khatib Bongsu outside the nature reserves. It is also hoped that the authorities will review plans to gazette at least some parts of Pulau Ubin as a nature reserve. Other biodiversity can be expected benefit from the conservation actions targeting the bulbul.
Studies on the long-term population trends of birds in Singapore would not be possible without the citizen science surveys carried out by the Nature Society and supported by a large team of volunteers since 1986. These surveys include the Mid-year, Fall, and most importantly, the Annual Bird Censuses. Additionally, there are also dedicated censuses focused on monitoring raptor migration and parrots in urban areas. During these censuses, as many as 50 volunteers may be surveying birds across the country concurrently. Over the last two decades, these censuses have allowed us to track population trends of threatened species such as the globally endangered Straw-headed Bulbul.”
By Yong Ding Li.