Long-term surveys reveal Singapore as the global stronghold of endangered songbird
Singapore – 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.
In a recent study published in Bird Conservation International, authors from The Australian National University and Nature Society (Singapore) found that wild populations of the Straw-headed Bulbul in Singapore have steadily risen over the last 15 years, and may now be the largest in its entire distribution.
“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,” said Yong Ding Li from The Australian National University, who led the study. “The bird has gone extinct from Thailand and most parts of Indonesia where it used to be found, including the whole island of Java. Its populations have also collapsed across Malaysia.”
Using data gathered from more than 15 years of the Annual Bird Census, a yearly bird survey organized by the Nature Society (Singapore), BirdLife International’s national partner in Singapore, the authors 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, the authors found no evidence that the population on mainland Singapore had increased, remaining stable over 2000-2016.
The authors estimated that the population of the Straw-headed Bulbul for the whole of Singapore to be at least 202 individuals. However this estimate is likely to be conservative since western Singapore was not comprehensively surveyed due to limited access. Moreover, new sites for the bulbul has been discovered very recently. 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.
“The bulbul is also found in pockets of woodland such as Bukit Brown and Khatib Bongsu. More should be done to protect such places which are currently outside the existing reserve network,” said co-author Dr Ho Hua Chew from the Nature Society (Singapore), who is also vice-chair of its conservation committee. “Other biodiversity could also 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. These surveys include the Mid-year, Fall, and most importantly, the Annual Bird Censuses. During a census, as many as 50 volunteers may be surveying birds across the country concurrently.
“Citizen science efforts to monitor wild bird populations in Singapore, including the Straw-headed Bulbul, have been led by the Nature Society’s Bird Group since 1986,” says co-author Lim Kim Seng who is the society’s coordinator of the Annual Bird Census. “On a predetermined morning, scores of enthusiastic members will sacrifice sleep to be out in the wild at their assigned sites, counting birds for the census. 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.”
The article “Significance of the globally threatened Straw-headed Bulbul (Pycnonotus zeylanicus) populations in Singapore: a last straw for the species?” published in Bird Conservation International is available to download for free until 9th March 2017.
Photo credits: ‘Straw-headed Bulbul’ Lee Tiah Khee and Francis Yap
The Australian National University, Fenner School of Environment and Society, Mr. Yong Ding Li (Tel: +61-04666 77126; email: [email protected]); Nature Society (Singapore), Dr. Ho Hua Chew (Tel: +65-9829 9217; email: [email protected]) & Mr. Lim Kim Seng (Tel: +65-9843 2318; email: [email protected])