SINGAPORE - The warm weather and rich mudflats of Singapore make the country a tropical paradise for many migratory shorebirds - including those that make arduous journeys across the Himalayan mountain range, a new study has found.
This finding puts Singapore at the intersection of two major flyways, the superhighways in the air that migratory birds take every year to escape the winter chill in the Northern Hemisphere.
Previously, Singapore was thought to be a stopover for birds only along the East Asian-Australasian Flyway, the world's largest migratory route, spanning the Arctic Circle down south to Australia and New Zealand.
But the new study showed that some birds which spend their winters in Singapore had journeyed here using the Central Asian Flyway across the Himalayas.
The latest study was published on Friday (Dec 11) in the scientific journal Nature's Scientific Reports.
It was co-authored by researchers from the National Parks Board (NParks), who had made this discovery using a suite of bird tracking technology deployed on common redshanks and whimbrels, two species of birds known to spend the boreal winter months in Singapore.
Some 2,000 migratory shorebirds from more than 40 species stop over here between August and March every year, in places like the Sungei Buloh Wetland Reserve and Pulau Ubin.
Many of them are thought to have made their way here along the East Asian-Australasian Flyway, which skirts the Himalayan mountain range. This would help the birds avoid the harsher conditions of thinner air and lower oxygen levels there.
But the latest study showed that some birds could have arrived here from the Central Asian Flyway.
"This is the first time that shorebirds spending their winter months here in Singapore were shown to have migrated across the Himalayas," said the study's lead author, Mr David Li, NParks' manager for conservation at the Sungei Buloh Wetland Reserve.
The latest findings add to the mysteries surrounding bird migration, a phenomenon considered one of nature's most spectacular, with the diminutive feathered travellers taking cues from the stars in the skies or landmarks on earth to make journeys spanning thousands of kilometres.
The five-year study from 2015 to 2019 involved the researchers tagging common redshanks and whimbrels in Singapore with satellite tags or geolocaters. Under guidelines based on scientific studies, such equipment should weigh less than 3 per cent of the bird’s body weight.
The data was gleaned from the migratory flight paths of 15 birds – 10 common redshanks and five whimbrels. Of these, four birds (three common redshanks and one whimbrel) had navigated across the Himalayas 5,000m to 6,000m above sea levels during the northward migration. Another three common redshanks made the crossing during southward migration.
Mr How Choon Beng, NParks' director for wildlife management and outreach, said this shows that while humans consider the range a daunting physical barrier, the mountains may not be as big a challenge for birds as previously thought.
The researchers hypothesise that these birds chose to fly across the Himalayas instead of around the mountain range to reduce flying time, as the direct route reduces the distance to and from the birds' breeding grounds in the Qinghai-Tibet Plateau by around 600km.
Ms Yang Shufen, NParks' director for conservation at the Sungei Buloh Wetland Reserve, said the latest findings have implications for conservation strategies for shorebirds.
"The study illustrates the value of conserving wetland habitats, including mangroves, mudflats and freshwater marshes in Singapore to provide migratory birds using either flyway for feeding or roosting sites along their stopover here," she said.
She noted that many conservation initiatives in Singapore focus on the East Asian-Australasian Flyway, with NParks establishing partnerships with other conservation agencies in nations along this flyway.
But the data shows that more partnerships can be forged along the Central Asian Flyway as well.
She added: "Continued efforts in documenting and learning about the birds' behaviour, breeding patterns and stopovers will allow NPaks and the global conservation community to come up with more focused conservation strategies for the long-term survival of these birds."