Jakarta, Indonesia Sentinel — The Barn Swallows (Hirundo rustica), a migratory bird species, has once again arrived in Yogyakarta, Indonesia, this October. The arrival is a part of the barn swallows annual migration journey to escape the extreme winter conditions of Siberia, Russia, Mongolia, and China. However, in 2024, local birdwatchers have observed a significant decline in their numbers.
A recent observation by the Jogja Birdwatchers Association (PPBJ), an amateur birdwatching group based in Yogyakarta, revealed a steep drop in the population of Asian swallows migrating to the region. Nicosius Liontino Alieser, PPBJ coordinator, noted that this year’s count is nearly three times lower than previous years.
“In 2020, we recorded about 17,300 barn swallows in the Gondomanan intersection area. In 2021, the count reached 23,300 individuals. This year, on October 2nd, we only recorded 8,305 individuals, which is a dramatic decline”, Nico said, as cited from Kumparan on October 6.
The birdwatchers have consistently conducted their annual observations on the same date, October 2nd, which coincides with Indonesia’s National Batik Day. Despite the stable timing, this year’s steep drop in numbers is alarming. While the exact cause remains unknown, Nico suggested that similar declines have been observed in other regions, including Bali, where fewer migratory shorebirds have been recorded this year.
Climate Change Suspected as a Key Factor
One leading speculation behind the drop in the barn swallows migration population is climate change. Nico believes that changes in weather patterns may have caused higher mortality rates, either in the birds’ breeding grounds or during their long migration journey. He also noted that migratory shorebirds in Yogyakarta’s southern coast, particularly at Trisik Beach, have shown signs of exhaustion, with some even found dead.
“There’s a possibility that these birds are forced to find new migration routes to avoid extreme heat, or they may be losing resting spots due to deforestation. This would lead to more exhaustion and higher death rates during their migration,” Nico explained.
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Another possibility is that the peak migration season of barn swallows has shifted. In previous years, the barn swallows would typically arrive in Yogyakarta between June and July. This year, however, they didn’t begin arriving until late August or early September. Nico suggested that the lower numbers recorded during this year’s count could be attributed to this delay.
Human Activity and Urbanization
Nico also pointed to the increasing bustle of Yogyakarta’s urban areas as another potential factor. During the COVID-19 pandemic, many of the observation areas in Yogyakarta were quieter due to strict lockdowns, which likely made the city a more suitable migration stopover for the barn swallows. However, with tourism now resuming and restrictions easing, the area has become busier, potentially causing the birds to seek alternative locations.
“We need to study this further, but it’s possible that urbanization is making these areas less attractive to the swallows. If this trend continues, we might see even fewer birds in the years to come,” Nico added.
As the mystery behind the decline in barn swallow numbers persists, further observation and research will be crucial in determining the exact causes and finding solutions to protect these migratory birds from further population drops. For now, the fate of Yogyakarta’s visiting swallows remains uncertain, raising concerns among conservationists and birdwatchers alike.
(Raidi/Agung)
