The autumn winds sweep across northern China, signaling the start of the raptor migration season from Siberia, Russia, and Northeast China toward the south. Standing on a platform overlooking the Bohai Gulf, patrolmen and bird enthusiasts have been monitoring the annual migration since early this month.

Monday proved to be a momentous day for them. At the platform atop Laotie Mountain, within the Snake Island-Laotie Mountain National Nature Reserve in Lyushunkou district of Dalian, Liaoning province, they witnessed a remarkable avian event — the first "10,000 raptors day" on the Chinese mainland. In a single day, they counted 11,175 raptors in flight, shattering the previous record of 7,561 observed on Sept 22 last year.

The significant achievement unfolded against the backdrop of the recent inclusion of the Migratory Bird Sanctuaries along the Coast of the Yellow Sea-Bohai Gulf of China (Phase II) in the World Heritage List at the World Heritage Committee meeting in July. The Dalian reserve is one of the five protected areas included in the new heritage site, and it is the first reserve in Liaoning to be part of a World Heritage site.

Situated on the southernmost tip of the Liaodong Peninsula, Laotie Mountain overlooks the Shandong Peninsula, serves as a crucial passage for migratory birds through the Bohai Strait and is known as a vital site along the East Asia-Australasia flyway of migratory birds.

The reserve launched its raptor monitoring initiative in 2018 and has continued its work over the past seven years, with an average annual monitoring count exceeding 60,000 raptors, according to Guangming Daily. The record-breaking year of 2023 saw the count peak at 85,567 birds, achieving a daily average of over 1,000 raptors. As of Monday, 43,449 migrating raptors have been recorded this year.

"The exciting news not only indicates that Laotie Mountain is an important node for raptor migration along the East Asia-Australasia flyway, but also demonstrates that we have begun to standardize and normalize our raptor monitoring efforts," Professor Liu Yang, an ornithologist at Sun Yat-sen University in Guangdong province, told China Daily.

With clear skies, gentle breezes and high visibility following three days of strong winds, the raptor monitoring team finally encountered ideal conditions for raptor migration on Monday.

"At 6 am, we arrived at the monitoring point and waited. Based on past experiences, everyone believed that today we would see a significant surge in the number of observations," said volunteer Du Le.

Anticipation ran high as the team arrived at the monitoring site at dawn, expecting a surge in the number of the Oriental honey buzzard, a prominent raptor species observed during the autumn migration.

As the hours passed, the count did not initially meet expectations. It wasn't until nearly 11 am that the count surpassed 1,000, leading many participants of the survey to believe it would be just another ordinary "thousand raptor day".

However, the situation took a dramatic turn as volunteers, using thermal imaging devices, spotted countless tiny black dots on a distant hillside. A massive group of honey buzzards was coming. Reserve patrolmen and the volunteers sprang into action, steadying their binoculars and counting attentively.

The honey buzzards came, appearing along the entire ridge from west to east, soaring in formation, creating a colossal "eagle ball". After spiraling upward and ascending rapidly, they formed an "eagle river", flying over the volunteers' heads across the Bohai Strait, Du said.

"After that, every hour we saw over a thousand, and by midafternoon, the number had reached close to 10,000, setting a new record," Du said.

Wang Xiaoping, an official with the nature reserve, said that around the time of the autumn equinox each year, the raptors resting at Laotie Mountain would take flight again to continue their migration southward toward Shandong.

According to previous years' experiences, the honey buzzards usually stop their mass migration over the sea around 2 pm or return after attempting to cross. However, this year, the takeoffs continued until 5 pm. The observers recorded 11,175 raptors, with 10,870 being Oriental honey buzzards, setting a new single-day migration record for the species on the Chinese mainland.

"This year, the volunteer observers used infrared thermal imaging equipment, which can scan life forms in high altitudes and then assist in observations with binoculars," said volunteer Cheng Ming. "To witness such a massive migration of raptors all at once, I can now depart this life without regrets."