In downtown Xiamen, Fujian province, a 6-meter-high mound that stretches for 60 to 70 meters stands in stark contrast to the surrounding high-rise buildings.

The mound sits in the center of a 3-hectare reserve in Huli district and is a vital sanctuary for the blue-tailed bee-eaters, which is under second-level State protection.

The blue-tailed bee-eater, or Merops philippinus, is renowned for its colorful plumage and on the Chinese mainland is found in coastal provinces such as Fujian, Hainan and Guangdong.

Every spring, they migrate to China to breed and in winter they return to Southeast Asian countries including Myanmar, Thailand and the Philippines.

The Huli nesting site and a 37-hectare foraging site 2 kilometers away make up the Wuyuanwan Nature Reserve, the first reserve for the blue-tailed bee-eaters on the Chinese mainland.

Established in 2011 as Xiamen's inaugural city-level nature reserve in an urban area, it provides a crucial habitat for the species.

In recent years, with improved environmental conditions in Xiamen and increased attention to biodiversity, the blue-tailed bee-eaters have become regular visitors and their recorded population has seen a slight increase.

"Before 2015, we observed some 70 to 80 birds in the area," said Cai Libo, director of the Nature Reserve Affairs Center in Xiamen.

In 2023, over 200 of the birds were observed at the nesting site and more than 3,000 at the foraging site, Cai said.

Peng Zhiwei, head of the birdwatching association in Xiamen, said due to the challenges posed by coastal development in China, the birds should have national priority protection.

Peng said that he was impressed by the city government's commitment to nature conservation despite the high cost of putting aside land in the downtown area. The nesting habits of blue-tailed bee-eaters require designated places that need to be maintained, he said.

Every year when the birds arrive at the habitat, they use their beaks and claws to dig into the porous mound and spend around 10 days building a tunnel 60 to 100 centimeters long to house their nests.

The birds, which are sensitive to smell, build a new nest every year. Therefore, the mound must be cleared and refilled after the blue-tailed bee-eaters fly south.

"Fledgling blue-tailed bee-eaters depend on their parents for food, heat and protection during the 20-day incubation period, so the nest and foraging sites require proximity," said Peng. The diverse plant species in Xiamen provide ample insects for the birds, including dragonflies, butterflies, and bees, he added.

To better safeguard their habitat, the city government issued a notice in 2017, establishing a protective zone around the nesting site prohibiting noise and pollution-producing industries, such as catering, entertainment and auto repairs.

"Our 13-year experience of preserving blue-tailed bee-eaters has given us a grasp of their habits and made the Wuyuanwan Nature Reserve a stable habitat for them. I can see the potential for international collaboration to monitor migration patterns and enhance the protection of this species. Wildlife preservation transcends boundaries," Peng said.

Established in 2019, the Wuyuan River National Wetland Park in Haikou, Hainan province, learned from the successful experiences of Xiamen. Since last year, the 8.39-hectare nature reserve has imposed a ban on large numbers of tourists and bird watchers who might scare the birds away during the breeding season.