Chongqing- While it drizzled endlessly throughout the Qingming Festival holiday from April 3rd to 5th, adult Indian spot-billed duck populations and their young birds enjoyed the journey through the Chongqing Liangping Shuanggui Lake National Wetland Park.

The Park's superior ecological environment and the abundance of rare flora and fauna constitute a treasure trove of biological resources and a base of tourism resources. Especially the Indian spot-billed duck, a migratory bird first discovered at Shuanggui Lake in 2018, has become a resident bird in the lake.

From "tourists" to "residents"

Shuanggui Lake was built in 1953 and is located in Duliang New District, Liangping. In 2015, Liangping piloted the construction of Shuanggui Lake National Wetland Park, which passed acceptance in 2017.

Wetlands are the "kidneys" that regulate water and filter waste from the landscape. Shuanggui Lake National Wetland Park covers a total area of 349.97 hectares, which is divided into three functional areas, including the conservation area, restoration area, and rational utilization area.

The wetland area is 190.76 hectares, and the wetland rate reaches 54.51%.

"Indian spot-billed ducks are large ducks with a body length of 50cm to 64cm and a weight of about 1kg," said Tang Hong, director of the Liangping Wetland Protection Center. "They mainly inhabit various inland lakes, reservoirs, rivers, sandbars, and swamps."

According to Tang, Indian spot-billed ducks usually migrate south from southeastern Siberia or northeastern China at the end of September and the beginning of October every year.

"Those ducks come in December and leave in February of the next year," said Yang Xiuyong, a middle school teacher in Liangping and a volunteer for bird protection in Liangping Shuanggui Lake, who fancies photographing. "Shuanggui Lake should be a temporary habitat for Indian spot-billed ducks during migration." 

In April 2021, Yang accidentally photographed baby birds of the Indian spot-billed ducks at Shuanggui Lake. "The discovery of young birds indicates that some Indian spot-billed ducks have become resident birds," said Yang.

"Although Indian spot-billed ducks are migratory birds, some stay in the middle and lower reaches of the Yangtze River, the southeast coast, and Taiwan all year round and become resident birds," said Tang.

He thinks the staying of Indian spot-billed duck shows that the ecological environment of Shuanggui Lake has been improved and recognized.

Not only the Indian spot-billed duck but more than 200 species of birds live in Shuanggui Lake, including Chinese merganser and Baer's pochard, have been wintering in Shuanggui Lake for many years. Furthermore, the greylag goose in Chongqing also appeared in Shuanggui Lake after 39 years.

"Recently, we have also observed migratory birds such as moorhens and Eurasian coot in Shuanggui Lake," said Tang.

With the continuous improvement of the ecological environment of Shuanggui Lake, he believes that more and more wild animals will inhabit and breed here.

Good water quality for wildlife

Water serves as the soul of the wetland. Shuanggui Lake has improved its water quality as well. 

In recent years, Liangping District has taken the protection of the source as the foundation, treatment, purification, and protection as measures to ensure the water quality safety of Shuanggui Lake from various aspects.

For example, a 13-kilometer rain and sewage pipe network has been set up around Shuanggui Lake to divert rain and sewage and prevent seeping into the lake. Organic, ecological planting is also encouraged, where pesticides and fertilizers are not applied to reduce the lake's nitrogen and phosphorus pollution and nutrient enrichment.

On this basis, Liangping District focuses on the ecological restoration of small and micro wetlands around the lake. With the help of ecological barriers such as biological ditches, rain gardens, habitat ponds, and cascade small and micro wetlands, the rainwater is purified layer by layer to ensure the lake's water quality reaches the standard.

Today, the water quality of Shuanggui Lake has been stable above Class III all year round, providing suitable habitats for wild animals.

For Class III water supplies in which high-level maintenance can be expected, the limit is around 2500 to 5000 MPN per 100 ml. For bathing, 1000 MPN per 100 ml was established as the standard.

In recent years, the biodiversity of Shuanggui Lake National Wetland Park has increased significantly, with the number of vertebrate species increasing to 277 (including 207 birds) and the number of plant species increasing to 623.

(Wang Lu, as an intern, also contributed to this report.)