What should we do to prevent the “Lost Gull” from being lost again?

A flash by the Ruoshui River

In 1931, the Swedish Museum of Natural History received a batch of specimens from the Far East. In the previous few years, the scientific expedition to Northwest China jointly carried out by China and Sweden continued to deepen, and many world-renowned academic achievements had been made in the fields of archaeology, geology and biology. But at this moment, the museum director Lomborg was still attracted by a specimen: according to the label, it was a gull collected by Swedish guide Georg Söderborn on the banks of the Ruoshui River in Ejin Banner, but even an ornithologist like Lomborg could not accurately classify this bird for a while - he first classified it as a Far Eastern subspecies of the black-headed gull, but soon overturned his conclusion. Later that year, Lomborg wrote a special article analyzing the differences between this gull and other gulls known to the Western academic community at that time, and identified it as an independent species - the Lost Gull (Larus relictus).

In the following decades, the Lost Gull in the Far East has been a hot topic of discussion among Western ornithological researchers, but unfortunately, its whereabouts are so difficult to find that even a complete specimen is difficult to obtain. Some scholars boldly hypothesized that this might just be a Brown-headed Gull with darker feathers, but some scholars found that it was not exactly the same as the Brown-headed Gull, but instead had some characteristics of the Fishing Gull, so they determined that this specimen might be the product of a hybrid between the Fishing Gull and the Brown-headed Gull.

Discussions about the Lost Gull continued until 1971. On the shore of Lake Ala in Kazakhstan today, Soviet ornithologist Auezov finally witnessed the "Lost Gull" with his own eyes. He found that among the gulls breeding on the lakeside, there were large groups of brown-headed gulls and "Lost Gulls" that were exactly the same as the specimens in the Swedish Museum. There was no sign of hybridization between the two, and their ecological habits were also different. This was enough to confirm Lomborg's conjecture that the Relict Gull was indeed a new and independent species. As the latest medium-sized gull recognized by the scientific community, the confirmation of the Relict Gull once again shocked the world. Since then, scholars have discovered a group of Relict Gulls in Lake Torei, Russia, and they have also appeared in the hinterland of Mongolia.

Image source: Tuchong Creative

However, the joy of discovering a new bird species did not last long. As field observations deepened, ornithologists became increasingly worried about the survival status of the Relict Gull: whether in the Soviet Union or Mongolia, the breeding population of the Relict Gull seemed to fluctuate dramatically frequently. In some years, more than a thousand pairs of Relict Gulls could gather in a breeding ground, but they might disappear completely the next year.

What is the size of their population? What affects the reproduction of the relict gulls? Where are there new breeding grounds?

The world's eyes are on the place where Sheng Ruiheng first discovered the relict gull - the banks of China's Ruoshui River.

However, the Ruoshui River at this time no longer had the majestic scenery of water. Ruoshui River, also known as the Heihe River, the second largest inland river in my country, has seen a sharp decline in its flow due to agricultural development in the middle and upper reaches. Its tail lake, the Juyan Lake, has completely dried up, and the Eqi Na section where the relict gull specimen was found has often been cut off, which has dealt a heavy blow to the survival of the relict gulls: According to research on the relict gull breeding grounds in the Soviet Union and Mongolia, the reproduction of the relict gulls is highly dependent on independent sandbar islands in lakes or rivers. The nests of the relict gulls are also very simple. They simply dig out a shallow nest on the beach, and the eggs are directly placed on the gravel. It is conceivable that if the water level near the sandbar is too high, the wet gravel will affect the heating of the eggs, and if the water level near the sandbar is too low, the sandbar may be connected to the nearby riverbank and lakeshore to form a peninsula, and terrestrial predators will wait for the island to prey on the bird eggs. In fact, the reason why the relict gull breeding grounds in the Soviet Union and Mongolia were suddenly abandoned was because of the changes in lake water temperature in different years. At this time, the banks of the Ruoshui River have obviously lost the basic conditions for becoming a breeding ground for relict gulls.

The Lost Gull is lost again.

The lost gull is always wandering

The turning point came in 1987. In Ordos, thousands of miles away from Ruoshui, Chinese scholars accidentally collected a female relict gull, and the subsequent dissection results were even more surprising - its follicles were highly mature, which meant that there must be a breeding ground for relict gulls nearby. In the following years, Chinese scholars continued to explore with Ordos as the center, and finally found a huge breeding ground consisting of 581 nests in Taolimiao-Alashan Bay Lake (Tao'a Lake)! The following year, signs of relict gull breeding were also found in nearby Aobai Nur and Aoken Nur. Since then, the breeding population of relict gulls in Tao'a Lake has continued to expand. By 1998, there were more than 3,600 pairs of breeding relict gulls in Tao'a Lake, accounting for more than 60% of the global relict gull population at that time. Tao'a Lake was soon upgraded to a national protected area and was rated as the 1148th International Important Wetland.

In less than 10 years, the breeding scale of relict gulls in Taoa Lake has expanded sixfold, which of course greatly alleviated people's concerns about the situation of relict gulls, but conservation workers also smelled a hint of worry. According to the recollections of local residents, this "black-hatted" bird actually appeared here in the early 1950s. Hydrological records also prove that the water level of Taoa Lake before the 1950s was higher, and there were no sandbanks suitable for the breeding of relict gulls. The nearby Aobai Nur and Aokun Nur may be their more traditional breeding grounds. However, the area of ​​these two small lakes has shrunk year by year, and Aokun Nur eventually dried up. The water level of Taoa Lake, which was also declining, happened to expose some lake bottom sandbanks, which just met the needs of relict gulls that had nowhere to go. In other words, the increasing number of relict gulls in Taoa Lake is certainly due to people's careful protection, but more of it is a helpless choice after the disappearance of other breeding grounds of relict gulls. If the water level of Taoa Lake continues to fluctuate, this vital breeding ground may be lost again.

As people had inferred, the glorious scene of Taoa Lake did not last long. In 1999, the water level of Taoa Lake surged due to abnormal rainfall, and the sandbar was submerged. After 2000, the continuous drought once again hit the relict gulls breeding there. In 2004, this world's only internationally important wetland dedicated to protecting the relict gulls and their wetland habitats was finally abandoned by the relict gulls because the sandbar was connected to the land.

Let the lost gull no longer be lost

Fortunately, Hongjiannao, which belongs to the same lake and wetland group on the Ordos Plateau, took on the last flame of hope for this wandering population.

Hongjianao is not a stable area of ​​water. It was originally a large lake with an area of ​​100 square kilometers, and was once the largest desert freshwater lake in China. However, today, the area of ​​Hongjianao has decreased by 60%. Around 2000, the water level of Hongjianao was still dropping at a rate of 30 to 50 centimeters per year. The sandbar exposed from the bottom of the lake has become a new choice for the reproduction of relict gulls. However, if the shrinking trend of Hongjianao continues to intensify, it will become just like Tao'a Lake, and can only become a short springboard for the wandering journey of relict gulls.

In fact, since the first discovery of the relict gull breeding in Hongjiannao in 2000, the impact of water level fluctuations on the breeding activities of the relict gull has been extremely significant. The drop in water level not only connected some sandbars to the land again, but also changed the salinity of the lake water. Hongjiannao, which has gradually changed from a freshwater lake to a saltwater lake, is not only unable to support the survival of freshwater fish, but also has sharply reduced the number of chironomids and damselfly larvae, which are important food sources for the relict gulls during the breeding season.

To be fair, the environment of the Gobi lakes is inherently unstable, and the relict gulls must have been drifting in such turbulence for thousands of years. However, the tenacious relict gulls may be able to fight against the harsh nature, but under the influence of human activities such as agricultural irrigation, industrial water use and coal mining, the groundwater level subsidence has destroyed the fragile stability of plateau lakes and swamps, and the extreme climate impact of global climate change on plateau arid areas, it is gradually becoming unsustainable.

Fortunately, the future of this legendary bird is still hopeful because of human intervention. In order to avoid the decline of the breeding ground function caused by the connection between the sandbar and the land, the Hongjiannao Nature Reserve has restored at least four lake islands through artificial excavation; since 2018, the ecological water replenishment work of the two large lakes, Taoa Haizi and Hongjiannao, has been actively promoted under the close cooperation of Shaanxi and Inner Mongolia; and in Tianjin Baguatan, the wintering wetland of the relict gull, the local fishing activities and sea-hunting have also attracted attention. For this legendary bird that has been associated with it for less than a hundred years, we still have many mysteries to solve. Perhaps the bitter journey of wandering is its nature, but whether we can prevent them from being lost again, the answer must be in our hands.

The article is produced by Science Popularization China-Starry Sky Project (Creation and Cultivation). Please indicate the source when reprinting.

Author: Wandering science writer

Reviewer: Huang Chengming, Researcher, Institute of Zoology, Chinese Academy of Sciences