CHENGDU, China -- Li Shang-yin, a writer of the Northern Song Dynasty (960-1127), is said to have kept five species of birds in his garden, including a graceful gull whose head and bill were black, and which had a distinctive semicircle of white behind its eye.

However, though ornithology took root early in Li's homeland of China, neither there nor anywhere else was there any record of such a gull, despite the hundreds documented, drawn and stuffed for display from the 18th century onward.

That was until the winter of 1871, when a European traveler called Robert Swinhoe reported just such a bird inhabiting coastal areas of Xiamen, a bird he named Saunder's gull (Larus saundersi). Though there were sketchy reports of a French explorer claiming two sightings in the Lake Baikal area of Russia in 1884, for more than a century after that Saunder's gull eluded the best efforts of the world's bird-watchers to track it down and learn anything about its habitat, habits or breeding.

In the 1970s, the trail appeared to be getting warm again, with reports of sightings in Mongolia. Some professional ornithologists duly went out there with high hopes -- only to come back having failed in their quest.

And so it went on, prompting ornithologist David Melville, then executive director of the World Wide Fund for Nature Hong Kong, to declare Saunder's gull the world's rarest gull, whose breeding region was still unknown.

Then, when he returned from studying waterfowl in coastal marshes at Yancheng, in China's Jiangsu Province in spring 1988, Shi Ze-rong brought with him specimens of Saunder's gull, eggs and nestlings. Undoubtedly, his discovery was one of the most important achievements in 20th-century ornithology.

That breakthrough was followed on May 22, 1989 with the discovery of two nests and four eggs of Saunder's gulls by Liang Yu, working in coastal marshland in the Shuangtaihuokou (STHK) Nature Reserve at Panjin in China's Liaoning Province.

Immediate surprise

This news shook the world of ornithology, and a joint Chinese-international investigation team soon descended on the STHK, where more than 180 species of birds -- including ducks, gulls, storks and cranes -- can regularly be spotted. After so many years, even centuries, of mystery, the team was immediately surprised by the large breeding area occupied by Saunder's gulls. During a 100-day stay, the team was able to observe in some detail the bird's distribution, nest-building, mating, egg-laying, feeding, brooding and raising of young. In all, the team put the STHK population of Saunder's gulls at around 1,200 adults and 310 nestlings -- some 70 percent of the world's estimated total.

In recent summers since then, as if in a dream come true, this writer and colleagues have spent time at STHK making further valuable firsthand observations and gathering data on the Saunder's gull.

Located at 40°45" to 41°10" N. and 121°30" E., STHK is an 80 sq. km area of reeds and marshes located in the alluvial plain of the lower reaches of the Liao, Hung, Taizhi, Raoyang and Daling rivers, which is a paradise both for its thousands and thousands of resident and migratory species.

To see the Saunder's gull there is to behold such a graceful bird that it is easy to understand why it has been loved since ancient times. About 37-40 cm long, with that characteristic black head and white crescent behind the eye, the gull's back feathers are gray-white and its belly is the color of snow. A good flier that seems to dance and glide so gracefully in the sky, in sunshine a Saunder's gull can look like an airborne white flower with a black stamen. Also, although its feet are webbed, it spends very little time in water, which sets it apart ecologically from other gulls.

We now know that these gulls winter in coastal regions south of the Yangtze River, from its mouth to Hainan and Taiwan. In the latter half of March, they begin returning to STHK and, after courtship and pairing, mate from April until the middle 10-day period in May. They build their shallow, dishlike nests of grasses and reeds on shoals and mud flats. Sometimes, many nests occur in a particular area (called group-nesting), with each about 5 meters from its neighbor.

Eggs, usually in clutches of one to seven, with three seemingly the norm, are laid at the end of April. Elliptical in shape, and dark green with many brown spots, these are brooded by the male and female birds in turn for about 30 minutes at a sitting for 24-26 days before the chick emerges. Within an hour, these hatchlings are tottering around, and 30 days later they can fly.

One thing that has particularly impressed us on every visit at this time of year to STHK has been how territorial the Saunder's gulls are in protecting their nests. One morning, for instance, we were trudging through the marshes in search of nesting sites, loaded down with cameras and camping gear, when a flock of them suddenly appeared overhead, crying "ga-ga-ga," then wheeling and diving and almost pecking us with their sharp black beaks. As we walked on, after about 300 meters we came to the first nest (in which there were six eggs), then about 10 paces further on we found another . . . and then we found ourselves in sight of more than 20 altogether in an open, flat area of about 100 sq. meters.

Sweltering tents

As we began pitching our tents nearby in a good position from which to observe the site, more and more Saunder's gulls began mobbing us, all crying "ga-ga-ga" in a rising cacophony as they pelted us with feces that splattered like volleys of bullets on the tents. All we could do was to remain silent and motionless in the sweltering tents, but amazingly, after about 30 minutes, everything returned to peaceful normality. Perhaps the gulls had realized we were an unthreatening presence in their midst, and so just went back to brooding on their nests, allowing us a fascinating opportunity to record their behavior.

All that day, despite scorching temperatures in the 40s, we decided to stay in our saunalike tents so as not to disturb the gulls any more. Finally, as the sun was sinking in the west, and with our food and water finished, we quickly broke camp, loaded up and headed back to base. As we did so, a small flock of Saunder's gulls came over, crying "ga-ga-ga" and seeming to give us a great sendoff after what had been a marvelous day spent observing this beautiful and for so long elusive bird.