ASIAN OPENBILLS: NEW CHINESE IMMIGRANTS
In recent years, a large bird who originally lives in South and Southeast Asia—the Asian openbill, has become new bird immigrants to China. What stories do they have to tell?
In recent years, a large bird has gradually infiltrated the lakes, wetlands, and rice fields of Southwest China. It has come in great numbers, and flourished. These new additions to China’s avian fauna are Asian openbills ( Anastomus
oscitans ), members of the stork family with an eye-catching beak that seems to never close. As unique as their beak may be, the more perplexing question is just how these openbills got to China in the first place. And why so suddenly? What was their route? Bird researcher Han Lianxian has followed and monitored these new immigrants for the last four years, and brings us a first look at China’s newest storks.
In Bangkok, along the shores of a suburban wetland in the spring of 1992, I saw my first Asian open bill( An as tom us os cit ans ). I was a shortterm visitor at Mahidol University, and during a break from class I headed out to the wetland, a known bird haven, for some fresh air. An experienced birder, I was able to quickly piece together its taxonomy—legs… body… habits… plum age; it was a stork—and the beak, once one turned allowing me to see them side-on, was unmistakable: it was an openbill. But I was not an expert on Thailand birds, so I carried my curiosity back to the office and after a short check with local bird identification guides I was able to pin down the exact species—asian openbill. At the time there were no records of such birds in China, so everything about them was new to me. I learned that they were commonly found “throughout South and Southeast Asia” and that they were “mainly tropical waders”. Scanning a map of their known range, I listed off the countries in my mind that these charismatic birds called home: India, Pakistan, Nepal, Myanmar, Thailand, Sri Lanka, …
At the time of my chance encounter, I could never have expected that more than 20 years later my professional work would bring me back to these birds. After leaving Thailand I returned home to China, and began working as a bird researcher. When left Thailand, I also left the birds, never expecting to see them again. However, after years of living apart I one day found myself facing down another Asian openbill— but this time, they came to me.
In tropical Yunnan Province, in the wet, sunny, and warm southwestern regions of China, the Asian openbills have made a new home: they are China’s newest immigrants. Species often change their ranges—shifting, expanding, and shrinking—but often it is done slowly. These storks have ignored the ecological rules and have instead come in droves. The arrival of such a great number of these birds caused quite stir for multiple reasons. The most pressing question was “how”: how did they get here? To try to answer this and other questions, for the past few years we have tracked a group of these storks, carrying out a systematic study of not only how many there are and where they are, but also their ecological behavior. All I knew of them at the time were the tidbits I remembered from the identification books I skimmed through all the way back in Thailand. To really know the birds, and understand their role within China’s ecosystems, we would have to get to know them a whole lot better.
In Constant Fluctuation: Asian Openbills in China
To the Chinese, these strange storks came as quite a surprise. On October 3, 2006, the first official observation within China was made by Beijing birder Wang Yitian in Yunnan’s Eryuan West Lake, a picturesque oasis well known to birders. At the time he had
no idea exactly what it was, but he was experienced enough to know that it didn’t belong here; he uploaded his photo to a birders website and waited. It was on that very website that I saw this lonely image of an out-of-place bird on the shores of a lake I knew so well. My heart stopped, flooded by memories of my first encounter so many years ago in Thailand. I sat back in my chair, wide-eyed and stunned, and said to myself: “They’re in China.”
A few years later, in the spring of 2010, I received an early morning phone call from Xiong Shengxiang, an employee of the Zhenkang County Forestry Bureau in Yunnan. He told me that some “black and white birds” had recently appeared around the local fish ponds and rice paddies throughout the county. “Nobody knows what they are,” he told me, hinting that he needed my help. “Let me have a look, I’ll try my best” I replied, not sure that I would be able to outdo a host of local experts from a region I was not overly familiar with. “I’ve already emailed you the picture…it’s waiting for you” he said. Hanging up the phone and opening my laptop, I considered what it might be. I had suspicions—zhenkang County is close to Myanmar, a place rich with openbill storks—but I would have to wait a few more moments to find out. I waited impatiently as the computer loaded, and finally clicked on the attachment. The moment it opened, I knew what it was: An Asian openbill. They just kept following me.
Shortly afterwards, the openbill floodgates opened: reports of openbills started to come in from places all throughout Yunnan. Pu’er and Xishuangbanna in particular became hot news items among both amateur birders and professional ornithologists, and the sightings began to explode. It soon became obvious that these were not rare, accidental sightings of lone birds. In many instances there was a dozen, sometimes dozens, of individuals; the Asian openbill had arrived, with vigor, to South China.
The range of any given species is naturally fluid. Animals move, guided by the biota, topography, and climate, and are otherwise unobstructed by invisible lines drawn on maps; the fact that the Asian openbills have “entered China” is in itself nothing noteworthy. That they have moved into China, to novel ecosystems, in such numbers and in such short times is, however, ecologically breathtaking. What would normally take generations to accomplish, the openbills have done in a proverbial flash.
Observing these new arrivals is relatively easy. Having a tendency to flock, Asian openbills are hard to not notice. Their imposing size makes it somewhat easier, too. Waders, these birds also cluster together on the water’s edge, their long legs plodding along the shallows as they peck their beaks through the still water searching for a meal. When they arrived to China, the wetlands, rice paddies, and lakes exploded with openbills. This is a blessing for biologists. With the increased awareness of environmental issues coupled with an increase in wild species protection, easily
observable species—particularly novel species to an ecosystem—are important and easy barometers of ecosystem health. How long will the birds stay? What is their impact on the aquatic ecosystem that supports them? Are they pushing out native species?
We collected data on these Asian openbills for almost four years, between 2010 and 2014. We undertook extensive fieldwork, did in-depth reviews of scientific literature and local birding reports, participated in staff exchanges with local agencies experienced with the openbills, and we collaborated with a wide range of local and international wildlife protection agencies. It was a wide ranging and exhaustive endeavor, but from it we learned much. To answer the most pressing question of “where?”, we finally have a map: Asian openbill storks are now found in 24 regions in Yunnan Province, seven regions in Guizhou Province, three regions in Sichuan Province, and one location in Guangxi Zhuang Autonomous Region. Combining these data, a roadmap of how this bird came to China is starting to become clearer, answering the second question of “how?”
Beginning in the spring of 2010, Asian openbills appeared in great numbers across southern and central Yunnan. From there they spread north, until 2011 when there was an eerie silence: during the entire year there were no new reports. But as suddenly as the reports stopped, they picked up again. Between 2012 and 2014 reports came in from Yunnan and then progressively outwards to Guizhou, Guangxi, Sichuan, and eventually Guangdong. It was
a clear wave of immigration, and Yunnan was their window into China.
Not only did their geographical distribution blossom in a short period, but so too did their numbers: in 2010, the largest flock had only 90 birds; by 2012 and 2013 flock size had increased to almost 500. Since 2013 their distribution has decreased slightly, a sign that they may have met their geographical limits and may not venture any further into China. But, at the same time, their population has become more robust, becoming more concentrated in the places they inhabit. Today there are more than 100 large flocks dotted throughout Southwest China.
Interestingly, while their spread across China has been rather steady, their total numbers have been prone to substantial and surprising fluctuations. For example, in the spring of 2012, when the openbills arrived at Changqiao Lake in Yunnan Province, their total population barely reached 200. By the end of the study in 2014 there were more than 500, but by May of 2015 their numbers had plummeted to just 39. Throughout 2015 their numbers again rose to almost 1,000, only to crash once again by December. These patterns were reported elsewhere across their newfound range, too. I never could have imagined such dramatic changes in a bird’s population over such a short period. It was as peculiar as their sudden appearance. Later, a follow-up report came out adding even more surprise to the Asian openbill story: in April 2016, there were more than 1,300 wading on Changqiao’s placid shores.
Studies examining behaviors of Asian openbills show that they are not seasonal migraters, choosing instead to remain in a single area throughout the year. However, they do respond to the whims of their environment—a change in food supply or dramatic climatic shifts—and it is not uncommon for them
to move based on their needs. These surges can be dramatic: in West India, for example, local Asian openbills were found 800 kilometers to the west of their native range, while another group from Thailand was found in Bangladesh, astounding 1,500 kilometers from their home. These new immigrants to China seem to be following the same routine as exhibited by these distant birds; however, unlike these instances of major range changes, where the birds eventually all returned home, this one seems to be permanent. Despite their fluctuating numbers and a tightening of the original range they had when they first arrived in China, the openbills are here to stay. With ample wetlands and lakes, reservoirs and rice paddies, fish ponds and ditches—perfect habitat for the openbills, and their favorite food—they seem to have stumbled upon a new permanent home.
Though they fluctuate in numbers, it seems that they have established a pattern. Our studies in Yunnan, for example, show that the Asian openbill population increases quickly each year around February and March, finally peaking around late April. Come autumn, their numbers begin to drop, and by October they are mostly gone. But never totally gone. In regions where the food is rich, and the habitat suitable, they are more reluctant to make their retreat. In Dali, the uniquely large and shallow Caohai Lake has attracted a small group of openbills for a whole year; in Mengla, a bustling county in Xishuangbanna, a group of openbills was monitored stayed in the region for over 20 months straight, and counting.
There is a belief among many, called the “rare bird hypothesis”, which goes: “The presence of rare birds means the local environment is getting better”. Put another way, if you can spot a rare bird there is nothing to worry about—the ecosystem is strong. People have tried to use this to explain the connection between China’s ecosystems and the presence of openbills. There are, however, two striking errors in this line of thought: first, Asian openbills are not rare, and not endangered; second, the natural causes of bird movement are many and in no direct way reflect the minutia of a given ecosystem. While they are not commonly found in all of China, these birds are definitely plentiful in their native range. And this range borders China, and shares a relatively similar “South Asian tropical” ecosystem. Moreover, the movement of birds across their range and into new area is completely natural and normal. Sometimes the ecosystem they once inhabited becomes inhospitable—climate change, loss of a key food source, or increased competition, for example—and sometimes, just by raw numbers, the population grows to a point where the species needs to cover a greater area to accommodate its population. When they spread out, for whatever reason pushed them out of their old range or pulled them into their new one, they settle. Their range expands, and maps are redrawn. It’s natural.
Thailand, India, and other places throughout Asia’s southern realm have a large and strong population of Asian openbills. Their ability to adapt
to new habitats is known, and evidenced by their relatively saturated distribution throughout their range. To understand their proliferation in China, it is necessary to know more than just where they are; we need to know if their population in their native range has itself changed over time. In search of these answers, I spoke with Chen Chengyan, a researcher with Bird Life International. He told me by email that “thousands of Asian openbills were found in the Kuala Gula wetlands in Malaysia in January 2013”. In Vietnam, he wrote, “more than 100 openbills were observed in the northern region”. Both of these areas, he reminded me, are not traditionally known as openbill territory. To Vietnam and Malaysia, just like in China, openbills are spreading out to new places all across their range.
I contacted ornithologists from Thailand, hoping to clarify the specific range and movement of openbills within Thailand. Originally confined to the southern part of the Chao Phraya River, the warmer and more tropical regions near the Gulf of Thailand, in the year 2000 they were observed in large numbers in the rivers northern reaches. This was a large shift in their range, and like their movement into China years later, it was fast— many birds arrived all at once, and called it home for good. Their expansion along a single river system is understandable, following a single thread of suitable habitat north. But their eastwest movement has also been observed, spreading out to the far away Laos border. Something strange has taken place during this time: as this population moves and expands, they tell me, their original territory is becoming depleted in openbills. It seems that in this case it is not just that the birds are “expanding” their range, but that their range is instead “shifting”.
This is an important ecological distinction, and the Chao Phraya River in Thailand is a good case study of this phenomenon. In 1969 there were 20,000 openbills, and nearly 100,000 by 1991, an increase that was rather constant throughout the intervening years. By 2007, an astounding 470,000 birds called the river home. However, as their population was increasing, and expanding outwards across Thailand, the original Chao Phraya population began to
precipitously drop. By 2008, there were only about 150,000 openbills on its banks. The explosive growth of these birds in other places seems to be perfectly mirrored by their equally impressive loss from the Chao Phraya.
How does this reflect on the phenomenon taking place within China? What we know of the openbill population and arrival into China is this: Asian openbill came to China as a result of an expanding population. Their numbers seem to be growing, and their need for new space drove them north to China. During the early period of their arrival, when reports were just starting to trickle in, there was a total of 892 birds reported at 22 different locations across Yunnan. Most of these reports included a vitally important detail, supporting the “population expansion” hypothesis: the birds moving into China were all young or sub-adults, new offspring moving outward to new lands. It seems that these Chinese immigrants were not here for the same reason of those in Laos, Vietnam, and Malaysia; the openbills in China are a spillover from their native range—still thick with openbills—while those moving to other parts of Southeast Asia are appearing to be refugees or explorers, mostly adult birds leaving their home range. In China, the population was expanding. In Southeast Asia, the population was shifting.
There have also been connections made between global warming and the movement and distribution of certain species of birds. Does the Asian openbill add another data point to this pattern? Are they expanding northward only as a result of an increasing population, or is there a climate connection? We just don’t know enough yet.
Interestingly, it could be twist on the climate-related connection that allows them to thrive in China: they seem to be tropical birds who love the cold. The wintertime temperatures in their new Chinese range are oftentimes frigid, temperatures unseen in their native range, yet they stay and they survive. Caohai Lake, for example, drops below freezing for much of the winter but the openbills that have come to live on the lake are almost all year-round residents. This suggests a strong cold tolerance, and as the shallow-lake provides a wide range of their key food items, particularly the channeled apples nail( Pomaceacanaliculata ), a freshwaters nail and open bill’ s delicacy. Together, the expanding population, driven perhaps by climate change, and their tolerance to cold and the bounty of food in their new home all provide their own piece of the puzzle in explaining why the Asian openbill is now, officially, a Chinese bird.
However, if it were not for one snail, the openbills would never prevail.
The Main Attraction: The Invasive Apple Snail
In Thailand, the channeled apple snail is the Asian openbill’s favorite, and most important, food. They basically live off the snails. Leaving Thailand and moving hundreds of kilometers north to China would normally mean a change in diet, but our studies show that their menu did not change. And this may be another clue as to why they have done so well there. In Yunnan’s Changqiao Lake, we conducted a systematic observation of Asian openbill feeding. Despite being invasive—originally from South America—here in China, just like in Thailand, the channeled apple snail comprises almost 90% of their diet, the rest filled in by various other snails, frogs, mussels, and crabs.
These invasive snails have become impressively important to the survival, and growth of the openbills. In the 1970s and 1980s they were introduced to
China as a food for humans. However, many of them went unsold and, inevitably, were discarded in lakes and rivers and roadside ditches. Nobody at the time thought that they would become a staple in Chinese aquatic ecosystems—nobody anticipated that they would be able to survive. But survive they did: impressively adaptable, they spread rapidly and found a perfect home in the almost constantly wet landscape of lakes, wetlands…and rice paddies. Those rice paddies, while providing China’s most important staple crop, were also responsible for giving these invasive snails a chance to take over. Once their harm was realized, ecologists and farmers together tried to come up with ways to remove them, but to little effect. The snails became a part of China, and left a great trail of ecological destruction in their wake.
The Asian openbill, a voracious snail eater, unexpectedly became part of their solution. With their arrival, and skillful and dedicated predation on these unwanted snails, their population finally seemed to be in check. And, their prevalence meant that the openbills had an almost endless supply of food.
Watching them feed is a treat, too. The wading openbills will wander the shallow water’s edge and furrows of rice paddies, gently dipping their beak into the water to explore. Once they spot a snail, it will violently grasp it in its beak and rip it from the muddy bed below. It will walk to the shore where it can rest the snail on the ground, and being shaking its beak deep into it the snail shell. Finally extracting it from its shell, it will gulp down the now shell-less gastropod, and return to the shallows in search of more. The whole intricate process takes no more than five seconds. As the Asian openbills line up along the shallows eating their daily dose of invasive snails, a sea of empty snail shells lines the shore. We
note one interesting thing about their feeding—they never eat the snail eggs. Large clumps of bright pink eggs are strewn around the lake, some still attached to the snails themselves. These are never touched.
Adult and chicks compete for the same snails, but their skills are definitely not equal. In the time it takes a young bird to consume one snail, an adult will have consumed three. Clumsy and slow, the young chicks seem less to be taking their time, and more just figuring out how to deal with their unique beak.
While the adult feeding is quick and concise, they don’t appear rushed. As the adults finish feeding on a snail they often look up and pause, scanning the lake for potential predators or possibly taking in their new scenery, and we get a perfect look at those unique beaks. More than unique, their beaks are eccentric, resembling pliers more than a beak; they are, however, perfect weapons for their shelled prey and a mes- merizing testament to the pervasive creativity of evolution. Watching the openbills eat, I noticed another peculiarity. Walking along with the openbills are two other species, western swamp hens( Porphyrioporphyrio ) and little egrets( Egrettagarzetta ), and I notice the swamphens purposely walking behind and picking up snails missed by the openbills. Normally strict vegetarians, feasting on the young shoots of aquatic grasses that grow along the lake’s edge, this is the first time I have ever seen swamphens eating meat. Have these invasive snails turned them into carnivores? Are they mimicking the storks, noticing the bounty of food available just a few wading steps into the lake? Unfortunately, our survey only lasted 12 months, and we did not get a chance to monitor the long term feeding habits of these vegetarians-turned-carnivores. Otherwise, I am certain that we would have uncovered even more interesting behaviors.
It now appears that the channeled apple snail is in Yunnan to stay; despite the valiant efforts of ecologists and farmers, and the voracious appetite of the Asian openbills— and the now meat-eating swamphens— the snails prevail. So too have the Asian openbills become part of China’s fauna. A large area, rich with snail-filled watery rice fields, lakes, wetlands has become—despite the sometimes frigid temperatures—a new oasis for these birds.
New Crisis for New Immigrants
For these new arrivals to China, life is not perfect. Like the abundance of rich resources and suitable habitat, so too are the crises abundant. Local agriculture has certainly benefited from their presence— helping control a wildly imposing invasive snail— but humans, as always, have made their mark in other ways. During the openbill study, we found several carcasses of what seem to be healthy individuals in several locations.
In 2010, the year when the Asian openbill stork began to enter Yunnan, particularly in the Luosuo River region of Mengla County, local villagers began to hunt them for their meat. Fortunately for
the birds, word quickly got out that their meat was neither plentiful nor palatable; before hunting could take its toll on its population, people knew it was not worth their worry and no sustained hunting ever took root in the community. In this case, the bird’s lackluster meat saved its hide.
But in the spring of 2012, evidence of a renewed hunting crisis emerged. In Jingdong Yi Autonomous County of Yunnan, where a population of 60 Asian openbills was observed, the local government tried to stem any potential hunting— poaching, really, as is illegal to hunt them—by posting notices and handing out educational fliers warning the public not to hunt, while also trying to raise awareness that the population was important. Regardless, only a few days after the word got around that these large and uniquely-beaked birds had arrived, only eight remained. A similar situation has also developed in the Changqiao Lake region, where hunting has become pervasive in these regions for something other than their meat. Liu Qiang, an ornithologist of the Southwest Forestry University, fitted three Changqiao Lake openbills with satellite radio tracking devices. To attempt to track them in both time and space— where do they go, and when do they go there—he attempted to follow these birds in a long-term, multi-
year study. However, not long after fitting the birds with the trackers he found two dead, killed by poachers. He was left with no data, and no birds.
For these new immigrants to China, even though they seem to have found their niche and have found a way to fit in, life is not easy. While they have seemed to be coping masterfully with nature, it is the new crisis—humans—that will pose the greatest threat in the years to come.
Strange Bills The most distinctive feature of the openbill is its odd-looking bill. The upper bill of the adult is almost straight, yet the lower one is obviously bending, meaning that this bird can never close its long, strong bill.