Sun Yuan-hsun's Owl Search

When the once shy and laconic Sun Yuan-hsun goes up the mountains in search of tawny fish owls and runs into trout farmers or aboriginal tribespeople, he first opens his mouth and hoots a few times like a tawny fish owl, then asks them whether they have heard any owl hoots like that nearby.

Since the year before last, when with the approval of his doctoral mentor he returned to Taiwan to research tawny fish owls, Sun Yuan-hsun must surely have become the person in Taiwan who does the best imitation of their call. Who knows, if the owls themselves were to pass judgement, they might even say: "Sun Yuan-hsun, you sound more like a tawny fish owl than we do!"

But sadly tawny fish owls do not show themselves so readily. Over the past two years, searching day after day and month after month, Sun Yuan-hsun has found just one nest in the wild, and seen only a dozen or so tawny fish owls. But he has been able to ring less than ten, and several of those were injured birds "generously donated" by mountain dwellers.

One person, on going into the mountains with Sun for the first time, asked: "Will we see any owls?" The second time, she lowered her sights somewhat and asked: "Will we hear any owl hoots?" The third time, she said she would be very happy just to see some tawny fish owl pellets. But usually even their pellets and droppings are hard to find, for whenever it rains, Taiwan's streams and rivers rise quickly, washing away the traces which tawny fish owls sometimes leave behind them on stream beds.

For Sun Yuan-hsun, a graduate of National Chunghsing University's forestry department, forests have a value far greater than being just "timber depots." The extraordinary interdependence between Taiwan's rich forest flora and its other organisms fascinated Sun so much that after graduating he entered the biology department at National Taiwan Normal University to survey forest bird life, and later went to the University of California to write his master's thesis on "Bird Communities in Cypress Cere."

The forests hold a deep attraction for Sun. After researching bird communities for a while, he wanted to try his hand at researching individual bird species, so he found a mentor at Texas A&M University. He says that to fulfill his family's expectations and for the sake of his own vanity, he followed the crowd and went to get a qualification overseas. But research into Taiwan's wildlife suffered a long hiatus after the end of the Japanese occupation. In the last few years the Council of Agriculture has been looking for people to survey and research wild animals to provide the basis for natural resource management, and Sun's professor in the US also hoped Sun could find his own funding and research topic. Before setting off for the US, Sun, who has never thought of settling permanently overseas, quite naturally accepted a research plan on the tawny fish owl (Ketupa flavipes), proposed by the Council of Agriculture, as the topic for his doctoral research.

Academic research need not normally closely follow practical need, but there is indeed an urgency and deeper significance in the Council of Agriculture's efforts to protect the rare tawny fish owl. The tawny fish owl is a large nocturnal bird of prey. Birds of prey are at the top of their food chains, and understanding the state of their populations helps us assess the stability of the ecosystem. Furthermore, unless we are prepared to see the tawny fish owl disappear from Taiwan, measures to protect it must be stepped up.

In fact, for species to go extinct is something perfectly natural, but throughout the long history of life on earth, species have never been disappearing as fast as they are today. In the past, species would go extinct in the natural world at a rate of around one every 190 years, but today, with the growth in the human population and the overexploitation of plant and animal resources, a living species disappears from the face of the earth every 20 minutes.

In recent years, scientists have discovered that sharks are not susceptible to cancer, the Pacific yew is also now used to combat cancer, and in September a consignment of Taiwan yew was sent from Taiwan to the USA for research. This all goes to show that organisms do not simply exist as pretty ornaments to enrich the natural world--every one of them interacts with others and has its part in maintaining the ecological balance. The disappearance of any single species affects all others--including mankind, who depends on natural resources for survival.

For Sun Yuan-hsun, researching the tawny fish owl offers the opportunity to rethink our relationship with nature, and is also highly challenging.

In December the year before last, after Sun finished attending some courses in the USA, he packed his bags and returned to Taiwan.

As he drives along the road that follows the Nanshih River to Fushan Village, Sun Yuan-hsun keeps turning his head and looking across the river to the mountains, as if he has something on his mind or as if searching for something.

Suddenly he stops the van against the hillside, gets out and points across the water to three green mountains, asking his research assistants: "Can you guess where we would be most likely to see a tawny fish owl?"

His gaze sweeping across the neat rows of makino bamboo, the sparse-canopied secondary forest and the ramrod-straight China firs, Sun Yuan-hsun points to an area half-way up one of the mountains, and says: "Look carefully at that patch of forest--aren't the trees' crowns rounder and broader?" It is a patch of virgin forest: the trees are big and tall with trunks about two armspans around, and enough space between their branches for the tawny fish owl, which stands about two feet high, to move around fairly easily. The canopy of the virgin forest is broad and dense and relatively cool and safe, unlike the lower secondary forest where the birds may easily be spotted and followed by hunters. "Tawny fish owls always select large patches of virgin broad-leaved forest in which to sleep during the daytime," Sun explains.

Although he knows that this spot is a favorite haunt of tawny fish owls, this trip into the mountains ends no differently for Sun Yuan-hsun than most of his other forays since returning to Taiwan. After a heavy tropical rainstorm the streams have risen, and in the valleys we hear nothing but the sound of rushing water, and see only the distant mountains shrouded in mist; there is no sign of the tawny fish owl.

As an object of research, the tawny fish owl is less dangerous than the Formosan black bear, and not as rare as the now extinct clouded leopard. The tawny fish owl is found in India, mainland China and Taiwan, but in the almost 20 years that birdwatching has been popular in Taiwan, this owl has been sighted very few times, and has always been regarded as rare.

Apart from a few scattered records in the travel journals of early Western adventurers, there has never been any formal survey or research of the tawny fish owl reported in the biological literature.

And this is Sun Yuan-hsun's purpose in researching the tawny fish owl. Understanding such aspects of the owl's ecology and behavior as its feeding, reproduction and present distribution will on the one hand provide him with the materials to write his thesis, and on the other hand give the Council of Agriculture reliable data with which to approach the conservation and management of this animal resource.

Difficulty in getting close to the object of one's research has always been a problem faced by all wildlife researchers, and when one chooses to write one's doctoral thesis on a rare species like the tawny fish owl, about which there is an almost complete lack of information, then one must always be ready to pick a new topic and start again from scratch.

Research is not the same as birdwatching for pleasure. Researchers must also find the birds' nests and habitat, and to gain a more complete understanding of the animals themselves, must trap them and attach radio transmitters to them to assist tracking.

But where can one find the rare tawny fish owl?

The fish-eating fish owls account for just seven species among the owls, and are found in Asia and Africa. The only one found in Taiwan is the tawny fish owl. Because their diet is different from owls that eat land animals such as rodents and insects, fish owls usually live along the banks of streams and rivers. According to bird guide books, in Taiwan the tawny fish owl is to be found along rivers at elevations up to 1000 meters above sea level.

This is why since returning to Taiwan, Sun Yuan-hsun has spent more time on the river banks than anywhere else except at home.

Owls are nocturnal birds, active mainly at night. During the day, they hide in the virgin forest and sleep. So Sun Yuan-hsun has to work at dead of night, when one can't see one's hand in front of one's face, yet cannot use a light either for fear of frightening the birds away. A few months ago when he was at Fushan on the upper reaches of the Nanshih River, he didn't get so much as a glimpse of an owl.

Sun Yuan-hsun is no stranger to sleepless nights and to days spent running hither and thither in the mountains and wilds. Sometimes he spends nights outside without so much as a tent, with just a blanket on the bare earth for a bed and the dark blue vault of the heavens for a ceiling.

The students and research assistants who go into the mountains with Sun all know that if you want to see a tawny fish owl you have to scale mountains, follow rivers upstream and chase after clues day and night. But although the ability to endure hardship is essential when searching for wildlife, it is not the only requirement.

The home-made traps with which Sun Yuan-hsun catches his birds are different from those used by hunters. For fear of harming the owls, Sun does not want to use too much force. So his traps have springs to let them stretch, their wires are covered with a protective layer to avoid causing discomfort to the birds' feet, and the foot snares are deliberately loose so it is quite easy for the birds to slip out of them. This causes hunters to mockingly ask just how Sun expects to catch anything in a trap like that.

But one Fushan villager who used to go hunting in the mountains, on hearing that Sun wanted to catch the far-flying tawny fish owls without killing or injuring them, said: "Catching birds alive isn't easy." The birds of prey which hunters used to show and sell on the streets almost always had broken legs or wings and would be unlikely to fly again.

After a string of failures, a turning point came when Sun Yuan-hsun discovered that on the middle to upper reaches of Taiwan's rivers there are now over a hundred trout farms. The trout farmers build rows of fish breeding pools like terraced fields along the banks of the rivers. River fish are fish owls' favorite food, and quite a few trout farmers have said that they have seen or even captured tawny fish owls which were "stealing" their trout. So Sun Yuan-hsun lay in wait hoping to catch many of the birds.

But in fact Sun's first successes were thanks to his work in former years. Seven or eight years ago, when the Taroko National Park was set up, Sun Yuan-hsun assisted in a birds' nest survey there. Early this year he went back, but with another purpose: he remembered that along the Shakatang River, a tributary of the Liwu River, he had seen tawny fish owls.

Sun stayed by the river for two weeks, and by chance in a seven-or eight-meter high large-leaved Nanmu tree by the stream where he was camped, he found a tawny fish owl nest one-and-a-half meters across at the base, built on a parasitic fern of the species Pseudodrynaria coronans.

Owls don't usually build nests, instead often making their homes in hollow trees. But large owls can rarely find trees with hollows big enough for them, and when their breeding season arrives they use cliff caves or the nests of crows or other birds. But a nest constructed on a fern was a new discovery by Sun Yuan-hsun.

Experience shows that as birds' breeding seasons advance, they become less and less likely to react to outside disturbance by abandoning their nests. So Sun waited until the owls' eggs were nearly hatched before setting up his equipment near the nest to photograph and record the adult birds' nighttime feeding and the owlets' hatching out.

At that time he received word from a trout farmer on the Nanshih River that a tawny fish owl had been seen there too. At this news Sun leapt excitedly into his van and sped to the fish farm, where he set up his bird traps. As the number of such sources of information increased, Sun's survey became more successful.

Today, not only can Sun Yuan-hsun answer many previously unanswered questions about tawny fish owls, but his observations have also overturned some past misconceptions about the birds.

Many raptors regurgitate the indigestible parts of their prey, such as fur, scales and bones, and spit them out in fibrous balls known as pellets or casts. By examining the pellets' contents, researchers can determine what the birds have eaten. The pellets which Sun diligently collects from stream beds have given him a new understanding of tawny fish owls' diet. He has discovered that although 90% of tawny fish owls' food does indeed come from the water, the proportion of fish is not as high as had been imagined. Instead, the largest component in their diet is freshwater crabs. The Taiwan common toad, which most birds will not eat because of its poison glands, is also seen as a delicacy by tawny fish owls, and forms their second most common food.

In the laboratory, picking through the little heaps of bones collected from the river banks, Sun Yuan-hsun says that in one day a tawny fish owl may eat fifteen small crabs weighing three to twenty grams each. Among the bones are also those of mice, lizards and of course fish. Despite the pellets' small size, a great deal of information can be gleaned from them. But why does the tawny fish owl belie its name by eating toads? Sun Yuan-hsun says the fact that the tawny fish owl doesn't eat so much fish does not necessarily mean it doesn't like to eat fish; it may be that the numbers of fish have fallen. As for eating toads, it may be that as a large and rather slow-moving bird, the tawny fish owl has no choice but to overcome its "distaste" and eat the Taiwan common toad, which is also large and slow-moving compared to other toads.

Sun Yuan-hsun has gradually grown familiar with the tawny fish owls' language, and has recorded several previously unknown calls in addition to the few basic ones described in the literature.

Owls have complex systems of calls, and different owl species make all kinds of different sounds to express different meanings.

Sun Yuan-hsun was once a student at the University of California's Spotted Owl Laboratory. Every year when the laboratory's 10 or so postgraduate students presented their reports, the classroom would be filled with the sound of hoots and screeches. But it was not the spotted owls which had come there in person, but the students who had all learned to imitate the way the owls communicate. Their perfect imitations of the owls' calls are helpful in finding the birds.

Many people also believe that it is a mark of "respect" to the birds. Even if we don't understand the meaning of every call, if we want to enter the birds' world we should first learn their language.

Today, in the depths of the mountain forests, Sun too calls out to the tawny fish owls. Once when he went out calling for "friends" along the Tunghou River, some owlets and their parents came over together to "chat" with him. Sun Yuan-hsun says modestly "I can't be sure that it was me that attracted them there." But it would appear that Sun is close to being accepted by the tawny fish owls as one of their own.

Sun explains that of Taiwan's other few owl species, the spotted scopes owl's call can travel 200-300 meters, and the brown wood owl's and tawny owl's voices even carry as far as 500 meters. But the furthest away the tawny fish owl's call can be heard is around 150 meters, and it is often drowned out by the sound of running water. Because of this, and because tawny fish owls' ranges are large, it is hardly surprising that even old hands at birdwatching very rarely catch sight of them.

Once, picking his way up the Shakatang River, Sun discovered a tawny fish owl with a range extending four or five kilometers and spanning 10 or more mountaintops.

Thus there is no way one can find and observe these birds just using one's own two legs. Therefore when Sun Yuan-hsun catches owls he attaches radio transmitters to them so that he can trace their movements in the mountains.

However, the transmitters have a limited range, and so for a time along the forestry roads near the Nanshih River and the Tunghou River, one could often see someone driving back and forth through the mountains for no apparent reason. This was none other than Sun Yuan-hsun, searching for angles from which he could receive the signals from the owls' transmitters.

But along Hualien County's Shakatang River there are no forestry roads, so he makes his way upstream with a rucksack on his back, looking for traces of the owls' presence as he goes.

As Sun Yuan-hsun runs here, there and everywhere, almost imperceptibly the scope of his research has grown ever broader, and his mission ever more daunting.

Surveying around a number of tourist spots, he discovered that in the past tawny fish owls were often caught by hunters, mounted as specimens and sold to Japanese tourists.

Hunting flying squirrels with a crossbow is still widespread, and tawny fish owls, which are not such quick or agile fliers as the smaller owls, have often been brought back as an "extra bag" by hunters.

Tawny fish owls' survival is inseparable from that of the virgin forests and the rivers. How much the owls have been affected by past logging is now impossible to determine, but its after-effects still continue to threaten them. Along the Nanshih River soil erosion means that a heavy nighttime shower will immediately turn the rivers into swollen muddy torrents. Mud in the water reduces its transparency, and if the water rises too high it covers all the spots on the river bed where the tawny fish owls might perch, and this affects their feeding.

The pressures which have reduced tawny fish owls' numbers have not disappeared, and today the owls are also faced with the problem of their conflict with trout farmers.

It is true that it was through trout farmers that Sun Yuan-hsun discovered that the tawny fish owl may not be quite as rare as had been imagined, for almost 20 fish farmers told him they had seen tawny fish owls. Trout farms are also where Sun has seen the largest numbers of tawny fish owls. But the trout farmers hate to see their fish stolen, and often set traps for the owls. Many of the birds Sun has "observed" have been injured and dispirited creatures which require treatment and convalescence before they can be released back into the wild. Some are even permanently crippled, and Sun has to find them new homes.

From a conservation angle, animals whose habitats are in conflict with mankind suffer even greater pressure and are even more in need of protection. But the trout is being promoted by the Taiwan Fisheries Bureau as a fish species suitable for breeding in high mountain areas, and it is hard to expect the fish farmers simply to accept losses without taking any action to catch the birds. From the trout farmers' point of view, the tawny fish owl is a "pest" which threatens their fish stocks. If the Council of Agriculture wishes to protect the tawny fish owl, it will have to reach some compromise with the trout farmers.

How many of the farmers' fish tawny fish owls eat in one year, what loss this entails and how to remedy it, have all become topics which Sun Yuan-hsun is investigating. But Sun would also urgently like to find out what the effect is on the tawny fish owl, which relies on rivers for its survival, of trout farmers blocking off streams and using artificial feeds.

All these problems await solutions, but naturally Sun Yuan-hsun's biggest wish is to find more owls and nests. "There's no going back for me," says Sun. He urgently wants to improve the technique of catching the birds, for he feels that surveying the tawny fish owl is something which genuinely needs to be done.

Many years ago, National Geographic Magazine described people who research accipiters as being merely accipiter observers, because the birds are so hard to get close to. As for owls, which are many times more difficult to approach than accipiters, those who wish to research them are generally regarded as dreamers.

But Sun Yuan-hsun has to change this dream into reality.

This year there have been unusually many typhoons, and when Sun went to the mountains in mid-September, he ran into the torrential rains following in the wake of a typhoon system. There was nothing he could do but stop his trapping work for the time being, and with the rivers in spate he could not go looking for owl pellets either. The next morning the rain showed no sign of letting up, but driving up the road along the Nanshih River, Sun Yuan- hsun still kept looking out of the windows, and stopped off at several trout farms along the way to ask if any tawny fish owls had appeared recently.

After checking out the Nanshih River, he turned his attention to the Tunghou River. But after the van had struggled across a stretch of gravel forestry road, its path was blocked by a landslide. With the stones still rolling down, Sun Yuan-hsun, who has seen many such landslides over the last few years, calmly turned around to head back.

As we left the mountain valleys and approached the plain, the rain eased off and hot air came in through the windows, as the weather began to show a different face. Someone said: "Sun Yuan-hsun, your wife will be pleased to see you home early." "Oh yes," he replied, "she'll say: 'That's another few extra days it'll take him to finish his thesis!'"

[Picture Caption]

p.88

(courtesy of Sun Yuan-hsun)

p.89

Sun Yuan-hsun sets traps baited with trout to catch tawny fish owls. He wants to attach radio transmitters to them with which to track them.

p.90

Tawny fish owls are found along rivers at elevations up to 1000 meters above sea level. Pictured is the Nanshih River, one of the main areas of Sun Yuan-hsun's research.

p.91

By the Shakatang River in Hualien County, Sun Yuan-hsun discovered a tawny fish owl nest built on a parasitic fern. The owlet in the picture is watching an adult bird bringing food back to the nest. (courtesy of Sun Yuan-hsun)

p.92

A research assistant from National Taiwan Normal University's biology department accompanies Sun Yuan-hsun upriver to find the tawny fish owl's habitat.

p.92

Although it is an owl, the tawny fish owl is not only active at night, but also sometimes hunts during the day. (courtesy of Sun Yuan-hsun)

p.94

On hearing that Sun Yuan-hsun is researching tawny fish owls, a trout farmer allowed him to examine and ring an owl which he had captured some time previously. But unfortunately the bird had been captive too long to be released into the wild.

p.95

Sun Yuan-hsun adjusts his antenna to test whether it can locate the signal from the transmitter attached to a tawny fish owl.

p.96

Crossbow hunting and conflict with trout farmers--the main threats faced by tawny fish owls today-- mean that nowadays one can see more owls in captivity than in the wild.