Birds on the Brink of Oblivion--Taiwan's Orioles

As day breaks over the Martyrs' Shrine in Tanshui, the dawn chorus is in full swing. From among the Formosan sweetgum and mango trees that stand tall over the grass comes the constant call of black-naped orioles, sometimes near, sometimes distant. Bathed in this babble of birdsong, if one looks out from the Martyrs' Shrine towards the far-off Kuantu Plain one can see white egrets flying lazily over paddy fields. The poet's lines, "Man tills, woman weaves, life is peaceful,/ Orioles sing brightly among spring grasses and trees," could have been describing the scene at the little town of Tanshui.

Amateur ornithologist Chu Hung-pin, who for the last six years has been tirelessly observing the black-naped orioles here, says that the birds' yellow plumage is a familiar sight in the area around the Martyrs' Shrine, the golf course and Wenhua Elementary School. Local residents all recognize the oriole's golden raiment and black-barred wings.

There is a Taiwanese saying that "the oriole is an emperor, the drongo is a disappointed scholar, and the kite is a beggar." This is simply because the black-naped oriole's golden-yellow plumage is like the robes of an ancient emperor, and the black drongo's inky plumage gives it the air of a down-at-heel scholar, while the black kite's rough and mottled feathers, and its habit of snatching chicks to fill its belly, suggest a starving mendicant.

Shady summer woods

While Tanshui is echoing to the sound of black-naped orioles greeting the spring, the maroon orioles of southern Taiwan are also opening their throats and singing with all their might. At Shanping, nearly two hours' drive from Kaohsiung, bright red maroon orioles flit back and forth amid the rustling leaves of the evergreen broadleaved tropical woodland, their bright voices carrying clearly from one hilltop to the next. But as the weather grows hotter and the oriole fledglings begin to leave the nest and learn to fly, the resounding song with which the male birds call to their mates in the mountain valleys changes to the low, deep call that they use to declare and defend their territories.

If the black-naped oriole is known as a "golden prince," the maroon oriole too is greatly admired for the noble elegance of its red body and black wings. It was regarded by 19th-century adventurers as one of the most beautiful of Taiwan's rare birds.

The black-naped oriole and maroon oriole are both exquisite in appearance. Of the 28 members of the oriole family worldwide, they are the only ones native to Taiwan. Members of the oriole family are generally medium-sized mountain birds around 25 centimeters long, with body feathers of a single bright color, a shining black cap and wings, a large, thick bill, and a white ring around each eye. This striking plumage has always attracted people's attention. In particular, thanks to folk songs like the Taiwanese "The Snail and the Oriole" and the Mongolian "The Little Oriole," the black-naped oriole is familiar even to modern urbanites who have never seen one in the flesh.

A marginal bird

As for the red-feathered maroon oriole, despite its delightful appearance it rarely gets a mention in Chinese literature. However, this is not because the ancients were biased against maroon orioles, but simply because they had never clapped eyes on one. If we look at a map of oriole habitats, the territory occupied by the black-naped oriole stretches across half of mainland China, all the way from the northeastern provinces down to Taiwan and across to the foothills of the Himalayas. But the maroon oriole lives "on the edge," being found only on Hainan Island, in Yunnan Province and on Taiwan. In olden times, the only educated folk likely to see one would be hapless officials banished into exile at the fringes of the empire.

Taiwan has the good fortune to be home to both the black-naped oriole and the maroon oriole. Early naturalists often happened upon flocks of ten to 20 maroon orioles, and black-naped orioles were by no means scarce either. After a journey through southern Taiwan in 1858, British adventurer Robert Swinhoe wrote of seeing many black-naped oriole in the bamboo forests at Fangliao, along with many black bulbul nesting on the curved bamboo branches.

But today, the maroon oriole and the black-naped oriole have both become rare species. "Nowadays you hardly ever see a large flock of maroon orioles. At most you'll only see two to four birds flying together," say birdwatchers. In their experience, maroon orioles are to be found at the edges of Taiwan's natural and planted woodlands at elevations below 1000 meters, in a "discontinuous distribution." After surveying maroon oriole populations, researchers from the biology department at National Sun Yat-sen University (NSYSU) estimated that there are less than 1000 of the birds left in all of Taiwan.

Mainland immigrants?

Maroon orioles are rare, but in Taiwan those hot literary properties, the black-naped orioles, now only breed at Tanshui in the north of the island, and at Yingta Farm in Pingtung County in the south, and their breeding populations in each of these locations have long remained static at three to five pairs. "Their numbers just don't increase," says Tseng Yi-shuo, a postgraduate student in the wildlife conservation department at National Pingtung University of Science and Technology. Tseng even suspects that these birds may be "immigrants"-birds from central and southern China which, driven by intense habitat competition on the mainland, attempt to settle and breed in Taiwan when they pass this way on their summer migration.

Why is the black-naped oriole faithful only to Tanshui and Pingtung? This remains a mystery. Because most members of the oriole family live in Africa or Asia-Europe has only one native oriole-internationally there are very few reports on oriole species. For a long time there was no systematic observation of the maroon oriole or black-naped oriole in Taiwan either, and there was a dearth of basic information on such topics as in which months they breed, what proportion of their eggs successfully hatch, and how much their populations fluctuate over time.

It was not until 1989 that the Council of Agriculture first placed the maroon oriole on its list of nine endangered bird species in Taiwan. In order to gather the basic data needed for wildlife conservation, six years ago, with funding from the COA, the biology department at NSYSU began observing maroon orioles at Shanping.

In March spring is in the air, and the male maroon orioles yield to their seasonal urges and begin calling continuously for a mate. In their hurry to raise their brood before the end of summer, the oriole pairs have little time for romance, but quickly get down to the practical task of finding places to build their nests, in large trees such as batai or African tulip. When it comes to raising the chicks, the male and female birds have a clear division of labor. The female builds the nest and incubates the eggs, while the male stands guard. For about five days the female can be seen shuttling back and forth, carrying in her beak dry twigs and pine needles from which she constructs the nest. Once the structure is stable she gathers dry leaves to make a soft, comfortable layer on top. Finally, she lifts up her tail and plumps herself down on her bottom, moving round in a circle, to make the nest dense and firm. The finished nest is shaped like a bowl hanging below the branch.

While the female is hard at work, the male is not idle. As soon as the nest site is chosen, the male oriole begins busily announcing: "This is my territory!" If a squirrel comes near, or a bird of prey such as a Japanese lesser sparrowhawk, the male bird swoops down on it, face to face, to drive it away. No matter how fierce the intruder, the male bird usually succeeds in chasing it off.

As the young are gradually fledged, their attentive father constantly brings tasty tidbits in his beak to tempt his offspring to practice walking or hopping from one tree to another, and then teaches them how to fly and to find their own food. No effort is too great.

Thanks to researchers' efforts, some of the mysteries of the maroon oriole's reproductive cycle have now been revealed. When it comes to the black-naped oriole, however, there are so few nests that there is hardly the material for a research dissertation. But fortunately one birdwatcher has been faithfully observing the birds in Tanshui and Pingtung for many years. In Chu Hung-pin's eyes, the depth of affection between male and female black-naped orioles is just as heartwarming as that between maroon oriole fathers and their young.

Once, when Chu Hung-pin arrived at the Martyrs' Shrine at dawn one June day, he discovered a female black-naped oriole lying under a hibiscus tree. Her chicks had been taken by a squirrel, and in her desperate struggle with the predator she had lost most of her primary flight feathers. Chu hurriedly took her to the Wild Bird Society's rescue center for treatment. "After that, the male bird stood watch in the tree every day, standing by the nest and calling. He stayed there for 20 days, until the female was brought back," recalls Chu.

Overrated singers

Through their close observation of maroon and black-naped orioles, ornithologists have discovered that the "orioles' voices and swallows' language" from which humans have so long drawn emotional sustenance actually play an important role in the birds' reproduction.

The ancient Book of Songs says of the oriole: "Yellow bird with deep-set eyes, how sweet your voice." The 16th-century Compendium of Materia Medica declares: "Its voice is as smooth as the sound of the loom." "Willows, Waves and Oriole Song" is a famous scenic spot on West Lake at Hangzhou in mainland China.

But when one asks birdwatchers who are familiar with orioles, they shake their heads in embarassment and say that it is very hard to associate the birds' calls with the phrase "oriole from the valley," which in Chinese describes a person with a beautiful singing voice. Tseng Yi-shuo says bluntly that the black-naped oriole's song is like the bleating of a sheep. Chu Hung-pin says that during the mating season, the call of the male black-naped oriole is deep and rasping, but the sound is very distinctive and carries over long distances, and the bird will sing for one to two hours at a stretch. Maybe this is why the oriole's song attracted people's attention. The oriole's incessant mating calls made one distracted ancient, torn from a pleasant dream, want to "shoo away the yellow oriole, and not let him squawk upon the branch"!

Unlike the passionate poets of old, modern birdwatchers are more interested in facts, and have "unmasked" the reasons why "the darting orioles coo each day among the flowers." In her master's thesis on "Songs and Breeding Behavior of the Maroon Oriole," Chang Su-ching, a graduate student in NSYSU's biology department, probes the question why maroon orioles spend so much time warbling sweet nothings.

After analyzing large quantities of recorded maroon oriole song, Chang divided the calls of the male bird during the mating season into five categories, according to their sound spectrum. They include a rough and rasping "a-," a graceful whistle, a rapidly repeated "ga-ga-ga. . ." and so on. Professor Chang Hsueh-wen of NSYSU's biology department says that some birds, such as the Chinese bulbul, seem to have only one song, but in fact that song includes a great many variations on a basic theme. The maroon oriole has a greater number of different songs, yet there is little variation within each, and what variation there is, is often only a matter of length. But each song has a clear function.

For example, the call the male maroon oriole makes most often, a loud "wu-wu-," has the lowest frequency of all his songs, but also carries the furthest. When the female is incubating her eggs, she gets "time off" every two to three hours to find food and water. If she does not return within about 15 minutes, the male bird starts up a constant "wu-wu-" that grows ever more rapid and urgent. On hearing her husband's call, the female is sure to hurry home.

"Birds' singing not only expends energy; it also reveals their position, exposing them to danger." Chang Hsueh-wen explains that each of the maroon oriole's calls has a meaning. It is no coincidence that they are known to humans as heralds of spring, for once their breeding season is over they are much quieter.

Thanks to birdwatchers' efforts, our understanding of Taiwan's orioles has advanced greatly. But their diminishing populations are a cause for concern.

Fully grown maroon orioles are fierce birds with few natural enemies, and they generally feed in mixed flocks with other bird species. But in the breeding season their chicks are much coveted by snakes, squirrels, crows and sparrowhawks, and an attack will often prompt the sensitive parent birds to abandon the nest they have built. Though nearly ready to lay her eggs, the unrested female sets to work to build a new nest as quickly as she can. But the strain this puts on her is in itself part of the reason for the birds' low success rate in rearing chicks. In 1997, Chang Hsueh-wen found that of eight maroon oriole nests near Shanping in southern Taiwan, in only one did the birds raise their chicks successfully. "Human disturbance is another major reason for nests being abandoned," says Chang.

The preferred habitat of birds of the oriole family is at the edge of artificially planted woodland where it borders on broad grassland. Poets have often depicted harmonious rustic scenes with farmers and orioles each going about their business and leaving each other in peace. But many activities of modern people, such as building scenic pavilions or riding noisy motorcycles along woodland paths, may cause maroon orioles to abandon their nests.

The same applies to their black-naped cousins. "In the past," says Chu Hung-pin, "the area around the Martyrs' Shrine in Tanshui was an excellent habitat for black-naped orioles-there was more rough woodland, with plenty of food and little human activity." But after the Tanshui line of Taipei's Mass Rapid Transit system opened, the woodland was tidied up and the number of visitors increased greatly. "Five years ago, three pairs of black-naped orioles raised 12 chicks here, but the next year only half that many hatched out, and the year after that things were even worse: one pair built five nests in succession, but didn't manage to hatch a single egg." Chu says that next year he himself will have to leave the Martyrs' Shrine and go looking for black-naped orioles elsewhere.

When the orioles are gone, who then will herald the arrival of spring?