Today we are going with Hsu Yu-feng, a professor in the Department of Life Science at National Taiwan Normal University, to Houtong in New Taipei City’s Ruifang District to observe butterflies. The almost pristine mountains and waterways surrounding this famous “cat village” are a great butterfly habitat.

Hsu Yu-feng, an internationally known butterfly expert, especially loves butterflies of the family Lycaenidae, the gossamer-winged butterflies. He admires butterflies not only for their beauty, but also for aspects of their lives that humans do not share.

Butterflies’ hidden powers

Hsu points to a caterpillar on a leaf and asks: “How does it stay on the leaf even through wind and rain?” A white track on the leaf blade offers a clue. The caterpillars spin silk onto the leaf, then use hooks on their feet to hold fast, like Velcro. After eating, they always return to the leaves with silk on them to avoid falling to the ground in storms.

Next, a caterpillar with yellow, red, and green hues appears. “That’s the caterpillar of a satyrine butterfly.” Given its bright coloring, its hard to imagine that when it becomes an adult butter­fly it will be a plain brown color. Hsu explains that when caterpillars pupate and turn into adult butterflies they are completely transformed, in a process know as meta­morphosis. The cells that develop in a butterfly egg include both larval cells and adult cells. When the egg hatches and becomes a caterpillar (larva), the adult cells remain dormant until the caterpillar forms a chrysalis (pupa), after which the nutrition taken in by the caterpillar is provided to the developing adult (imago).

In Houtong one can see butterflies from almost all the butterfly famillies found in Taiwan. Hsu gently grasps a nymphalid butterfly and explains that the family Nymphalidae (the brush-footed butterflies) is distinguished by short, reduced front legs which may have taste-related sensory functions. Because their larvae eat only specific plants, before they lay eggs they tap the leaf surfaces with their front legs to ensure that these are food sources that their caterpillars can eat.

A female Formosan swallowtail (Papilio thaiwanus).

Male (left) and female Kuafu hairstreaks (Sibataniozephyrus kuafui).

A male Hoppo peacock(Papilio hopponis)

Taiwan’s endemic butterflies

Taiwanese endemic butterflies—species or subspecies that are found only in Taiwan—mainly live at middle to high elevations. Examples include the aurora swallowtail (Atrophaneura horishana), with black-spotted red coloring on the rear part of its hindwings, and the Hoppo peacock (Papilio hopponis), with its rare double ring markings. Hsu adds that the endemic Kuafu hairstreak (Sibataniozephyrus kuafui), which he discovered 30 years ago, also lives at high elevations amid Taiwan beech trees (Fagus hayatae).

Normally the larger an area of land and the nearer it is to the Equator, the more butter­fly species will be found there. Hsu says that while Taiwan can’t compete with South America and Southeast Asia in the size of its butterfly popu­la­tions, it has a high proportion of endemic species. “There are also few places in the world like Taiwan where one can drive from sea level to a height of 3,000 meters in only three hours, and where one can find both tropical and temperate-zone butterflies.”

Besides endemic species, Taiwan boasts other note­worthy butterfly phenomena. For example, every autumn the chestnut tiger (Parantica sita niphonica) flies from Japan to winter in Taiwan. According to records compiled by a Taiwanese research team, the chestnut tiger flies across more than 1,000 kilometers of sea from Japan to the Taiwanese islands of ­Penghu and Lanyu, in a rare trans­oceanic migra­tion. In recent years it has even been seen in places like Shanghai, Hong Kong and the Philippines.

When caterpillars pupate and metamorphose into adult butterflies, they undergo a complete transformation, gaining an entirely new appearance.

In Houtong, protected bretschneidera trees (Bretschneidera sinensis) provide a habitat for the Taiwanese endemic subspecies of the Naga white butterfly (Talbotia naganum karumii).

Butterflies as environmental indicators

Hsu emphasizes: “Butterflies are not just pretty to look at. Their species and populations reflect environmental change.” Over the past decade Hsu has worked with the Forestry Bureau and National Ilan University to survey stands of Taiwan beech, where they have found over 140 butterfly and moth species, including four previously unnamed ones.

However, climate change models used by the research team indicate that as global temperatures rise and rainfall declines, within 50 years the number of Taiwan beech trees will fall to 5% of the current figure, and they may completely disappear from Mt. Chatian and Mt. Lala, so that the diverse species living on them will be lost. Therefore the Red List of threatened species in Taiwan names the Kuafu hairstreak, which lives in beech forest, as a critically rare indicator species. “When these species’ populations falls, it means the environment is deteriorating, and ultimately people will suffer,” concludes Hsu.

Butterflies, birds, lichen, and various vascular plants are en­viron­mental indicators for land-based ecologies. Knowing about butterflies means more than just remembering their characteristics; it also helps us understand the en­viron­ment we live in.

To make a complete record of Taiwan’s butterflies and show their richness to the world, the Forestry Bureau and Hsu’s research team collaborated to publish the five-­volume Butterfly Fauna of Taiwan. This illustrated field guide not only describes the characteristics and distribution of each species, but also details changes in their scientific names, and includes cross-sectional images of their reproductive organs. “To determine whether a butterfly is a new species, researchers look at the reproductive organs, as it is very difficult to tell just from the overall appearance,” explains Hsu. The individual volumes cover the families Papilionidae, Pieridae, Hesperiidae, Lycaenidae, and Nymphalidae, with text in both Chinese and English.

Chang Jung-hua says that thanks to the efforts of volunteers, the Jiannan Butterfly Eco-Education Park currently has 160 butterfly species.

The Butterfly Conservation Society of Taiwan has printed a handbook to help visitors to the Jiannan park to identify butterflies when taking guided tours.

Jiannan Butterfly Park

In 2003 the Butterfly Conservation Society of Taiwan began undertaking habitat restoration along the Jian­nan Butterfly Trail in Taipei’s Shilin District. The trail had been ravaged by a typhoon, but after cleanup and planting work by volunteers, more than 160 butterfly species can now be found in the Jiannan Butterfly Eco-Education Park.

On the day of our visit, BCST chairman Chang Jung-hua leads us through this open-plan butterfly park right in the city. BCST volunteers have planted native host and nectar plants for consumption by caterpillars and adult butterflies. To avoid competition over food, they have also specially arranged the distribution of plants in the park. Whenever a new food plant species is added, volunteers record the number of butterflies feeding or taking up residence, to assess how attractive the plant is to butterflies.

Interesting aspects of butterflies’ natural history can often be observed in the park. For example, on a Formosan wendlandia tree (Wendlandia formosana) near the entrance, caterpillars of the staff sergeant (Athyma selenophora laela) use their silk to string together fecal pellets into “frass chains” and barriers to protect themselves from predators. Meanwhile, a chocolate albatross (Appias lyncida eleonora) flutters about a spider tree (Crateva adansonii ssp. formosensis) looking for a suitable place to lay its eggs.

In the park, butterflies continually flit past. There is the lemon swallowtail (Papilio demoleus), which seems to disappear before your very eyes, as well as the common emigrant (Catopsilia pomona), which is likewise found at low elevations and is the star attraction at Yellow Butterfly Valley in Kao­hsiung’s Meinong District. Looking up, we see a white-banded leopard (Timelaea albescens formosana), with its leopard-skin pattern, resting on a branch.

“One Australian girl who visited the park told us that Taiwanese are lucky to able to see so many kinds of butterflies in one place,” recalls Chang Jung-hua. In fact, though Australia is 215 times as large as Taiwan, they each have about the same number of butterfly species. 

The BCST also uses the park to teach citizens about butterfly ecology. For example, in the canopy observa­tion area, people can look down into the treetops to see butter­flies drinking nectar. Also, near the rest area, Chang explains, “There is our treasure—a headache tree [Premna serratifolia]. This is a shrub that attracts many butter­flies and, thanks to its upturned flower clusters, makes it easy for visitors to observe and photograph them.”

The Butterfly Conservation Society of Taiwan laid out this path to give shade-loving butterflies a place to stay out of the sun.

Butterfly protectors

Taiwan not only has many butterfly species, it takes some admirable approaches to their conservation. Hsu Yu-feng notes that there are many interesting lessons on butter­flies in elementary and middle-school nature classes, and some schools have planted host plants to attract butterflies to lay eggs. At Fuxing Ele­mentary in New Taipei’s Zhonghe District, which is located next to the lushly wooded Mt. ­Niupu, some of the teachers are BCST volunteers, and they have launched a series of butterfly ecology courses.

In addition, many volunteers join in the task of surveying Taiwan’s butterflies. By observing the behaviors of butterflies in different locations they provide important data for scientific research. For example, three years ago Chang Jung-hua discovered a population of the protected great purple emperor (Sasakia charonda formosana) in the mountains of Northern Taiwan. “I was able to get close enough to distinguish males from females, and I saw about 36 of them at one time.” For an endangered species, this is a surprisingly large number. Chang told scholars of his discovery and later joined in on-site observation by a research team to better understand the species. The great purple emperor (Sasakia charonda), also known as the Japanese emperor, is the national butterfly of Japan. The subspecies S. c. formosana is endemic to Taiwan.

The BCST has some 400 volunteers, mainly divided into two groups: those doing restoration work at Jiannan Butterfly Park and guides for the Taiwan broad-tailed swallowtail (Agehana maraho). Early on the BCST invited butterfly experts to teach volunteers about butterflies and their ecology. Prospective guides also have to learn from current guides for two years, and be certified by the BCST, to become guides in their own right. Meanwhile, habitat restorers must learn to distinguish butterfly species and observe caterpillars, as well as regularly recording observations of the environment and microclimate (such as temperature, humid­ity, sunshine, and wind speed), which can help the BCST make timely adjustments to the park operations.

As author Wu Ming-yi wrote in The Book of Lost Butter­flies, observing butterflies is “a way to get to know the thoughts and feelings of a different life form.” He also believes: “Humans are not without wings, it’s just that they have atrophied.” Through butterflies, we can see not only life wisdom that we ourselves do not possess, but also the diverse and fragile environments in which they live, which deserve to be appreciated and protected.

The Jiannan Butterfly Eco-Education Park is an open-plan butterfly park located in the city. Butterflies are free to come and go as they please, adding to biodiversity.

Satyrium tanakai, a lycaenid butterfly endemic to Taiwan. (courtesy of Hsu Yu-feng)