Winter has set in. Shining flashlights into ditches, Yang Yi-ru and her students explore Meilun Mountain in Hualien, looking for frogs. Croaking sounds pierce the stillness of the night.

With thirteen years of experience in looking for frogs, Yang Yi-ru stands out among the many bird- and butterfly-watchers in Taiwan as unique. She was dubbed "Mother Frog" because of the many things she has done for these creatures. She has traveled to mainland China in search of their original habitats. She has performed CPR on a frog. She goes into the mountains in the middle of the night and crouches in the grass, just waiting for another frog to croak.

Frogs like it warm and moist, Yang says, and summer nights after afternoon thundershowers, when the air is warm and humid, are the best times for them to find food. On one rainy night in summer, Yang found nineteen kinds of frogs around Lienhua Pond, quite a large number considering that only thirty-one species are known to exist in Taiwan.

Even on one autumn night in 1998, when the weather had turned cool and frogs had become a rare sight, Yang was still able to find eight kinds of frogs in the Hualien mountains, including the precious Chinese bullfrog, a protected species in Taiwan. Rejoicing over her discovery, she set out to find all the various species. Within a short three months, she took field trips to townships like Fuli, Tungho, Yuli and Shoufeng in Hualien County, even though she had just started her new job at the Tzu Chi College of Medicine.

A chorus of frogs

In order to spark people's interest and deepen their understanding of these amphibians, Yang made a video entitled The Sound of Yangming Mountain--Frog Songs, which records different frog calls, including those of the spectacled toad, the rice field frog, the ornate rice frog and the Java tree frog. To make this video, Yang often had to sit motionless amid tufts of grass in the mountains, even in wind and rain, waiting for frogs to croak.

Yang can easily distinguish between their calls, which, according to her, convey a wide variety of meanings and emotions that are often lost on an inexperienced ear. Some frogs produce sounds that are especially interesting. For example, Guenther's brown frog sounds like a barking dog, the Java tree frog makes a knocking sound, and Swinhoe's frog sings like a bird.

"Gou-gi gou-gi," a frog calls when it is looking for a mate. Or you may hear "gou, gou, gou-gou" or "gi-gi-gou-gou" when a male is trying to attract the attention of a female or when it is confronting a competitor.

When a female Taipei tree frog is mating with a male, other males may just fall silent and quietly join the mating. So don't be surprised when you see a female frog mating with two male frogs at the same time! "Actually, frogs are very smart," Yang remarks with a smile.

If you want to go frog-watching after dark, you'll need a large flashlight, warm clothes, and boots with non-slip treads. Most importantly, you'll have to be quiet and patient. Since snakes are their natural enemy, the places frogs live in also tend to be frequented by snakes. You need to watch your step!

Generally, people don't need to scale mountains and ford streams to see these animals at night. Because frogs are cold-blooded and their body temperature depends on their surroundings, most can only live in low- and mid-range mountainous areas that offer them a warm, humid habitat.

"Some frogs like to stay close to streams and waterfalls, like Swinhoe's frog, Sauter's frog, the Central Formosan toad and the brown tree frog. Others enjoy spending their time in shallow, slow-moving waters of well-shaded ditches, like the Japanese Buerger's frog and Kuhli's wart frog. Buerger's frogs are particularly fond of bathing in hot springs, so you can often see their tracks near spas. The long-legged frog, the Kuatun frog and the Taipei tree frog, on the other hand, like to hang around rain puddles by the road."

Yang has suggestions for parents whose children are interested in these amphibians. They can foster their children's interest by encouraging them to keep tadpoles. Being herbivorous, tadpoles can subsist on fish food and boiled spinach, which makes them easy to feed and take care of. "After a tadpole grows into an adult frog, you can return it to its natural habitat. By doing so, children will learn to respect life and all living creatures on the planet." It's obvious that Yang Yi-ru has a deep love for these creatures. "Frogs have lived on earth for over twenty million years, and in Taiwan for one million years. They truly deserve to be called the 'aborigines' of Taiwan."

A modern version of the "Frog Prince"

When Yang was still a graduate student in the zoology department at National Taiwan University, she studied Taipei tree frogs, which are common throughout the Taipei basin. By making comparative analyses of the calls produced by these frogs and by using her skills in molecular biology, she discovered that there were remarkable genetic differences between green tree frogs living in northern Taiwan and those living in central Taiwan. Because the green tree frogs in these two areas seldom interact, the genetic gap between them is getting wider and wider.

In order to trace the ancestors of the Taipei tree frog, the Nantou tree frog, the emerald tree frog, the farmland tree frog, and the orange belly tree frog, Yang even traveled to mainland China. Based on her research there, she found that these five species all migrated from China to Taiwan at different times.

Seeing her passion, Yang's friends nicknamed her "Mother Frog." One anecdote--we can call it a modern version of the "Frog Prince"--especially shows her love for these animals. Yang once came upon a dying frog near a spa. Without hesitating for even a second, she pressed its heart with her finger and breathed into its mouth. After a few moments of this CPR, the frog miraculously came back to life. It's hard to question Yang's love for frogs after hearing this story.

Many years ago, some American bullfrogs were brought into Taiwan and released in the Yangmingshan National Park. Reproducing freely, the frogs rapidly multiplied in numbers. Big in size, they easily preyed upon the smaller frogs in the area.

Yang was heartbroken to witness the destruction of the native frogs' natural habitat, especially since it was caused by the careless actions of human beings. "Now the American bullfrog has taken root in Taiwan," she says with anguish. It is like the history of the apple snail repeating itself. After apple snails were introduced into Taiwan in 1980, their numbers spiraled out of control and now they are omnipresent on farms and fields all over Taiwan!

Because frogs breathe through their skin as well as with their lungs, any change in the environment reflects quickly upon their wellbeing. Yang evaluates the livability of a place based on the characteristics of the frogs there and their ability to adapt to that environment. If you have never seen or heard a frog in your community, it is probably unfit for human beings to live in. If you find the ornate rice frog, the spectacled toad, or the rice field frog where you live, it means that though the place may have been developed, its environmental quality is good. If a place hosts the Java tree frog or the Nantou tree frog, it ranks as one of the best environments to live in.

For the time being, the two most serious threats facing Taiwan's amphibian populations are loss of habitat and abuse of pesticides. The green pond frogs that like to hide among aquatic vegetation or in well-shaded farmlands, for example, are threatened by loss of habitat. As a result, their numbers are declining drastically. The best way to deal with the problem is to set aside lands as nature reserves. As Yang strongly believes, "What happens to frogs will one day happen to human beings--a planet where you can find no frogs is definitely no place for mankind."

A long, happy journey

When Yang decided to study frogs, her parents backed her decision by giving her material help. When Yang told them that she needed Chinese tree frogs to carry out her research, her mother immediately spread the news to the children in the neighborhood and said that she would give ten dollars [US$0.31] for each frog caught. Since "generous rewards lead to heroic acts," frogs were soon caught and handed over to Yang. Yang's parents marveled that their daughter could turn child's play into a doctorate.

Yang's husband, Dr. Lee Peng-hsiang, is even keener on frogs than she is. In order to tape frog calls, he and Yang travel all over the mountainous areas of Taiwan. Their journeys in search of the creatures are full of interesting episodes. Once they had to climb on top of their car to film a tree frog that was calling from a tree, three meters [almost ten ft] off the ground. Another time they tried to outflank a harpist frog, only to find that the little beast had outwitted them by hopping around them and was eyeing them smugly from behind!