ASIAN TOADFROGS: Megophryidae

PHYSICAL CHARACTERISTICS

Most of the Asian toadfrogs have vertical, cat-like pupils, paddle-shaped tongues, and colors and patterns on their heads and backs that blend in with their environment. Some species have warty skin, but others have smooth skin. A few do not have the cat-eye pupils. These include species like the Asian mountain toad, which has a diamond-shaped pupil. The males and females look quite similar for most of the year. In the breeding season, the males of some species develop bright red-, yellow-, or orange-colored spots on their sides and upper legs or some colorful tints on their front toes or on their vocal sacs. The vocal sac is a balloon-like area under the chin that blows up and deflates when the male performs its call. Also during the mating season, the males of some species, including those known as alpine toads and cat-eyed frogs, develop rough patches on the chest and front toes. Male moustache toads are unusual in that they grow spiny "moustaches" when they are ready to mate.

Asian toadfrogs are split into two main groups. One group includes the leaf litter and dwarf litter frogs, the slender mud frogs, the lazy toads, and the moustache toads. All of these frogs have a bump that runs from the second toe onto the first, or big, toe. They usually have large or small "horns" on their eyebrow ridges. The horns are actually pieces of flesh that are pointed. In fact, the name of the family, Megophryidae, is from two Greek words that mean "large eyebrow." Some, like the Asian horned frog, have large, pointed eyebrows. The "horns" on other species are much smaller, and some do not have them at all. This group of frogs has tadpoles with mouths that are pointed upward on their heads and look like funnels. The tadpoles also have a small, fingernail-like beak on the lower jaw.

The other main group of Asian toadfrogs include a variety of mostly large-eyed frogs that have a large bump at the bottom of the second front toe but not on the first toe. Species in this family are the horned frogs, broad-headed frogs, Asian mountain toads, Burmese spadefoot toads, and others. Their tadpoles have larger beaks on both the upper and lower jaws, and mouths that open on the bottom of the head.

The species in this family come in many sizes, too. The smallest only grow to 0.7 inches (1.8 centimeters) long from snout to rump, but the largest top 5.5 inches (14 centimeters) in length. The broad-headed toads can grow to 6.6 inches (16.8 centimeters) long. The females usually outgrow the males, but in the moustache toads, the males are slightly longer.

GEOGRAPHIC RANGE

Asian toadfrogs live in many areas of Southeast Asia and Indonesia.

HABITAT

Although Asian toadfrogs live in many different habitats, most tend to prefer old, thick forests that have ground covered by layers of leaves. Most of them move into clean and clear streams, usually those with slow currents, to breed.

DIET

Many Asian toadfrogs eat a wide variety of invertebrates (in-VER-teh-brehts), or animals without backbones. Some, like the Annam broad-headed toad, are opportunistic (ah-por-toon-ISS-tik) feeders. An opportunistic feeder is an animal that will eat almost anything it can catch, get into its mouth, and swallow. Many Asian toadfrogs hunt by sitting still and waiting for prey to wander by. This type of hunting is called ambush hunting.

BEHAVIOR AND REPRODUCTION

The typical Asian toadfrog spends its days resting under rocks, logs, or leaf piles on land and comes out at night to look for food. They are mostly slow-moving frogs that rarely climb and are not particularly good hoppers or swimmers. The leaf litter frogs, for instance, do a slow, waddling walk on land. A few species, like the Asian mountain toad, do some climbing, especially during the mating season. They climb onto branches above the stream, where they mate. Despite the slow speed of most Asian toadfrogs, they are able to avoid the mouths of predators by blending into the background. Most of them have backs and heads in grays and browns that are similar in color to the leaf piles scattered on the forest floor. Many of them also have horn-like eyebrows that make the frog look like a dead leaf. At the slightest sound, these frogs hunker down and stay still and wait for the predator to pass by. The broad-headed toads have another defense tactic. If a predator comes too close, these frogs will spread open their big mouths and hold them wide. Sometimes the sight frightens off the attacker.

PUT YOUR HEAD ON MY SHOULDER

Some male frogs use other methods besides calling to convince females to mate with them. One of the Asian toadfrogs is the slender mud frog, also known as the mountain short-legged toad, which is a dark-speckled, orange to tan, somewhat warty frog. When a female comes close to a male, he lays his chin on her shoulder, then moves toward a rock in a shallow mountain stream. If she is interested, she follows him, they mate, and she lays her eggs underwater and beneath the rock.

For those that live in cool or dry areas, the mating season begins when rainy weather arrives. Those whose homes are in places that are mild and wet all year may mate over longer periods. During the mating season, the males usually move to stream shores and begin calling. Although a male may make a few half-hearted calls during the day, it mainly does its calling after sundown. Depending on the species, the male's call may sound like a honk, a loud clank, a low bark, a repeating whistle, or some other noise. During mating a male climbs onto the female's back. The males of some species then grasp her at her front legs, while other males hold on to her above her hind legs. The female lays her eggs so they attach, often in clumps, to the bottom of large rocks along the stream's bank. The adults leave, and the eggs soon hatch into tadpoles. The moustache toads mate a bit differently. In these species, several males may group together at a nesting site and, after mating with females, remain with the eggs until they hatch. Tadpoles of many Asian toadfrogs stay in slower parts of the stream, but a few, like the slender mud frog, prefer faster currents in stony streams. Some tadpoles do not change into frogs until they are two years old. A few species, like the Bana leaf litter frog, appear to lay their eggs on land.

ASIAN TOADFROGS AND PEOPLE

People who live near the larger species sometimes eat them, but for the most part, people rarely see any of the Asian toadfrogs. These frogs, however, may prove to be quite important to humans. Since the tadpoles must have clean streams to live and grow, they are good bioindicator (bie-oh-IN-dih-KAY-tor) species. A bioindicator species is an animal that people can use to tell whether the environment is healthy. For example, if a population of Asian toadfrogs were to disappear suddenly from an area, the change might mean that the water in the streams has become polluted.

CONSERVATION STATUS

Of the 107 species in this family, the World Conservation Union (IUCN) considers three species to be Critically Endangered, which means that they face an extremely high risk of extinction in the wild; 14 to be Endangered and facing a very high risk of extinction in the wild; and 26 to be Vulnerable and facing a high risk of extinction in the wild. In addition, 13 are Near Threatened and at risk of becoming threatened with extinction in the future; and 28 others are Data Deficient, which means that the IUCN has too little information to make a judgment about the threat of extinction.

The three Critically Endangered species are the web-footed dwarf litter frog, the Liangbei toothed toad, and the spotted lazy toad. The web-footed dwarf litter frog has a very small population that lives only in one place: near a small, clear, rocky stream in a forest reserve of Sabah, in Malaysian Borneo. Although the stream is inside a reserve, loggers are removing the surrounding forests. Since this species probably spends much of its life in those vanishing forests, it may soon become extinct. The Liangbei toothed toad also lives in a tiny area and breeds in just one small, mountain stream in southern Sichuan province, China. Scientists believe the entire species has fewer than 100 members. The stream is not in a protected area, and the surrounding forests are disappearing to logging. If its forest habitat disappears from logging or from a fire, this frog could easily become extinct. The last of the three Critically Endangered species is the spotted lazy toad, which is known from just a few individuals that were collected in the 1970s from mountains in China. Although scientists have made numerous searches since then, they have not been able to find any more of these frogs and fear they may already be extinct.

Many of the other Endangered, Vulnerable, and Near Threatened species in this family are in danger because their habitat is disappearing, mainly due to people cutting down forests for lumber or to make way for farming or houses. In some cases, the number of frogs is dropping because fertilizers and pollutants are draining into the streams where the frogs have their young. The tadpoles typically cannot survive in anything but clean, clear water. Changes in the habitat are especially dangerous for those species that live in very small areas. In fact, scientists believe that nearly one of every four Asian toadfrog species lives or breeds in only one place, such as a tiny part of a mountain forest or stream. For them, a few days of tree-cutting or a change to one stretch of a stream can wipe out their entire home.

BANA LEAF LITTER FROG (Leptobrachium banae): SPECIES ACCOUNTS

Physical characteristics: The Bana leaf litter frog has a body that looks too big for its skinny legs. It has a wide head with huge, bulging eyes. The eyes are black on the bottom, white on top, and circled with a thin, white circle. Its back is dark brown with tiny, red spots along the sides and also on its hind legs. Its front and back legs are brown with darker bands continuing down onto its toes. It has a white-spotted gray underside. Adult females can grow to 3.1 to 3.3 inches (8 to 8.4 centimeters) long from the snout to the rump, but adult males typically only reach 2.3 to 2.9 inches (5.7 to 7.3 centimeters) in length.

Geographic range: The Bana leaf litter frog lives in the Gia Lai province of south-central Vietnam and in the Annamite Mountains of Laos.

Habitat: The Bana leaf litter frog lives in thick, evergreen primary forests, which are forests that have never been cut down. These forests are located where the land is higher—between 2,620 and 5,240 feet (800 to 1,600 meters) above sea level.

Diet: The Bana leaf litter frog probably eats insects.

Behavior and reproduction: By day, this frog hides under the leaves that coat the forest ground. It comes out at night to wander about on land. Often, this species actually walks, rather than hops. Unlike many other frogs that mate and lay their eggs in the water, this frog does both on land. People have heard lone males calling from beneath logs and in burrows that are nowhere near a stream. More studies will provide additional information about this species.

Bana leaf litter frogs and people: People rarely see or hear this nighttime frog.

Conservation status: The World Conservation Union (IUCN) considers this species to be Vulnerable, which means that it faces a high risk of extinction in the wild. In Vietnam, its habitat is disappearing as people clear the land for farming or through logging. ∎

SCHMIDT'S LAZY TOAD (Oreolalax schmidti): SPECIES ACCOUNTS

Physical characteristics: Sometimes called the webless toothed toad, the Schmidt's lazy toad is a grayish brown animal with warts dotting its body, thin forelegs, and rather short back legs. All of its legs have dark bands. Their undersides are pinkish tan and almost see-through. Adults grow to 1.7 to 2.0 inches (4.5 to 5.4 centimeters) long from snout to rump. Males are usually just a bit smaller than the females. The males also have many spines on the first toe of each front foot and two, large, rough spots on the chest. These rough spots, called nuptial (NUHP-shul) patches or nuptial pads, help the male hold onto the female's slippery back during mating.

Geographic range: The Hengduanshan Mountains of southern Szechwan and Yunnan, which are located in central to southern China, are home to this species.

Habitat: Schmidt's lazy toad lives in marshes and streams within mountain forests and valleys.

Diet: No one knows what this toad eats.

Behavior and reproduction: Schmidt's lazy toad lives most of its life on land. During mating season, the males begin calling, often from underneath a rock. Unlike most other frogs, they will keep on calling even if a person walks up and flips over their rock, leaving the frog in plain sight. When the males spot a female, they will surround her and continue calling. Male and female pairs mate in the water, and the female lays a sticky ball of about 120 eggs onto the bottom of a stream rock. The eggs hatch into green- and gold-speckled tadpoles, which turn into froglets shortly after breeding season the following year.

Schmidt's lazy toads and people: People and these frogs rarely see one another.

Conservation status: The World Conservation Union (IUCN) considers this species to be Near Threatened, which means that it is at risk of becoming threatened with extinction in the future. Because it lives in a very small area and its numbers are low, any changes to its habitat could be dangerous to this frog. ∎

AILAO MOUSTACHE TOAD (Vibrissaphora ailaonica): SPECIES ACCOUNTS

Physical characteristics: The small spines that stick straight out of the male's upper lip give the Ailao moustache toad, also known as a Yunnan moustache toad, its common name. Its other common name, the Ailao spiny toad, also refers to its prickly lip. The females do not have spines and instead have tiny white spots on the upper lip. They have large eyes that are black on the bottom and bright green on the top and have vertical, cat-like pupils. Their bodies are reddish brown with faint, darker brown spots on the back and pale, dark brown bands on their front legs, unwebbed front toes, back legs, and webbed back toes. Their skin may be very rough and make them look as if they had been dipped in sand. Young frogs are tan instead of reddish brown and have more noticeable spots and bands on their bodies. Unlike many other species in this family, the males are a bit larger than the females. Males typically reach 3.2 inches (8.2 centimeters) long from snout to rump, while females usually grow to 3.1 inches (7.8 centimeters) in length.

Geographic range: The moustache toad lives in the Ailao Shan and Wuliang Shan mountain ranges in central Yunnan, China, and possibly in northern Vietnam.

Habitat: The moustache toad spends most of the year on land in thick, shady forests high in the mountains, usually between 7,220 to 8,200 feet (2,200 to 2,500 meters) above sea level. During the mating season, it moves into slow-moving, clear streams.

Diet: It appears to eat various invertebrates, such as worms and snails, that it catches on the forest floor.

Behavior and reproduction: The Ailao moustache toad stays on land most of the year, but moves into a stream during the two- to six-week-long mating season in late winter. Several males share a nesting site under a large rock, and each male begins to sprout the 10 to 16 spines in his "moustache." At the same time, the male's front legs become thicker, and the skin on his back and sides starts to droop and become baggy. Females come to the nest, mate with the males, and lay their eggs in the nest. In most other species of frogs, both the male and female leave after the female lays her eggs, and the eggs hatch and develop on their own. In the Ailao moustache toad, however, the females leave, but the males stay with the eggs. The males may continue to mate with other females, who also lay their eggs in the same nest. In about 40 days, the eggs hatch into tadpoles. The brown-colored tadpoles change into froglets in their second year.

Ailao moustache toads and people: Few people have ever seen this frog.

Conservation status: The World Conservation Union (IUCN) considers this species to be Near Threatened, which means that it is at risk of becoming threatened with extinction in the future. The Ailao moustache toad seems to be quite rare. However, most if not all of its habitat is inside nature reserves, where it is protected. ∎

ASIAN HORNED FROG (Megophrys montana): SPECIES ACCOUNTS

Physical characteristics: The Asian horned frog, which is sometimes called the Asian spadefoot toad, looks as if it has horns over its dark brown eyes. It is a big-bodied frog with a large head that sometimes has a fleshy lump on the end of its snout. Its back is tan to reddish brown and has several ridges that run from the head to the rump. Its hind legs usually show dark banding, but the bands may be faint. Other than a few small lumps on its back and sides, the frog has smooth skin. Males and females look alike, but the females are usually larger. Females can grow to 2.6 to 4.4 inches (6.7 to 11.1 centimeters) long from snout to rump, while the males usually only reach 1.7 to 3.6 inches (4.4 to 9.2 centimeters) in length.

Geographic range: Asian horned frogs are found in parts of Southeast Asia and Indonesia, including Thailand, Malaysia, the Philippines, Sumatra, Java, Borneo, and tiny Natuna Island northwest of Borneo.

Habitat: Asian horned frogs live in thick, shady, humid, tropical forests, sometimes high in the mountains. They may also live in farm fields.

Diet: This frog looks for food on the forest floor at night, eating larger invertebrates, such as cockroaches and land snails, as well as scorpions that may be as long as the frog itself.

Behavior and reproduction: This frog takes advantage of its leaf-life body to hide from predators. When it crouches down and sits still, as it does whenever a possibly dangerous animal approaches, the frog looks like any other dead leaf lying on the ground. This ability to stay out of sight is important for this species, because it cannot move very fast on land or in the water, and it does not climb. The Asian horned frog is mainly active at night. During the day, it hides under leaves, logs, or rocks. It stays on land most of the year, but moves to small- and medium-sized streams during the mating season. The male's mating call is a loud, echoing honk or clang. The males appear to call more on nights with a full moon. Females lay their eggs in the water along the shore, and the see-through eggs hatch into brown-colored tadpoles that hide among underwater plants until they change into froglets, which probably happens when they are about two months old.

Asian horned frogs and people: People rarely see this well-camouflaged, nighttime frog in the wild.

Conservation status: This species is not considered threatened or endangered. In the areas where it lives, it is quite common. ∎

ANNAM BROAD-HEADED TOAD (Brachytarsophrys intermedia): SPECIES ACCOUNTS

Physical characteristics: Annam broad-headed toads, also known as Annam spadefoot toads, have so many ridges on their bodies that the head and back almost look as if they are covered with an armor shield. Two ridges begin at the back of the wide head, carry up over the eye to make a pointy eyebrow, then run forward to meet at the tip of the frog's pointed snout. Other, sometimes broken, ridges run from the rear of the head over the broad back or down its sides to the rump. Its head and back are usually light brown to reddish brown. Large for an Asian toadfrog, a female Annam broad-headed toad can grow to 5.5 inches (13.9 centimeters) long from snout to rump. The males are smaller and can reach 4.6 inches (11.8 centimeters) in length.

Geographic range: The Annam broad-headed toads are found in southern central Vietnam.

Habitat: Annam broad-headed toads live in mountainside forests that are between 2,460 to 3,940 feet (750 to 1,200 meters) above sea level. During mating season, they move into nearby streams.

Diet: This toad is an opportunistic feeder that will eat everything from insects and spiders to small frogs and rodents.

Behavior and reproduction: This frog sits still most of the time and blends into the background, which is useful for ambushing prey and for keeping out of sight of predators. If a predator does spot the frog and approach, the frog will open wide its mouth, which may scare away the predator. Unlike most frogs that mate in the spring, or in the spring and summer, this frog mates early in the spring and also late in the fall. The males move to streams and start calling from a sheltered spot under a large rock. Females come to the streams, mate with the males, and lay their eggs under the rocks.

Annam broad-headed toads and people: People rarely see this frog in the wild.

Conservation status: The World Conservation Union (IUCN) now considers the Annam broad-headed toad to be Vulnerable, which means that it faces a high risk of extinction in the wild. Once a common species, its habitat has disappeared in the past 100 years, and the number of frogs has dropped. ∎

FOR MORE INFORMATION

Books:

Cogger, Harold G., and Richard G. Zweifel. Encyclopedia of Reptiles and Amphibians. San Diego, CA: Academic Press, 1998.

Inger, Robert F. "Distribution of Amphibians in Southern Asia and Adjacent Islands." In Patterns of Distribution of Amphibians: A Global Perspective, edited by William Duellman. Baltimore: Johns Hopkins University Press, 1999.

Zhao, Er-Mi. "Distribution Patterns of Amphibians in Temperate Eastern Asia." In Patterns of Distribution of Amphibians: A Global Perspective, edited by William Duellman. Baltimore: Johns Hopkins University Press, 1999.

Web sites:

"Black-eyed Litter Frog." Ecology Asia.http://www.ecologyasia.com/verts/amphibians/black-eyed_litter_frog.htm (accessed on February 16, 2005).

"Draft Report Assessing the Impact of Importing Live Asian Horned Frog (Megophrys montana) into Australian Zoos." Australian Government Department of the Environment and Heritage. http://www.deh.gov.au/biodiversity/trade-use/publicnotices/archive/draft-report/m-montana.html#range (accessed on February 17, 2005).

"Frogs in Kerinci Seblat." Kerinci Seblat National Park.http://www.kerinci.org/about_frog.html (accessed on February 17, 2005).

"Malayan Horned Frog." Ecology Asia.http://www.ecologyasia.com/verts/amphibians/malayan_horned_frog.htm (accessed on February 16, 2005).

"Mountain Litter Frog." Ecology Asia.http://www.ecologyasia.com/verts/amphibians/mountain_litter_frog.htm (accessed on February 16, 2005).

"Spotted Litter Frog." Ecology Asia.http://www.ecologyasia.com/verts/amphibians/spotted_litter_frog.htm (accessed on February 16, 2005).

"Yunnan Moustache Toad." Science Museums of China.http://www.kepu.com.cn/english/animal/class/cls404.html (accessed on February 16, 2005).