Lizards of Taiwan - Discussions of Taiwan’s lizards

(1) Primer on Taiwan’s lizards: White-spotted Chinese Skink

A new species has been found in Taiwan!

Dr. Wen-Shan Huang, a researcher at the National Museum of Natural Science, has discovered the White-spotted skink on the Green Island. This species, which was thought to be the common Chinese Skink, was proven to be a Taiwanese endemic species after verification by Dr. Huang. According to Dr. Huang, these lizards were discovered by Japanese on the Green Island, and the finding was subsequently published. However, only juveniles were discovered at the time. Dr. Huang not only has discovered juveniles, he also found the presence of adults as well. Their appearances change drastically as they mature from juveniles into adults.

Dr. Huang named these lizards the White-spotted skink, based on the presence of white pots on the adults. However, these spots disappear from the adult males, although they remain on adult females. 

The young White-spotted skins are very pretty, sporting a bright violet coloration on its skin, and glistens underneath the sunlight. However, this beautiful coat disappears when they mature into adults. 

There are three types of Chinese skinks in Taiwan, remarked by Dr. Huang. They are the White-spotted Chinese Skink, the Chinese Skink and the Elegant Five-Lined Skink, the latter two can also be found in China. Many people are confused by the distinction between a skink and a lizard, however a closer look at their morphology will resolve this confusion. 

Dr. Huang said, “the skinks are shorter, chubbier and more active; they are more sensitive to intrusions by foreign objects. In contrast, lizards are thinner, more slender and smaller than the skinks, and they are less sensitive to foreign intrusions.” 

The White-spotted skinks are not difficult to find on Green Island; they can be seen sunbathing around 8 and 9am in the morning. If you have a chance to visit Green Island, try to observe one of these fascinating lizards. 


 (2) Primer on Taiwan’s lizards: Hsueshan's Grass Lizard

Hsueshan’s Grass Lizard is an endemic species of Taiwan, first discovered in 1981 by Professor Jun-Yi Lin of Tunghai University, and Professor Hsien-Yu Cheng of the Chinese Culture University. Named after its place of discovery, Central Taiwan’s Xiao Hsueshang, the holotype specimen of this species is preserved at Tunghai University’s Department of Life Science. Long and stout, this is the largest of all endemic lizards in Taiwan, primarily distributed in regions of high altitudes, ranging from 1,800m to 3,500m. This grass lizard can be found in mountainous areas like the Xiao Hsueshang, Mount Nanhu, Dayuling, Mount Hehuan and Mount Chilai. Adult body length ranges from 60 to 66cm long. 


During March, when the snow finally melts, the Yushania niitakayamensis underneath the snow mounds gradually turn from brown to green, and the mountainous flowering plants bloom in full effects, attracting insects for pollination. Butterflies can be seen dancing among the Dendranthema chanetii on the stair wells. As the sunlight warms up the ground, Hsueshan Grass lizards awake from their hibernation, ready to satisfy their hunger as they cross the stair wells and straight into the bushes. They can be seen around vegetable patches and flower bushes in front of alpine households, and also foraging and sunbathing around the edges of Yushania niitakayamensis. Their feeding provides them with energy for activities, growths and reproduction. Excessive energy is stored in two yellow adipose tissues alongside the dorsal regions of their bodies. In the months before hibernation, especially during November, the females feed continuously and their body fat reaches its maximum weight; the fat mass drops to its lowest weight during the egg laying seasons in July. In addition, the liver mass of the females also reaches its peak during November, although it is less prominent in the adipose tissues. This alternating pattern of adipose tissue and liver mass accumulation is not observed in males, however. 


The dorsal region of the Hsueshan Grass lizard is colored olive brown, with a black stripe along the side of its body. It is more difficult to determine the gender solely based on color differentiation. They only appear when there is sufficient sunlight warming the ground, being residents of alpine regions (at 1,800 m or higher), and lower temperature during the nights. However, they go into hibernation a month later than most other species of lizards (like its neighbor, the Elegant Five-tailed Skink), and can be found in bushes as late as November. After December, they disappear entirely as the temperature drops significantly, appearing only during the spring of the following year. 


They live in dirt holes or rock openings on the grassy fields, and can be found near the PVC pipes or crevices in the concrete walls, which warm up rapidly after heating and are suitable areas for activity. Often, they can be seen poking their heads out from their hiding places, checking to see if everything is safe and clear. If threatened, they will remain motionless and wait at the opening. The author had a standoff of nearly one hour with one, and after failing to spark its interest, drove the lizard out with a stick. Hsueshan grass lizards are not territorial like the japalura and have a wider range of activity, foraging constantly. They can be spotted on bundles of dried grass near the edge of the Yushania niitakayamensis fields, because places like this warm up easily after sun light has shined on them. They will hiss and seek refuge when approached by humans. 


Unlike skinks, the Hsueshan grass lizards are not as strong, and move slower on grass fields. However, they are very sensitive to foreign intrusions, although they are not alerted by the presence of members of same species. The sight of several grass lizards appearing at the same time can be frequently observed. During an emergency, these lizards will conduct autotomy, cutting off their tails to attract the attention of predators and escape. Lizards do not always autotomize their tails, since they are important storage places of energy, and will only do so during immediate danger. 


On July 2nd, 1993, the author discovered that female grass lizards captured from the wild have laid 4 eggs, and that most females in July bear around 2 to 4 eggs. On average, each egg weighs about 0.33 grams and is 13mm long and 6mm wide. No pregnant females are observed during August to November. According to previous literature, the breeding period of these lizards is between May and July, and they lay eggs twice a year. The pregnant female’s body length measures from 54 to 69mm long; however, since only six accounts of data exist, it is not enough to analyze the relationship between pregnant body length and numbers of eggs. The conclusion from available data suggests that there is no correlation between body length and egg numbers; that larger females do not always lay more eggs. 

Current available data cannot accurately assess the reproductive periods of this lizard, though it has been established that from December to February of the following year is its hibernation period.


 (3) Primer on Taiwan’s lizards: Taiwan Alpine Skink

The Taiwan alpine skink is one of the endemic lizard species distributed primarily in the 2,200m high alpine regions of the Central Mountain Range. It was discovered in 1987 by Professor Shi-Huang Cheng and Professor Guang-Yang Lu of the National Taiwan Normal University. The holotype specimen is preserved at the Department of Life Science of the National Taiwan Normal University. These lizards have been discovered in regions such as Mount HeHuan, Alishan, the Batongguan ancient trail, Mount Xiang Yang and Tianchih; however, with so few numbers documented, they are now designated as a protected species. Therefore, few data is available on their lifestyles and behaviors. The Alpine skink is similar in appearance to the Indian forest skink, albeit with a smaller stature. Due to the lack of data, the information presented here will be based on specimens available to the museum.

The adult alpine skink body length ranges from 51 to 61mm long, and weighs about 1.9 to 5 grams. Most alpine skinks have smooth yellow abdomens. 

They feed primarily on alpine insects and other arthropods, grazing and living in rock roles on alpine grass fields. They especially thrive in the crevices of rock walls erected by farmers, which provide them with suitable shelter from predators and are ideal for nesting purposes. The Taiwan alpine skinks are diurnal animals and like to sunbathe during the day, lying leisurely at the entrance of their caverns. When large predators approach, they can swiftly escape back into their lairs. Sometimes Hsueshan grass lizards can be seen near their lairs, but they co-exist peacefully without confrontation. Nevertheless, the alpine skinks need to leave their hideouts in order to feed, foraging in cabbage fields or the Yushania niitakayamensis fields, and sometimes prey on insects like bees and butterflies in flowering bushes not far from their homes. During May to June, the nine Alpine skinks that are kept in the museum bear eggs, ranging from 4 to 8 eggs each. It seemed that the larger the maternal body is, the more eggs it will lay. A female that has a body length above 61mm will tend to lay 7 to 8 eggs at a time. There are no mature eggs in the females around July; therefore it is presumed that their spawning period is between May and July.


(4) Primer of Taiwan’s lizards: Short-legged Japalura

The reptiles in Taiwan account for 55 species of snakes, 31 species of lizards, 5 species of terrestrial turtles and 4 species of marine turtles; there are a total of 95 species of reptiles in Taiwan. Some of the recent academic publications on reptilian study include the “Guide to Taiwan’s Lizard,” authored by Professor Jun-Yi Lin and Professor Hsien-Yu Cheng; “Study of Taiwan’s turtles,” written by Professor Shou-Xian Mao; and the yet to be published “Study on Taiwan’s common terrestrial poisonous snakes.” In the realm of popular science literature, books like Professor Guang-Yang Lu’s “The amphibians and reptiles of Taiwan’ and field reports on reptiles and amphibians published by major National Parks are available for reference. However, few publications are concerned with the living histories of these reptiles; only the Swinhoe’s japalura has been studied in-depth by Professor Jun-Yi Lin and Professor Hsien-Yu Cheng.

The author has been a member of the museum for over two years and is specialized in amphibian specimen collection and field research on some endemic lizard species. Already having obtained some preliminary results, the author has studied species that include short-legged japalura, Indian forest skink, elegant Five-tailed skink, Hsueshan grass lizard and the Hart’s glass lizard. Starting in this issue, we will begin to introduce a series of reports on the aforementioned lizards. For ease of reference, the reports will be categorized according to a lizard’s diet, color, habitat, activity and breeding behavior; however, each category is close related with each other.

We will begin our introduction with the Short-legged Japalura. This is an endemic species of Taiwan, mainly distributed in 1200m to 2500m high altitude regions in Central and Southern Taiwan. It was first discovered by Gressitt, an American, at Wushe in 1936, and was named Japalura breuipes. However, it was later perceived to be the same species as the Swinhoe’s Japalura, until 1989 when it was corrected again by a Japanese researcher named Ota. Therefore, data is scarce on this type of lizard. The body length of an adult short-legged japalura measures between 5.5 to 7.5 cm, relatively small when compared with other three types of japalura. Gender dimorphism is displayed in this species; males have green stripes on the dorsal and lateral sides of the body, females do not. Some females are colored entirely in green. 


As the sun rises and the rising air temperature evaporates the dew drops hanging between the leaves and bushes, the short-legged japalura begin its day of activities. During spring and summer times when the purplish-white passion fruit flowers are blooming in full effect, the short-legged japaluras are attracted by the plethora of insects busying feeding on the nectar. They can also be seen in vegetable patches and flower beds on the edges of mountains. When they awake from hibernation in March, sightings of these lizards increase significantly as they replenish their energy and look for potential mates. Another peak of japalura activity is around October. Before they go into hibernation, these lizards will continuously search for food, in order to store enough energy for the upcoming hibernation and reproductive periods. The energy is stored in two yellow adipose tissues along its dorsal sides and in the liver. The glycogen levels in the adipose tissues and liver drop to their lowest between March and April, and maximize in October. 


The green pattern is beneficial for activities in the foliage, hiding the lizard from its natural enemy – birds. The external skin of the short-legged japalura is covered in numerous tiny scales, preventing moisture escape and evaporation. This animal is a poikilotherm; its body temperature varies with the ambient environmental temperature, and will adjust to a temperature suitable for normal activities. Therefore, sunbathing is the favorite activity of this lizard. During hot summer time when its 30℃ outside, it will scurry underneath tree shade or cling onto small branches, trying to cool off. When humans approach, it will move to another end of the branch, attempting to hide itself from intruders. It does this because it’s afraid. During winter nights when the temperature between November and the February can drop below 0℃, these lizards will hibernate in tree holes. 


Tree holes or dry leaf clusters make for a suitable permanent or temporary hiding places. These japaluras are territorial; therefore two lizards will not co-exist close together. When japalura B intrudes the realm of japalura A, the latter immediately responds, displaying behavior like push-ups and pattern demonstrations. Usually, most intruders will back off after seeing these signs of territorial proclamation. To male japaluras, possessing territories means ensuring places to rest and grow, as well as increasing the chances of mating and successful breeding. Therefore, territorial claims are an important subject in male rivalries. 


In terms of animal behaviors, those that perch on branches usually have feathers and can fly; those that cling on tree bark have claws and can climb well; those that have strong muscles can run fast, or dig well. The short-legged japalura excels at motor activities; moving about the tree tops most of the time and only coming down to the ground during feeding. When in danger, it will immediately dart back up the tree. 


During March and between June and July, mature eggs can be found inside the bodies of female short-legged japaluras, indicating that there are two spawning periods per year. 

The number of eggs laid by each lizard differs, ranging from 3 to 7 eggs. In terms of the relationship between spawning female body lengths and egg numbers, it was found that larger individuals do not always spawn more eggs. The same conclusion is obtained when the total weight of the eggs are compared to the total body weight. Those that are pregnant in March could have conceived between September and October of last year. The eggs develop gradually during hibernation months. Those that are pregnant in June or July could have conceived during March or April of the same year; however, the eggs will mature faster, which could be related to temperature and time allotted for feeding. 

To summarize the above findings, the year round activities of a short-legged japalura can be categorized as follows: (1) Hibernation, November to February; (2) Reproductive period, March to July; (3) Energy consumption period, September to October.


 (5) Primer on Taiwan’s lizards: Common house geckos

The author recalled that during the first night staying at the university’s dormitory, most people were exhausted by the day’s activities and hot weather, and immediately fell sound asleep. However, one roommate was having a harder time sleeping because he was bothered by the crackling sounds on the wall. This sound was made by the geckos. It was said that geckos south of the Da-An rivers will call, while those in the north don’t; this roommate lived in Taipei and was hearing the geckos call for the first time.

Common house geckos are mainly distributed in Southern China, Okinawa, Southeast Asia, Africa, Madagascar, Southern North America, Central and South America. The gecko populations in Taiwan are huge, mainly distributed in Central, Southern and Eastern Taiwan, including the islands of Lanyu, Lamay and Penghu. The geckos are now (Lin and Cheng, 1990) gradually dispersing to Northern Taiwan. Geckos have two rows of skin flaps beneath their toes, and each toe is clawed. There are warts like scales on the dorsal side on the body. The tails that regenerated from autotomy lack visible annuli and wart scales. They are active from dusk till dawn of next day, calling out frequently during the night, rarely during the day. 


In the summer evening after rainfall, a dimly lit light bulb attracts grey and white moths and mating termites, congregating around the walls that surround the light bulb. These insects, which have either just finished mating or were exhausted from chasing the light, are suddenly consumed rapidly by several creamy-yellow colored reptiles that seem to come out of the misty dark corners. These reptiles, eating and chattering like squawking housewives, are common house geckos. The liver mass or adipose tissues of a gecko do not vary regularly in a year, but the adipose mass does reach its maximum during January, and decreases to its lowest from February to April. The storage of fat in geckos seems to be related to reproductive needs and not for hibernation use (Lin and Cheng, 1977). They also prey on smaller geckos of the same species. 


The geckos are about to change their colors to adapt to the ambient environments. On transparent glass or in lightly colored environments, their bodies are creamy yellow and appear transparent, the organs and eggs can be easily identified. In darker environments, they are colored deep brown, with a few small spots on their backs. This alteration of colors is a type of camouflage, necessary for survival, which reduces the chance of predation by natural enemies. 


Geckos are fond of living in buildings and structures, the artificial scaffolds used to support small trees, tree bark, large boulders, and even inside the fluorescent light covers. They are the most widely distributed Gekkonidae species in Taiwan, owing to their closeness with humans and variety of living conditions. They seem to be social animals; often several geckos can be seen living together in the wild. 


Geckos have two rows of skin flaps beneath their toes, and each toe is clawed. These allow them to cling onto different surfaces, climbing on rough tree bark, walls, or smooth glass and other surfaces. They can even defy gravity and walk upside down on the ceiling, scurrying around effortlessly. Sometimes they will fall, but few will perish from such a fall. 


The body length of a small adult gecko is about 3.6 cm long. Although they can breed all year long, the spawning periods seem to be concentrated in between March and August. They spawn twice a year, laying two eggs at a time. Geckos will lay eggs in the crevices of concrete walls, tree holes or decomposing bark. The eggs are 5x12mm large, and the incubation period is around 46 to 58 days (Lin and Cheng, 1990).


 (6) Primer on Taiwan’s lizards: Elegant Five-tailed Skink

I remember that while living in the countryside, adults used to warn us not to get too close to grass bushes, or the poisonous “color changing lizards” (Elegant Five-tailed skinks) would bite us. Therefore we used to throw rocks at them from afar. In reality, five-tailed skinks are non-venomous (the real poisonous animals are venomous snakes like the banded kraits); the intention of the adults was for us to stay clear of the bushes, where real danger may await. These places are favored by the skinks and thus they become subjects of warning. After twenty years, such warnings are no longer useful for us to teach our next generation, because the skinks are gradually declining in number, due to overuse of pesticides, sewage pollution of creeks, removal of patches of striped abutilons, and destruction of habitats. Fortunately, these lizards are widely distributed in the world, from flat lands to areas 2500m above sea level. In China, they are found in regions south of the Yangtze River, and also on Okinawa Islands as well. Our experiment ground is located at the 2100 m high National Taiwan University’s Mei-Feng Experimental Farm, situated in Ren-Ai Township of Central Taiwan’s Nantou County. The five-tailed skinks were first discovered and named in China by Boulegier, a British national, back in 1887. The holotype specimen is now preserved at the British Museum.  


During March and April, the red or yellow flowers of foxgloves (digitalis) are blooming, and the left over cabbages from harvests also blossoms with white flowers. Elsewhere, unknown purple flowers dotted the scenery, not to mention the full blossoms of Baby’s breath in the fields. These flowers attract the attention of bees, moths, and butterflies. Even humans can be lost in the tides of blossoms. During daytime when the temperature is high, the coldness of the night air is fully dispersed, and the skinks that hide under the rocks and dirt mounds begin to forage and go about their daily routine. It is interesting to note that most of the skinks in the vegetable patches are adults; juveniles are rarely seen here, which could be due to differences in activity levels or intra species competitions. The food consumed by these lizards is turned into energy, stored in adipose tissues and livers. With the abundance of food in the months between July and October, these skinks forage constantly and their adipose masses increase dramatically. Natural enemies like the Stink rat snake, Asian Tiger snake and the Oriental Turtle dove are also present, which increase the chance of being eaten. However, since these areas are suitable for living, the population of these skinks is also quite large. 


The elegant Five-tailed skink do not change colors like that of the short-legged japalura, instead it is colored according to its ages; the juveniles have bluish black dorsal color, blue tails and five conspicuous golden stripes along their backsides. They typically measure about 4.0 to 10mm long. The adult males are colored bluish black, have brown tails and no golden stripes; they measure about 9.1 to 19.1 mm long and have red reproductive spots on their cheeks. The smaller adult males measure about 7.0 to 9.7 mm long, are colored in bluish black, and the stripes and the tails fade in colors. The adult females measure about 7.0 to 12.6mm long, have five visible stripes and light blue tails. Since these lizards are brightly colored, they like to move about in grass bushes. After November, the temperature drops, and skinks are rarely found. Sometimes we can find them frozen and curled up underneath boulders, and they would not defrost even when put under direct sunlight. They will become active only when the temperature rises again in March of the following year. 


The Mei-Feng area provides skinks with excellent habitats. The mountain cliffs are rocky and fragile, so farmers usually build rock walls beneath the mountain sides to prevent rock slides. The crevices between the stone walls become safe havens for the skinks. They can also be found in brick walls beneath the flower patches and in weed patches around rock piles. They have the habit of digging lairs and can usually be seen inhabiting holes underneath large boulders. These lizards are also territorial and will return to their hiding places; often when we fail to catch them, we can usually find them again at the same places. We once tagged and released 210 skinks, only to catch 11 when we went to look for them again. All were caught at the original place of discovery except for one, who has a slightly larger range of activities. Despite our efforts, there is not yet enough data to support our findings. 


Similar to the Indian forest skinks, the five-tailed skinks are very sensitive to intruders, hiding in caves before they come close. Therefore, it is quite difficult to catch them on the stone walls. Only when they come out to forage in the vegetable fields can we stand a chance catching them. Due to overlapping masses of weeds in the fields, the movements of the skinks are slowed, allowing us to catch them. There are many water reservoirs that are made out of concrete in the farm. During seasons of drought, because temperature increases faster in a warmed-up concrete, many skinks will come to the bottom of the pool to warm up their bodies. When there is water, however, sometimes we will find skinks that have drowned. 


The author once witnessed no mature eggs or embryos in females during a full year of research; however, past literature stated that these lizards can spawn up to twice each year, laying 4 to 8 eggs at a time. Our data showed that juvenile skinks can be collected from March to October, especially during the months of September and October (16 and 31 individuals, respectively). Therefore, it is possible that these skinks breed all year round, with August and September being the height of the spawning periods. 

To summarize the above, the annual activities of five-tailed skink are: (1) Hibernation, November to February; (2) reproductive periods, March to October.


 (7) Primer on Taiwan’s lizards: Indian Forest Skink

The reproductive models of animals can be categorized into three types, based on the supply of nutrients to the embryos and the method of parturition: (1) Viviparous, the embryos are nourished by the placenta of the mother, and grow to full infant size before parturition (e.g. cows); (2) Ovoviviparous, the embryo supplies its own nutrients and remains inside the maternal body until fully grown (e.g. Indian Forest Skink); (3) Oviparous, the embryo supplies its own nutrients, matures in an egg and incubates through ambient temperature (e.g. short-legged japalura). Nowadays, scholars studying lizard reproduction no longer categorize species by embryo development; instead they group the lizards according to their parturition morphologies. For example, lizards born from eggs are oviparous and lizards that born as infants are viviparous. The mode of reproduction of the Indian Forest Skink belongs to the latter, viviparous. What determines the modes of reproduction in a lizard? Why are some lizards viviparous and some oviparous? Is it related to temperature? Are the skinks in tropical or subtropical zones oviparous? Are the skinks in cold climates viviparous? Do predators influence their modes of breeding? Aside from the Indian Forest Skinks, other lizards that inhabit the alpine regions of Wushe, including Five-tailed skinks, short-legged japaluras, Swinhoe’s japaluras, Formosan grass lizards and Hart’s glass lizards, are all viviparous. Why do these lizards select different modes of reproduction in an environment that is equal for everyone? Questions and issues of evolution, mentioned in the above, have yet to be answered.

The Indian forest skinks were first discovered in 1912 by Van Denburgh, an American. The holotype specimen was collected from Guanziling, Tainan County, and is now preserved at the California Academy of Sciences. These lizards are distributed in Southern China and the Indochina peninsula. In Taiwan, they are widely distributed, ranging from plains to areas 1200 above sea level. The mature individuals weigh between 22 grams (females with embryos) and 5 grams, and the body length measures between 60 to 90mm. 


Indian forest skinks have a diverse repertoire of diets, ranging from annelids to insects. The invertebrates in the detritus at the bottom layer of the forest are also enjoyed by these lizards. I have once seen a forest skink, mouth full of earthworms, quickly dart into the leaf mould when it sees me approach. I have the habit of leaving any feasting animals (or humans) to their own business. During summer and spring, the thorny polygonum on the mountain sides bloom with pink flowers, attracting bees and butterflies to their nectar. These lizards will wait patiently in the polygonum bushes and prey on these insects. They store everything they ate as energy, however they do not store it in adipose tissues like other lizards (e.g. Hsuehsan grass lizard). Instead, they store it primarily in their livers. The liver mass of an Indian forest skink reaches its maximum during August and September, months before its scheduled hibernation. Liver mass drops to its lowest during reproductive months from March to July, especially in females; their liver masses drop to the lowest during June, their spawning period. 


The forest skinks are colored brown, which help them move about in fallen leaf piles. If not for their highly sensitive nature toward invasions, we would have a hard time finding them among the leaves. The high sensitivity of these lizards ensures their survival from predators like snakes; however, it is also our clue to their whereabouts. Once approached by an intruder, these lizards immediately react and escape, either hiding in leaf piles or darting up the mountain sides. If it’s the former, then we may stand a chance catching them, although it’s a slim chance; if it’s the latter, then the chase is unlikely, due to their incredible speeds and the thick patches of thorny polygonums where they hide from. Therefore, few specimens can be caught between the cliff sides, which can range from 2 to 3 km long. The skinks awake from hibernation in March, and disappear in September to October when temperature gradually drops. 


These lizards dwell on the bottom layers and edges of forests, preferring hiding places like the fallen tree bark on the grounds. These areas provide them with ample food and excellent shelter; we often found signs of forest skink activities on tree bark that has fallen onto roads or lake sides. The forest is a humid and warm place, which gives birth to many types of animals, especially the shredders that feed on detritus and rotten leaves. The time needed for the leaves to decompose and their food energy to return to the food web is long; however, if these leaves were first broken down by shredders, then the skinks eats these animals, and predators like snakes and birds prey on these lizards, the flow of energy will be accelerated. Therefore, these lizards play an important role in the balance of food chain in the forest ecosystems. There are a few five-tailed skinks that also dwell on the bottom forest layers, but their numbers are not as many as the forest skinks which dominate the area. 


As mentioned before, Indian forest skinks are highly sensitive to foreign intrusions. They are incredibly agile, able to escape up the mountain sides as high as 3-4 m above ground. They are usually gone by the time we find their presence. These lizards have different feet structures than the japaluras; forest skinks have shorter feet, their bodies are closer to the ground and are adapted for running; japaluras have longer feet and sharp claws, suitable for climbing. During the two years of the study period the author has never seen a forest skink climb up a tree. 


After the monsoon seasons have passed, the Indian forest skinks reproduce primarily during the months of June and July. Mature eggs can be observed inside female bodies during April, and by June the infant lizards take shapes in fully grown embryos. The infants are born in July, and can be seen everywhere in the wild. The juvenile lizards weigh about 0.36 grams and measures 28mm from snot to anus. They can grow rapidly; the body weight increases to 1.15 grams and the length up to 38mm after a month. Females can give birth to between 4 and 11 juveniles individually. Based on data from 20 female skinks, it was found that the number of spawning is positively correlated with body length; those that are larger can give birth to more juveniles. This is in stark contrast with the species of Agamidae. The evolutionary significance of this development is yet to be delineated. 

To summarize, the reproductive cycle of an Indian forest skink can be grouped into the following: (1) active reproductive periods, March to July, (2) Energy storage, August to September; (3) Hibernation periods, October to February.


 (8) Primer on Taiwan’s lizards: Stejneger's Grass Lizard

Stejneger's Grass Lizard is an endemic species of Taiwan, and was thought to be identical to the Chinese grass lizards of Mainland China. In fact, these two lizards are quite different; on average, the Chinese grass lizard is larger (11mm longer), has less scales (6-8 on Stejneger's Grass Lizard and 4-6 on the Chinese grass lizard) and more eggs (3-4 compared to Formosan grass lizard’s two eggs). Stejneger's Grass Lizard was first discovered by an American, Van Denburgh, in 1912 in Taiwan. The holotype specimen is now stored at the California Academy of Sciences. This type of lizard is often mistaken for another grass lizard, the Formosan Grass lizard, which is similar in morphology and appearance. The easiest way to indentify one from another is to count the groin openings, located at the hind limb regions. Stejneger's Grass Lizard has 1 pair (1 on both sides) and the Formosan grass lizard has two pairs (two on each side). The body length of a Stejneger's Grass Lizard measures between 31.0 to 54.5mm long, and averages about 49.5mm (Lin and Cheng, 1990). They are distributed all across Taiwan and can be found on plains, hill tops 500m above sea level, and on islands like Penghu and Lamay. 


As the first morning sun light breaks through the clouds, these lizards leisurely drink from dew drops on the leaves of White Lead trees, and forage as they go about their business. They are migrant feeders, loitering and taking precaution while feeding in their activity zones. Lizards that feed in such fashion often have excellent vision or a sense of smell, and can obtain food easily. However, they are also more susceptible to predation during their feeding. A Stejneger's grass lizard’s main diet includes insects like grasshoppers, beetles and woodlice. The liver mass of a female lizard increases from January and reaches its maximum in July, then gradually decreases to its lowest in December. The adipose tissue drops to the lowest during March and April, and increases to its maximum in November.


Stejneger's grass lizards are usually colored olive brown or light brown, and have a yellowish brown stripe along their lateral sides. These color patterns camouflage them from predators when they hide in fallen leaf piles. However, some individuals are colored green and are more suitable to thrive in grassy environments. These lizards are poikilotherms, their body temperature is regulated by ambient air temperature; therefore they are more active on bright sunny days. During summer and spring times, these lizards are at their highest activity levels, mating and reproducing. After October, the temperature drops, and they disappear from the wild. 


Stejneger's grass lizards favor habitats like drought fields, grass fields, flower beds and the forest. They can be easily found on terminal leaves on small branches. The White Lead trees on Penghu Island grow in convoluted shapes, intertwining with that of the thorny nettle plants, which make it difficult for larger predators like snakes to navigate freely. These are also favored hiding places of Stejneger's grass lizards. They are social animals, and territorial behavior has not yet been observed. 


These lizards are diurnal, fond of scurrying about in tree branches or weed piles. They are thin and slender and can dart up trees quickly, navigating between branches with ease. Unless threatened, these lizards move about leisurely, and will likely pose for photography – if you observe them quietly. 


The smallest adult individual of a Stejneger's grass lizard measures about 4cm from snout to anus. The spawning periods are between March and August, occurring twice a year. They are multiple-nested types (spawning twice or above per year), lay 2 to 3 eggs at a time, and the eggs average 0.6 x 1.0 cm in sizes. The incubation period is 32 days on average. The newly hatched infants measure about 2.1cm long. The males are fertile all year around except the months of August to October (Lin and Cheng, 1990).


 (9) Primer on Taiwan’s lizards: Hart’s glass lizard

Hart’s glass lizards, also named “Mountain dirt dragons,” are characterized by their lack of limbs, similar to a snake. Unlike snakes, however, they have clear outer ear openings, and long stretches of horizontal skin folds along their lateral sides. The glass lizards are distributed in the Zhejiang, Fujian and Sichuan Provinces of Mainland China. Their distribution in Taiwan is rarely reported, located mainly in the Northern alpine regions like Tamsui, Yangmingshan Mountain range, Mount Chatianshan, Mount Lala, Taipinshan in Yi-Lan, Hapen in Wulai and Chihshang in Taitung. Recently, we have found 3 lizards in Central Wushe, SunLinkSea and Chiayi’s Fencihu, with the Wushe specimen being a juvenile individual.

Hart’s glass lizards like to live in moist forest soil. During downpours or sequential rain storms, they will come out their flooded holes and breathe. The specimen from Wushe was discovered after a rainfall. During sunny days, they can sometimes be seen sunbathing among the fallen leaf piles on forest paths. These lizards primarily feed on insects and are oviparous, laying 13 to 14 eggs at a time. They seem to be protective of their eggs, the females will encircle around the eggs. If an egg is removed, the female will push it back with its head (Lin and Cheng, Guide to Taiwan’s Lizards, 1990).

There are few reports on the Hart’s glass lizard in Taiwan, therefore its lifestyle is seldom understood; there is another endemic glass lizard in Taiwan, called the Ophisaurus formosensis (Formosan Glass lizard), which is even more rare than the Hart’s glass lizard. Therefore, its living history is also an enigma to the scientific community. To differentiate between these two lizards, one would count the numbers of scales between its snout and nose/forehead. Hart’s glass lizard has two scales, and the Formosan glass lizard has only one. However, the juvenile Hart’s glass lizard differed greatly in morphology with the adult individuals, and was once mistaken as two different species. The following table listed the differences between their body color, head spots and whether or not lateral skin folds are present.

It was once said that these lizards can be found during cultivation or excavation, but there have been few records of glass lizards being found on plains in the last twenty years. If the above was true, then the present distribution of glass lizards could probably be used as an index of pollution to the plain grounds.

  Adult Juvenile
l. Body color Grayish brown or yellowish brown with metallic sheen; metallic blue spots on the dorsal surface, arranged in stripes; a black stripe extend from mid section to the posterior tail end.

Grayish white dorsal surface with 16 black spots arranged in stripes; lateral and ventral sides are colored in black.
2. Head spots none Black spots on head plate and top scales; black spots beneath the pair of top scales

3. Lateral skin fold                          present none


National Museum of Natural Science