A complete guide to the invasive herpetofauna of Taiwan

Invasive species has been a major threat to local ecosystem all over the world, especially for island ecosystem where animals are isolated and distinctly evolve. Taiwan, locating at the centre of east Asia archipelago, has long been taken as a transfer station for trade among adjacent regions since 16 century. Heaps of goods including agricultural products, fishery products, garden plants, live animals, and wildlife products are imported into this island country.


〈東印度與諸島鄰近圖〉,1570 年。臺史博收藏的台灣相關地圖之一。《經緯福爾摩沙》,頁55。
https://sobooks.tw/latitude-longitude-formosa-bookreview/

Taiwan is ranked as the 10th most invaded country by herpetofauna in the world by the review of Capinha et al. (2017). However, this review underestimated the problem of invasive species in Taiwan. Some invasive reptiles and amphibians were recorded in this review, yet that was not all of them. The question was raised, how many invasive reptiles and amphibians are there in Taiwan? How many species are taken as a native but in fact are invasive? How many species are actually resulted from constant releasing instead of actual invasion? In a nutshell, there are 12 species of amphibians and reptiles successfully invading Taiwan, and 6 species with a controversial status. Moreover, we listed another 14 species having high chance to become invasive in Taiwan if without proper management.

Although this paper is not a research paper, which is usually hypothesis-driven, it provides the most up-to-date information about the invasive herpetofauna in Taiwan including distribution, colonization history, threats, and current status. These paper will provide valuable information for people who are interested in studying invasive herpetofauna in adjacent regions of Taiwan and countries that are suffering similar invasive species issues. I also expect this paper will give our government in Taiwan a fundamental document for making related conservation policies.

Amphibians

  • Kaloula pulchraGray, 1831; Banded Bullfrog
  • Polypedates megacephalusHallowell, 1861; Spot-legged Tree Frog
  • Fejervarya cancrivora(Gravenhorst, 1829); Mangrove Frog
Captured Banded Bullfrog in Pington.

Most of the people recognise Kaloula pulchra and Polypedates megacephalus as two main invasive amphibians in Taiwan. However, few are aware of Fejervarya cancrivora actually one of invasive amphibians as well. Genetic evidence indicated F. cancrivora in Taiwan was closely related to Malay Peninsula regions rather than nearby China and the Philippines.

Turtle

  • Trachemys scripta elegans (Wied, 1838); Red-eared Slider

T. s. elegans has long been a notorious invader not only in Taiwan but worldwide. This turtle is probably the first reptile pet for many children during primary school. I can still recall when I was a kid, My friends and I used to unleash this little turtle to school pond and watched it swimming, some just never came back.

Large size reptiles

  • Physignathus cocincinus Cuvier, 1829; Chinese Water Dragon
  • Iguana iguana (Linnaeus, 1758); Common Green Iguana

These two similar looking reptiles are sometimes scary to local people. There are no native lizards in Taiwan can grow to such big size. Some people described that they saw a Godzilla or crocodile in their garden at the beginning of invasion. Water dragon distributes in only two streams in northern Taiwan, but green iguana invades many area in southern Taiwan and is still spreading.

Medium size reptiles

  • Eutropis multifasciata (Kuhl, 1820); Many-lined Sun Skink
  • Chamaeleo calyptratus Duméril and Bibron, 1851; Veiled Chameleon
  • Gekko gecko (Linnaeus 1758); Tokay Gecko
  • Gekko monarchus (Schlegel, 1836); Spotted House Gecko
The first found adult Tokay gecko in Kaohsiung. It was a gravid female who hatched two offspring in captivity

I think most of the people know well about the invasion of Eutropis multifasciata. But it cannot be stressed enough that Kuroshio current might be able to help the spread of this species from the Philippines to Green Island and Orchid Island. That would make the population on these two islands native rather than invasive. The invasion of Chamaeleo calyptratus was beyond imagination because it was expensive in pet market. I heard C. calyptratus could steadily breed in captivity but didn’t know that it was able to establish wild population until Chung-Wei confirmed the invasion in Cijin. On the other hand, Gekko gecko is a species that has been sporadically reported since Japanese colonisation period. However, this was the first time that we found a breeding population in the wild. Somehow, my concern lays on the other Gekko species, G. monarchus, which is more likely to spread in Taiwan. Both of these species need be closely monitored.

Small size reptiles

  • Anolis sagrei Dumeril and Bibron, 1837; Brown Anole
  • Hemidactylus brookii Gray, 1845; Brook’s House Gecko
Brown anolis sleeps on leaves at night. It’s very hard to capture them during the day but much more easier when it falls asleep.

The flexibility of A. sagrei has made it the most notorious invasive species around the world. It seems to be useless that Chiayi government rewards citizens by giving them money for each individual caught. The fencing strategy in Hualien is likely to be effective to prevent the spread.
H. brooki is the most recently discovered species in Taiwan. Little is known about this species. But considering the population size, it must have invaded Taiwan long time ago. No one pays much attention to this small gecko, and that’s probably why it is able to establish a population without being found.

Article link

Lee K-H, Chen T-H, Shang G, Clulow S, Yang Y-J, Lin S-M (2019) A check list and population trends of invasive amphibians and reptiles in Taiwan. ZooKeys 829: 85-130. https://doi.org/10.3897/zookeys.829.27535

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