Recent Records of Exotic Reptiles on Pohnpei, Eastern Caroline Islands, Micronesia

Abstract

Seven nonindigenous species of reptiles (two freshwater turtles, one gekkonid lizard, and four snakes) were recorded on Pohnpei and adjacent Ant Atoll (Federated States of Micronesia) for the first time within the past 15 yr, three within the past 3 yr. They apparently reached Pohnpei by deliberate or inadvertent human-assisted transport, originating from widespread and distant areas including North America, Southeast Asia, Indoaustralia, and other Pacific islands. Pohnpeians (and many other Pacific islanders) often do not perceive exotics as a potential threat to the balance of natural ecosystems. Additional training and education addressing the potentially disastrous consequences of alien species and directed especially toward agencies entrusted with monitoring environmental quality are recommended to help preserve biodiversity on these small island nations.

Pohnpei is a ruggedly mountainous (nearly 800 m high), densely forested, sparsely populated (31,540 people censused in 1994 [Office of Planning and Statistics 1996]) volcanic island in the west-central Pacific (Figure 1). It is located 766 km north of the equator. As the political and economic hub of the Federated States of Micronesia, Pohnpei hosts a broad spectrum of international visitors for business and recreation, despite its relatively small size (about 355 km²) and remote location. In addition, yachts in transit from different parts of the world frequently anchor at Pohnpei and its satellite atolls for indefinite periods of time. The potential for deliberate and inadvertent transport of exotic flora and fauna increases with the growing accessibility and popularity of the island. Recent human-assisted transport and establishment of exotic species of plants and animals throughout the Pacific Basin are well recognized (McCoid 1993 from Drake et al. 1989). Guam and the Hawaiian Islands are notorious examples (Eldredge 1988, McCoid 1993, 1995, Fritts and Rodda 1998, Wiles in press) of the disastrous consequences of exotic flora and fauna. This study reports on the probable human-assisted occurrence of seven species of reptiles on Pohnpei and adjacent Ant Atoll recorded for the first time during the past 15 yr, three of them within the last 3 yr.

Species Accounts

Ocadia sinensis

An adult female Chinese stripe-necked turtle (169 mm carapace length [CL]) was collected in a rain-filled rut or puddle near the power plant at Nipaip, about 3.0 km SSW of Kolonia on 16 July 1999. It was found by a local college student and given to a representative of the Fisheries Section of the Department of Economic Affairs; they in turn passed it to biologists at the College of Micronesia, and it is now deposited in the Smithsonian collections (USNM 529967). C. H. Ernst confirmed our identification. Ocadia sinensis is indigenous to Taiwan, southern China, and northern Vietnam (Ernst and Barbour 1989). The Pohnpei specimen is the first record for a west-central Pacific island. It may have been transported by Asian visitors possibly via international flight or aboard one of the numerous foreign fishing vessels as a "pet" or as alternative food. Although O. sinensis is reported as being herbivorous (Ernst and Barbour 1989), a recent study of its food habits (Chen and Lue 1999:467) revealed it to be "an opportunistic omnivore with both plant and animal matter contributing substantially to the diet" in nature as well as in captivity. The Pohnpei specimen readily consumed small (approximately 20-40 mm standard length) gobiid fishes, as well as hawk moths (Sphingidae) and scincid lizards (Emoia jakati) during its brief period of captivity at the college.

Figure 1.

Location map for Pohnpei and Ant Atoll. AUS, Australia; NG, New Guinea; broken line indicates the equator.

Trachemys scripta elegans

A female red-eared turtle (170 mm CL) was captured at the public dump at Tekehtik near the Pohnpei airport on 20 January 1997 (Buden in press). It was examined by D.W.B. before being adopted as a "pet" by a government worker. Letters to several government offices pointing out the environmental problems often caused by exotic species and recommending that the turtle be preserved as a voucher specimen were officially...