CORE Metadata, citation and similar papers at core.ac.uk Provided by ScholarSpace at University of Hawai'i at Manoa Reptiles of Ngulu Atoll, Yap State, Federated States of Micronesia1 Donald W. Buden2 Abstract: Fourteen species of reptiles (two sea turtles, six geckos, six skinks) are recorded from Ngulu Atoll, Yap, Micronesia, all but the turtles for the first time. None is endemic and most occur widely in Oceania; the phylogenetic status of an undescribed species of Lepidodactylus is undetermined, and a phenotypically male Nactus cf. pelagicus is recorded from Micronesia for the first time. Lepido- dactylus moestus is the most common gecko on Ngulu Island, and Emoia caeruleo- cauda, E. impar, and E. jakati are the most abundant skinks. The islands are an important nesting site for green turtles, Chelonia mydas. Isolation, a small resi- dent human population, and traditional conservation practices contribute to sustaining turtle populations, although occasional poaching by outside visitors persists. The report of a small snake on Ylangchel Island, possibly a species of Ramphotyphlops, requires confirmation. Many of the west-central Pacific islands distribution and relative abundance of the composing Micronesia are poorly known bio- reptiles of Ngulu, and it is based largely on logically, especially the numerous, small, low- my personal observations and specimens that lying, and faunistically impoverished coralline I collected during approximately a month- atolls. These islands are difficult to reach. long field study, mainly on Ngulu Island, Those that have been studied appear to be in- and with brief visits to adjacent Ylangchel habited largely by widespread, weedy species and Wachlug islands. Results of concomitant that are common also on the high, volcanic surveys of birds, butterflies, and dragonflies islands, which offer contemporary visiting bi- will be published elsewhere. ologists both easier access and a richer biota to investigate. Much of the albeit scanty in- formation on the more remote islands stems Study Area from the nineteenth- and early twentieth- century European voyages of exploration that Ngulu Atoll (8 17 0 to 8 34 0 N and 137 25 0 involved many months at sea. But an under- to 137 35 0 E) is located in the western Caro- standing of the biogeography of Oceania re- line Islands, in Yap State, Federated States mains incomplete without a more thorough of Micronesia (FSM), approximately 100 km assessment of the distribution and abundance southwest of Yap proper and 300 km east- of plants and animals on these minuscule par- northeast of the Republic of Belau (Palau). cels of land. The terrestrial biota of Ngulu The atoll is approximately 40.0 km long Atoll, Yap, for example, has never been sur- (north to south) but has a total land area veyed. This study is the first report on the of approximately only 0.3 km2 distributed among two northern and three southern is- lands (Figure 1); Ngulu Island (0.1 km2)is the largest and southernmost. Bryan (1971) 1 Manuscript accepted 19 June 2009. mentioned other islets on the atoll, but all 2 Division of Natural Sciences and Mathematics, Col- lege of Micronesia-FSM, P.O. Box 159, Kolonia, Pohn- those I saw were tiny sand cays or gravel pei, Federated States of Micronesia 96941 (e-mail: bars devoid of vegetation and likely awash [email protected]). during high tides and storms, and they are not recognized as distinct islands by Ngulu residents. Pacific Science (2010), vol. 64, no. 3:473–480 doi: 10.2984/64.3.473 Coconut (Cocos nucifera) forest is the main : 2010 by University of Hawai‘i Press vegetation type, at least on the three southern All rights reserved islands. Scaevola (S. taccada) thickets occur in 473 Figure 1. Location map for islands of Ngulu Atoll. Reptiles of Ngulu Atoll . Buden 475 patches along the upper beach on Ngulu and largely on the work of Kolinski (1993a,b, Wachlug islands but apparently are absent 1994, 1995). from Ylangchel, which is higher than the other islands (ca. 4–5 m in elevation), has a rocky shoreline devoid of any sandy beaches, results and has a grove of tree heliotrope (Tournefor- Turtles tia argentea) on the lagoon side that hosts nu- merous breeding seabirds of several species. Chelonia mydas (Linnaeus). Pritchard (1977) Eight people were living on Ngulu Island at reported that green turtles nest on the two the time of this study, but more than 100 re- northern islands of Ngulu Atoll but gave no sided at times during the late 1900s (M. Rag- indication as to numbers. Kolinski (1994) mau, pers. comm.); the four other islands are briefly mentioned a turtle tagging and moni- uninhabited. The two northern islands were toring program conducted on Lathow not visited during this survey, but Kolinski (¼ Losau ¼ North) Island and on Meseran (1993a,b) described them as having beaches Island in 1992 and 1993. During the 1992 mainly of sand (Meseran Island) or coral survey (3 May–22 July), 54 (78%) of the 69 rock and sand (Lathow Island [¼ North Is- females found on land were encountered dur- land]) and being moderately vegetated with ing the month of May, 73 adult C. mydas were shrubs, trees (e.g., coconut; breadfruit, Arto- tagged, 225 nests were recorded (187 on Me- carpus spp.; and papaya, Carica papaya), and seran, 38 on Lathow), and a total of five mat- patches of grass. ing couples was observed, the last being in early July (Kolinski 1993a). During the 1993 materials and methods survey (10 days on Lathow and 57 on Me- seran, between 22 April and 15 July), 78 adult Fieldwork was conducted on Ngulu Island females were tagged (63 on Meseran [plus 2 during 13 July–10 August 2008, with brief in nearby shallows], and 13 on Lathow), a visits to nearby Wachlug (¼ Uatschaluk) Is- minimum of 107 nests were laid (on Me- land on 18 and 19 July, and Yalangchel seran), and five mating couples were ob- (¼ Jalangaschel) Island on 27 July and 9–10 served, the last being in early May (Kolinski August 2008. Two hundred and twenty three 1993b). specimens of 12 species of lizards were col- I observed green turtles nesting on Ngulu lected by hand, fixed in 10% formalin, and Island regularly during the last 2 weeks of transferred to 35% isopropanol (Table 1); tis- July and first week of August 2008, and a sue samples from several Lepidodactylus spp. visitor from Yap told me of seeing at least were preserved in ethanol for later study. two mating pairs at Ngulu Island on several Specimens were deposited in the Bishop Mu- different occasions during 6–9 August. I re- seum (bpbm); California Academy of Sciences corded a maximum of five turtles that came (cas); Museum of Comparative Zoology, ashore during the night of 18/19 July, and Harvard University (mcz); U.S. Geological George Mangthaw, the resident caretaker for Survey San Diego Field Station; and the Na- the island, remarked (pers. comm.) that 10 tional Museum of Natural History, Smithson- nested in one night earlier in July, just before ian Institution (usnm). Measurements of my arrival, and he recalled a maximum of 15 turtles were recorded in inches using a metal nesting in one night during the 2004 season. tape measure and later converted to centi- Children from the village found four hatch- meters. Carapace length was measured as the lings on the beach at one site and another at straight-line distance from the middle of the a different site during the afternoon of 6 nuchal notch to the posteriormost edge of August 2008, and 115 eggs were removed the shell, and carapace width as the straight- from a nest on the same day. Eggs also were line distance across the widest part of the collected from several nests by visitors to shell. Herpetological data for the two north- Wachlug Island during 9/10 August. I saw ern islands are limited to turtles and are based numerous old tracks on Wachlug during my 476 PACIFIC SCIENCE . July 2010 visit on 18 and 19 July but saw no turtles that he had not seen any on the atoll since nesting. Turtles do not nest on Ylangchel about the year 2000. Island, which is completely surrounded by rocky and, for the most part, steep-sided Lizards beaches. I measured nine females that were cap- Geckos: tured on shore on Ngulu Island during mid- Gehyra mutilata (Wiegmann). The stump- July to early August: carapace length 89.5– toed or mutilating gecko is relatively uncom- 100.3 cm (avg. 96.0 cm), carapace width mon on Ngulu Island. Only seven specimens 69.2–79.4 cm (avg. 74.1 cm). The turtles were recorded during the approximately were intended for consumption by the island month-long study (Table 1): four in edificar- residents and the chief’s family and guests of ian habitats (buildings, walls, and other exam- honor who were expected to arrive from Yap ples of human construction), three on tree proper on the next ship. Ngulu tradition al- trunks, and one on the ground under a de- lows for the killing of turtles for food only composing palm-frond basket. None was en- when the chief is present on the island, al- countered on Wachlug and Ylangchel islands. though eggs may be harvested at other times. Gehyra oceanica (Lesson). The oceanic However, M. Ragmau and G. Mangthaw gecko was common at night on the walls of (pers. comm.) both indicate that poaching by buildings and scaevola shrubs along the visitors from Yap proper and elsewhere oc- beach, and less frequently encountered on curs, and, because of the relative inaccessibil- tree trunks (Table 2).