Reptiles of Enewetak Atoll 



Chapter 28 



JANET O. LAMBERSON 



U. S. Environmental Protection Agency 



Hatfield Marine Science Center, Newport, Oregon 97365 



Seven species of lizards and one species of blind snake 

 comprise the known terrestrial herpetofauna of Enewetak 

 Atoll, based on specimens in the U. S. National Museum 

 of Natural History, the B. P Bishop Museum, the Ameri- 

 can Museum of Natural History, the Museum of Compara- 

 tive Zoology, and the Mid-Pacific Research Laboratory col- 

 lections (Table 1). Species found on nearby atolls may also 

 be present on Enewetak; however, no additional species 

 have been collected from there. No amphibia or sea 

 snakes are known from Enewetak. 



None of the species of reptiles known from Enewetak 

 is endemic to Micronesia. Presumably, Gefiyra oceanica, 

 Lipinia noctua. and Emoia Ci/anura originated in Papua 

 New Guinea, and Hemiphi;llodact\;lus t[;pus and Lepido- 

 dacti/lus lugubhs evolved in southern Asia (Burt and Burt, 

 1932; Brown, 1957). All are now widely distributed 

 among the islands of the Pacific (McCoy, 1980). 

 Hemidactxjlus frenatus and Ramphoti/phlops bramina are 

 known from tropical Asia, India, and Africa and have been 

 introduced to Central America and the islands of the 

 Pacific and Indian Oceans, including Hawaii (Hunsaker, 

 1966; Hunsaker and Breese, 1967; Bustard, 1970; 

 McKeown, 1978; McCoy, 1980). Varanus indicus probably 

 originated in the Indo-Australian archipelago or Papua New 

 Guinea and has been intentionally introduced to a number 

 of the Mariana, Caroline, and Marshall Islands (Fisher, 

 1948). This species is extensively distributed on Pacific 

 Islands, including the eastern part of the Indo-Australian 

 archipelago, Papua New Guinea, northern Queensland, 

 Bismarck archipelago, Solomons, Trobriands, Carolines, 

 Marianas, and the Marshalls (R. Crombie, USNM, personal 

 communication). Keys for identification of the reptiles of 

 Enewetak, distribution records, notes on natural history, 

 and excellent color illustrations may be found in booklets 

 by McKeown (1978) and McCoy (1980). 



The most often seen lizard on Enewetak is the house 

 gecko, Hemidactt^lus frenatus, which frequents areas of 

 human occupation. It is common on or inside buildings, 

 especially near lights, or on windows at night where it 



stalks insects attracted by the light. It is also found under 

 scrap metal, plant debris, and driftwood or other debris on 

 the beach. 



Hemidact^ilus frenatus is an aggressive species that 

 may replace other resident species of geckos when it is 

 introduced to a new area. In Hawaii it is reported to have 

 replaced Hemidacti^ilus garnoti (McKeown, 1978) and possi- 

 bly also Lepidodact{;lus lugubhs to some extent (Hunsaker 

 and Breese, 1967). McKeown (1978) reports that L. 

 lugubhs, which also frequents areas of human habitation, is 

 still quite abundant in Hawaii. On Enewetak Atoll, L. 

 lugubhs is common on Enjebi Islet but is infrequently col- 

 lected relative to the collection of H. frenatus on Enewetak 

 Islet (Table 1). Hemidact]^lus frenatus is highly vocal, and in 

 encounters with other geckos, it frequently emits a series 

 of five to six chirping call notes. If attacked, it emits a 

 squeak. An extensive discussion of vocalization in this spe- 

 cies is given by Marcellini (1974). The female H. frenatus 

 lays two round white eggs in crevices, and the eggs or 

 adults may be introduced to new areas as stowaways 

 among materials or equipment moved among islands 

 (McKeown, 1978). 



The mourning gecko, Lepidodact\;lus lugubhs, is found 

 on buildings; trees and bushes; among coconut, pandanus, 

 and other plant debris in areas occupied by people; in 

 open forest; and among beach driftwood. This species is 

 parthenogenic (McKeown, 1978), and its highly adhesive 

 eggs are easily transported among goods carried by boat. 

 This gecko has been widely distributed around the Pacific 

 and is known from several islets on Enewetak Atoll (Table 

 1). Its call has been compared to the sound of two pebbles 

 being hit together (Marshall, 1951). It sometimes emits a 

 squeak when attacked by another gecko or captured by a 

 collector. 



The tree gecko, Hemiph\/llodacti^lus typus, is repre- 

 sented from Enewetak by only two specimens in the 

 USNM collection. This gecko, however, is reported to have 

 a quick escape reaction (Oliver and Shaw, 1953) and to be 

 wary and agile (Hunsaker and Breese, 1967). Therefore, it 

 may be more abundant on Enewetak than indicated by the 

 frequency of collection. In Hawaii it is found in low den- 

 sity in forested areas, rock and wood piles, occasionally on 

 the sides of buildings and on tree trunks at night, and 

 under the bases of coconut palm fronds. It is not generally 



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