Mammals of Eneivetak Atoll 



Chapter 30 



ERNST S. REESE 



Department of Zoology 

 Uniuersitii of Hawaii 

 Honolulu. Hawaii 9681 7 



Man is the dominant mammal of Enewetak Atoll. 

 Humans arrived at least 2000 years ago (Craib, 1983). In 

 all probability the Polynesian rat, Rattus exulans, and the 

 domestic pig, Sus scrofa, accompanied him. Domestic 

 dogs, Canis familiahs, and cats, Felix catus, most likely did 

 not arrive until European contact in the 19'^ century. 



The ubiquitous common house mouse, Mus musculus, 

 and the roof rat, Rattus rattus, apparently arrived early in 

 the 20th century when foreign contacts were more fre- 

 quent. There is no evidence of the Norway rat, Rattus nor- 

 vegicus, on Enewetak, although it occurs elsewhere in the 

 Marshall Islands (Jackson, Vessey, and Bastian, Chapter 12 

 of Volume I). All of these species of rats and mice are 

 considered as human commensals and have been spread 

 widely throughout the world through the activities of man 

 (Eiscnberg, 1981; Nowak and Paradiso, 1983). 



Domestic cats, pigs, and goats, Capra hircus, were left 

 on Otdia (Wotjii) Atoll of the Ratak, or sunrise chain, by 

 Otto von Kotzebue in 1816 and 1817. There is, however, 

 no evidence that goats ever lived on Enewetak Atoll, 

 which lies far to the northwest in the Ralik, or sunset 

 chain of atolls. Kotzebue did not visit this chain until his 

 second voyage in 1824 (Kotzebue, 1830). 



Marine mammals are occasional visitors to Enewetak 

 Atoll. Unfortunately there are only two positive identifica- 

 tions based on skeletal remains, beached specimens, 

 and photographs collected by Philip Lambcrson, former 

 laboratory manager of the Mid-Pacific Marine Laboratory, 

 1974-1977, and sent to William F. Perrin, National 

 Marine Fisheries Service, La Jolla, California, for 

 identification. 



The spinner dolphin, Stenella longirostris, is identified 

 from photographs (Fig. 1) and by observations of its dis- 

 tinctive spinning breaching behavior (Perrin, 1972), while 

 the striped dolphin, Stenella coeruleoalba, is identified from 

 a skeleton. The occurrence of this species at Enewetak 

 represents a new record for the central Pacific (Hubbs, Per- 

 rin, and Balcomb, 1973; W. F. Perrin, personal communi- 

 cation to P. Lambcrson, 1977). 



A checklist of mammals of Enewetak Atoll is provided 

 in Table 1. 



Twenty-seven species of whales, dolphins, and fxsr- 

 poises may be expected to occur at Enewetak Atoll (W. F. 

 Perrin, personal communication). These are listed below in 

 the order they are presented in Leatherwood et al. (1982), 

 which provides a guide to their identification. 



Large whales with a dorsal fin: 



Blue whale, Balaenoptera musculus 

 Fin whale, Balaenoptera physa/us 

 Sei whale, Balaenoptera borealis 

 Bryde's whale, Balaenoptera edeni 

 Humpback whale, Megaptera novaeangliae 

 Sperm whale, Physeter macrocephalus 



Medium-sized whales with a dorsal fin: 

 Minke whale, Balaenoptera acutorostrata 

 (Southern ?) bottlenose whale, Hi;peroodon sp.? 

 Cuvier's beaked whale, Ziphius cauirostris 

 Beaked whales of the genus Mesoplodon 

 Stejnegcr's beaked whale, M. stejnegeri 

 Blainville's beaked whale, M. densirostris 

 Ginkgo-toothed beaked whale, M. ginkgodens 

 Killer whale, Orcinus orca 

 False killer whale, Pseudorca crassidens 

 Short-finned pilot whale, Ghbicephala macrorhi^nchus 

 Risso's dolphin. Grampus griseus 



Small whales, dolphins, and porpoises with a dorsal fin: 

 Spotted dolphin, Stenella attenuata 

 Spinner dolphin, Stenella longirostris 

 Striped dolphin, Stenella coeruleoalba 

 Common dolphin, Delphinus delphis 

 Eraser's dolphin, Lagenodelphis hosei 

 Bottlenose dolphin, Tursiops truncatus 

 Rough-toothed dolphin, Steno bredanensis 

 Pygmy killer whale, Feresa attenuata 

 Melon-headed whale, Peponocephala electro 

 Pygmy sperm whale, Kogia breviceps 

 Dwarf sperm whale, Kogia simus 



Other marine mammals, such as seals and sea lions, 

 are not known to occur in the Marshall Islands. 



According to Lambcrson, the Marshallcsc recognize 

 two kinds of porpoises. One is small and travels in large 



333 



