General Information

Habitat Requirements

habitat requirements consist of cave types, including overhanging cliffs, crevices, lava tubes, and limestone caves in mature well-structured forest with a high, dense canopy (Grant 1993, p. 51; Grant et al. 1994, pp. 134–135; Hutson et al. 2001, p. 139; Palmeirim et al. 2005, p. 28).

Food Habits

All Pacific sheath-tailed bat subspecies are nocturnal, and typically emerge around dusk to forage on flying insects (Hutson et al. 2001, p. 138; Craig et al. 1993, p. 51). The Pacific sheath-tailed bat’s preferred foraging habitat is mature well-structured forest with a high, dense canopy (Kalko 1995, pp. 262–265; Esselstyn et al. 2004, p. 307; Palmeirim et al. 2005, p. 29; Gorreson et al. 2009, p. 336; Valdez et al. 2011, pp. 306–307; Marques et al. 2015, pp. 6–EV–9–EV).

Movement / Home Range

The South Pacific sheath-tailed bat was historically found in Samoa (on Savaii and Upolu), American Samoa (on Manua (Ofu, Olosega, and Tau) and Tutuila), Fiji, Vanuatu (from the southern end of the 540-mile long archipelago located 600 miles to the west of Fiji), and Tonga (on Eua and Niuafoou). Currently, the Pacific sheath-tailed bat persists as small and isolated populations on smaller islands in Fiji, and has been extirpated from historically occupied areas in Samoa, American Samoa, Rotuma, Vanuatu, and Tonga. In Fiji, it was found on Taveuni, Ovalau, the large island Viti Levu, Levu Lakiba (or Lakemba), the Yasawa Group (approximately 30 miles (mi)(48 kilometers (km)) to the northwest of Viti Levu), and Rotuma (approximately 300 mi (482 km) to the northwest of Vanua Levu)(Palmeirim et al. 2005, pp. 31–32, Clunie 1985, pp. 154– 155). It has been lost from the Yasawa Group, and it is likely gone from Rotuma fairly recently (Scanlon et al. 2014, p. 453., Cibois et al. 2019, p. 139). The South Pacific sheath-tailed bat was found on Manu‘a (Ofu, Olosega, and Ta‘u) and Tutuila in American Sāmoa. This species was last detected in American Sāmoa within the cave at Anapeapea Cove on the north shore of Tutuila in 1998 (Hutson et al. 2001, p. 138). Recent surveys in American Sāmoa have failed to detect the Pacific sheath-tailed bat (Table 1; DMWR 2006, p. 54; Fraser et al. 2009, p. 9; Uyehara and Wiles 2009, p. 5; Tulafono 2011, in litt., entire; DMWR 2013, in litt., entire; Miles 2015, in litt., entire). In American Sāmoa (Figure 2), Amerson et al. (1982, p. 74) estimated a total population of approximately 11,000 Pacific sheath-tailed bats in 1975 and 1976. A precipitous decline of the bat on the island of Tutuila had occurred by 1990 (Grant et al. 1994, p. 134; Koopman and Steadman 1995, pp. 9–10; Helgen and Flannery 2002, pp. 4–5). Knowles (1988, p. 65) recorded about 200 in 1988, and in 1993, observers caught one bat and saw only three more (Grant et al. 1994, p. 134). A single bat was also observed on two occasions in a small cave north of Alao (Grant et al. 1994, pp. 134–135). Additional small caves and lava tubes have been checked more recently for bats however, Tutuila is entirely volcanic and does not have the extensive limestone cave systems that provide bat roosting habitat in the Mariana Islands and other Pacific island groups (Grant et al. 1994, p. 135). Two individuals were last observed in the cave at Anapeapea Cove on the north shore of Tutuila in 1998 (Hutson et al. 2001, p. 138). Surveys conducted by the Department of Marine and Wildlife Resources (DMWR) in 2006 failed to detect the presence of this species (DMWR 2006, p. 53). In an attempt to ascertain whether the species is still extant, DMWR conducted surveys consisting of acoustic sweeps and cave checks on all main islands in 2008 and 2012, and no bats were detected (Fraser et al. 2009, p. 9; Tulafono 2011, in litt., entire; DMWR 2013, in litt., entire). Based on its decline and the lack of detections since it was last seen in 1998, this species is thought to be extirpated in American Sāmoa (DMWR 2006, p. 54; Uyehara and Wiles 2009, p. 5). DMWR continues to conduct acoustic surveys in search of the Pacific sheath-tailed bat in American Sāmoa (Miles 2015, in litt., entire).

Reproductive Strategy

Reproductive strategy of this subspecies (semicaudata) are unknown. A field investigation of the Aguiguan population of the Mariana subspecies rotensis several lines of evidence to infer an annual litter size of one pup per female in late summer (Wiles et al. 2011, p. 303).

Other

A Samoan specimen was first described by Peale in 1848 as Vespertilio semicaudatus (Lyon and Osgood 1909, p. 259). The species was later included in the genus Emballonura (Temminck 1838, cited in ITIS 2021) and is now known as Emballonura semicaudata (Smithsonian Institution 1909, entire; Tate and Archbold 1939, p. 8).