Animal Info - Large-eared Sheath-tailed Bat

(Other Name: Diana's Sheath-tailed Bat)

Emballonura dianae

Status: Vulnerable


1. Profile
2. Tidbits
3. Status and Trends (IUCN Status, Taxonomy, Countries Where Currently Found, History of Distribution, Threats and Reasons for Decline)
4. Data on Biology and Ecology (Size and Weight, Habitat, Birth Season, Birth Rate, Diet, Behavior, Social Organization)
5. References


The large-eared sheath-tailed bat is a medium-sized sheath-tailed bat.  The length of the head and body is approximately 5 cm (2").  Except for several individuals that were collected at 1400 m (4600') in mossy forest on New Britain Island, most reports of this bat have been from lowland forests from sea level to an altitude of 300 m (1000').  It roosts in caves during the day and flies into the forest before dusk to hunt for insects.

The large-eared sheath-tailed bat occurs on several of the Solomon Islands and in Papua New Guinea (the Bismarck Archipelago and New Guinea).  It is declining due to loss of habitat. 


*** The name "sheath-tailed" refers to the juxtaposition of the tail and the membrane that stretches between the hind legs, whereby the last half of the tail protrudes free from the membrane.  By adjustment of the hind legs in flight, the membrane can be lengthened or shortened as it slips over the tail, giving these bats precise maneuverability in flight.  They utilize acrobatic flight as they fly within the understory of the rain forest hunting both airborne and foliage-clinging insects. (Bonaccorso 1998)

*** Etymology of the scientific name of the large-eared sheath-tailed bat: genus name - "to throw in" + "tail" (Greek), a reference to the separation of the membrane between the hind legs from the tail; species name - for the collector of the holotype, Mrs. Diana Bradley (Flannery 1995a).

Status and Trends

IUCN Status:

Countries Where the Large-eared Sheath-tailed Bat Is Currently Found:

2004: Occurs in Papua New Guinea and the Solomon Islands (IUCN 2004).


Subspecies: Emballonura dianae dianae (occurs in the southern Solomon Islands: Guadalcanal, Malaita and Rennell); E. d. fruhstorferi (New Guinea portion of Papua New Guinea); E. d. rickwoodi (New Ireland and New Britain Islands, both in the Bismarck Archipelago/Papua New Guinea; and Santa Isabel in the Solomon Islands) (Flannery 1995a, Bonaccorso 1998)

Specimens of E. d. rickwoodi are larger than specimens of E. d. dianae, and E. d. fruhstorferi is larger than both of them (Flannery 1995a, Bonaccorso 1998).

History of Distribution:

The large-eared sheath-tailed bat occurs in the islands of Guadalcanal, Malaita, Rennell and Santa Isabel in the Solomon Islands; the islands of New Britain and New Ireland in the Bismarck Archipelago/Papua New Guinea; and the New Guinea Island portion of Papua New Guinea (Flannery 1995a, Bonaccorso 1998).

Location Map (131 Kb JPEG) (Univ. Texas/Maps)

Threats and Reasons for Decline:

The large-eared sheath-tailed bat is declining due to loss of habitat (Nowak 1999).

Data on Biology and Ecology

Size and Weight:

The large-eared sheath-tailed bat weighs 5 - 13 g (0.2 - 0.5 oz).  The head and body lengths of various specimens have been measured at 42 - 64 mm (1.7 - 2.5").


Though early reports found the large-eared sheath-tailed bat only in lowland forests from sea level to an altitude of 300 m (1000'), five individuals were subsequently collected at 1400 m (4600') in mossy forest on New Britain Island.  It roosts in caves. (Bonaccorso 1998)

The large-eared sheath-tailed bat lives in the East Melanesian Islands Biodiversity Hotspot (Cons. Intl. 2005).

Birth Season:

The scant data available to date for the large-eared sheath-tailed bat suggest that births occur around June and October, at least in the Bismarck-Solomons region (Bonaccorso 1998)

Birth Rate:

Available data suggest that there are 2 births/year per female (Bonaccorso 1998)


The large-eared sheath-tailed bat is an insectivore, capturing insects that are in flight or on foliage.


The large-eared sheath-tailed bat roosts by day in dim light just beyond cave entrances.  These bats are visually alert during the day and fly to alternate roost sites if predators or humans approach.  They fly before dusk within the deep shade of the rain forest understory or tree fall gaps, and they apparently return each night to establish a feeding territory.   (Bonaccorso 1998)

Social Organization:

The social behavior of sheath-tailed bat species at the day roost includes interactions between rival males, between males and harem females, and between mothers and infants. Individual large-eared sheath-tailed bats cling singly to vertical walls, widely separated from neighboring conspecifics. (Bonaccorso 1998)


Bonaccorso 1998, Cons. Intl. 2005, Flannery 1995a, IUCN 1996, IUCN 2000, IUCN 2003a, IUCN 2004, Nowak 1999, Univ. Texas/Maps

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Last modified: March 5, 2005;

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