Pacific Islands Fish and Wildlife Office
Pacific Region

Endangered Species in the Pacific Islands

Hawaiian Hoary Bat / Lasirus cinereus semotus  / ‘ope‘ape‘a

Photo of Hawaiian hoary bat
The ‘ope‘ape‘a usually weighs 14 to 18 g (0.49 to 0.63 ounces), is nocturnal, and eats insects. Females are larger than males. Their wing span is about 10.5 to 13.5 inches.

It has a heavy fur coat that is brown and gray, and ears tinged with white, giving it a frosted or "hoary" look. It is believed to be related to the North American hoary bat and it is the only native land mammal of Hawai‘i. 
Hawaiian hoary bat - Photo credit © Jack Jeffrey

Habitat & Behavior:
Bats are found primarily from sea level to 2,288 m (7,500 ft), although they have been observed near the island's summits above 3,963 m (13,000 ft). Relatively little research has been conducted on this endemic ‘ope‘ape‘a and data regarding its habitat and population status are very limited. Most of the available documentation suggests that this elusive bat roosts among trees in areas near forests.

The ‘ope‘ape‘a feed on a variety of native and nonnative night-flying insects.

It is a solitary bat that typically leaves its roost shortly before or after sunset and returns before sunrise. Breeding has only been documented on Hawai‘i and Kaua‘i. Like their North American relative, the ‘ope‘ape‘a gives birth to twins during the summer months.

Past & Present:
The ‘ope‘ape‘a has been seen on the islands of Hawai‘i, Maui, Moloka‘i, O‘ahu, and Kaua‘i, but may only live on Hawai‘i, Maui, and Kaua‘i. A large population might have lived on O‘ahu before the early 19th century, but it is based on a single observation of an unknown number of bats.

Population estimates for all islands have ranged from hundreds to a few thousand, however, these estimates are based on limited and incomplete data. The magnitude of any population decline is unknown. Observation and specimen records do suggest, however, that these bats are now absent from historically occupied ranges.

‘Ope‘ape‘a populations are believed to be threatened by habitat loss, pesticides, predation, and roost disturbance. Its decline may be primarily due to the reduction of tree cover in historic times, and they may be indirectly impacted by the use of pesticides.

Conservation Efforts:
The ‘ope‘ape‘a was listed as an endangered species on October 13, 1970, under the Federal Endangered Species Act and the State of Hawai‘i's Endangered Species List. The Hawaiian Hoary Bat Recovery Plan, completed in 1998, and the State of Hawai‘i's Comprehensive Wildlife Conservationist Strategy recommend conservation of known occupied habitat, development and implementation of conservation plans that guide the management and use of forests to reduce negative efforts to known bat populations and, continued support for the ‘ope‘ape‘a research cooperative.


Last updated: September 20, 2012
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