The Hawaiian hoary bat (Lasiurus cinereus semotus), also referred to by its Hawaiian name Ōpe‘ape‘a, is a bat subspecies or distinct species endemic to the Hawaiian Islands. It belongs to the family Vespertilionidae (the vesper or evening bats) and is the only native terrestrial mammal known to occur naturally in Hawaii.
Taxonomy
- Kingdom: Animalia
- Phylum: Chordata
- Class: Mammalia
- Order: Chiroptera
- Family: Vespertilionidae
- Genus: Lasiurus
- Species: Lasiurus cinereus (hoary bat)
- Subspecies: L. c. semotus (Hawaiian hoary bat)
Some taxonomic authorities treat the Hawaiian population as a separate species, Lasiurus semotus, based on genetic divergence from mainland populations; however, consensus remains variable.
Description
The Hawaiian hoary bat is a small to medium‑sized bat, with a head‑body length of approximately 8–9 cm and a wingspan of 30–34 cm. Adults weigh 12–20 g. Its fur is typically a cryptic brown‑gray coloration with a frosted (hoary) appearance, providing camouflage against tree bark. Like other members of the genus Lasiurus, it exhibits a relatively long, narrow wing shape suited for maneuverable flight in forested habitats.
Distribution and Habitat
The subspecies is found exclusively on the main Hawaiian Islands, with confirmed records from Kauaʻi, Oʻahu, Maui, Hawaiʻi (the Big Island), and occasionally Molokaʻi. It inhabits a range of forested environments, including native dry and mesic forests, as well as agricultural and urban wooded areas. Roost sites include foliage, tree cavities, and occasionally man‑made structures.
Behavior and Ecology
- Diet: Insectivorous; captures a variety of nocturnal insects (e.g., moths, beetles, flies) using aerial hawking techniques.
- Foraging: Primarily nocturnal; forages in forest edges and open areas, often within a few kilometers of roost sites.
- Reproduction: Females typically give birth to a single offspring each year, usually in late spring or early summer.
- Roosting: Uses foliage and tree cavities for daytime roosts; seasonal movements between roosts have been documented, but long‑distance migration is not characteristic of the Hawaiian population.
Conservation Status
The International Union for Conservation of Nature (IUCN) has evaluated the broader species Lasiurus cinereus as “Least Concern,” but the Hawaiian subspecies has not been assessed separately by the IUCN. In the United States, the Hawaiian hoary bat was listed as an endangered species under the Endangered Species Act in 2018, reflecting concerns about its limited distribution and declining population trends.
Key threats include:
- Habitat loss and fragmentation due to urban development, agriculture, and invasive plant species.
- Mortality from wind turbines and other structures.
- Predation and competition from introduced mammals (e.g., rats, cats, and mongooses).
- Potential impacts of disease (e.g., white‑nose syndrome), although no confirmed outbreaks have been documented in Hawaii.
Conservation actions underway comprise habitat protection, research on population size and trends, mitigation of wind‑energy impacts, and public education initiatives focused on protecting roosting sites.
Cultural Significance
The bat holds cultural importance in Hawaiian tradition, where it is known as Ōpe‘ape‘a. Traditional stories describe the bat as a messenger or omen, and its presence is sometimes associated with certain mythological narratives.
Research Needs
Current knowledge gaps include precise estimates of population size, detailed migratory or dispersal patterns within the archipelago, and the long‑term effects of emerging threats such as climate change and disease. Continued genetic studies are also needed to resolve the taxonomic status of L. c. semotus relative to mainland L. cinereus populations.