The Hawaii Volcanoes National Park website says this type of bat is Hawaii’s only native land mammal
The opeapea, or Hawaiian hoary bat, is Hawaii’s only native land mammal, according to the National Park Service website on Hawaii Volcanoes National Park. The opeapea is not only native but endemic, meaning it is found nowhere in the world except Hawaii, NPS further states.
The ancestors of the opeapea likely arrived from North America by flying along the trade winds for more than 2,000 miles, says the NPS website. While there are more than 1,300 known species of bats, no other bat is known to have ever made an overwater journey that long and successfully established a new population after it. This happened more than 10,000 years ago, explains NPS.
According to a University of Hawaii genetic study published on the United States Geological Survey website, the opeapea’s North American ancestors actually arrived in Hawaii on two different waves. While the first wave happened over 10,000 years ago, the second wave happened as few as 800 years ago.
Once these bats made it to the islands, the UH study states, they adapted to the conditions and evolved into the opeapea they are today. When the second wave of bats arrived 800 years ago, they interbred with the population that had already been here for over 9,000 years.
The opeapea is listed as endangered under the Endangered Species Act. Their biggest threats, according to Pacific Rim Conservation, include fatal collisions with manmade structures, such as buildings, barbed wire and wind turbines.
One key argument in the 2019 Kahuku wind farm protests was the potential death of opeapea, according to Ku Kiai Kahuku protesters. Posts expressing concern are still available on their Facebook group page.
The Hawaii Department of Land and Natural Resources released guidance in 2015, with the latest update in 2021, on how wind farms can protect the opeapea. The guidance focuses on measures to minimize damage to opeapea populations.
A graph included in the DLNR guidance indicates in August and September of 2020, more than 40 opeapea were killed via collision with wind turbines. DLNR also noted the opeapea’s breeding season ends in August and the bats may still have had pups dependent on their parents in September.
DLNR notes, in a separate document for its Endangered Species Recovery Committee, the opeapea population is estimated to be anywhere “from a few hundred to a few thousand.”
The largest opeapea populations are found on the Big Island, Maui and Kauai, states a PRC flier. Sightings on Oahu are described as “infrequent.”