KILAUEA — A new monitoring system at Kilauea Point National Wildlife Refuge is now active and listening for Kauai’s creatures of the night.
It’s one of three bat detectors active in Hawaii, constructed as part of an ongoing U.S. Fish and Wildlife Service project to learn about the distribution and habits of Hawaii’s only native land mammal — the opeapea, or Hawaiian Hoary Bat.
“We’ve learned in the past five years that pretty much on all the islands, there’s a lot more bats than we thought,” said Jared Underwood, with the USFWS Pacific Island Refuges and Monuments inventory and monitoring program. “We don’t know exactly where they are and we don’t know that much about them.”
Distribution of the bat detectors began in October. They’ve been installed at two refuge locations on Oahu, as well as the location at KPNWR.
The goal is to put detection systems at refuges across the state. The last one is expected to be up by the end of the year.
“I’m excited Kilauea Point NWR is a part of the I&M’s (Inventory and Monitoring) program for opeapea monitoring,” said Jennifer Waipa, supervisor at KPNWR. “Sometimes the smaller, less charismatic wildlife, like the opeapea, don’t often get the attention they deserve.”
And once they are up, the detectors will recording the mammal’s sounds and transmit the data back to Underwood and his team at I&M, so they can learn more about bat activity.
“They’re specifically designed to record bats in that frequency that is about 10-100 kilohertz,” Underwood said. “That’s a really high frequency; most of our sound is below 10.”
Those sounds are used in echolocation, or the bouncing of high-pitched sounds off things, which is used for navigation and hunting. The bats also use high-frequency noises for other types of communication.
One drawback to the bat detectors is that they can’t distinguish how many bats are making the noises. But if there’s a lot of activity, Underwood said, that could indicate the area is of importance to the lives of the bats.
“These systems have nothing that can count them, so it could be the same bat going back and forth across the monitor, or it could be 20 different bats,” Underwood said. “It’s hard to say that, but we’re trying to find the important places for them.”
Why they’re hard to find
Bats on the Mainland usually congregate in caves and roost together, Underwood said, but these bats — which have a wingspan of 12 inches and are only about 4 inches high — roost in trees.
“They don’t form big roosting colonies, it’s two or three to a tree, and they’re hard to find in the large trees,” Underwood said. “They’re hard to find, they’re hard to catch and they’re hard to document.”
So far, USFWS has observed that the bats seem to spend the winter months in the mountains and the summer months in the lowland. Bats have been observed on Kauai mostly on the Westside, near the Pacific Missile Range Facility.
“There hasn’t been much work done on the North Shore and that’s why we’re looking at that, and Lihue also,” Underwood said. “Mostly on Kauai it’s just observational — people have seen bats.”
USFWS will monitor bat activity with the detection systems for a year to help determine where the bats are and try to determine relative abundance, or how common a species is relative to other species.
“It’s hard to recover a species if we don’t understand their needs and what’s important for them,” Underwood said. “We’re after knowledge about these bats so we can understand how to manage for them better.”