Maui News

ʻIo research expected to provide new insights on the range, behaviors of the Hawaiian hawk

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VC: DLNR Hawaiʻi

‘Io, the Hawaiian hawk, is the subject of simultaneous research projects underway on Hawai‘i Island. The DLNR Division of Forestry and Wildlife and San Diego Zoo Wildlife Alliance are conducting the researching which is expected to give conservationists new insights into the majestic birds’ range and behaviors. 

The ‘Io is one of two raptors native to Hawai‘i–The other is Pueo, the Hawaiian short-eared owl.

  • Ka‘u Forest Reserve ‘io research (Feb. 9, 2023) PC: Scott Cate.
  • Ka‘u Forest Reserve ‘io research (Feb. 9, 2023). PC: DLNR Hawaiʻi.
  • Ka‘u Forest Reserve ‘io research (Feb. 9, 2023). PC: DLNR Hawaiʻi.
  • Ka‘u Forest Reserve ‘io research (Feb. 9, 2023). PC: DLNR Hawaiʻi.
  • Ka‘u Forest Reserve ‘io research (Feb. 9, 2023). PC: DLNR Hawaiʻi.

Earlier this month, DOFAW crews ventured into the Ka‘u Forest Reserve to attract, trap, and band ‘io.


“Once we get to a location we think is good ‘io habitat, we begin playing back ‘io calls to attract birds,” said Kate Maley in a department news release. The screech of an ‘io sounds through the canopy for eight minutes while Maley and coworker Bri Bishop scan the sky. When they don’t spot a bird in that time frame, they move onto another location and try again.

At the third spot on this particular day, an ‘io flew into the area to investigate shortly after the pair played calls. They prepared a cylinder-shaped wire trap, with a lure inside, and within minutes the bird swooped down thinking it was in for an easy meal. Instead, the bird was trapped by its talons and several hours of processing began. 

Officials with DLNR say the adult female is the seventh bird captured since the DOFAW study began last fall. The SDZWA research in the Pu‘u Maka‘ala Natural Area Reserve has resulted in six birds caught, banded, and now tracked. 


A species recovery project, aimed at reintroducing ʻalalā (Hawaiian crow) back into the wild, failed, with ‘io shouldering some of the blame. It’s believed the hawks attacked numerous crows and the remaining ‘alala were subsequently recaptured.

Department officials say plans are underway now to try again on Maui, where there are no ‘io. The current research is expected to provide invaluable data for another ʻalalā introduction project on Hawai‘i Island in the future. 

“So far, we’ve gotten some cool data that show ‘io using the habitat on the edge of the Kaʻū Forest Reserve and in the pastures. They seem to be using this edge habitat, moving into the forest sometimes, sometimes hanging out in the pastures and sometimes flying all the way to coffee plantations around Pāhala,” Maley said.  


Much of the team’s time with bird-in-hand is spent attaching a tiny GPS tag to its back. The tags use cellular tracking technology, so that researchers can pinpoint each ‘io’s location at any given point in time. 

“That’s one thing that’s cool about the work we’re doing here. Eventually it’s hoped ʻalalā will be released again and knowing where the ‘io are spending their time and how they’re utilizing the landscape will help identify places where there’s not much ‘io presence,” Maley said. “Between what we’re doing, what the zoo wildlife alliance is doing, and past efforts by the US Geological Survey, we’re going to develop a really impressive data set.”  


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