[4] George C. Munro noted that its wings could produce a buzzing sound while flapping quickly, which was not recorded in other birds present in its habitat.

[3] It was typically shy and timid, but it was highly aggressive towards other birds when they approached its territory, even interrupting its own acts to drive them away.

[5] Nests and eggs of the Hawaiʻi ʻōʻō have never been discovered,[3] mainly because the species preferred to settle in the highest of branches.

[3] Some were even caught and put in cages to be sold as songbirds, only to live for a few days or weeks before diseases from mosquitoes befell them.

As late as 1898, hunters were still able to kill over a thousand individuals in one hunt, but after that year, the Hawaiʻi ʻōʻō population declined rapidly.