Ou vs Kauai Nukupuu

The Ou and Kauai Nukupuu can be distinguished primarily by their bills and plumage. The Ou has a distinctive heavy, pink, parrotlike bill with a longer upper mandible that curves over the tip of the lower mandible, while the Kauai Nukupuu has a long, decurved upper mandible and a short, decurved lower mandible. Additionally, the Ou male has a bright yellow head, whereas the Kauai Nukupuu male has a bright orangish-yellow head.

Look for the heavy, pink, parrotlike bill of the Ou with a longer upper mandible. In contrast, note the long, decurved bill of the Kauai Nukupuu with both mandibles decurved. For males, the bright yellow head of the Ou versus the orangish-yellow head of the Kauai Nukupuu is a key distinction.

The Ou is slightly larger than the Kauai Nukupuu.

Male Ou has a bright yellow head and olive green back, while the Kauai Nukupuu male has bright orangish-yellow head, throat, and breast with a white belly. Female and immature Ou are dull olive green, whereas female and young Kauai Nukupuu have greenish-gray or gray upperparts and whitish underparts.