Aging and sexing guide to the forest birds of Hawai‘i Island

We banded birds in Hakalau Forest National Wildlife Refuge from 2012 to 2016, collecting photographs of birds and making detailed observations on coloration, morphology, and molting patterns. While we believe the criteria in this guide are applicable to forest birds across Hawai’i Island, as well as on other Hawaiian islands for ‘Apapane, ‘I‘iwi, and Hawai‘i ‘Amakihi, certain characteristics such as morphometrics may vary across populations, and users should verify the guide’s criteria with other available field data.