Kuhn’s discovery prompted research into the plight of three of Kauai’s six remaining honeycreeper species: the anianiau, the Kauai amakihi, and the akekee. His hunch was correct — the three species now sing much more similar songs, with less complex vocal signals, due to the decreasing size of their populations, especially among mature birds that pass on song repertoires to younger offspring. It’s the first time this type of behavior among endangered birds has been recorded, says Kristina Paxton, lead author of a paper on honeycreepers published last year in the journal Royal Society Open Science, and a postdoctoral researcher in the Department of Biology at the University of Hawaii at Hilo.

—Danielle Beurteaux, in “The Disappearing Songs of Hawaii’s Endangered Native Birds”