Hawaii Songbirds Steal Nest Materials From Each Other
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- Erin Wilson Rankin and UC Riverside colleagues documented nest-material theft among Hawaiian forest birds over six months, tracking 200+ nests in the first systematic study of kleptoparasitism in these species.
- The Apapane emerged as both the most frequent thief and the most common victim, with the behavior occurring even within the same species, likely due to the bird's abundance in the forest.
- The I'iwi, Apapane, and Hawai'i Amakihi were among native canopy-nesting species whose nests the team observed, including ones still holding eggs or chicks.
- Roughly 5% of observed nests failed after theft incidents, and about 10% of thefts targeted active nests — failure came from structural damage or parents abandoning the site.
- Height overlap drove most thefts, with birds stealing from nests built at similar canopy levels, supporting the researchers' "height overlap hypothesis."
- Wilson Rankin said the behavior compounds pressure on birds already stressed by habitat loss, avian malaria, and climate change, though none of the studied species are currently listed as endangered.
- The American Naturalist published the study in 2026 (DOI: 10.1086/740144), a collaboration between Wilson Rankin, a UCR entomologist, and her husband, biologist David Rankin, who led nest-finding efforts.
Why it matters: For conservationists managing Hawai'i's shrinking high-elevation forests, a documented 5% nest-failure rate from within-species theft adds a previously unmeasured stressor to native birds already fighting mosquito-borne avian malaria and habitat loss. Wilson Rankin says identifying where the behavior peaks would help direct interventions to at-risk species as nesting materials and safe sites grow scarcer.
