Evaluating the Seed Dispersal Efficacy of Hawaiʻi’s Last Functionally Extant Frugivore
Koa Matsuoka
University of Hawaiʻi at Hilo, Hilo, Hawaii

Track

IV. Putting Research into Practice for Thriving 'Åina

Abstract

On islands worldwide, mass avian extinctions related to anthropogenic activity have allowed exotic generalist to fill ecological niches left vacant by larger native specialist. Consequently, ensuring the survival of the ʻōmaʻo (Myadestes obscurus) or Hawaiian thrush, Hawaiʻi’s last functionally extant native frugivore, may be integral in preserving seed dispersal function in Hawaiian forests. In lieu of settling on exotic birds as proxies for native seed dispersers, recent management strategies have proposed utilizing ʻōmaʻo reintroductions to refill empty niches caused by localized ʻōmaʻo extinctions. Previous studies suggests that ʻōmaʻo consume a greater diversity of native fruiting plants than exotic frugivores and therefore, have different effects on seed dispersal. In light of this, this study compared diet and germination success of Hawaiian fruiting plants dispersed by exotic and native birds in a naturally fragmented forest on Hawaiʻi Island. To compare seed dispersal proficiency between native and exotic birds, seeds were collected from the fecal samples of ʻōmaʻo and Japanese white-eye (Zosterops japonicus) to answer the following questions: 1. How does seed germination success vary by gut-passge through ʻōmaʻo and Japanese white-eye? 2. What fruiting plant species benefit from the presence of ʻōmaʻo? Preliminary diet results show that ʻōmaʻo have greater diet diversity and abundance of fruiting plant seeds compared to the Japanese white-eye. These results may substantiate the use of ‘ōmaʻo reintroductions as a strategy to promote regeneration of Hawaiian forests while giving insight into potential changes in the native plant community composition should ʻōmaʻo go extinct and replaced by exotic frugivores.