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Student Regular 10-Minute Presentation

Plant-Insect Ecosystems

Student

Student Regular 10-min: P-IE, General 2

Of the birds and the bees: How bird extirpation affects pollination in an island ecosystem

Sunday, November 9, 2025
3:54 PM - 4:06 PM Pacific
Location: Oregon Convention Center, E146, OCC
Oral Presentation
Bird decline could affect pollination directly through the loss of avian pollinators, or indirectly through a trophic cascade affecting insect pollinators. Guåhan, one of several islands in the Marianas island chain, has functionally birdless forests as a result of the invasive and predatory Brown Tree Snake (Boiga irregularis), whereas neighboring islands like Saipan retain their bird populations. We aim to understand how bird loss has affected pollination on Guåhan, using Saipan as a reference. In 2024, we installed camera traps in front of flowering trees on both islands, then reviewed footage to identify visitors. Simultaneously, we collected environmental DNA (eDNA) left behind on flowers and are using metabarcoding to identify visitors. Our camera footage found the most frequent visitors on both islands to be ants, moths, flies, butterflies, and bees. We found greater visitation by ants on Guam, and we recorded two species of native birds on Saipan, the Canario (Cleptornis marchei) and Nosa’ (Zosterops conspicillatus), visiting flowers, with zero visits from birds on Guam. However, >99% of visits on Saipan were from insects, so impacts of bird loss are likely to be via an indirect trophic cascade rather than loss of avian pollinators. Approximately 30% of activity across both islands was at night. Floral eDNA results are awaiting sequencing. The next step is to sample and identify pollen from visitors to distinguish likely pollinators. Collectively, these data sets will offer further insight into the effects of bird extirpation on Guåhan with potential applications to systems globally experiencing bird declines.