EEB Graduate Student Wieteke Holthuijzen received the best PhD poster award at the 50th Annual Meeting of the Pacific Seabird Group and also received the Chairs Choice Award for assistance in organizing the conference. Per their website, “The Pacific Seabird Group (PSG) is a society of professional seabird researchers and managers dedicated to the study and conservation of seabirds…PSG members include biologists, wildlife managers, post-docs, students and conservation biologists from 16 countries including the United States, Mexico, Canada and Japan. PSG annual meetings and publications provide forums where members can share their findings on all research topics related to Pacific seabirds, and discuss local and large scale conservation issues.”
Title: Determining arthropod consumption by Laysan Ducks to inform non-target mitigation efforts during rodent eradication
Authors: Wieteke Holthuijzen, Carmen Antaky, Beth Flint, Jonathan Plissner, Coral Wolf, Holly Jones
Abstract: The critically endangered koloa pōhaka (Laysan Duck, Anas laysanensis) in the Northwestern Hawaiian Islands has wild populations on Kamole (Laysan Island), Kuaihelani (Midway Atoll NWR), and Hōlanikū (Kure Atoll). Although its population and distribution have increased since its listing in 1967, the koloa pōhaka faces a new risk on Kuaihelani: non-target poisoning via a pending House Mouse (Mus musculus) eradication. After mice were observed attacking and depredating mōlī (Laysan Albatross, Phoebastria immutabilis) on Sand Island of Kuaihelani in 2015, plans to eradicate mice with rodenticide were quickly developed. To reduce exposure to rodenticide, ducks will be captured and translocated to Eastern Island (mouse-free) during eradication activities. Even so, ducks may risk secondary poisoning by ingesting arthropods that feed on brodifacoum bait. Therefore, it is crucial to monitor rodenticide residue in arthropods to determine when koloa pōhaka can be safely released post-eradication. Because duck diet is unknown on Kuaihelani, we used next-generation sequencing (NGS) to identify which arthropods ducks consume. We found that Sand Island’s ducks most frequently consume cockroaches (Blattodea), freshwater ostracods (Cyprididae), midges (Chironomidae), and isopods (Porcellionidae). Notably, Sand Island’s ducks consume entirely different arthropods from ducks on Kamole, which mainly eat flies (Diptera) and brine shrimp (Anostraca, Artemia sp.). Our study adds to the literature on the biology and ecology of translocated koloa pōhaka populations by using advanced techniques to uncover their diet with a high degree of taxonomic precision. In addition, our study serves as a model for risk mitigation during invasive rodent eradications.