Searching Mohotani Island for the Marquesan Monarch

Field staff and local Marquesan community members venture to Mohotani Island to find and study the Marquesan Monarch in preparation for the restoration of the island.

In French Polynesia, roughly 1500 kilometers from Tahiti and 5000 km from the nearest continent sits the Marquesas Archipelago: a group of mostly volcanic islands, with high, rugged mountain peaks with steep cliffs that drop down into the blue ocean below. The islands are home to a unique array of wildlife and vegetation, but have faced substantial losses due to extinction with more species following along the same path. In November 2019, a team of conservationists from Island Conservation, BirdLife, SOP Manu (BirdLife in French Polynesia), Auckland Zoo, and local Marquesans set out to the island of Mohotani.

Nestled within the Southern Marquesas Islands, Mohotani hosts one of the only remaining intact and thriving native forest in the Archipelago. Towering Pisonia trees provide critical habitat for noddies, terns, and frigatebirds. In the understory of the forest, nests the Marquesas Monarch, a small species of flycatcher once found throughout the Archipelago that now survives only on Mohotani with a population of fewer than 400 individuals. While the island may appear to be untouched by humans, slowly the ecosystem is unraveling due to predation invasive species. Left unaddressed, the Marquesas Monarch will soon be added to the list of extinction species in the region.

Female Marquesan Monarch perched in a tree. Credit: Fred Jacq/SOP Manu

Island Conservation and our partners are working to save this and other native wildlife by removing invasive species from Mohotani and six other uninhabited islands. Before restoration can begin, the team needed to understand more about the Marquesan Monarch and the seabirds that rely on these islands.

The team ventured out into the forest of Mohotani to find the small population of Monarchs. This was not entirely challenging, as Monarchs will quickly come to investigate what people are doing, a behavior that is common for island wildlife, which are often considered evolutionarily naive. This naivety stems from an evolutionary history without predators and leaves them susceptible when invasive species are introduced.

The team’s objective was to study the Monarchs feeding behavior, watching the birds as they searched for food underneath leaves and caught small insects. This as well as a series of trials helped the team to understand if the Marquesan Monarch could adapt to living in aviaries, which would serve as an additional level of protection for the population while implementing the restoration project. Sadly, they found that the Monarchs do not adapt well to captivity and the team will instead need to find another way to ensure the health of the population. The species’ inability to adapt to new surroundings further highlights the urgency of restoring Mohotani and protecting their native ecosystem.   

Phoenix Petrel is one of the ground-nesting seabirds that conservationists hope to protect by restoring Mohotani and the other uninhabited islands. Credit: Richard Griffiths/Island Conservation

In addition to the Marquesan Monarchs, the team needs to understand what species of seabirds are visiting and utilizing the island. Seabirds play an integral role in the islands’ ecosystems, acting as a significant contributor of nutrients for plants and invertebrates through bird guano. In an otherwise nutrient-poor environment, this ecosystem service is essential for the overall health of the island. Historically, five species of ground-nesting seabirds relied on the island, but due to predation by invasive rats and feral cats very few if any seabirds remain. There is some suspicion that a few species may still reside in burrows on the island’s cliffs. The team set out to test this theory, using audio recorders to determine if any seabirds are emerging at night or if they have indeed been extirpated from the island.

These efforts are all part of a much larger conservation plan, which first began when Island Conservation, SOP Manu, Birdlife International, and the local community of Ua Huka to successfully remove invasive rats from Teuaua Island, protecting a population of 90,000 Sooty Terns. This served as a vital stepping stone and confirmed that successful removal of invasive species can be done in the region. Now, the partners are moving forward with the restoration of seven uninhabited islands and look forward to a time when Mohotani and other islands are free of invasive predators and secured for native wildlife.

About Josh Sellers

Josh received his BA in History from the University of California, Santa Cruz. Having been lucky enough to live on the California coast his entire life, Josh has developed a deep sense of appreciation for the environment. This passion for the environment has manifested in Josh’s participation in various environmental campaigns, an interest in environmental history – studying the relationship between peoples and their surrounding environment(s) – and past employment with the United States House of Representatives, where he was afforded the opportunity to see how government policy impacts conservation efforts. In his spare time, Josh enjoys surfing, backpacking, and reading anything related to recent history, and fantasy novels. He is excited to be working with Island Conservation and help support the amazing work the organization does.

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