28 Apr 2020

Marquesas fact-finding mission sheds light on Endangered native birds

In November 2019, a BirdLife-led team camped out on one of the world’s remotest islands to learn more about the Endangered birds we urgently need to save. Here’s what they discovered…

Even reaching the islands and unloading equipment was a major challenge © Fred Jacq
Even reaching the islands and unloading equipment was a major challenge © Fred Jacq
By Liv Grant

As a wave swells, an impeccably-timed leap from boat to sharp rock is required to access Mohotani. But it’s well worth the effort, according to the BirdLife-led team that clambered ashore bearing precious research equipment. This exceptionally biodiverse uninhabited island in the Marquesas Archipelago, French Polynesia, is the last to still retain a significant proportion of its native forest. Rising in steep crags from a turquoise sea, the lower slopes of this 1,500 hectare ancient volcanic island are cloaked in a resilient dry forest. This unique ecosystem is adapted to drought and hosts a suite of endemic insects and birds that have evolved to exploit these harsh conditions.

As the island climbs, temperatures cool, giving way to a vibrant forest from which giants emerge: towering Pisonia trees whose crowns are festooned by noddys, terns and frigatebirds. Rare endemic species such as the Marquesas Monarch Pomarea mendozae (Endangered) find refuge in the understory below.

Sadly, this paradise is under severe threat: the introduction of rats, feral cats and sheep has seen the forest shrink dramatically; many ground-nesting birds have been extinguished altogether, and Mohotani’s remaining unique plants and animals are struggling to survive. To prevent this natural wonder from becoming a dusty footnote in history, BirdLife has embarked upon an ambitious mission to restore Mohotani and six other islands within the Marquesas archipelago.

The Marquesas Monarch is Endangered due to the impacts of invasive species © Fred Jacq

BirdLife brought the restoration of these islands one step closer with a three-week field expedition to Mohotani, seeking to increase our understanding of the Marquesas Monarch and how to mitigate or avoid any unintended risks from the restoration operation. The nineperson expedition team comprised experts from BirdLife, SOP Manu (BirdLife in French Polynesia), Auckland Zoo, Island Conservation and local Marquesans. The logistics of coordinating the team were eye-watering, with members travelling from five countries and communicating across three languages.

The location of Mohotani presented its own set of challenges: not only are the island’s shores rugged and difficult to reach, but it is in one of the most remote islands in the world, situated over 1,500 km from Tahiti (French Polynesia’s capital) and over 5,000 km from the nearest continental landmass.  The expedition was only made possible thanks to the strength and expertise of the local people who tirelessly supported the operation. Their support ranged from safely landing everyone on the island, to keeping everyone hydrated – carrying almost a tonne of water to the field camp.

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Here the team spent their first night sleeping in caves embedded in the cliffs, listening to the crashing of waves and the cries of seabirds returning to roost. Rested or not, the next day they immediately set to work assessing the seabird population and studying the behaviour of the Marquesas Monarch. Since this species is only found on this one island, and nowhere else in the world, it is vital to understand its behaviour and needs, to inform its protection from the impact of non-native species.

Researchers woke up to a fantastic view after their first night on the island © Tehani Withers

The team were soon charmed by the Monarch’s inquisitive nature: these territorial flycatchers live in tight family units, and far from being difficult to track down (as you might assume with an Endangered species with less than 400 birds remaining), it is almost more difficult to avoid them. As soon as you wander into their territory, each member of the family will hop down onto a nearby branch to investigate. The team were delighted to see many juvenile Monarchs, but are concerned that these youngsters will be unable to create territories of their own, as overgrazing continues to erode the forest on which the Monarchs depend. The team observed that the birds feed almost constantly, flitting after flying insects and probing under leaves in trees whilst patrolling their territories or displaying to their mate.

This feeding behaviour observed in the wild, alongside observations of how the birds behaved and responded to a short period of time in purpose-built aviaries, confirmed that the Monarchs would not adapt well to captivity. This further highlights the importance of restoring the island’s habitat and protecting the species where they are now, before it is too late. This is also likely to be true of its two Critically Endangered sister species, the Tahiti Monarch Pomarea nigra and Fatu Hiva Monarch Pomarea whitneyi.

Seabirds were once a major driver of the island’s ecosystem. Their guano (droppings), containing nutrients from the sea, fuelled the plants and invertebrates inhabiting the island’s low-fertility soil. Today, the seabird community is a shadow of its former self, restricted to the terns, noddys and boobies that find refuge from invasive predators in the treetops. However, even these species are not immune. The forest floor is littered with skeletal wings: a calling card of feral cats which have caught fledglings just as they took their first steps beyond the nest.

Scientists think that at least five ground-nesting seabird species used to live on the island, but have since succumbed to invasive species and other human threats. Although the team did not see any, they maintain the hope that a few elusive ground-nesters may still be clinging on among the island’s massive cliffs. In order to confirm these suspicions, they set up sound recorders across the island (not as simple a job as it sounds given the cliff-side exposure) which will operate every night for the next year, giving an insight into the hidden lives of seabirds on one of the most remote islands in the world.

Islands are microcosms where the threats facing nature more broadly are amplified. Their isolation creates an opportunity for evolution to happen at an almost accelerated scale, and they are some of our most precious natural treasures. They have also been devastated by the impact of introduced species, with 90% of bird extinctions suffered by island-dwellers. This makes Mohotani and its birds all the more precious, and this recent expedition has been a leap forward in its conservation. The next time the team leap off a boat onto Mohotani’s shores, we hope it will be the dawn of a new future for the island’s feathered inhabitants.

Help us restore paradise in the Marquesas

© Fred Jacq

The removal of introduced species is the only solution to restoring the ecological balance and ecosystem resilience in these remote islands, and preserve their cultural importance. Together with the local community, BirdLife has identified seven islands (including Mohotani) as the focus for our ambitious multi-island restoration operation that will secure over 2,000 hectares of predator-free habitat, providing safe havens for five globally threatened birds and protecting a range of endemic plants from extinction. As preparations advance, we continue to raise the vital funds necessary to save these irreplaceable species.

Visit birdlife.org/marquesas to learn more and lend your support.