Mussau Triller: Lost Bird Species Rediscovered After 44 Years

The Mussau triller (Lalage conjuncta), last documented in 1979, was rediscovered in June of this year by Australian bird photographer Joshua Bergmark during a tour with a group of birdwatchers. This songbird species, part of the cuckooshrike family, is endemic to Mussau Island, located in the Bismarck Archipelago north of Papua New Guinea in Oceania. The Mussau triller is also listed on The Search for Lost Birds, which tracks 126 lost bird species.

According to re:wild, the birdwatchers recorded a total of nine Mussau trillers in three flocks, making the first known photo and audio recordings of this rare and little-studied species. The birds prefer the taller trees in the dense central forests of the island, making them particularly difficult to locate.

Deforestation as a potential threat

The exact distribution of the Mussau triller on Mussau Island and its population size remain unknown. Nevertheless, the International Union for Conservation of Nature (IUCN) has classified the species as “vulnerable” on its Red List, due to the ongoing threat of deforestation on Mussau since the 1980s.

Intensive logging has destroyed large areas of the island’s original primary forest, severely impacting the habitats of many endemic species. According to Global Forest Watch, the New Ireland Province, which includes Mussau, lost approximately 7.2 percent of its primary forest between 2000 and 2023. Although the newly constructed logging roads enabled the birdwatchers to access the island’s interior forests and ultimately led to the rediscovery of the Mussau triller, these developments could also pose a long-term threat to the habitat of this and other species.

Monitoring island birds as a precautionary measure

The rediscovery of the Mussau triller highlights the importance of regularly monitoring island birds, especially those that have not been sighted for years. “Looking at satellite images of forest cover, we can have a tendency to assume that species like the triller are doing fine despite the lack of recent records,” says John Mittermeier, Director of the Search for Lost Birds project at ABC. “But in fact it is vitally important to check up on island species, like the triller. We don’t know how a bird like this responds to these habitat changes caused by logging and invasive species. The fact that Josh and his group found the triller and confirmed its presence after so many years is stunning news.”

Mittermeier also recalls the case of the Makira moorhen (Gallinula silvestris) from the Solomon Islands, last documented in 1929 and now considered lost. For a long time, it was assumed that the species was safe due to the extensive forest cover on the island. However, the population declined rapidly, and the species was ultimately not found again. “The moorhen is always in my mind when I think about the importance of checking up on island birds,” Mittermeier says. “t should be a red flag if no one has documented a species in more than ten years.”

Island birds are particularly vulnerable to environmental changes due to their isolated habitats, and the lack of regular documentation can be a warning sign for potential extinctions. The rediscovery of the Mussau triller is therefore a crucial step in understanding the current status of this species and developing appropriate conservation measures.

Birdwatching groups as a valuable resource for conservation

The rediscovery of the Mussau triller also serves as a powerful example of the importance of birdwatching groups for conservation. Thanks to the efforts of experts like Joshua Bergmark and the participation of birdwatchers worldwide, invaluable data is collected that plays a critical role in protecting endangered species. Platforms such as eBird, Xeno-canto, and iNaturalist, where bird sightings can be documented and shared, have become indispensable for scientific research and conservation efforts. According to a recent study, these platforms contain records of 98 percent of all bird species worldwide. The ability of birdwatching organizations to reach remote and difficult-to-access areas is crucial in rediscovering species like the Mussau triller and gaining a better understanding of their habitats.

Organized birdwatching tours, such as those offered by Ornis Birding Expeditions, co-founded by Joshua Bergmark, provide opportunities to observe rare and endangered species in remote regions and collect vital data. These tours not only allow participants to make unique observations but also contribute valuable information for conservation initiatives. The rediscovery of the Mussau triller and the continued documentation of other rare bird species demonstrate the significant impact of collaboration between birdwatchers and conservation organizations in preserving biodiversity.