Data Zone
Justification of Red List category
This species has a highly restricted range on a single island. Knowledge of its population size and trend is very limited, but there is ongoing forest loss and degradation within the range and it is likely restricted to few locations. It is therefore assessed as Vulnerable.
Population justification
This species is very poorly known and the population size has not been quantified. It is currently only known from a very limited number of specimens and field observations, but may be locally common (Dutson 2011). The last documented record of this species is a specimen collected in 1979 (LACM 91065, per Rutt et al. in prep), though there have been a number of unconfirmed records since. It was not recorded by rapid surveys in 2014 suggesting that the species is potentially very rare and restricted to higher altitude or localised areas (Aplin et al. 2015).
Trend justification
There are no data on population trends, but extensive logging is continuing on the island (Taylor 2020). Although the species is poorly known, it is thought to be restricted to closed forest (Dutson 2011, Aplin et al. 2015) and is precautionarily suspected to be declining as a result. In the three generations to 2022, remote sensing data indicate that c.5% of forest was lost in this species' range (Global Forest Watch 2023, using data from Hansen et al. [2013] and methods disclosed therein). The rate of forest loss has rapidly accelerated in recent years however, reaching an equivalent rate of c.10% in three generations based on losses in 2017-2022. Based on even steeper losses in 2022 alone, forest loss may continue at a rate equivalent to c.20% within three generations if this is ongoing. Assuming declines are roughly equivalent to the rate of forest loss, they are tentatively placed in the range 1-9% in the past three generations, 1-15% between 2017 and 2027 and 1-19% over the future three generations.
This species is endemic to the island of Mussau in the St Matthias group of the Bismark Archipelago (Papua New Guinea).
Its ecology is poorly known, but the species is possibly restricted to closed forest in hills (Dutson 2011, Aplin et al. 2015).
Primary forest cover was severely reduced from the 1980s onwards as a result of commercial logging operations (Aplin et al. 2015). Although this slowed since 2000, remote sensing data indicate that forest loss is now accelerating again within this species' range (Global Forest Watch 2023, using data from Hansen et al. [2013] and methods disclosed therein). Feral pigs are a major pest species on the island but any impact on the species is unknown.
Conservation Actions Underway
No targeted conservation actions are known for this species.
Conservation Actions Needed
Carry out further surveys to assess the status of this species at higher altitude sites and across a wider area of forest (Aplin et al. 2015). Produce population and trend estimates. Study the basic ecological requirements of the species. Protect remaining areas of habitat.
Text account compilers
Vine, J.
Contributors
Dutson, G.
Recommended citation
BirdLife International (2025) Species factsheet: Mussau Triller Lalage conjuncta. Downloaded from
https://datazone.birdlife.org/species/factsheet/mussau-triller-lalage-conjuncta on 05/01/2025.
Recommended citation for factsheets for more than one species: BirdLife International (2025) IUCN Red List for birds. Downloaded from
https://datazone.birdlife.org/species/search on 05/01/2025.