Data Zone
Justification of Red List category
This species has a very restricted range and there is ongoing forest loss and degradation within its range. It is therefore assessed as Near Threatened.
Population justification
Spatially explicit habitat models linked to density functions for R. longirostra predicted a contemporary population of 36,123 birds on Pohnpei (Oleiro and Kesler 2015), which is rounded here to 36,100 and equivalent to approximately 24,000 mature individuals.
Trend justification
Surveys in 1994 found significantly fewer individuals than in 1983 in both the lowland and uplands, with nearly 90% of the sightings on c.10% of the land area (Buden 2000). However, results from a comparison between these surveys (Engbring et al. 1990, Buden 2000) and detections from surveys in 2012 indicated a mean change in detection rates of -18% and +359%, respectively (Oleiro and Kesler 2015). Compared to Buden (2000), increasing detection rates were observed at lower elevation zones and a slight decline was observed above 600 m (-7%) (Oleiro and Kesler 2015). Despite this, the species is positively associated with upland old-growth forest (Oleiro 2014) and modelling of 1,000 future landscape scenarios by Oleiro and Kesler (2015) indicated a mean population decline of 3.6% (SD 7%) in R. longirostra populations during the next 100 years, with anthropogenic vegetation changes to undisturbed habitats most likely to drive declines. Global Forest Watch (2022) data are not available for Pohnpei such that estimating a rate of habitat clearance is not possible, but growing of sakau is widespread and currently considered the main cause of the island's upland deforestation (Ellis et al. 2018). Given predicted population declines, ongoing deforestation and increasing demand for sakau (Oleiro and Kesler 2015, Ellis et al. 2018), the species is suspected to be declining at a slow rate.
Rukia longirostra is endemic to the island of Pohnpei, Federated States of Micronesia.
It occurs in palm and broadleaf forest, rarely using plantations (Engbring et al. 1990). It feeds mostly on nectar, but also takes insects and sometimes fruit (Engbring et al. 1990). Its affiliation with the uplands may be the result of its nectarivorous feeding habits, which have allowed it to subsist on the nectar of the abundant native palm, and it may also be excluded from the lowlands by competition with other native passerines (Engbring et al. 1990). Oleiro (2014) describe this species as associated with low amounts of forest edge, high canopy height and crown closure in uplands – all characteristics of climax forest.
Overall, there was a reduction of undisturbed upland forest on Pohnpei of over 60% from 1975 to 1995 (Buden 1996, 2000; B. Raynor in litt. 1995, 2012; Oleiro and Kesler 2015). The majority of the island's forests have been to various degrees converted or at least degraded to mixed forest (native species mixed with lowland secondary species), largely attributable to the cultivation of sakau (= kava) Piper methysticum, a major cash-crop (B. Raynor in litt. 2012). The fragmentation of such forest by sakau clearings also introduces and encourages the spread of invasive species in isolated areas throughout the forest. Although efforts over the past 20 years to reduce the amount of clear-cutting for sakau plantations have resulted in the slowing of native forest conversion rates, the trend remains negative (B. Raynor in litt. 2012). Long-standing tradition and custom surround the use of sakau, but this has given way to more widespread recreational use with the result that clear-cutting 1-2 ha plots for sakau has increased, reaching to the edge of cloud forest at c.600 m in some areas (Buden 2000, Oleiro and Kesler 2015). Growing of sakau is currently considered the main cause of the island's upland deforestation (Ellis et al. 2018), the use of which continues to be widespread (Sakai and Nakazawa 2022). The rate of deforestation has slowed due to alternative methods for growing sakau in the lowlands and the establishment of a watershed line, but deforestation continues in municipalities where this was not implemented and farmers still favour upland areas (Ellis et al. 2018). There have been proposals for large-scale impacts including the development of large resorts, golf courses, and reservoirs for Pohnpei and other Micronesian islands (Oleiro and Kesler 2015). Anthropogenic processes underpinning the forest loss and degradation are likely to continue or even increase in the future, and these impacts are also likely to be exacerbated by climate change through habitat alteration and increased incidence of extreme rainfall and flooding events (Oleiro and Kesler 2015).
Conservation Actions Underway
No targeted conservation actions are known for this species.
Text account compilers
Vine, J.
Contributors
Raynor, B.
Recommended citation
BirdLife International (2024) Species factsheet: Long-billed White-eye Rukia longirostra. Downloaded from
https://datazone.birdlife.org/species/factsheet/long-billed-white-eye-rukia-longirostra on 23/12/2024.
Recommended citation for factsheets for more than one species: BirdLife International (2024) IUCN Red List for birds. Downloaded from
https://datazone.birdlife.org/species/search on 23/12/2024.