Data Zone
Justification of Red List category
This species is classified as Endangered owing to its very small and contracting range where habitat degradation is ongoing. The population is declining at a rate exceeding 60% in ten years and is highly susceptible to avian malaria, with climate change projected to cause an increase in the elevation below which regular transmission occurs.
Population justification
Estimates based on surveys of both the interior and exterior areas of the Alaka'i Plateau in 2012 placed the population at 10,787 individuals (95% CI: 8,396 – 13,434) (Paxton et al. 2016). Surveys in 2018 placed the population at 8,703 individuals (95% CI: 6,467–11,221) (Paxton et al. 2020), roughly equivalent to 4,300-7,500 mature individuals overall. Assuming declines have continued at the same rate (The most recent population estimate suggests a decline of c.64% within the time period 2008-2018 [Paxton et al. 2020]), this would now place the population in the band 3,000-5,000 mature individuals. There is possibly a small, isolated population in the Makaleha Mountains (Camp et al. 2009), however this is precautionarily assumed not to host mature individuals given the lack of recent records.
Trend justification
In 1968-1973, surveys estimated 24,230 birds, largely restricted to upper elevations (USFWS 1983). In 1992, Hurricane Iniki devastated forests throughout Kaua'i and all bird populations on the island appeared to have been drastically reduced (Pratt 1993, 1994). Surveys of the Alaka`i and Kôke`e areas in 2000 yielded an estimate of c.34,500 individuals in these areas however, suggesting the species had recovered and was possibly increasing (Foster et al. 2004). Surveys in 2012 placed the population at only 10,787 birds, suggesting more recent declines (Paxton et al. 2016). The most recent population estimate of 8,703 individuals suggests a decline of c.64% within the time period 2008-2018 (Paxton et al. 2020), and as such the rate of decline is placed here in the range 60-70% within ten years.
This species is endemic to Kaua`i in the Hawaiian Islands (USA), where it occurred almost throughout the island in the 19th century but, by 1900, had become uncommon to rare in lowland forests (Lepson 1997).
It inhabits `ohi`a and native mixed forest mainly above 600 m, to highest point of island at 1,600 m with densest populations above 1,100 m (Lepson 2020). but has been previously found as low as 100 m (especially in the north-west of the island) (USFWS 1983, Pratt et al. 1987, Lepson 1997). It is able to tolerate considerable habitat disturbance, but at lower population densities (Lepson 1997). It feeds on nectar and arthropods (especially caterpillars and spiders) and nests in `ohi`a trees (Lepson 1997). Nest construction begins as early as February, and may continue into late July (Eddinger 1970), with mean nest height being estimated at 6.1 m in the late 1960s (Eddinger 1970) and 7.7 ± 2.2 m SD in a study conducted in 2012-2013 (Hammond et al. 2016). The species is only known to nest in `ohi`a trees (Eddinger 1970, Lepson 1997, Hammond et al. 2016). Males help females with nest construction to a lesser extent. Females are the sole incubators, but males feed females during incubation, typically away from the nest. Both males and females provision nestlings and fledglings (Eddinger 1970).
From the late 1890s, significant declines have been associated with habitat loss and degradation (either owing to clearance for timber and agriculture, or to introduced herbivores), and the spread of avian diseases (Lepson 1997). Ongoing development in the Kôke`e area continues to diminish the amount of habitat available, and the spread of exotic plants into native habitats, although tolerated, is associated with lower densities (Lepson 2020).
The species is particularly vulnerable to avian malaria (Whitaker 2022). Introduced mosquitoes, which spread avian pox and malaria, are now common at 900 m, and may be breeding as high as 1,200 m elevation (Lepson 1997, Glad and Crampton 2015). Climate change is projected to cause an increase in the elevation below which transmission of avian malaria occurs (Liao et al. 2017). Under a 2oC warming scenario and an increase in rainfall over high-elevation forests during the next 100 years, in keeping with climate model predictions for the region, the prevalence of malaria on Kaua`i is predicted to increase within the remaining habitat (Benning et al. 2002). The 17 oC isotherm, below which Plasmodium prevalence peaks, is predicted to shift upwards by around 300 m, decreasing the area of forest where Plasmodium prevalence is limited by 85% (Benning et al. 2002). Such changes are already associated with increased prevalence of avian malaria in this species (Atkinson et al. 2014) and the species' range is contracting (Paxton et al. 2016).
Feral pigs facilitate the spread of both alien plants and mosquitoes and, with other ungulates, continue to degrade native forests (Pratt 1994, VanderWerf 2012). Predation by introduced animals (rats and possibly cats and Barn Owls Tyto alba) is an additional pressure (Lepson 1997, Hammond et al. 2016), while other introduced taxa (especially the Mountain White-eye Zosterops japonicus, wasps and ants) may compete for arthropod resources (Lepson 1997). Invasive plants have degraded significant portions of Kôke`e State Park and threaten the remainder of the habitat (P. Roberts in litt. 2007, Behnke et al. 2016). In addition to exacerbating the threat of introduced diseases, climate change is predicted to increase the geographic extent and intensity of habitat loss, invasive plants and non-native predators (Paxton et al. 2018).
This species' restriction to Kaua`i and dependence on canopy species makes it vulnerable to catastrophic events such as hurricanes (P. Roberts in litt. 2007) which have caused substantial declines in the past (Pratt 1993, 1994). The emergence of the Ceratocystis wilt pathogen that causes rapid ‘ohi‘a death may also be a potential threat (Camp et al. 2019).
Conservation Actions Underway Conservation Actions Proposed
Much of current range protected to some extent by Kōke'e State Park and Alaka'i Wilderness Preserve (Lepson 2020). Removal of ungulates and invasive plants is ongoing (USFWS 2017). Portions of the Alaka`i Wilderness Preserve and the Hono O Na Pali reserve have been fenced (VanderWerf 2012). Weed control has been conducted by The Nature Conservancy and Kōke‘e Resource Conservation Program (VanderWerf 2012). Since 2014, expanding grids of Goodnature A24 rat traps have protected nests and breeding birds in the Alaka’i Wilderness Preserve (L. C. Crampton in litt. 2016). Development of genetic tools to reduce transmission of avian malaria is ongoing. This includes transgenic or genetically modified mosquitoes that have reduced ability to transmit pathogens and also incompatible insect techniques, for example using a different strain of Wolbachia bacteria to produce males that cannot produce viable offspring (USFWS 2017, Miranda Paez et al. 2022).
Continue genetic research in disease immunity in Hawaiian honeycreepers (Paxton et al. 2018). Continue research in the fields of genomic technologies and genetically modified mosquitoes for disease control and their field application (USFWS 2017). Continue conducting periodic range-wide surveys to monitor status (VanderWerf 2012).
Protect core forest habitats (Paxton et al. 2018). Control and prevent further introductions of non-native animals and plants, particularly in the Alaka`i Wilderness Preserve (Scott et al. 1986, Lepson 1997). Implement a phased disease vector control program (Paxton et al. 2018). Restore habitats (Lepson 1997, 2020). Strengthen captive breeding capacity. Expand outreach to increase conservation attention and funds to the Kauai conservation crisis (Paxton et al. 2018).
10 cm. Small honeycreeper with short, thin, slightly curved bill. Male bright yellow with no dark feathering in lores. Dark wing and tail feathers broadly edged yellow. Female and juvenile similar but less bright. Similar spp. Kaua`i `Amakihi Chlorodrepanis stejnegeri, `Akeke`e Loxops caeruleirostris, and Kaua`i Nukupu`u Hemignathus hanapepe all have dark lores and different bill shapes. Introduced Japanese White-eye Zosterops japonicus has straight bill and bold white eye-ring. Voice Song a vigorous trill of doubled or tripled notes weesee-weesee-weesee- or weesity-weesity-weesity- etc. Typical call a two-note tew-weet, down then up. Also a loud, single chirp similar to call of C. stejnegeri. Hints Easily seen at Koke`e.
Text account compilers
Vine, J.
Contributors
Crampton, L., Lepson, J. & Roberts, P.
Recommended citation
BirdLife International (2024) Species factsheet: Anianiau Magumma parva. Downloaded from
https://datazone.birdlife.org/species/factsheet/anianiau-magumma-parva on 22/12/2024.
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 22/12/2024.