Justification of Red List Category
This species qualifies as Vulnerable because it has a very small range. It survives in a very small occupied area of upland forest on one island, where it is at risk from the effects of exotic taxa. It is close to qualifying as Endangered, but appears able to tolerate some disturbance to its habitat.
Estimates based on surveys in 2012 placed the population at only 10, 787 birds (95% CI:(8,396 – 13,434) (Paxton et al. submitted) and so has been placed in the band 10,000 - 19,999 individuals.
The species seemed to have recovered from Hurricane Iniki in 1992, and appeared to be increasing (Pratt 1994, Foster et al. 2004), with data suggesting an increase in the Alaka`i and Koke`e areas equivalent to c.17% over the last ten years (Foster et al. 2004). Surveys in 2012 however placed the current population at only 10, 787 birds, suggesting more recent declines (Paxton et al. submitted).
Hemignathus parvus 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). 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). However, surveys of the Alaka`i and Kôke`e areas in 2000 yielded an estimate of c.34,500 individuals in these areas (Foster et al. 2004, and in 2003, the total population was put at 44, 359 individuals (USFWS in litt. 2003). But now the species seems to be dramatically declining; estimates based on surveys in 2012 placed the population at only 10, 787 birds (95% CI: (8,396 – 13,434), which represents declines of -57% in the core of the range, and -91% in the periphery of the range (Paxton et al. submitted).
It inhabits `ohi`a and native mixed forest mainly above 600 m, but has been found as low as 100 m (especially in the north-west of the island) (USFWS 1983, Pratt et al. 1987, Lepson 1997), although no reports at low elevation have been made since 2010 (L. C. Crampton in litt. 2016). 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).
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 1997). 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). 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). Feral pigs facilitate the spread of both alien plants and mosquitoes and, with other ungulates, continue to degrade native forests (Pratt 1994). 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 Japanese 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). This species's restriction to Kaua`i and dependence on canopy species makes it vulnerable to catastrophic events such as hurricanes (P. Roberts in litt. 2007).
Conservation Actions Underway Conservation Actions Proposed
Its habitat is partially protected from development by the Alaka`i Wilderness Preserve the Kôke`e State Park (P. Roberts in litt. 2007), and several Natural Area Reserves. Recently, the top portion of the Alaka`i Wilderness Preserve and the Hono O Na Pali reserved have been fenced, from within which ungulates will be removed; control of rats and cats is ongoing in the latter. Also, since 2014, expanding grids of Goodnature A24 rat traps have protected nests and breeding birds in the Alaka’i Wilderness Preserve (40 traps in 2014, 150 traps in 2015, 300 traps in [L. C. Crampton in litt. 2016]). Actions implemented as part of the Hawaiian Bird Conservation Action Plan will likely have indirect benefits to this species (VanderWerf 2012).
Conservation Actions ProposedMonitor population trends through regular surveys. Control and prevent further introductions of non-native animals and plants, particularly in the Alaka`i Wilderness Preserve (Scott et al. 1986, Lepson 1997). Restore habitats (Lepson 1997). Identify and encourage disease-resistant lineages, e.g. by translocation, captive propagation (Lepson 1997), provision of supplementary resources, nest protection and introduced predator/competitor control.
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 H. kauaiensis, `Akeke`e Loxops caeruleirostris, and Kaua`i Nukupu`u H. lucidus 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 H. kauaiensis. Hints Easily seen at Koke`e.
Text account compilers
Benstead, P., Derhé, M., Isherwood, I., Stattersfield, A., Stuart, T., Taylor, J. & North, A.
Camp, R., Fretz, S., Gorresen, M., Lepson, J., Pratt, H., Roberts, P., VanderWerf, E., Woodworth, B. & Crampton, L.
BirdLife International (2020) Species factsheet: Magumma parva. Downloaded from http://www.birdlife.org on 22/09/2020. Recommended citation for factsheets for more than one species: BirdLife International (2020) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 22/09/2020.