VU
Kauai Elepaio Chasiempis sclateri



Justification

Justification of Red List Category
This species qualifies as Endangered because it is restricted to a single island, on which it has a very small range, and where it is susceptible to the impacts of catastrophic events, such as hurricanes or the introduction of new alien species, and where it is experiencing continued degradation of habitat.

Population justification
Surveys in the Alaka`i Plateau and Kôke`e region in 2008 yielded a population estimate of 82,437 individuals (95% CI: 60, 973 - 107,155) (Paxton et al. submitted), thus the population is placed in the band 50,000 - 99,999 individuals. Current population trend is increasing in core of the range and decreasing in the periphery (Paxton et al. submitted).

Trend justification
The population was apparently reduced by c.50% by the effects of Hurricane Iniki in 1992 (Pratt 1994, Jacobi and Atkinson 1995); however, there is recent evidence from surveys that the species is now recovering, with a 13% increase in mean density in the Alaka`i Plateau from 2000 to 2008 (M. Gorresen in litt. 2011).

Distribution and population

Chasiempis sclateri is endemic to Kaua`i in the Hawaiian Islands (USA) (VanderWerf et al. 2009). It had an estimated population of nearly 40,000 individuals in 1968-1973, apparently reduced by c. 50% in the 1990s (Jacobi and Atkinson 1995), although this apparent decrease may be due to differences in methodology, rather than a genuine population decrease. The species now appears to be recovering in some areas, with an increase of 88% in abundance recorded on the Akala`i Plateau, but a decrease  of 64% recorded in the Kôke`e region between 2000 and 2012, resulting in an estimated population size of 82,437 individuals (60,973 - 107, 155) in 2012 (Paxton et al. submitted).

Ecology

The species is most abundant in wet to mesic montane forest, also occurring in mesic woodland at lower densities. It feeds on insects and other invertebrates (Scott et al. 1986).

Threats

In 1992, Hurricane Iniki drastically reduced all populations (Pratt 1994). Although the species is recovering well in some areas, it is decreasing in others (Paxton et al. submitted) and it remains vulnerable to future catastrophic events such as hurricanes. Diseases, such as avian pox and malaria, spread by mosquitoes, are a problem at all elevations, increasing mortality and possibly preventing birds from nesting (E. VanderWerf in litt. 1999, USFWS 2001, VanderWerf et al. 2006). High prevalence of mosquito-borne diseases and local declines in the species's population are associated with high rainfall (USFWS 2006, VanderWerf et al. 2006) and prevalence is likely to increase with climate change (Atkinson et al. 2014). The species is increasing in some areas despite the potentially negative impacts of introduced species, with cats (Felis catus) being potential predators, rats (Rattus spp.) a documented nest predator (Hammond et al. 2016), and ungulates and alien plant species causing habitat degradation. However, it is decreasing in others, and it remains susceptible to the consequences of further introductions.

Conservation actions

Conservation Actions Underway
The species is monitored to a limited extent (M. Gorresen in litt. 2011) and there are several protected areas within its range. Since 2014, expanding grids of Goodnature A24 rat traps have protected nests and breeding birds in the core of its range (40 traps in 2014, 150 traps in 2015, 300 traps in 2016). Ungulate proof fences have been erected and are continuing to be erected in core habitat, and will help prevent further habitat degradation from weeds (L. Crampton in litt. 2016).

Conservation Actions Proposed
Continue to monitor the population. Monitor actual and potential threats, particularly diseases and rats.

Identification

14 cm. Small monarch flycatcher that often cocks its tail. Adults have white tips to tail feathers, white rump, and white wing bars. Immatures are reddish-brown and have rufous wingbars (VanderWerf 2001). Adult grey above, white below, rusty-tinged breast has indistinct sooty border, white throat. Similar spp. Introduced Japanese Bush-warbler Cettia diphone duller with prominent eyebrow and no white markings. Introduced juvenile White-rumped Shama Copsychus malabaricus larger, darker above, with dark spots on breast and pink legs. Voice Song a lively whistled eh-leh-PYE-o, given in series of two or three with all phrases equally emphasised (del Hoyo et al. 2006); calls include sharp chup, two-note squeak-it like dog's toy, and raspy chatter.

Acknowledgements

Text account compilers
North, A., Benstead, P., Derhé, M., Stuart, T., Taylor, J., Stattersfield, A.

Contributors
Camp, R., Fretz, S., Gorresen, M., Pratt, T., VanderWerf, E., Woodworth, B. & Crampton, L.


Recommended citation
BirdLife International (2022) Species factsheet: Chasiempis sclateri. Downloaded from http://www.birdlife.org on 06/12/2022. Recommended citation for factsheets for more than one species: BirdLife International (2022) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 06/12/2022.