Justification of Red List Category
This species has an extremely small range confined to mixed tree-fern forest on one small island, where recent surveys have shown it to have an extremely small population which may be declining. It is therefore listed as Critically Endangered.
The current population size is uncertain, with some survey techniques yielding estimates of c. 140 individuals (I. Hahn in litt. 2012), with others giving estimates closer to 500 individuals. It is precautionarily placed in the band 50-249 mature individuals, which equates to 75-374 individuals in total, rounded here to 70-400 individuals.
The species seems to have shown a rapid decline between the mid-1980s and early 2000s, but seems to have stabilised at around 140 individuals since then (I. Hahn in litt. 2012).
This species is endemic to Alejandro Selkirk (Más Afuera) in the Juan Fernández Islands, Chile. The population was estimated at c. 500 individuals in the mid-1980s (Brooke 1988). Its size is now uncertain, with estimates in 2002 (Hahn et al. 2006, I. Hahn, P. Hodum and M. Wainstein in litt. 2003) and 2011 (I. Hahn in litt. 2012) both putting the population at c. 140 individuals (representing a 72% decline since the 1980s), but survey work in between (2006-2007) estimating a population similar to the c. 500 individuals estimated 20 years previously (Tomasevic et al. 2010). Its breeding range is restricted to one fifth of the island (Hahn et al. 2005, 2011).
This gleaning insectivore is found primarily in Dicksonia externa fern forest, and has a strong association with canelo Drimys confertifolia, an endemic species of tree. It also regularly occurs in Lophosauria quadripinnata dominated slopes in the upper elevations of the island (P. Hodum in litt. 2012). It is most common along stream courses where luxuriant Dicksonia grows to a height of 5 m. There are records at elevations as low as 600 m, but it occurs primarily at 800-1,300 m in the austral summer (Hahn and Römer 1996). The species has a minimum territory size of 4 ha per pair in optimal habitat, although most are larger due to poorer habitat quality, and it nests in natural and man-made cavities, particularly in small natural holes in steep rocks (Hahn et al. 2004, P. Hodum in litt. 2007, 2008, Hahn et al. 2010, 2011). Nesting occurs from late November to early February (Hahn et al. 2011) and fledglings have been noted in January and February (P. Hodum in litt. 2006, 2012). Only four natural nests have ever been found (Hahn et al. 2010), but three complete and four incomplete nests were constructed in nest boxes (Tomasevic et al. 2010). All known nest sites have shown a strong association with canelo (Hahn et al. 2010, Tomasevic et al. 2010). The nests found in nest boxes had a supporting structure of canelo and tree-fern Dicksonia externa rootlets and a soft cup of petrel (Pterodroma externa and P. longirostris) feathers (Tomasevic et al. 2010). Adults fed nestlings with arthropod prey, particularly lepidopteran larvae (Hahn et al. 2010). It is typically skulking and found in pairs, or family groups during the summer months (P. Hodum in litt. 2012).
It is probably secure as long as mature tracts of the ferns Dicksonia and Lophosauria remain intact, but a large proportion of natural vegetation on the island has been degraded and fragmented by goat-trampling, fire and timber-cutting (I. Hahn in litt. 2004, Hahn et al. 2004, Anon. 2007). Mature trees are important for foraging, roosting and probably provision of nesting cavities (P. Hodum in litt. 2007, 2008, 2012). Introduced mammalian predators are thought to have a significant impact on the population, with rats (Rattus spp.) and possibly mice (Mus musculus) impacting on brood survival, and feral cats impacting on juvenile and adult survival (Hahn and Römer 2002, Tomasevic et al. 2010). Significantly, it is absent from the lowlands, where the forest understorey has already been destroyed. An unusual increase of native Red-backed Hawk Geranoaetus polyosoma during the last decade, as illegal hunting of this species by fishermen has ceased and the hawk population has benefited from preying upon introduced mammals (Hahn et al. 2004), may have contributed modestly to any recent declines, with several cases noted of hawks preying on rayaditos (I. Hahn in litt. 2004, Hahn et al. 2004). Having a montane distribution that is close to the maximum altitude within its range, this species is also potentially susceptible to climate change (BirdLife International unpubl. data).
Conservation Actions Underway
The Juan Fernández Islands were designated as a national park in 1935 (protected from 1967) and a UNESCO Biosphere Reserve in 1977. Sheep were removed from the island in 1983 (Carboneras 1992). A goat control programme was undertaken from 1998-2003 but has only continued on a sporadic basis since (P. Hodum in litt. 2007, 2008). The Chilean government began a habitat restoration programme in 1997 (J. C. Torres-Mura in litt. 1999), but that effort concluded in 2003. The islands have been nominated for World Heritage listing (Hulm 1995). There is one ranger posted on Alejandro Selkirk (J. C. Torres-Mura in litt. 1999), but there are plans to begin having two rangers working on the island. Eighty-one nest boxes were installed in a variety of habitats in 2006 (P. Hodum in litt. 2006), with at least three having been used during the 2006-2007 breeding season. Other monitoring work is ongoing and efforts continue to improve current population estimates and knowledge of the species's ecology and habitat requirements, to quantify threats and to develop a conservation plan for the species (P. Hodum in litt. 2006). A protocol for monitoring the species has been developed and the species is a priority for monitoring (Anon. 2012). Educational materials including posters and community talks have been produced by Juan Fernández Islands Conservancy and Oikonos (P. Hodum in litt. 2007, 2008, 2012).
16 cm. Small, distinctive furnariid. Generally dull greyish-buff. Dusky brown crown and auriculars. Dull buff throat and eyebrow. Blackish wings with two cinnamon-buff bars across remiges. Black tail with pale rufous central feathers and broad tip to outer rectrices. Slender bill. Voice Often delivers churring trrrt call.
Text account compilers
Capper, D., Bird, J., Symes, A., Khwaja, N., Ashpole, J, Westrip, J., Harding, M., Pople, R., Sharpe, C.J.
Brooke, M., Hahn, I., Hodum, P., Torres-Mura, J.C., Wainstein, M. & Wallace, G.
BirdLife International (2022) Species factsheet: Aphrastura masafuerae. Downloaded from http://www.birdlife.org on 01/10/2022. Recommended citation for factsheets for more than one species: BirdLife International (2022) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 01/10/2022.