I’m writing a series of posts which will highligt the Juan Fernández Islands (JFI) and the Critically Endangered Juan Fernández Firecrown Sephanoides fernandensis and the Critically Endangered Másafuera Rayadito Aphrastura masafuerae. I’m doing this primarily to draw attention to these two extremely rare species and to the conservation work that’s being coordinated by Oikonos.org, a California-based non-profit organisation that has been working on the islands for ten years.
Over a series of posts I will be looking at the islands themselves, the endangered birds found there, the work of Oikonos, and the effects of the dreadful tsunami that smashed into the islands earlier this year destroying much of the infrastructure and killing sixteen people.
I would particularly like to thank Peter Hodum, Director, Juan Fernandez Islands Conservancy and Oikonos.org, who has not only given me permission to use his fantastic images but has written a status update to the islands’ birds – the information in these posts, therefore, is absolutely as current as anything on the internet.
The Critically Endangered Másafuera Rayadito Aphrastura masafuerae is a little-known species endemic to the 32m2 Isla Alexander Selkirk, part of the Juan Fernandez Archipelago some 400 miles off the coast of Chile.
A member of the Furnariidae (Ovenbird) family the Másafuera Rayadito is a lively, sparrow-sized bird closely related to the more common Spine/Thorn-tailed Rayadito A. spinicauda found in central and southern Chile and the adjacent extreme western edge of Argentina. Masafuera Rayaditos occur primarily in Dicksonia externa fern forest, and has a strong association with canelo Drimys confertifolia. It is most common along stream courses where luxuriant Dicksonia grows to a height of 5 m, gleaning their food mainly from fern fronds, epiphytic mosses, and lichens. They will also clamber up tree trunks like creepers, or hang upside down, chickadee-like, while searching for arthropods. They typically skulk in dense vegetation though, often in pairs, rarely flying above the fern cover they favor and are detectable mostly by their “churring” calls (making the excellent photos taken by Peter Hodum of Oikonos (and used here with his permission) even more remarkable). There are records at elevations as low as 600 m, but it occurs primarily at 800-1,300 m in the austral summer.
The Másafuera Rayadito was designated Critically Endangered on the grounds that the 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”. Peter Hodum supports the current designation, writing in an email to me that, “Our data to date suggest a population that is well below 1000 individuals, more likely in the range of 400-500″ (a figure likely to be more accurate than the partial census by Brooke1 in 1986 and periodic work by Hahn2 which estimated c.200 individuals in 1992-1993 and just c.140 individuals in a repeat survey in 2001-2002).
According to BirdLife the threats the species currently face, like its fellow JFI endemic the Juan Fernadez Firecrown, include invasive animals (rats and cats especially) and habitat loss:
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. Mature trees are probably important for foraging, roosting and provision of nesting cavities. 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. Significantly, it is absent from the lowlands, where the forest understorey has already been destroyed. An unusual increase of native Red-backed Hawks Buteo polyosoma exsul 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; they may have contributed modestly to any recent declines, with several cases noted of hawks preying on rayaditos. Having a montane distribution that is close to the maximum altitude within its range, this species is also potentially susceptible to climate change.
The IUCN, as I pointed out in yesterday’s post on the Juan Fernandez Firecrown, in a January 2010 press-release for a new report on invasive alien species, ‘Global indicators of biological invasion: species numbers, biodiversity impact and policy responses’ used one of Peter Hodum’s photographs of the Juan Fernández Firecrown, to highlight the threat posed by introduced plants and animals to this unique species (and, incidentally, revealing that a rather startling total of 542 species were documented as invasive aliens, including 316 plants, 101 marine organisms, 44 freshwater fish, 43 mammal, 23 bird and 15 amphibian species – making invasive alien species one of the top three threats to life on this planet!). They could just have pertinently used a photo of the Másafuera Rayadito…
In general terms the JFI 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. A goat control programme was undertaken from 1998-2003 but has only continued on a sporadic basis since. The Chilean government began a habitat restoration programme in 1997, but that effort concluded in 2003.
More specifically a programme has been insitigated to learn more about this extremely rare bird’s breeding biology. To date only three nests have ever been discovered: all were on or near the ground, making them vulnerable to predation by introduced cats, Norway rats and house mice (all three of which occur in the forested habitat that the rayadito occupies). Virtually nothing else is known about what nesting sites the birds utilise, or whether therefore the small population is being restricted by a lack of breeding sites and/or predation. In 2006 Oikonos, funded by an American Bird Conservancy William Belton Conservation Grant, installed eighty-one nest boxes. The boxes were placed in a variety of habitats. and at least three were used during the 2006-2007 breeding season (which yielded the first observations of an egg of the species).
Peter Hodum is on his way out to the JFI as I write and told us that Oikonos has been unable to follow the usage of these nest boxes for the past couple of years, but view their placement as an interim measure until a multi-species eradication can be undertaken that would remove threats to the ground-nesting rayadito. It would be devestating to learn that increased use of supplied nesting-boxes was leading to an increase in predation rather than a substantial increase in population.
Oikonos’ plans for 2011 include completion of the population survey and a re-checking of all nest boxes. Peter would also like to develop a community-based observation program for Selkirk in which interested fishermen can conduct informal surveys for rayaditos when they are in the interior of the island. This would allow the organisation to track distribution and relative abundance over time. Educational materials including posters have already been produced by the Juan Fernandez Islands Conservancy, and the Selkirk community has apparently expressed interest in participating in such a program.
The February tsunami which destroyed most of the infrastructure on Isla Robinson Crusoe fortunately mostly bypassed Selkirk, but the community on the island is small and isolated. Expecting the members of what is virtually a subsistence fishing economy to undertake conservation work in the interior of the island without recompense is of course unrealistic.
Nevertheless conservation projects are ongoing, and the work being done across the entire archipelago is critical to the survival of its threatened birds. If you would like to donate directly to this work please consider using the button to the left.
- 1 Brooke, M. 1987. ICBP Technical Report.
- 2 Hahn, I., U. Römer and R. Schlatter. 2004. Journal of Ornithology 145: 93-97
All images copyright Peter Hodum and used with permission.
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