Archived 2014 discussion: Rusty-faced Babbler (Robsonius rabori): downlist to Near Threatened?

This discussion was first published as part of the 2013 Red List update, but remains open for comment to enable reassessment in 2014.

BirdLife species factsheet for Rusty-faced Babbler

Rusty-faced Babbler Robsonius rabori is found in northern Luzon in the Philippines and, although tape playback indicates it may be widely overlooked (del Hoyo et al. 2007), it has been described as fairly common around Adams in northwest Luzon and at Mt. Cagua in northeast Luzon (P. Hosner in litt. 2012).

It is currently listed as Vulnerable under criterion B1ab(ii,iii,v) because it was thought to have a small range, restricted to ≤10 locations, with its habitat  undergoing continuing declines both in area and quality as a result of deforestation. However, P. Hosner (in litt. 2012) recently gathered information on this species’s distribution and reported that it is found in more than 10 locations, including reports in Isabela and Aurora (R. Hutchinson in litt. 2012). A research programme on mammals reported a number of new localities for this species, previously considered a lowland specialist, including in montane forest up to 1,300m (P. Hosner in litt. 2012). Observations suggest that habitat quality may not be important for this species; it might actually prefer scrubby forest (R. Hutchinson in litt. 2012) and can exist in degraded habitat (P. Hosner in litt. 2012). Also, this species is notoriously difficult to detect in the field and so it may be largely undetected (P. Hosner in litt. 2012) and more common that previously suggested (del Hoyo et al. 2007).

If this information is confirmed, and the species is found at more than 10 locations, it would no longer qualify as Vulnerable and would warrant downlisting to Near Threatened, on the basis that it approaches the thresholds for Vulnerable under criterion B1ab(ii,iii,v).

The term ‘location’ defines a geographically or ecologically distinct area in which a single threatening event can rapidly affect all individuals of the taxon present. The size of the location depends on the area covered by the threatening event and may include part of one or many subpopulations. Where a taxon is affected by more than one threatening event, location should be defined by considering the most serious plausible threat. (IUCN 2001). For example, where the most serious plausible threat is habitat loss, a location is an area where a single development project can eliminate or severely reduce the population. Where the most serious plausible threat is volcanic eruption, hurricane, tsunami, frequent flood or fire, locations may be defined by the previous or predicted extent of lava flows, storm paths, inundation, fire paths, etc.

Further information is requested on the distribution, population size and trends of this species. Comments on the proposed downlisting are also welcome.

Reference:

del Hoyo, J., Elliott, A. and Christie, D. (2007) Handbook of the Birds of the World, vol. 12: Picathartes to Tits and Chickadees. Lynx Edicions: Barcelona, Spain.

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4 Responses to Archived 2014 discussion: Rusty-faced Babbler (Robsonius rabori): downlist to Near Threatened?

  1. Desmond Allen says:

    You need to remember that this species has been split, and Robsonius rabori is now Cordillera Ground-warbler, and only occurs in the Ilocos Norte-Apayao region and not the Sierra Madre.

    • Joe Taylor says:

      Thank you for your note. This forum topic follows our current taxonomic treatment of these populations. The evidence published by Hosner et al. (2013) will be considered by the BirdLife Taxonomic Working Group.

      Reference:

      Hosner, P. A., Boggess, N. C., Alviola, P., Sánchez-gonzález, L. A., Oliveros, C. H., Urriza, R. and Moyle, R. G. (2013) Phylogeography of the Robsonius Ground-Warblers (Passeriformes: Locustellidae) Reveals an Undescribed Species from Northeastern Luzon, Philippines. Condor 115(3): 630-639.

  2. Andy Symes says:

    Preliminary proposals

    Based on available information, our preliminary proposal for the 2014 Red List would be to maintain Rusty-faced Babbler Robsonius rabori as Vulnerable whilst recently-published proposals to change the taxonomic treatment of the taxon are considered.

    There is now a period for further comments until the final deadline of 31 March, after which recommended categorisations will be put forward to IUCN.

    The final Red List categories will be published on the BirdLife and IUCN websites in mid-2014, following further checking of information relevant to the assessments by both BirdLife and IUCN.

    Near Threatened, approaching the threshold for Vulnerable under criterion A3.

  3. Andy Symes says:

    Recommended categorisation to be put forward to IUCN

    Following further review, there has been no change to our preliminary proposal for the 2014 Red List status of this species.

    The final categorisation will be published later in 2014, following further checking of information relevant to the assessment by BirdLife and IUCN.

Comments are closed.