Mindanao Miniature-babbler (Micomacronus sordidus): list as Least Concern?

This discussion was first published as part of the 2017 Red List update. At the time a decision regarding the status of several was pended, but to enable potential reassessment of these species as part of the 2018 Red List update this post remains open and the date of posting has been updated.

Mindanao Miniature-babbler (Micromacronus sordidus) is a tiny, canopy dwelling passerine formerly considered conspecific with Visayan Miniature-babbler (M. leytensis). It is currently listed as Data Deficient, on the basis that as the species’ tolerance of forest was unknown, with the potential to be highly restrictive. Hence it has been considered that there was insufficient information to assign the species to a threat category. In recent times sightings have become regular, although only at a very limited number of locations, suggesting that it may be possible to undertake an assessment of the species’s status.

Sightings in recent years have come from forest and forest edge in the south of Mindanao. The altitudinal range of the species is 600–1,670 m with most records above 1,000 m. Within this elevation the area of forest cover has declined only slightly within the last 10 years. After rapid forest loss during the 1990s, rates of forest loss on Mindanao slowed considerably in the 2000s, and the area of primary forest has been roughly maintained on Mindanao since 2005. As a result, it can be inferred that should the species be declining, as has been assumed, it is currently likely to be only at a slow or negligible rate.

This leaves the potential extent of habitat available to the species. The area of Mindanao above the 1,000 m contour is in excess of 18,000 km2, and the species has been recorded at lower elevations. While infrequent, there are records from the majority of the separate highland areas on Mindanao suggesting that the species may occur throughout this area. If only a fifth of this area were suitable, the species would only need to occur at densities of three mature individuals per square kilometre to comfortably exceed the population threshold for listing as Vulnerable. As a tiny passerine described as common where it has been regularly observed this would seem likely to be the case. Obviously this is a very approximate approach and density estimates at even one location would be useful, but it indicates that the population is likely to exceed the threshold for listing as Threatened.

Bearing in mind the uncertainties that still remain around the species (for example, why are there no recent records from locations that appear suitable and are frequently visited such as Mount Kitanglad?), there remains the possibility that it is patchy and highly localised in occurrence, greatly reducing the potential area of occupancy and any projected population estimate. While not likely to meet the thresholds for listing in one of the Threatened categories, this uncertainty suggests that the species could be considered as Near Threatened. If it can be reasonably concluded that the species occurs relatively commonly at the sites across Mindanao where there are historical records (listed and mapped in Threatened Birds of Asia, BirdLife International 2001; species account) then the species may be listed as Least Concern.

Any information and additional recent records from the north or west of Mindanao would be particularly useful, but all comments are welcome!

 

Reference

BirdLife International. 2001. Threatened Birds of Asia: the BirdLife International Red Data Book. BirdLife International, Cambridge, UK.

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2 Responses to Mindanao Miniature-babbler (Micomacronus sordidus): list as Least Concern?

  1. Pete Simpson says:

    From the Threatened Birds of Asia, BirdLife International 2001; species account) I agree with the statement “The species is regarded as very rare (Dickinson et al. 1991) and believe that as stated there, the call remains unknown and unrecorded.

    Whilst I would agree that ” …..600–1,670 m with most records above 1,000 m. Within this elevation the area of forest cover has declined only slightly within the last 10 years.” and “the area of primary forest has been roughly maintained on Mindanao since 2005”, I believe that the quality of forest/forest fragments in the 600-1200m range have been continually reduced/degraded due to encroachment and more intensive farming methods.

    It is stated the bird has been recorded up to 1670masl and that the potential extent of habitat available to the species on Mindanao above the 1000m contour is in excess of 18000km2. Just in case the species does not reach above its currently highest recorded altitude, any idea how much of that habitat is between 1000m and 1670m?

    “As a tiny passerine described as common where it has been regularly observed”, I am not sure if that is a historical reference, but I would it is not common now where observed.

    I agree that “it is patchy and highly localised in occurrence” as there are few/no recent records from Mt Kitanglad which is frequently visited by birdwatchers”, but also Mt Talomo in Davao (part of the Mt Apo National Park) and Mt Tagubud (adjacent to Mt Pasian) where I have spent a lot of time but not recorded the species.

    Pete Simpson
    Birding Mindanao

  2. Andy Symes (BirdLife) says:

    Preliminary proposals

    Based on available information, our proposal for the 2017 Red List would be to pend the decision on this species and keep this discussion open until 2018, while leaving the current Red List category unchanged in the 2017 update.

    There is now a period for further comments until the final deadline of 4 August, after which the recommended categorisations will be put forward to IUCN.

    Final 2017 Red List categories will be published on the BirdLife and IUCN websites in early December, following further checking of information relevant to the assessments by both BirdLife and IUCN.

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