Javan Frogmouth (Batrachostomus javensis) and Blyth’s Frogmouth (B. affinis) are being lumped as B. javensis: list the newly defined species as Near Threatened?

This is part of a consultation on the Red List implications of extensive changes to BirdLife’s taxonomy for non-passerines

Lynx Edicions and BirdLife International will soon publish the HBW-BirdLife Illustrated Checklist of the Birds of the World, building off the Handbook of the Birds of the World series, and BirdLife’s annually updated taxonomic checklist.

The new Checklist will be based on the application of criteria for recognising species limits described by Tobias et al. (2010). Full details of the specific scores and the basis of these for each new taxonomic revision will be provided in the Checklist.

Following publication, an open and transparent mechanism will be established to allow people to comment on the taxonomic revisions or suggest new ones, and provide new information of relevance in order to inform regular updates. We are also actively seeking input via a discussion topic here regarding some potential taxonomic revisions that currently lack sufficient information.

The new Checklist will form the taxonomic basis of BirdLife’s assessments of the status of the world’s birds for the IUCN Red List. The taxonomic changes that will appear in volume 1 of the checklist (for non-passerines) will begin to be incorporated into the 2013 Red List update, with the remainder, and those for passerines (which will appear in volume 2 of the checklist), to be incorporated into subsequent Red List updates.

Preliminary Red List assessments have been carried out for the newly split or lumped taxa. We are now requesting comments and feedback on these preliminary assessments.

Javan Frogmouth Batrachostomus javensis and Blyth’s Frogmouth B. affinis are being lumped as B. javensis, following the application of criteria set out by Tobias et al. (2010).

Prior to this taxonomic change, both Javan Frogmouth B. javensis (BirdLife species factsheet) and Blyth’s Frogmouth B. affinis (BirdLife species factsheet) were listed as Least Concern. These species were estimated to have very large ranges, and hence did not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence of less than 20,000 km² combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). Their population trends appeared to be stable, and hence these species did not approach the thresholds for Vulnerable under the population trend criterion (at least a 30% decline over ten years or three generations). Their population sizes have not been quantified, but they were not believed to approach the thresholds for Vulnerable under the population size criterion (fewer than 10,000 mature individuals with a continuing decline estimated to be at least 10% over ten years or three generations, or with a specified population structure).

The lumped species, B. javensis, is found in Indochina (including the Thai-Malay Peninsula), Sumatra, Java, Borneo and the western Philippines, where it mainly inhabits lowland evergreen forest, typically mature forest, reaching foothills and lower montane elevations in some areas (Holyoak 2001). In some parts of its range, such as Java, it can be found in tree-rich scrub, and may be able to occupy secondary growth, but luxuriant undergrowth appears to be important (Holyoak 2001). It may qualify as Near Threatened under criteria A2c+3c+4c, as it could be undergoing a moderately rapid population decline (approaching 30% over three generations [c.23 years]), owing to on-going rapid rates of deforestation in lowland areas throughout its range.

Comments on this suggested categorisation are invited and further information would be welcomed.

References:

Holyoak, D. T. (2001) Nightjars and their Allies: the Caprimulgiformes. Oxford, UK: Oxford University Press.

Tobias, J. A., Seddon, N., Spottiswoode, C. N., Pilgrim, J. D., Fishpool, L. D. C. and Collar, N. J. (2010) Quantitative criteria for species delimitation. Ibis 152: 724–746.

Related posts:

1. Archived 2010-2011 topics: Newly-split Malayan Banded Pitta (Pitta irena), Bornean Banded Pitta (P. schwaneri) and Javan Banded Pitta (P. guajana): list all as Least Concern?
2. Green-backed Kingfisher (Actenoides monachus) is being split: list both A. monachus and A. capucinus as Near Threatened?
3. Lilac-cheeked Kingfisher (Cittura cyanotis) is being split: list both C. cyanotis and C. sanghirensis as Near Threatened?
4. Brown Barbet (Calorhamphus fuliginosus) is being split: list both C. fuliginosus and C. hayii as Near Threatened?
5. Archived 2011-2012 topics: Taxonomic change in the genus Cissa: list Javan Green Magpie (C. thalassina) as Critically Endangered and Bornean Green Magpie (C. jefferyi) as Least Concern?