Archived 2016 topics: Black-crested Bulbul (Pycnonotus melanicterus) is being split: list Ruby-throated Bulbul Pycnonotus dispar as Near Threatened?

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

Lynx Edicions and BirdLife International will soon publish the second volume of 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 2 of the checklist (for passerines) will begin to be incorporated into the 2016 Red List update, with the remainder 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.

Black-crested Bulbul (Pycnonotus melanicterus) is being split into P. melanicterus, P. gularis, P. flaviventris, P. dispar and P. montis, following the application of criteria set out by Tobias et al. (2010).

Prior to the taxonomic change Pycnonotus melanicterus (BirdLife species factsheet) was listed as Least Concern, on the basis that it was not believed to approach any of the thresholds for listing as Vulnerable under any of the criteria. The pre-split species had a very large range extending from Sri Lanka, the Western Ghats and east India, throughout the Himalaya, through Indochina, Peninsular Malaysia, Borneo and the Greater Sundas.

Following the taxonomic changes, Pycnonotus dispar is restricted to Sumatra, Java and Bali, and has been described as fairly common to common but rare in Bali (Fishpool and Tobias 2016). Considered to prefer disturbed habitats and previously considered common throughout much of Java and Sumatra, trapping pressure on the species continues to be high and the species was classified as ‘Severely Declining’ during an expert review process in 2014 (Harris et al. 2015). Additionally the trade price of the species is increasing while the trade volume has been decreasing, a pattern indicative of unsustainable exploitation (Harris et al. 2015).

While there is no quantification of the rate of decline, it is suspected that the species is likely to be declining at a moderately rapid rate (approaching 30% in nine years/three generations), sufficient to approach the thresholds of Vulnerable under criterion A2d+A3d+A4d. On this basis, it is proposed that the species should be listed as Near Threatened, and effort to quantify declines in the field are required throughout the range.

It is proposed that P. melanicterus, P. gularis, P. flaviventris and P. montis all be listed as Least Concern on the basis that they do not approach any thresholds for threatened status.

References:

Fishpool, L. & Tobias, J. (2016). Ruby-throated Bulbul (Pycnonotus dispar). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (retrieved from http://www.hbw.com/node/57929 on 31 August 2016).

Harris, J. B. C., Green, J. M. H., Prawiradilaga, D. M., Giam, X., Giyanto, Hikmatullah, D., Putra, C. A. & Wilcove, D. S. 2015. Using market data and expert opinion to identify overexploited species in the wild bird trade. Biol. Conserv. 187: 51–60.

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6 Responses to Archived 2016 topics: Black-crested Bulbul (Pycnonotus melanicterus) is being split: list Ruby-throated Bulbul Pycnonotus dispar as Near Threatened?

  1. James Eaton says:

    Another species I would recommend as Endangered. Have there been any sightings of confirmed wild birds on Java in recent years? On Sumatra, despite numerous visits to sub-montane forests throughout the island it is a bird I rarely see, despite seeing large numbers in trade. On Bali, it is extremely localised and rare, according to Hery Kusumanegara, a bird guide and ranger on Bali.

  2. Serene Chng says:

    TRAFFIC would like to share information on trade observations of this species, in a bid to quantify and better understand the threat from overexploitation.

    As James has mentioned, Pycnonotus dispar is regularly seen in fairly large numbers in markets in Indonesia. 132 individuals were recorded from 26 stalls in three markets in Jakarta surveyed in July 2014 (Chng et al., 2015); 95 individuals were recorded from 22 stalls in an inventory of five markets in Surabaya, Malang and Yogyakarta in June 2015 (Chng and Eaton, 2016); and a further 10 were recorded for sale in Bandung in September 2016, where one individual was priced at IDR 150,000.

    One seizure record was found for Pycnonotus dispar involving a 2014 operation in Selangor, Peninsular Malaysia, suggesting that the species may be smuggled from sources in Indonesia for sale in Malaysia. There are two further seizure records in Indonesia involving the species in 2016: both were attempts to smuggle birds including 22 Pycnonotus melanicterus (most likely to be dispar based on distribution) from South Sumatra to Java on a bus via Bakauheni port in Lampung (http://kabar24.bisnis.com/read/20160825/16/578354/penyelundupan-ribuan-burung-digagalkan and http://www.jawapos.com/read/2016/09/15/51096/penyelundupan-satwa-langka-digagalkan-aparat-kejar-pelaku).

    References:
    Chng, S.C.L. & Eaton, J.A. 2016. In the Market for Extinction: eastern and central Java. TRAFFIC. Petaling Jaya, Selangor, Malaysia.

    Chng, S. C. L., Eaton, J. A., Krishnasamy, K., Shepherd, C. R. & Nijman, V. 2015. In the market for extinction: an inventory of Jakarta’s bird markets. Petaling Jaya, Selangor, Malaysia: TRAFFIC.

  3. Andrew Owen says:

    A small number (5-6) of Ruby-throated bulbuls were seen by Bas van Balen, Anais Tritto and myself at a well known National Park in West Java in March 2016.
    This was the first time I had seen this species in the wild in Java in the 8 years I have visited.
    This species is still regularly seen in bird markets in Jakarta (20) recorded in pramuka in March 2016.
    Presumably these birds are being trapped in Sumatra.
    I would agree with the recommendation to list this species as endangered.

  4. Rob Martin (BirdLife International) says:

    Thank you for the comments on this topic.
    The numbers of records of the species observed in the wild appears to be far fewer than initially judged, while the numbers traded are clearly large. The link between numbers being traded and rate of population decline is difficult to estimate, however the classification as ‘Severely Declining’ from Sumatra appears to be reasonably extrapolated to Java also.
    However, the data on observations and numbers traded do appear to indicate that the species has become more difficult to find, but not that it has been rapidly lost from large areas of the range within 10 years as would be the case with a decline of greater than 50%. The increase in price, which the useful comment above clearly indicates is continuing, is suggestive of a species in moderate to rapid decline.
    With a clearer notion of the recent paucity of observations from the field, the pointers from the study of trade data indicate that the population is likely to be declining at a faster rate, suspected to be in excess of 30% in 10 years.

    Preliminary proposals

    Based on available information, our preliminary proposal for the 2016 Red List would be to list Ruby-throated Bulbul as Vulnerable under criterion A2d + A3d + A4d.

    There is now a period for further comments until the final deadline of 28 October, after which the recommended categorisations will be put forward to IUCN.
    Please note that we will then only post final recommended categorisations on forum discussions where these differ from the initial proposal.

    The final 2016 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.

  5. Bas van Balen says:

    As is the case with Blue-winged Leafbird, the vaste but under-surveyed woodlands in eastern Java may still have some good numbers. On Bali it has always been rare, it has been discovered on the island only 30 years ago. Ruby-throated is much less montane than for instance Black-crested and should be looked for in lowland woodlands, which are not as often visited by birders as the highlands. Nevertheless, with the present trends in the cagebird trade, vulnerable seems appropriate.

  6. Rob Martin (BirdLife International) says:

    Comments have been received from Burung Indonesia (in litt. 2016) supporting the listing of this species as Near Threatened.

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