This discussion was first published as part of the 2018 Red List update. At the time a decision regarding the status of several species was pended, but to enable potential reassessment of these species as part of the 2019 Red List update this post remains open and the date of posting has been updated.
The species which are still open for discussion are; Javan White-eye (Zosterops flavus), Sumatran Leafbird (Chloropsis media), Greater Green Leafbird (Chloropsis sommerati), and Javan Leafbird (Chloropsis cochinchinensis).
While historically recognised as a threat to species, the cage bird trade, and in particular the Indonesian songbird trade has been receiving more attention as a key driver behind species declines in Asia (see Chng et al. 2015, Eaton et al. 2015, Harris et al. 2015, 2017, Shepherd et al. 2013, 2016). In 2016 a suite of species were proposed to be uplisted to higher threat categories on the IUCN Red List of Threatened SpeciesTM as a result of recent information regarding the potential impacts of this trade on their extinction risk.
A species’s Red List status is calculated through the application of a range of criteria, each with their own threshold values, to give an indication of the species’s risk of extinction (see IUCN 2012). As a rough guide a species listed as Vulnerable has a high risk of extinction; a species listed as Endangered has a very high risk of extinction; and a species listed as Critically Endangered has an extremely high risk of extinction.
As part of the call for suggestions for species to review in 2018 for potential Red List status changes, the Asian Songbird Trade Specialist Group kindly provided a list of species that could warrant uplisting (D. Jeggo in litt. 2018). The list of these species, the proposed categories, and their current listings are provided in the table below.
|Common Name||Scientific Name||Current Listing||Proposed Listing|
|Straw-headed Bulbul||Pycnonotus zeylanicus||EN||CR|
|Javan White-eye||Zosterops flavus||VU||EN|
|Sumatran Leafbird||Chloropsis media||VU||EN|
|Greater Green Leafbird||Chloropsis sonnerati||VU||EN|
|Sunda Laughingthrush||Garrulax palliatus||LC||NT or VU|
|Javan Leafbird||Chloropsis cochinchinensis||NT||EN|
|Blue-masked Leafbird||Chloropsis venusta||NT||VU|
|Java Sparrow||Lonchura oryzivora||VU||EN|
|Bar-winged Prinia||Prinia familiaris||LC||potential for >LC|
To warrant a change in status though, we do need to provide to IUCN a justification based on the IUCN criteria. Most of these species (those with hyperlinks) were assessed in 2016 based on the available information at the time. To show that any of these species warrant uplisting to a higher threat category we therefore require some further information, particularly regarding population size and trends in the wild, so that we can compare the species to the IUCN thresholds, and as such have justifiable reasons for status change to submit to IUCN.
Taking Straw-headed Bulbul, for example, there is strong support for listing the species as Critically Endangered (Bergin et al. 2018, D. Jeggo in litt. 2018). Population estimates from Singapore suggest that the subpopulation there contains >50 mature individuals (minimum 202 individuals) (Yong et al. 2018), and so the species could not be listed as Critically Endangered under criterion C2a(i). As this sub-population occurs within the taxon’s natural range, has produced viable offspring and has been present for more than five years (considerably longer), this population is appropriately considered in the global population assessment, even if it were clearly established that it had been founded through escaped individuals in the past (IUCN Standards and Petitions Subcommittee 2014, Yong et al. 2018).
There are fears that population declines may have reached over 80% over 10 years (Bergin et al. 2018), but as of yet there is no clear evidence from population trends in the wild that such declines have taken place, and recent data from Singapore demonstrates that this population is stable (Yong et al. 2018). Bergin et al. (2018) urge that further research takes place on this species to allow for clearer Red List assessments, and we strongly agree with this, as to avoid any proposed status change being rejected by IUCN we would need a clear justification for the change.
Therefore, for all of these species we urgently request any further information regarding population sizes and trends in the wild as these are key to assessing the species’s Red List status.
We provide here further details regarding the three species in the table above for which there was no discussion topic in 2016. They could well qualify for uplisting, as they were excluded from the 2016 discussions largely due to a lack of evidence.
- Sunda Laughingthrush, Garrulax palliatus. Numbers being traded have increased dramatically in recent years, seemingly in line with the decrease in availability of Sumatran Laughingthrush bicolor (Shepherd et al 2016). Very few individuals observed were of the Bornean subspecies G. p. schistochlamys, and this subspecies is unlikely to be significantly impacted by trapping in the short-term. However the Sumatran birds are likely to be suffering a considerable decline as a result of trapping. Contributing to roughly half the range of the species (but with no comparative estimate of the proportion of the global population) significant declines here may be sufficient to approach or exceed the thresholds for listing as Vulnerable under criterion A (a 30-49% decline in a three generation period [14 years]). However, considerable numbers may persist in the less accessible parts of northern Sumatra, making a decline in excess of 60% over this period within Sumatra less likely. Consequently, the rate of overall decline is most likely to approach, rather than exceed, the threshold for listing as Vulnerable, indicating that an assessment as Near Threatened under criterion A2d+A3d+A4d may be appropriate. Clearly we would like more information from wild populations; proportion of discrete sites visited where the species is no longer recorded may be possible should enough people share their experience: for instance, has it disappeared from more than half of Sumatran locations at which it was present 14 years ago?
- Blue-masked Leafbird, Chloropsis venusta. Considered to be less of a target for bird trappers than Greater Green Leafbird, the species has been recorded in markets in Sumatra which is cause for concern given its relatively restricted range on Sumatra. Already considered generally uncommon, evidence of declines and local extinctions coupled with targeting for the cagebird trade may suggest that this species could warrant uplisting. However, the elevational range of the species contains a large extent of the more difficult to access parts of Sumatra and there does not appear to be any data indicating population declines or local extinctions as yet, nor data indicating increases in market price.
- Bar-winged Prinia, Prinia familiaris. A bird of open, scrubby habitats and secondary growth, including gardens and parks it has not been considered likely to be of conservation concern until recently. However it now has a dedicated class in the kicau mania, the bird singing competitions and has experienced intensive trapping pressure partly because of its ability to coexist with people. There is no quantification of the rate of loss, only that it has dramatically declined in Java. There is no apparent information on any impacts on Sumatra. More information is needed: is this previously abundant and resilient bird really threatened? Could the decline be sufficient to approach or exceed the threshold for listing as Vulnerable?
Please note that this topic is not designed to be a general discussion about the ecology of the species, rather a discussion of the species’ Red List status. Therefore, please make sure your comments are relevant to the discussion outlined above.
Bergin, D.; Chng, S. C. L.; Eaton, J. A.; Shepherd, C. S. 2018. The final straw? An overview of Straw-headed Bulbul Pycnonotus zeylanicus trade in Indonesia. Bird Conservation International 28: 126-132.
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.
Eaton, J. A.; Shepherd, C. R.; Rheindt, F. E.; Harris, J. B. C.; van Balen, S. (B.); Wilcove, D. S.; Collar, N. J. 2015. Trade-driven extinctions and near-extinctions of avian taxa in Sundaic Indonesia. Forktail 31: 1-12.
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. Biological Conservation 187: 51–60.
Harris, J. B. C.; Tingley, M. W.; Hua, F.; Yong, D. L.; Adeney, J. M.; Lee, T. M.; Marthy, W.; Prawiradilaga, D. M.; Sekercioglu, C. H.; Suyadi; Winarni, N.; Wilcove, D. S. 2017. Measuring the impact of the pet trade on Indonesian birds. Conservation Biology 31: 394-405.
IUCN. 2012. Guidelines for Application of IUCN Red List Criteria at Regional and National Levels: Version 4.0. Gland, Switzerland and Cambridge, UK: IUCN.
IUCN Standards and Petitions Subcommittee. 2014. Guidelines for Using the IUCN Red List Categories and Criteria. Version 11. Prepared by the Standards and Petitions Subcommittee. Downloadable from http://www.iucnredlist.org/documents/RedListGuidelines.pdf
Shepherd, C. R. 2013. Protection urgently needed for the endemic Sumatran Laughingthrush. TRAFFIC Bull. 25: 53–54.
Shepherd, C. R., Nijman, V., Krishnasamy, K., Eaton, J. A. and Chng, S. C. L. 2016. Illegal trade pushing the Critically Endangered Black-winged Myna Acridotheres melanopterus towards imminent extinction. Bird Conservation International 26: 147-153.
Yong, D. L.; Lim, K. S.; Lim, K. C.; Tan, T.; Teo, S.; Ho, H. C. 2018. Significance of the globally threatened Straw-headed Bulbul Pycnonotus zeylanicus populations in Singapore: a last straw for the species? Bird Conservation International 28: 133-144.