Archived 2016 topics: Long-tailed Antbird (Drymophila caudata) is being split: list D. striaticeps and D. klagesi as Least Concern? Request for information for D. caudata and D. hellmayri

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.

Long-tailed Antbird Drymophila caudata is being split into D. caudata, D. straticeps, D. klagesi and D. hellmayri, following the application of criteria set out by Tobias et al. (2010).

Prior to this taxonomic change, D. caudata was listed as Least Concern on the basis that it did not approach the threshold for Vulnerable under any criterion. D. caudata (as now defined following the taxonomic change) is found at Santander and Upper Magdalena Valley in the east Andes of Colombia (Extent of Occurrence: c.60,800km2). It inhabits understorey and mid-storey bamboo in evergreen primary and secondary forest (Zimmer and Isler 2016), and may be fairly common, but locally distributed (Zimmer and Isler 2016). Habitat clearance probably is occurring in the species’s range, but there has been no quantification of the extent to which this may be affecting the species, particularly because it can inhabit secondary growth. We request further information regarding population trends for this species, but with no further information the species is not likely to approach the threshold for Vulnerable under any criterion, and so would warrant listing as Least Concern.

D.striaticeps is found in the west and central Andes of Colombia, Ecuador, Peru (east slope) and north-west Bolivia (east slope in La Paz). D. klagesi is found in the highland of north-east Colombia and north Venezuela. Both these newly split species have large ranges, inhabiting bamboo understorey and mid-storey vegetation in montane primary and secondary evergreen forest (see Zimmer and Isler 2016). While habitat destruction may be occurring in both species’s habitats, given their very large ranges this is not thought to be sufficient to warrant listing as Vulnerable under criterion A. The population of these species has not been quantified, but the pre-split species was described as ‘fairly common but patchily distributed’ (Stotz et al. 1996) and so population sizes are unlikely to be small enough to warrant listing as Vulnerable. Therefore, it is proposed that these two taxa be listed as Least Concern.

D. hellmayri is found in montane forest of the Santa Marta region of northern Colombia (see Zimmer and Isler 2016) within an Extent of Occurrence of only c.3,000km2. The remaining forest in the Santa Marta mountains is threatened by agricultural expansion, logging and burning. Possibly only 15% of the vegetation is unaltered, with the south-east slope having been extensively deforested, and on the west slope between 800 and 1,600 m much of the forest has been cleared for coffee and illegal marijuana plantations, which have subsequently sprayed with herbicide by the government (Stattersfieldet al. 1998). This species may be tolerant of some habitat degradation, but it is still suspected to be in decline. With further information regarding population size and trends this species may warrant as listing as Vulnerable or possibly Endangered. However, in the absence of any further information it is proposed that this species be listed as Near Threatened under criteria A2c+3c+4c; B1ab(i,ii,iii,v).

Comments are invited on these proposed categories and further information would be welcomed.

References:

Stattersfield, A. J., Crosby, M. J., Long, A. J. and Wege, D. C. 1998. Endemic bird areas of the world: priorities for bird conservation. BirdLife International, Cambridge, U.K.

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.

Zimmer, K. and Isler, M.L. 2016. Long-tailed Antbird (Drymophila caudata). 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/56779 on 19 September 2016).

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5 Responses to Archived 2016 topics: Long-tailed Antbird (Drymophila caudata) is being split: list D. striaticeps and D. klagesi as Least Concern? Request for information for D. caudata and D. hellmayri

  1. Thomas Donegan says:

    I believe that D. caudata may require a listing as threatened. There are only two patches of records, one at the head of the Magdalena valley and another recent record on the East slope of the Yariguies (J. Avendano specimen in the recent taxonomic review paper). This is not a result of the species being overlooked pre-splitting, because otherwise one of the many birders active in Colombia’s East Andes would have seen it somewhere. This pattern and elevational distribution is shared only by S. rodriguezi (as far as I am aware). However, in the Yariguies, D. caudata is much rarer. In our series of expeditions to the region, which was fairly exhaustive of primary habitat/elevation combinations of the mountain range, we did not record it at all. But then, we only studied one 2000m locality on the east slope. On the west slope, the many birders to have “done” the Reinita reserve have not recorded the species either. Jorge Avendano found it when he returned to one of our original study localities – but only with respect to a single individual in a very small forest fragment which was netted and collected. A recent attempt to observe the species at the same place found no records and more degraded habitat compared to 2006. It probably occurs elsewhere on steep bamboo-covered parts of the Yariguies, but seems very rare. If S. rodriguezi is to remain VU, then this one should have a higher threat status, as it seems more difficult to find even in known regions of occurrence.

    D. klagesi is known in Colombia recently mainly from ProAves’ bushbird reserve. It is fairly common there and in nearby Agua de la Virgen church reserve, in the unusual bamboo-dominated habitats that dominate there. However, I know of only this one locality so it cannot be very widespread (although maybe there are Perija records now?). Probably the situation in Venezuela will determine its threat status.

    D. hellmayri occurs in poor habitat (overgrown farmland verges). I’ve only seen it at the same place most other people have, near “La Ye” on the way up to El Dorado reserve. I am not aware of another recent locality for the species (except the Rio Frio region, if surveys there can be called recent), although it must occur elsewhere where scrub subsists in Santa Marta. Given its small range and the threats of fire and drying habitat to Santa Marta right now, I would have thought NT to be a minimum recommendation.

    Your references should definitely include these two papers instead of those cited:

    Isler, M. L., Cuervo, A. M., Bravo, G.A. & Brumfield, R.T. 2012. An integrative approach to species-level systematics reveals the depth of diversification in an Andean thamnophilid, the Long-tailed Antbird. Condor 114: 571–583.
    https://www.researchgate.net/publication/259729201_An_Integrative_Approach_to_Species-Level_Systematics_Reveals_the_Depth_of_Diversification_in_an_Andean_Thamnophilid_the_Long-Tailed_Antbird

    Donegan, T., Quevedo, A., Salaman, P. & McMullan, M. 2012. Revision of the status of bird species occurring or reported in Colombia 2012. Conservacion Colombiana 17: 4-14.
    https://www.researchgate.net/publication/259082485_Revision_of_the_status_of_bird_species_occurring_or_reported_in_Colombia_2012

  2. Ottavio Janni says:

    Regarding D. caudata, in Jan 2016 several of us (myself, Jurgen Beckers, Brayan Coral Jaramillo, Nicole Desnoyers, and Justyn Stahl) found it at a new location, at about 1600 m asl along the old San Francisco-Mocoa mule trail in Putumayo department, Colombia. The record is documented by sound recordings (http://www.xeno-canto.org/303390) and a couple of poor photos archived in eBird. The identification of the sound recording was confirmed by Mort Isler. Not only is this a southwards range extension, it is also the first record away from the East Andes, as the location where we found it is on the eastern slope of the main Andean chain. This suggests it is somewhat more widely distributed that previously thought, and it would be interesting to know whether it extends even more to the south, the area between where we found it and the Ecuadorian border being essentially unbirded at the right elevations.

  3. James Westrip (BirdLife) says:

    Based on available information, our preliminary proposal for the 2016 Red List would be to list:

    D. straticeps and D. klagesi as Least Concern.

    D. hellmayri as Near Threatened under criteria A2c+3c+4c; B1ab(i,ii,iii,v).

    D. caudata as Near Threatened under criterion C2a(i).

    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.

  4. Thomas Donegan says:

    As above, I do not believe NT is appropriate for caudata, if S rodriguezi is VU. This is a much rarer bird with absence in many localities that ought to be suitable.

  5. James Westrip (BirdLife) says:

    Dear Thomas, many thanks for your comments particularly regarding the relative abundance of D. caudata to S. rodriguezi. However, S. rodriguezi is listed as EN under criterion B1ab(i,ii,iii) and so relative abundance may not be the most relevant method to categorise D. caudata in this case. The new potential subpopulation outlined above also extends this species’s Extent of Occurrence so that it would not meet the threshold for listing as Vulnerable under criterion B. Looking at D. caudata’s population size estimates, the presence of multiple sub-populations would require there to be fewer than 1,000 mature individuals in each sub-population for the species to be listed as Vulnerable. Based on population density estimates of closely related species and assuming only a proportion of its range is occupied would still lead to sub-population size estimates of over 1,000 mature individuals. We have taken into account your concerns over its relatively low abundance, though, and so the largest sub-population has been assumed to approach this threshold for listing as Vulnerable; and thus this species was put forward to be listed as Near Threatened under criterion C2a(i).

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