BirdLife species factsheet for Vilcabamba Spinetail
Vilcabamba Spinetail (Cranioleuca weskei) is endemic to Peru, where it occurs from the Cordillera Vilcabamba in Cusco north to Ayacucho and Junín. It inhabits humid montane and elfin forest at elevations of 2,400-3,500 m (del Hoyo et al. 2003). The population size has not been quantified, but the species is described as uncommon to locally fairly common (del Hoyo et al. 2020). Vilcabamba Spinetail is feared to be susceptible to forest fragmentation and edge effects.
Vilcabamba Spinetail is currently listed as Near Threatened, approaching the threshold for listing as threatened under Criterion A3c+4c (BirdLife International 2020). However, new information regarding trends in population size and habitat availability suggests that the species may warrant a change in Red List status. Therefore, it will be re-assessed against all Red List criteria:
Criterion A – The population trend has not been estimated directly. The only threat known to the species is forest loss; however, deforestation over the past ten years (one generation length being estimated at 2.4 years; Bird et al. 2020*) has been low within the range (potentially <2%; Tracewski et al. 2016, Global Forest Watch 2020). Given that the species is restricted to montane and elfin forest, it can precautionarily be suspected that population declines are exacerbated by habitat degradation and exceed the rate of forest loss. Nevertheless, it is unlikely that the rate of population decline surpasses 10% over ten years. The species therefore qualifies as Least Concern under Criterion A.
Criterion B – The Extent of Occurrence (EOO) for this species is 35,600 km2. This is too large to warrant listing as threatened under Criterion B1, and Vilcabamba Spinetail qualifies for Least Concern under this criterion. The Area of Occupancy (AOO) has not been quantified according to IUCN guidelines (IUCN Standards and Petitions Committee 2019), and so the species cannot be assessed against Criterion B2.
Criterion C – The population size of Vilcabamba Spinetail has not been quantified, and thus the species cannot be assessed against Criterion C. Considering the range size and the area of available habitat (see Global Forest Watch 2020), the population size is not thought to approach the threshold for listing as threatened under this criterion.
Criterion D – The population size is not known, but is not thought to approach the threshold for listing as threatened under Criterion D.
Criterion E – To the best of our knowledge no quantitative analysis of extinction risk has been conducted for this species. Therefore, it cannot be assessed against this criterion.
Therefore, it is suggested that Vilcabamba Spinetail (Cranioleuca weskei) be listed as Least Concern. We welcome any comments on the proposed listing.
Please note that this topic is not designed to be a general discussion about the ecology of the species, rather a discussion of its Red List status. Therefore, please make sure your comments are relevant to the discussion outlined in the topic. By submitting a comment, you confirm that you agree to the Comment Policy.
*Bird generation lengths are estimated using the methodology of Bird et al. (2020), as applied to parameter values updated for use in each IUCN Red List for birds reassessment cycle. Values used for the current assessment are available on request. We encourage people to contact us with additional or improved values for the following parameters; adult survival (true survival accounting for dispersal derived from an apparently stable population); mean age at first breeding; and maximum longevity (i.e. the biological maximum, hence values from captive individuals are acceptable).
An information booklet on the Red List Categories and Criteria can be downloaded here and the Red List Criteria Summary Sheet can be downloaded here. Detailed guidance on IUCN Red List terms and definitions and the application of the Red List Categories and Criteria can be downloaded here.
Bird, J. P.; Martin, R.; Akçakaya, H. R.; Gilroy, J.; Burfield, I. J.; Garnett, S.; Symes, A.; Taylor, J.; Šekercioğlu, Ç.; Butchart, S. H. M. (2020). Generation lengths of the world’s birds and their implications for extinction risk. Conservation Biology online first view.
BirdLife International. 2020. Species factsheet: Cranioleuca weskei. http://www.birdlife.org (Accessed 1 April 2020).
del Hoyo, J.; Collar, N.; Kirwan, G. M. 2020. Vilcabamba Spinetail (Cranioleuca weskei). 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, Spain. https://www.hbw.com/node/1343663 (Accessed 1 April 2020).
del Hoyo, J.; Elliott, A.; Christie, D. A. 2003. Handbook of the Birds of the World, Vol. 8: Broadbills to Tapaculos. Lynx Edicions, Barcelona, Spain.
Global Forest Watch. 2020. Interactive Forest Change Mapping Tool. http://www.globalforestwatch.org (Accessed 1 April 2020).
IUCN Standards and Petitions Committee. 2019. Guidelines for using the IUCN Red List Categories and Criteria. Version 14. http://www.iucnredlist.org/documents/RedListGuidelines.pdf.
Tracewski, Ł.; Butchart, S. H. M.; Di Marco, M.; Ficetola, G. F.; Rondinini, C.; Symes, A.; Wheatley, H.; Beresford, A. E.; Buchanan, G. M. 2016. Toward quantification of the impact of 21st-century deforestation on the extinction risk of terrestrial vertebrates. Conservation Biology 30: 1070-1079.