BirdLife species factsheet for Purple-backed Sunbeam
Purple-backed Sunbeam (Aglaeactis aliciae) is endemic to Peru, where it occurs in a small area in the upper Marañón drainage in La Libertad and Ancash. It inhabits alder woodland and montane shrub at an elevation of 2,900-3,500 m (B. P. Walker in litt. 1995, G. Engblom in litt. 2005, Schuchmann et al. 2020). The population is small; it has been placed in the band 1,000-2,499 mature individuals. Despite its apparent tolerance of open and degraded habitats, the species is threatened by the loss and conversion of woodlands for agricultural purposes, firewood cutting or infrastructural developments (Lambert and Angulo 2007, SERFOR 2018, Schuchmann et al. 2020)
Purple-backed Sunbeam has been considered Endangered under Criterion C2a(ii) (BirdLife International 2020). However, new information regarding the distribution range and population trend suggest that this species may warrant a change in Red List status. Therefore, we have fully reviewed the species here against all criteria.
Criterion A – Purple-backed Sunbeam is suspected to be in slow decline, owing to continuing habitat degradation within its range. Tree cover within the range has been lost at a rate of c. 8% over the past ten years (Global Forest Watch 2020; one generation length being 2.4 years; Bird et al. 2020*). Apart from woodland, the species is also found in open shrub and may tolerate a low level of habitat degradation (Schuchmann et al. 2020); therefore, population declines are potentially lower than the rate of tree cover loss. Overall, the rate of population decline is unlikely to exceed 10% over ten years. Purple-backed Sunbeam is therefore listed as Least Concern under Criterion A.
Criterion B – The newly calculated Extent of Occurrence (EOO) for this species is 1,100 km2. The maximum Area of Occupancy (AOO), as calculated by a 4 km2 grid over the area of mapped range, is 508 km2. Thus, the species meets the threshold for Endangered under Criterion B1 (EOO < 5,000 km2) and for Vulnerable under Criterion B2 (AOO < 2,000 km2). To be listed as threatened under these criteria does require at least two further conditions to be met though.
The species is thought to form just one subpopulation and can thus not be considered severely fragmented (see IUCN Standards and Petitions Committee 2019). The most severe threat is habitat loss and degradation for agricultural purposes, including the creation of industrial plantations. It is conceivable that this threat could impact a large area and subsequently large part of the population at once; while the number of locations** cannot be determined exactly, it is likely that the species occurs within 6-10 locations**. Purple-backed Sunbeam thus meets sub-criterion a at the level of Vulnerable. From historical records outside the currently known range and the moderate rate of forest loss, we can infer that EOO, AOO and habitat availability are in continuing decline, and sub-criterion b(i,ii,iii) is met. The species is not known to undergo extreme fluctuations, and thus sub-criterion c is not met. Overall, even though the EOO is very small, Purple-backed Sunbeam qualifies for listing as Vulnerable under Criterion B1ab(i,ii,iii)+2ab(i,ii,iii).
Criterion C – The population size is estimated at 1,000-2,499 mature individuals. This meets the threshold for listing as threatened under Criterion C. However, in order to do so, the species must meet further subcriteria.
All individuals are thought to form just one subpopulation. Despite its tolerance of converted habitats, the species is suspected to be in slow decline as the quality of its habitat is decreasing. A suspected decline, however, precludes a listing as threatened, and as such Purple-backed Sunbeam may be considered Near Threatened, approaching the threshold for listing as threatened under Criterion C2a(ii).
Criterion D – The population is placed in the band 1,000-2,499 mature individuals. Assuming that the true population size is closer to the lower end of the estimate, the species may qualify for listing as Near Threatened, approaching the threshold for listing as threatened under Criterion D1.
Criterion E – To the best of our knowledge, there has been no quantitative analysis of extinction risk conducted for this species. Therefore, it cannot be assessed against this criterion.
Therefore, it is suggested that Purple-backed Sunbeam (Aglaeactis aliciae) be listed as Vulnerable under Criterion B1ab(i,ii,iii)+2ab(i,ii,iii). We welcome any comments to 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 the species’ Red List status. Therefore, please make sure your comments are relevant to the species’ Red List status and the information requested. 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).
**The term ‘location’ refers to a distinct area in which a single threatening event can rapidly affect all individuals of the taxon present, with the size of the location depending on the area covered by the threatening event. Where a taxon is affected by more than one threatening event, location should be defined by considering the most serious plausible threat (IUCN 2001, 2012).
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: Aglaeactis aliciae. http://www.birdlife.org (Accessed 2 April 2020).
Global Forest Watch. 2020. Interactive Forest Change Mapping Tool. http://www.globalforestwatch.org/ (Accessed 2 April 2020).
IUCN. 2001. IUCN Red List Categories and Criteria: Version 3.1. IUCN Species Survival Commission. IUCN, Gland, Switzerland and Cambridge, U.K.
IUCN. 2012. IUCN Red List Categories and Criteria: Version 3.1. Second edition. IUCN Species Survival Commission. IUCN, Gland, Switzerland and Cambridge, U.K. www.iucnredlist.org/technical-documents/categories-and-criteria.
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.
Lambert, F. R.; Angulo, F. 2007. Distribution, status and notes on the ecology of Purple-backed Sunbeam Agaeactis aliciae in north Peru. Cotinga 28: 21-26.
Schuchmann, K. L.; Boesman, P. F. D.; Sharpe, C. J. 2020. Purple-backed Sunbeam (Aglaeactis aliciae), version 1.0. In: del Hoyo, J.; Elliott, A.; Sargatal, J.; Christie, D. A.; de Juana, E. (eds.). Birds of the World. Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.pubsun1.01 (Accessed 2 April 2020).
SERFOR. 2018. Libro Rojo de la Fauna Silvestre Amenazada del Perú. Primera edición. SERFOR, Lima, Peru.