Archived 2020 topic: Long-whiskered Owlet (Xenoglaux loweryi): revise global status?

BirdLife species factsheet for Long-whiskered Owlet

Long-whiskered Owlet (Xenoglaux loweryi) is endemic to northern Peru. From discovery in 1976 to the early 2000s, the species had been observed only twice and its life history had been almost unknown. But observations have been more regular during the last decade, shedding light on the distribution and status of the species (Lane and Angulo 2018). Long-whiskered Owlet inhabits a variety of habitats from wet elfin forest to tall forest, bamboo thickets, open woodland and small degraded forest fragments amid pastures (O’Neill and Graves 1977, Fjeldså and Krabbe 1990, Schulenberg et al. 2007, Lane and Angulo 2018). Known records come from 1,900-2,600 m elevation (Lane and Angulo 2018, F. Angulo in litt. 2020). The species is potentially threatened by habitat loss. However, it has been estimated that around 80% of the species’s presumed range are largely inaccessible and comprise pristine habitat (Lane and Angulo 2018).

In the absence of detailed information regarding its status, Long-whiskered Owlet has precautionarily been listed as Endangered under Criteria B1ab(i,ii,iii,v); C2a(ii) (BirdLife International 2020). However, new information regarding the distribution and population trend suggests that the species may warrant a change in Red List status. Therefore, it will be re-assessed against all criteria:

Criterion A – The population trend has not been estimated directly. The only threat known to the species is the loss and degradation of its habitat. Forest loss within the range has been negligible over the past ten years (Tracewski et al. 2016, Lane and Angulo 2018, Global Forest Watch 2020; one generation length being 2.8 years*), and the species is currently not thought to be under threat (Lane and Angulo 208). Therefore, in the absence of evidence for any declines, the species is assessed as stable, and it is listed as Least Concern under Criterion A.

Criterion B – The Extent of Occurrence (EOO) for this species is 2,200 km2. However, as habitat within the range is considerably intact and imminent threats to the species or its habitat appear minimal, the species cannot be considered severely fragmented sensu IUCN (IUCN Standards and Petitions Committee 2019) nor to occur only within a small number of locations**. As such, it does not meet subcriterion a. There does not appear to be evidence to infer a continuing decline nor extreme fluctuation in range size, habitat availability or population size, and thus the species does not meet subcriteria b and c. Even though Long-whiskered Owlet occurs in a small range, it does not meet the threshold for listing as threatened under Criterion B and may thus be considered Least Concern under this criterion.

Criterion C – The global population is thought to be small. However, as it is assessed as stable, the species does not warrant listing as threatened under Criterion C, and therefore qualifies as Least Concern under this criterion.

Criterion D – The population size is preliminarily placed in the band 250-999 mature individuals, and thus the species may be listed as Vulnerable under Criterion D1.

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 Long-whiskered Owlet (Xenoglaux loweryi) be listed as Vulnerable under Criterion D1. 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.

*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: Xenoglaux loweryi. (Accessed 10 March 2020).

Fjeldså, J.; Krabbe, N. 1990. Birds of the high Andes. Apollo Books, Copenhagen, Denmark.

Global Forest Watch. 2020. World Resources Institute. (Accessed 10 March 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.

IUCN Standards and Petitions Committee. 2019. Guidelines for using the IUCN Red List Categoreis and Criteria. Version 14.

Lane, D. F.; Angulo, F. 2018. The distribution, natural history, and status of the Long-whiskered Owlet (Xenoglaux loweryi). The Wilson Journal of Ornithology 130(3): 650-657.

O’Neill, J. P.; Graves, G. R. 1977. A new genus and species of owl (Aves: Strigidae) from Peru. The Auk 94: 409-416.

Schulenberg, T. S.; Stotz, D. F.; Lane, D. F.; O’Neill, J. P.; Parker III, T. A. 2007. Birds of Peru. Princeton University Press, Princeton, NJ, USA.

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.

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8 Responses to Archived 2020 topic: Long-whiskered Owlet (Xenoglaux loweryi): revise global status?

  1. Red List Team (BirdLife International) says:

    Global Forest Change data on tree cover loss up to 2019 have now been released and made available via Global Forest Watch. Based on these data, over ten years approximately 1.7% of tree cover with 75% canopy cover was lost from within the species’s range (Global Forest Watch 2020). This does not affect the above assessment under Criterion A.

  2. Fernando Angulo says:

    Besides what’s is stated on Lane & Angulo (2018), it has to be mentioned that in two birding lodges near Abra Patricia, where the species is seen by birders, there has been found multiple LWO territories, relatively close one from each other (some 500 m aprox). There is need of further searches and detailed stuedies on the LWO natural history, but at least from anecdotal information, there seems to be several territories where individulas are found.

  3. Sergio Reyes says:

    Long-whiskered Owlet (Xenoglaux loweryi)
    The species’ distribution is not known well, yet, the already restricted range of the species has suffered deforestation which could continue to expand. In the distribution map, you can see the species’ range outlined in blue, and the remaining forest in green, as of 2015. Palacio et al 2019, showed an EOO very low to this species (Around only 600 km2). It is a very small territory to think about expansion and increase the population numbers. The Amazonian basin is living several threats like deforestation, mining, and food production on a big scale, so, is very adventurous to think a decelerating deforestation rate.
    In our opinion, the IUCN committee must evaluate new methods for calculating the EOO and AOH, like in Ocampo et 2016 and Palacio et al 2019. Instead of relaxing the criteria about species evaluation, these methods refining EOO by considering the altitude model and the Forest/non-forest data. We suggest to stuck the species in “Endangered” status (Criteria B1ab i, ii, iii). Finally, we are sure about your scientific rigor evaluating new methodologies, and incorporating these to the IUCN Red List. If you need more technical context we would provide the maps and models. Thank you, Best Wishes. Atte. Sergio Reyes-Natalia Ocampo PhD

    • Red List Team (BirdLife International) says:

      The EOO of this species is 2,200 sqkm. IUCN’s Red List guidelines, which BirdLife International is obliged to follow, stipulate that the EOO is calculated as a continuous Minimum Convex Polygon around the mapped range; the guidelines do not allow clipping of the EOO by elevation or land-cover.

  4. Red List Team (BirdLife International) says:

    Many thanks to everyone who has contributed to this discussion. We greatly appreciate the time and effort invested by so many people in commenting. The window for consultation is now closed. We will analyse and interpret the new information and post a preliminary decision on this species’s Red List status on this page in early July.

    Thank you once again,
    BirdLife Red List Team

  5. Red List Team (BirdLife International) says:

    Preliminary proposal

    Currently available information suggests that the species is less threatened than previously feared. While deforestation remains a threat to any forest-dependent species, rates of forest loss have been very low within the distribution range of the Long-whiskered Owlet. Should evidence arise that deforestation rates are increasing in the future, this will be taken into account for a reassessment.

    Based on available information, our preliminary proposal for the 2020 Red List would be to list Long-whiskered Owlet as Vulnerable under Criterion D1.

    There is now a period for further comments until the final deadline in mid-July, 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 2020 Red List categories will be published on the BirdLife and IUCN websites in December 2020/January 2021, following further checking of information relevant to the assessments by both BirdLife and IUCN.

  6. Fernando Angulo says:

    I do agree with the proposed category. Unfortunately, I wasn’t able to locate “Palacio et al 2019” to see the above-mentioned map.

    On other matter, it would be good to ask people posting, to write the whole literature, so others can review sources.

  7. Red List Team (BirdLife International) says:

    Recommended categorisation to be put forward to IUCN

    The final categorisation for this species has not changed. Long-whiskered Owlet is recommended to be listed as Vulnerable under Criterion D1.

    Many thanks for everyone who contributed to the 2020 GTB Forum process. The final 2020 Red List categories will be published on the BirdLife and IUCN websites in December 2020/January 2021, following further checking of information relevant to the assessments by both BirdLife and IUCN.

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