Archived 2020 topic: Bearded Screech-owl (Megascops barbarus): revise global status?

BirdLife species factsheet for Bearded Screech-owl

Bearded Screech-owl (Megascops barbarus) occurs in the highlands of south-eastern Mexico and western Guatemala. It inhabits humid, montane evergreen and pine-oak forest at elevations of 1,800-2,500 m (Howell and Webb 1995, Enríquez 2007). The global population is thought to number fewer than 50,000 mature individuals (Partners in Flight 2019) and the species is here placed in the band 20,000-49,999 mature individuals.

Bearded Screech-owl is threatened by the loss and degradation of its habitat and has undergone a large, significant decline in the past (Partners in Flight 2019). Pine-oak forest is disappearing rapidly through logging, agricultural expansion and urbanization (Stattersfield et al. 1998, P. Enríquez in litt. 2020). In Chiapas (Mexico), montane forests have been reduced to less than 25% of their original extent by the year 2000 (Cayuela et al. 2006). A further threat is hunting (Enríquez 2007).

The species has been considered Vulnerable under Criterion B1ab(i,ii,iii,v) (BirdLife International 2020). However, this is no longer tenable because this was based on an Extent of Occurrence (EOO) value calculated as the ‘area of mapped range’. This is no longer appropriate and the EOO should be calculated using a Minimum Convex Polygon (see IUCN 2001, 2012, Joppa et al. 2016), as EOO is a measure of the spatial spread of areas occupied by a species, not the actual area it occupies. The resulting EOO value now exceeds the thresholds required to maintain the species’s current listing, and as such it potentially cannot retain its current Red List status. Therefore, we have fully reviewed the species here against all criteria.

Criterion A – The population trend for this species has not been directly estimated, but the species is suspected to be in decline owing to habitat degradation. One generation length has been quantified as 2.5 years for this species (see Bird et al. 2020)*; hence the relevant time frame for Criterion A is ten years. The rate of forest loss varies locally and over time; in the highlands of Chiapas (Mexico) forest loss amounted to 2.6% annually between 1975 and 2000 (Cayuela et al. 2006). More recent data across the entire range, however, suggest that forest loss is moderately low, numbering <10% over the past ten years (Tracewski et al. 2016, Global Forest Watch 2020). Bearded Screech-owl is highly forest-dependent and the most severe threat known to the species is habitat loss. Given that the species is also locally prosecuted, the rate of population decline is potentially higher than forest loss. Overall, the rate of population decline is unlikely to exceed 20% over ten years, and the species warrants listing as Least Concern under Criterion A.

Criterion B – The newly calculated Extent of Occurrence (EOO) for this species is 31,000 km2. This is too large to meet the threshold for Vulnerable under Criterion B1, and Bearded Screech-owl may be listed as Least Concern under this criterion. The Area of Occupancy (AOO) has not been quantified following IUCN Guidelines (IUCN Standards and Petitions Committee 2019), and therefore the species cannot be assessed against Criterion B2.

Criterion C – The population size is too large to meet the threshold for listing as threatened under Criterion C, and the species thus qualifies as Least Concern under this criterion.

Criterion D – The species’s population size and range are too large to warrant listing as threatened, and thus Bearded Screech-owl may be considered Least Concern under Criterion D.

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 the Bearded Screech-owl (Megascops barbarus) be listed as Least Concern.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).

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.

References

Bird, J. P.; Martin, R.; Akçakaya, H. R.; Gilroy, J.; Burfield, I. J.; Garnett, S.; Symes, A.; Taylor, J.; Şekercioğlu, Ç. H.; Butchart, S. H. 2020. Generation lengths of the world’s birds and their implications for extinction risk. Conservation Biology online first view.

BirdLife International. 2020. Species factsheet: Megascops barbarus. http://www.birdlife.org (Accessed 27 March 2020).

Cayuela, L.; Rey Benayas, J. M.; Echeverríá, C. 2006. Clearance and fragmentation of tropical montane forests in the Highlands of Chiapas, Mexico (1975-2000). Forest Ecology and Management 226: 208-218.

Enríquez, P.L. 2007. Ecology of the Bearded Screech-Owl (Megascops barbarus) in the Central Highlands of Chiapas, Mexico. University of British Columbia, Vancouver, Canada.

Global Forest Watch. 2020. Interactive Forest Change Mapping Tool. http://www.globalforestwatch.org (Accessed 27 March 2020).

Howell, S. N. G.; Webb, S. 1995. A guide to the birds of Mexico and northern Central America. Oxford University Press, Oxford, UK.

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.

Joppa, L. N.; Butchart, S. H. M.; Hoffmann, M.; Bachman, S. P.; Akçakaya, H. R.; Moat, J. F.; Böhm, M.; Holland, R. A.; Newton, A.; Polidoro, B.; Hughes, A. 2016. Impact of alternative metrics on estimates of extent of occurrence for extinction risk assessment. Conservation Biology 30: 362-370.

Partners in Flight. 2019. Avian Conservation Assessment Database, version 2019. http://pif.birdconservancy.org/ACAD.

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

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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6 Responses to Archived 2020 topic: Bearded Screech-owl (Megascops barbarus): 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 7.1% 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. Sergio Reyes says:

    M.barbarus is suffering from several threats: Deforestation, hunting, and hábitat destruction. On the Mexican side, the population is under pressure by deforestation of coniferous plantations (commercial use) and the Guatemalan population is not well-known yet (with few observations).
    So, the species is decreasing in a continuous mode, also there are other data about EOO. In the IUCN evaluation, EOO is 18.400 km2, but in a new methodology by Ocampo et al 2016, she and her team evaluated 2 additional concepts: Altitude and Forest cover. With an SRMT-Satellite model, they could demonstrate that the EOO of M.barbarus is around 5000 km2 with Elevation consideration and 4118 km2 combined Elevation and Forest concept.
    The Change to Near Threatened of this species would be a great mistake because the funds for its research will be cut or suspended and for sure the species is not suffering a recovery in its population or habitat. The evaluation will need a deeper study and preparation, then we suggest to maintain M.barbarus status on “Vulnerable”, B1ab i,ii, iii,v.
    Many thanks, Sergio Reyes and Natalia Ocampo PhD

    • Red List Team (BirdLife International) says:

      Thank you very much for your comment. The EOO of this species is 31,000 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. The utility of the approach proposed by Ocampo et al. 2016 for Red List assessments has been discussed among the relevant parties, but has not been adopted by IUCN. The Red List status of a species is a measure of its extinction risk; it is not a measure of conservation priority and as such, the Red List status cannot be decided by the need for funding.

  3. 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

  4. 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 Bearded Screech-owl. 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 Bearded Screech-owl as Least Concern.

    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.

  5. Red List Team (BirdLife International) says:

    Recommended categorisation to be put forward to IUCN

    The final categorisation for this species has not changed. Bearded Screech-owl is recommended to be listed as Least Concern.

    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.

Comments are closed.