Archived 2019 topic: Foothill Elaenia (Myiopagis olallai): revise global status?

BirdLife species factsheet for Foothill Elaenia

The recently discovered Foothill Elaenia (Myiopagis olallai) occurs in a severely fragmented range in the northern Andes. The species is restricted to a few, disjunct localities of occurrence in the Central Cordillera in Colombia, the Sierra de Perijá, the eastern slopes of the Andes in Colombia and Ecuador (Napo, Sucumbíos, Pastaza and Zamora-Chinchipe), as well as in southern central Peru (Pasco, Cusco) (Coopmans and Krabbe 2000, Cuervo et al. 2014, Fitzpatrick 2018). Many records and reported sightings of the species remain unconfirmed. The global population size has not been quantified, but the species is described as uncommon in Sucumbíos, Ecuador.

Foothill Elaenia occurs at elevations between 890 and 1500 m. It inhabits the interior and edges of very humid to wet primary submontane forest (Coopmans and Krabbe 2000). There is not much known about the ecological requirements of the species (Fitzpatrick 2018).

The species’s population is suspected to be in decline owing to ongoing habitat loss. On the eastern slope of the Ecuadorian Andes, forest clearance and less intensive habitat destruction and fragmentation may already have resulted in the loss of around half of the forest cover in the species’s range. It is reported that unspecified development projects, which have already received approval, are likely to increase the future rate of forest loss in Ecuador (D. F. Cisneros-Heredia in litt. 2010). Even within protected areas, forests within the species’s altitudinal range are under imminent threat of illegal logging (Fitzpatrick 2018). However, the species’s preferred areas in superwet forest are to date only under moderate risk of logging (Fitzpatrick 2018).

Currently, Foothill Elaenia is listed as Vulnerable under Criterion B1ab(i,ii,iii), indicating a very small Extent of Occurrence (EOO) and declines in habitat availability.

Following IUCN guidelines, the EOO for this species has been re-calculated using a Minimum Convex Polygon, which is “the smallest polygon in which no internal angle exceeds 180 degrees and which contains all the sites of occurrence” (IUCN 2001, 2012, Joppa et al. 2016). After re-calculating the EOO for Foothill Elaenia, this species appears to warrant a change in Red List status. Therefore, we present here our reassessment against all criteria for the species.

The initial topic on this analysis can be found here.

Criterion A – The population trend has not been estimated directly. However, Tracewski et al. (2016) measured the forest loss within this species’s range between 2000 and 2012 as c. 80 km2. This roughly equates to a rate of forest loss of 1.6% over three generations (10.8 years) for this species, with the assumption that habitat loss has continued at the same rate to the present day.For a highly forest-depending species like Foothill Elaenia, population changes may be proportional to forest cover change. Even though Foothill Elaenia is restricted to primary forest, it is highly unlikely that the rate of population decline based on habitat loss alone approaches the threshold for Vulnerable. Therefore, Foothill Elaenia may be listed as Least Concern under this criterion.

Criterion B – Using a Minimum Convex Polygon, the Extent of Occurrence (EOO) has been calculated as 1,020,000 km2. This is far too large for listing the species as Vulnerable under Criterion B1. Tracewski et al. (2016) estimated the remaining tree area within the species’s range to be c.4,300 km2. We can tentatively assume that for a highly forest-dependent species like Foothill Elaenia, the area of forested habitat equals the maximum Area of Occupancy (AOO); as such the maximum AOO is close to the threshold for Vulnerable under Criterion B2 (AOO < 2,000 km2). Given that Foothill Elaenia is known from less than ten locations and EOO, AOO and habitat availability are in decline, the species may approach the threshold for listing as threatened. As such, Foothill Elaenia may be listed as Near Threatened under Criterion B2ab(i,ii,iii), although in fact the maximum AOO may be too large even for this.

Criterion C – The population size of this species has not been estimated. Therefore, it cannot be assessed against this criterion.

Criterion D – The population size of this species has not been estimated. Therefore, it cannot be assessed against this criterion.

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 possible that Foothill Elaenia (Myiopagis olallai) could be listed precautionarily as Near Threatened under Criterion B2ab(i,ii,iii), although the maximum AOO value available may even be too large for this. Further information regarding the population size of this species is needed to get a clearer assessment of its extinction risk. We welcome any comments on this proposed listing and specifically request up-to-date information on the population size of Foothill Elaenia.

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.

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

Coopmans, P.; Krabbe, N. 2000. A new species of Flycatcher (Tyrannidae: Myiopagis) from eastern Ecuador and eastern Peru. Wilson Bulletin 112: 305-443.

Cuervo, A.M.; Stiles, F.G.; Lentino, M.; Brumfield, R.T.; Derryberry, E.P. 2014. Geographic variation and phylogenetic relationships of Myiopagis olallai (Aves: Passeriformes; Tyrannidae), with the description of two new taxa from the Northern Andes. Zootaxa 3873: 1–24.

Fitzpatrick, J. 2018. Foothill Elaenia (Myiopagis olallai). 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/57136 (Accessed 14 September 2018).

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.

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. 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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7 Responses to Archived 2019 topic: Foothill Elaenia (Myiopagis olallai): revise global status?

  1. Dan Lane says:

    The description “severely fragmented range in the northern Andes” is not accurate. It has a relictual distribution, the “spottiness” of its distribution is not due to habitat fragmentation by human activity (which I think is the inherent meaning of “fragmented” in this case), but is naturally spotty regardless of human activity. What determines its presence or absence is not clear. Furthermore, recordings deposited in online archives (Xeno-canto, Macaulay Library) that confirm the presence of the species in more localities than the published sources cited above seem not to have been consulted. These may be enough to push the population estimation into the “Least Concern” category that it may already qualify for, if I read the above account correctly.

    • Red List Team (BirdLife International) says:

      Thank you very much for your comment. Habitat fragmentation can occur through both human activity (e.g. deforestation) and natural causes (e.g. geological processes). You are right; the patchy distribution of Foothill Elaenia might indeed have been caused by the latter.
      We have consulted Citizen Science platforms like Xeno-canto and eBird, and the records published there align with BirdLife’s range map. If you have information that the species occurs in other locations, please let us know.

  2. Red List Team (BirdLife International) says:

    Preliminary proposals
    Based on available information, our preliminary proposal for the 2019 Red List would be to list Foothill Elaenia 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 2019 Red List categories will be published on the BirdLife and IUCN websites in December, following further checking of information relevant to the assessments by both BirdLife and IUCN.

  3. Oscar Johnson says:

    My only concern is regarding the note under Criterion B that the “Foothill Elaenia is known from less than ten locations”. A quick search of the xeno-canto and eBird databases shows at least 2-3 times that many localities (depending on how you group adjacent map points into localities). When those localities are combined with those published in Coopmans and Krabbe 2000, Cuervo et al. 2014, Fitzpatrick 2018, and in museum specimen databases, I strongly suspect that the estimated EOO and AOO will increase. Also, while it is clearly an uncommon and patchily-distributed species, much of this perceived rarity is almost certainly due to lack of surveys in intervening regions between known localities.

    • Red List Team (BirdLife International) says:

      Thanks very much for your comment! Yes, you have got a point here; the number of locations has been applied very precautionarily in the assessment. Per IUCN Guidelines (IUCN 2012), a location is an area where a single threat can rapidly wipe out the entire population. For this species, the most severe threat known is deforestation, which usually affects relatively small geographic areas at once. Hence, many independent logging events may affect the population, i.e. the number of locations per IUCN is larger than we assumed in the initial assessment. We have since corrected the proposal, in that we suggest the species to be listed as Least Concern.

  4. Thomas Donegan says:

    I agree with the comments of participants and would go further: It should be added that “Foothill Elaenia” is in many ways a “non-species”. It is a grouping for about 3-4 species under most species concepts (including Tobias scoring systems for sure), each of which has quite small and disjunct range. There is an East Andes foothill species, a Central Andes species (which probably includes San Lucas) and a Perija species. I don’t know anything about the Peru population. As regards Colombia, none of these is very common even where they occur. Cuervo et al. hint that Foothill Elaenia should be split up, and their reluctance to do so may be in part due to an omission to include the San Lucas population properly in analyses, since no specimens exist and only sound recordings that were picked up (by accident almost, of birds not seen) in the relevant study. Each population is vocally distinctive and differs quite impressively in mtDNA. BirdLife should focus on giving this group a taxonomic review using its new criteria, prior to implementing a downgrade.

    • Red List Team (BirdLife International) says:

      Thank you very much for your contribution. As Foothill Elaenia is currently recognized as one species by the HBW and BirdLife Taxonomic Checklist, we have to assess it as one taxonomic entity. In case that the species is split in the future, assessments will be carried out for the newly recognized taxa.

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