Archived 2016 topics: Blue Chaffinch (Fringilla teydea) is being split: list F. teydea as Near Threatened and F. polatzeki as Critically Endangered or Endangered?

This is part of a consultation on the Red List implications of extensive changes to BirdLife’s taxonomy for passerines

Lynx Edicions and BirdLife International will soon publish the second volume of the HBW-BirdLife Illustrated Checklist of the Birds of the World, building off the Handbook of the Birds of the World series, and BirdLife’s annually updated taxonomic checklist.

The new Checklist will be based on the application of criteria for recognising species limits described by Tobias et al. (2010). Full details of the specific scores and the basis of these for each new taxonomic revision will be provided in the Checklist.

Following publication, an open and transparent mechanism will be established to allow people to comment on the taxonomic revisions or suggest new ones, and provide new information of relevance in order to inform regular updates. We are also actively seeking input via a discussion topic here regarding some potential taxonomic revisions that currently lack sufficient information.

The new Checklist will form the taxonomic basis of BirdLife’s assessments of the status of the world’s birds for the IUCN Red List. The taxonomic changes that will appear in volume 2 of the checklist (for passerines) will begin to be incorporated into the 2016 Red List update, with the remainder to be incorporated into subsequent Red List updates.

Preliminary Red List assessments have been carried out for the newly split or lumped taxa. We are now requesting comments and feedback on these preliminary assessments.

Blue Chaffinch Fringilla teydea is being split into F. teydea and F. polatzeki, following the application of criteria set out by Tobias et al. (2010).

Prior to this taxonomic change, F. teydea (http://www.birdlife.org/datazone/species/factsheet/22720036) was listed as Near Threatened under D2, on the basis that it had small range and moderately small population, but because the population on Tenerife was suspected to be increasing in line with an increase in area of suitable habitat it did not sufficiently meet any criteria to be listed as Vulnerable. F. teydea (as now defined following the taxonomic change) is found only on Tenerife, Spain, and is suspected to be increasing due to an increase in the area of suitable habitat (Barov and Derhé 2011). The major threat to this species is from forest fires. The population size has been estimated at 1,000-2,500 pairs (2,000-5,000 mature individuals) (BirdLife International 2015). It is not thought to qualify as Vulnerable under any criteria, but its small range in combination with the ongoing threat from forest fires qualifies it to currently remain as Near Threatened under criterion D2.

F. polatzeki is found only on Gran Canaria, Spain, within a very restricted range. There are only an estimated 120-132 pairs on the island (BirdLife International 2015), found in pine forest. Illegal trade may be an issue (Clement and Sharpe 2016), but more severe for this species is continued habitat loss and fragmentation, for commercial gain and from forest fires (BirdLife International 2015; Clement and Sharpe 2016). Therefore, the species is inferred to be declining and may qualify as Critically Endangered under criterion C2a(ii) if the population size is at the mid-lower end of its estimate. Any evidence to suggest that the population is more likely to be at the higher end of this estimate, or even higher, would then mean the species warrants listing as Endangered under criterion C2a(ii).

Comments are invited on these proposed categories and further information would be welcomed.

References:

Barov, B and Derhé, M. A. (2011). Review of the Implementation of Species Action Plans for Threatened Birds in the European Union 2004-2010. Final report. BirdLife International, for the European Commission.

BirdLife International (2015) European Red List of Birds. Office for Official Publications of the European Communities, Luxembourg.

Clement, P. and Sharpe, C. J. (2016) Blue Chaffinch (Fringilla teydea). 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. (retrieved from http://www.hbw.com/node/61287 on 26 August 2016).

Tobias, J. A., Seddon, N., Spottiswoode, C. N., Pilgrim, J. D., Fishpool, L. D. C. and Collar, N. J. (2010) Quantitative criteria for species delimitation. Ibis 152: 724–746.

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10 Responses to Archived 2016 topics: Blue Chaffinch (Fringilla teydea) is being split: list F. teydea as Near Threatened and F. polatzeki as Critically Endangered or Endangered?

  1. Jan Terje Lifjeld says:

    According to my information (which is based on the most recent literature), the polatzeki population in the wild is restricted to the Inagua forest, with a more recently established population in the Cumbre forest (mostly due to birds released from the captive breeding program). The core population at Inagua was seriously affected by a wildfire in 2007. The official estimate of the size of the wild population was 122 individuals after this wildfire (Carrascal and Seoane 2008), and the Inagua population contains more than 90% of them. The Inagua population seems to have been stable since this incident (cf. Delgado et al. 2016, Bird Study in press). Hence, the polatzeki population should qualify for Critically Endangered under the C2a(ii) criterion (90% of individuals in one subpopulation) according to the current evidence.

  2. Nicolás Suárez says:

    In support of considering the Gran Canaria population as Critically Endangered, and following previous comments I would like to add that relevant information regarding the F.t. polatzeki subspecies and the population genetics consequences of the 2007 wildfire can be also found in Suarez et al 2012 (Conservation Genetics 13:499-507)

  3. Jan Terje Lifjeld says:

    The C2a(ii) criterion sets a limit to 250 mature individuals for being Critically Endangered . If the current number is higher than that, then criteria B1 might also apply, because the area of occurrence is less than 100 km2. Two other conditions (a-c) should then also be met, and I think these criteria would apply: “a. Severely fragmented or known to exist at only a single location”, and “c. Extreme fluctuations in (iv) number of mature individuals”. The latter refers to the wildfire incident in 2007 which reduced the number of individuals by50% (Carrascal and Seoane 2008), though I don’t know whether 50% is considered “extreme”. Unfortunately, these criteria does not assess the type of threat causing the fluctuation, which I think they should. A new wildfire could possibly wipe out the entire population. Then “common sense” would say it is Critically Endangered.

  4. Population density of Fringilla (teydea) polatzeki (hereafter “pinzul”) remained stable in Reserva Natural Integral de Inagua-Ojeda-Pajonales throughout the period 1994-2006 (8.0 – 12.7 birds square km during the breeding seasons). After the large forest-fire affecting the whole Reserve in July 2007, its population density decreased to 4.8 birds square km (DOI: 10.13140/RG.2.2.14165.63208; https://goo.gl/NA4WMy). The breeding population size was estimated in 122 individuals (90% confidence interval: 75-176 birds) in May 2008. Seventy-three percent of the estimated population size was concentrated in the pinewoods located on the norther slope of the Reserva and above 1,150 m a.s.l. in the pinewoods located on the southern slope (accounting for 44.7% of the total area of the Reserva, estimated in 34.85 square km; DOI: 10.13140/RG.2.1.1317.8089; https://goo.gl/p2RZrP). These sectors of the Reserva have been covered since 1994 by a fixed network of trails where the pinzul has been censused.

    Population density was estimated in 15.8 pinzules square km in May 2016 (95% confidence interval: 12.3-19.6). Thus, 192-305 pinzules are estimated only in the 44.7% of the total area of the Reserva (95% confidence interval). Population density of the pinzul has shown a steady increase from 2008 to 2016, in such a way that 2016 was the year with the highest bird density ever measured in the Reserva of Inagua. By 2010, pinzul density was on par with the densities recorded during the years previous to the forest-fire. Considering the same distribution pattern observed in 2008 in Inagua (73% of birds in 44.7% of the area of the Reserva), the population size should be around 337 birds in spring 2016. Nevertheless, it is highly probable that the actual number of birds may be slightly larger; some indications suggest that the relative occupancy of the southern pinewoods below 1,150 m a.s.l. is now higher than in 2008, when these pinewoods were severely damaged by the fire. Considering the confidence intervals previously estimated for the whole Reserva in 2008 (ratio of the lower 90% interval to the average estimation; as a tentative coarse-grained approach considering the lack of an extensive census program), a minimum of 207 birds are expected to be found in the whole area of the Reserva in spring 2016.

    Summarizing, Fringilla (teydea) polatzeki have shown a quick population recovery since the demographic crisis in 2007, from 2010 to 2016 the recorded densities were on par with those previously measured before the catastrophic forest-fire, the population density in 2016 was the largest one ever measured, and the population size in the whole Reserva Natural Integral de Inagua-Ojeda-Pajonales is estimated in around 337 birds in 2016 (with a minimum of 207 birds). These birds have to be added to the 30-50 existing in the high altitude pinewoods of La Cumbre.

  5. Eduardo Garcia-del-Rey says:

    1) Forest fire in the Canaries is not considered as a catastrophe for the blue chaffinch (https://www.researchgate.net/publication/232690805_Effects_of_Wildfire_on_Endemic_Breeding_Birds_in_a_Pinus_canariensis_Forest_of_Tenerife_Canary_Islands).
    2) Based on the minimum of 207 birds presented by Luis M Carrascal at the source (Inagua) the species should be considered as “critically endangered”. No confidence limits provided in 2016 and therefore even that minimum number questionable. This is most likely due to the small number of contacts during the survey (minimum of 60 needed to analyse with DISTANCE Sampling software). The are no 30-50 bird at La Cumbre (maximum of 15 pairs at most).

  6. Regarding the number of contacts with birds, the sample sizes to obtain the detectability estimations in the technical document DOI: 10.13140/RG.2.1.1317.8089 (https://goo.gl/p2RZrP) are as follows:
    1994-2004: 345
    2008: 32
    2006, 2009-2011: 265
    2013-2016: 350
    Thus, the population density estimated in 15.8 pinzules square km in May 2016 was obtained considering a large sample size of contacts (Inagua 95% confidence interval: 12.3-19.6). Moreover, the confidence interval of the density estimations also include the spatial variance in animal distribution, and not only the confidence intervals derived from the probability of detection.

    A forest fire of (say) 35 km2 is not a demographic catastrophe for a species such as Fringilla teydea in Tenerife island, but IT IS ACTUALLY A DEMOGRAPHIC CATASTROPHE if it affects 90%-100% of the population of a species, such as Fringilla (teydea) polatzeki, inhabiting in only one locality that is widely affected by the forest fire. That was the case for Inagua-Ojeda-Pajonales and Fringilla (teydea) polatzeki in 2007-2008.

    There are no published accounts of blue chaffinch numbers in La Cumbre (Gran Canaria). The unpublished information obtained by the team devoted to the study of the species in Gran Canaria suggests 30 or so birds, including breeders and not breeders. A population is more that the number of breeding pairs (e.g., https://goo.gl/XfBOKO; https://goo.gl/qZsT4o).

  7. James Westrip (BirdLife) says:

    Thanks to everyone who contributed to the forum discussion on this species.

    Based on available information, our preliminary proposal for the 2016 Red List would be to list F. teydea as Near Threatened under criterion D2.

    Regarding F. polatzeki:

    Its population size clearly remains small, and as some of the birds recorded by the annual monitoring scheme are probably not breeding individuals, it is prudent to use the lower estimate when assessing its extinction risk. This implies a minimum total population of 207 (Inagua) + 30 (Cumbre) = 237 birds, precautionarily qualifying the species as Endangered under Criterion D (<250 mature individuals).

    The results of the annual monitoring scheme, conducted by Carrascal et al. since 1994 (https://goo.gl/NA4WMy), show clearly that the species population is not declining, and can best be described as having fluctuated within a fairly narrow range over most of the last twenty years. Although the devastating fire in 2007 caused the population to halve in 2008, it subsequently recovered rapidly, with numbers back up to pre-fire levels by 2011, and around 50% higher again by 2016.

    As such, despite having a small population and a small, fragmented range, and currently being restricted to only two locations (Inagua and Cumbre), it is clearly not showing either a continuous decline or an extreme fluctuation as defined by IUCN, and therefore does not meet the requirements of Criteria A, B or C.

    Consequently, BirdLife’s recommendation to IUCN for the 2016 Red List is to list F. polatzeki as Endangered under Criterion D.

    There is now a period for further comments until the final deadline of 28 October, 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 2016 Red List categories will be published on the BirdLife and IUCN websites in early December, following further checking of information relevant to the assessments by both BirdLife and IUCN.

  8. Eduardo Garcia-del-Rey says:

    Dear James,

    Many thanks for updating this new endangered status. The Canarian Government is today trying to eliminate the captive breeding programme and hopefully this new status will oblige them to continue with the programme. It is patent the low avian management experience of their human resources, unable to remove this species from the endangered list since 1991. How many more years do we need to wait to see a final recovery?

    Kindest regards,
    Eduardo

  9. I find the recommendation “Endangered under Criterion D” for Fringilla polatzeki very sensible.

    The “common sense” proposal of “Critically Endangered” made by Dr. Lifjeld also seems reasonable (see his post on October 8, 2016). Nevertheless, and despite having a small population (one of the smallest in the Western Palearctic for a passerine), restricted to only two localities (very near each other; minimum distance: 1.5 km between them), Fringilla polatzeki has shown a notable resilience to critical events, from deforestation and bird collection in the second half of XIX and first half of XX centuries, to the recent devastating fire in summer 2007.

    One important consideration is that the designation of the “Reserva Natural Integral de Inagua” (https://goo.gl/HJFZro) in 1987 did not help to promote a clear increase of its population, at least since 1994. Moreover, its average density in its core area (the mature pine forests of Inagua Reserve; average of 10.5 individuals/km2 discarding those years when the forests were burnt, range: 8.0 – 15.8 birds/km2) is considerably lower than those estimations made for Fringilla teydea in Tenerife in less mature pine forests, many of them afforestations: 25-70 individuals/km2 (Moreno and Rodríguez 2007; https://goo.gl/1SGpH3) or 660 birds / km2 (García-del-Rey and Cresswell 2005; https://goo.gl/sXxu2I).

    Perhaps Fringilla polatzeki is a “woodland survivor” stranded in a suboptimal habitat in Gran Canaria Island (species richness and abundance of woodland bird species diminish towards SW of the Western Palearctic), that even in its emblematic, protected, core area shows low densities considering its body size … but it also has shown a high resilience to critical events.

    Perhaps we are also witnessing the vanishing existence of a woodland bird species in the eastern limit of the Canary forests of any kind (dry woodlands in this case). Consider these facts while sailing the “uncertain waters” going from “Endangered under Criterion D” to “Critically Endangered”.

  10. Ángel C. Moreno says:

    I would like to make some considerations but first, I am sorry because my English is very bad.
    I think that Endangered category is a great step in the category of threat for this taxon, considered as subopopulation of _Fringilla teydea_ until now.
    A priori, I think Critically Endangered it would be better category but the available data does not support it.
    But let’s think that the population of La Cumbre is incipient and we do not know if it will growing up without the releasing birds from captivity and traslocation. Probably not, without that reinforcement by the moment.
    And the population of Inagua are not extended through all forest, because there are important extentions without birds. Probably 50% or more is not good habitat and the natural regeneration of trees is very very slow in this dry forest in comparison with forests at the north of the island. Other woodlands have worst habitat quality, like Tauro and Pilancones. At the north, Tamadaba it would be good habitat but is far away and very few birds reached there in decades, not enough to stablish a new viable population.
    Wild fire in 2007 produced a hard reduction for population but the afection to the trees was lesser than understory. It could happen fires in future and it could be worst than 2007, and we do not know if the population recovery will happen again with the same way than 2007.
    Maybe we could consider only one sustainable population (Inagua) with hard fluctuations in population by eventual wild fire (Criterion B2)
    Thanks

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