Slaty Becard (Pachyramphus spodiurus): revise global status?

BirdLife species factsheet for Slaty Becard

Slaty Becard (Pachyramphus spodiurus) occurs in the Tumbesian and Chocó regions of western Ecuador and north-western Peru. It occurs mostly below 750 m, but locally ranges as high as 1,100 m. It inhabits lowland deciduous, semi-deciduous and humid woodland, but also shrubby clearings with scattered tall trees, patches of evergreen shrubbery and second growth within humid forest (Best and Kessler 1995, Clements and Shany 2001, Ridgely and Greenfield 2001). It forages in the canopy of tall trees. The species occupies a very small and fragmented range. Its population is estimated to number 600-1,700 mature individuals. Throughout the range, Slaty Becard is thought to be genuinely rare, and the paucity of recent records suggest that the species has suffered a serious decline, which is still ongoing.

Habitat loss and fragmentation are assumed to be the main drivers of the population decline. Throughout its range, forests are being rapidly destroyed, degraded and fragmented (Mobley 2018). In lowland western Ecuador, deforestation rates between 1958 and 1988 amounted to 57% per decade (Dodson and Gentry 1991). Forest loss is still ongoing, so that virtually all lowland forest outside protected areas is feared to disappear soon (Mobley 2018).

Forests are cleared for timber extraction and cattle farming. Even within protected areas, forests are lost through selective logging of valuable trees and persistent grazing by goats and cattle (S. Crespo in litt. 2012), the latter causing disturbance and degradation of the understorey in remaining deciduous woodland. Further threats are encroachment and the expansion of agricultural fields. Even though these imminent threats have strong negative impacts on the species and its range, Slaty Becard may show some tolerance of forest degradation. Occasionally, it has been reported to persist in substantially degraded areas and secondary growth (Ridgely and Greenfield 2001).

Currently, Slaty Becard is listed as Endangered under Criterion B1ab(i,ii,iii,v), indicating a very small Extent of Occurrence (EOO) and declines in population size and 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 Slaty Becard, 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 – Global Forest Watch measures forest loss within this species’s range between 2001 and 2017 as c.1,440 km2. This roughly equates to a rate of forest loss of 4.2% over three generations (13.8 years) for this species, with the assumption that it has continued at the same rate to the present day. Slaty Becard, however, appears to be able to tolerate a certain level of deforestation, as it is found in disturbed areas and secondary growth. Nevertheless, while it depends on the presence of tall trees for foraging, the species is further affected by selective logging, agricultural expansion and the degradation of understory caused by cattle grazing. Thus, it is conceivable that the population change is roughly proportional to the rate of forest cover change. Tentatively, the rate of population decline is placed here in the band 1-9% over three generations, and therefore Slaty Becard may be considered Least Concern under Criterion A.

Criterion B – Using a Minimum Convex Polygon, the Extent of Occurrence (EOO) has been calculated as 77,300 km2. This is far too large for listing the species as Vulnerable and therefore, Slaty Becard may be listed as Least Concern under this criterion. The Area of Occupancy has not been calculated; thus, the species cannot be assessed against Criterion B2.

Criterion C – The population of Slaty Becard is estimated to number 600-1,700 mature individuals. This may warrant listing the species under Criterion C, given it is considered to be declining, as long as other conditions are met. As the rate of population decline is suspected based on the rate of forest loss, Slaty Becard does not warrant listing as threatened under Criterion C1.

Given its highly localized occurrence throughout a severely fragmented distribution range, the species likely forms several subpopulations. However, considering the small population size it can be assumed that no subpopulation consists of more than 1,000 mature individuals. Therefore, Slaty Becard may be listed as Vulnerable under Criterion C2a(i).

Criterion D – The population size of this species is estimated at 600-1,700 mature individuals. Under the assumption that the population size is close to the lower band of the estimate and thus falling below 1,000 mature individuals, 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 proposed that Slaty Becard (Pachyramphus spodiurus) be listed as Vulnerable under Criteria C2a(i); D1. We welcome any comments on this 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.

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

Best, B.J.; Kessler, M. 1995. Biodiversity and Conservation in Tumbesian Ecuador and Peru. BirdLife International, Cambridge, U.K.

Clements, J.F.; Shany, N. 2001. A Field Guide to the Birds of Peru. Lynx Edicions, Barcelona, Spain.

Dodson, C.H.; Gentry, A.H. 1991. Biological extinction in western Ecuador. Annals of the Missouri Botanical Garden 78: 273-295.

Global Forest Watch. 2014. World Resources Institute. www.globalforestwatch.org (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.

Mobley, J. 2018. Slaty Becard (Pachyramphus spodiurus). 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/57537 (Accessed 14 September 2018). Ridgely, R.S.; Greenfield, P.J. 2001. The Birds of Ecuador: Status, Distribution and Taxonomy. Cornell University Press and Christopher Helm, Ithaca, U.S.A. and London, U.K.

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8 Responses to Slaty Becard (Pachyramphus spodiurus): revise global status?

  1. Re: Slaty Becard/ pachyramphus spodiurus — Criterion A: ” Global Forest Watch measures forest loss within this species’s range between 2001 and 2017 as c.1,440 km2. This roughly equates to a rate of forest loss of 4.2% over three generations (13.8 years) for this species, with the assumption that it has continued at the same rate to the present day. ”

    I am an artist, and I have lived in the Manabi Province area of the Slaty Becard’s range since 2008. In this area, I predict that the 2017- 2019 forest loss will be greater than the earlier years. My observations are based on living close to nature while noting subtle changes that many might overlook. The Global Forest Watch stats (above) were until 2017, the year after the devastating 7.8 earthquake hit this area. Since then I have noted an alarming acceleration of deforestation where hillsides are being cut, burned – desnuded. Scraps and smaller trees are used in the artisan brick-making industries. The land owners are planting crops – usually corn, but some land owners are selling the Samans that were in pastures.

    Areas outside of the earthquake zone are also losing habitat to deforestation. Perhaps these areas are in line with the 4.2% forest loss predictions, but it certainly appears to be a greater amount of clearing and burning.

    One other factor of concern is the unregulated herbicide use on pastures for broad-leaved plants, which affects the younger balsas as well. After a heavy dose last May 2018 in the area where I live, the seedeaters, grassquits and ground doves basically vanished until just recently. The past month there have been a few seedeaters and doves, but they are scarce, as are many other species, including one of two bee hive ‘collapse’ and the other was sick but is better. Last year there were lots of One-colored Becards – 7 nests near my house, and a few Slatys (?) but this year only a few One colored…

    I am extremely concerned. even the often-seen Brown Wood Rails are rarely seen.

    Before changing the IUCN status of any species for Western Ecuador, I recommend that an updated deforestation study is made.
    (Sorry this is long winded, edit as much as needed. The cyber is closing and waiting for me to post this!)

    • Red List Team (BirdLife International) says:

      Thank you very much for your comment. The 2016 earthquake in Manabí and the subsequent increase of logging are indeed of great concern.
      The question here is: Is the increase in the deforestation rate in Manabí in 2017-2019 large enough to outweigh the relatively stable trends in the rest of the range to bring the overall rate of decline over the last 13.8 years close to 30%? If this were the case, then Slaty Becard may indeed warrant listing as NT or even VU under Criterion A.

  2. Juan Freile says:

    From an Ecuadorian perspective –and take into account that this species range primarily in Ecuador– your estimate of potential range loss and population decline is underestimating the actual situation of this and other species endemic to the Manabí-Tumbes lowlands. This species does not only suffer from forest loss but also from forest degradation. Free-ranging cattle and goats cause major losses of understory, leaving a poor forest which looks continuous in satellite images and alike.
    In the Ecuador red list, we assessed this species as VU under criterion A (A2c+3c+4c), calculating a rough habitat loss of 20% using forest loss rates and better-guesses for understory loss. Habitat loss coupled with habitat impoverishment made us suspect that populations might be declined by a 30% and will continue declining in the next bird generations.

  3. Red List Team (BirdLife International) says:

    Preliminary proposals
    Based on available information, our preliminary proposal for the 2019 Red List would be to list Slaty Becard as Vulnerable under Criteria A2c+3c+4c; C2a(i); 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 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.

  4. I agree with Juan and the assessment of Slaty Becard being VU.

  5. Red List Team (BirdLife International) says:

    Recommended categorisation to be put forward to IUCN
    Following further review, the recommended categorisation for this species has been changed.
    Slaty Becard is now recommended to be listed as Vulnerable under Criteria A2c+3c+4c; C2a(i).
    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.

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