Proposed Status Changes of Forest-dependent Species

This discussion was first published as part of the 2017 Red List update. Further species reassessment will form part of the 2018 Red List update and so this post remains open and the date of posting has been updated.


A recent study by Tracewski et al. (2016) used the open-access Global Forest Change map (Hansen et al. 2013) to assess forest cover and loss between 2000 and 2012 within the range of over 11,000 species of forest-dependent birds, mammals and amphibians. This data was then used to assess whether species may qualify for uplisting on the IUCN Red List on the basis of whether the rate of forest loss within a species’s range, or the amount of available forest (a proxy for the Area of Occupancy) met the threshold for a higher Red List category.

Following the completion of the changes to BirdLife’s taxonomy (see del Hoyo and Collar 2014, 2016), the assessment of birds has been re-run taking into account these recent changes  (Ł. Tracewski unpublished data). The complete avian dataset is now in the process of being re-assessed, as not only will species require uplisting based on the data, but some species may require downlisting where the rate of forest loss has either decreased or was over-estimated in previous assessments. The dataset helps us not only to assess species against criteria A2 and B2, as described in Tracewski et al. (2016), but will also aid in assessing species against criterion C.

Assessments against criterion A2 are carried out by extrapolating the rate of forest loss between 2000-2012 across a 3 generation period or 10 years (whichever is the longer), with the assumptions that population change is equivalent to forest change and that habitat loss has continued at the same rate to the present day. In some cases the overall rate of change is assessed at a different rate from that of the forest loss, usually because there are additional threats such as hunting or invasive species that could be adding to overall declines in a species. Additionally, there may be some species which are inhabitants of forest edge/fragments and so forest loss may in fact be not having such a severe effect on them. The rate of decline is then compared to the threshold values for Vulnerable (30-49% declines), Endangered (50-79% decline) and Critically Endangered (≥80% decline). The Red List category Near Threatened does not have a threshold value, but to qualify for this category a species must approach the threshold for listing as Vulnerable. Therefore, species with a decline of >25% but <30% have been presented as Near Threatened.

Assessments against criterion B require the Area of Occupancy (AOO) to meet a threshold size (<10km2 for Critically Endangered; <500km2 for Endangered; <2,000km2 for Vulnerable; no threshold set by IUCN for Near Threatened but for this analysis one was arbitrarily at <2,500km2), and at least two further conditions must also be met. These further conditions are a) the species’s range is severely fragmented or restricted to a certain number of locations* (1 for CR; 2-5 for EN; 6-10 for VU), b) continuing decline in i) extent of occurrence, ii) area of occupancy, iii) area/extent/quality of habitat, iv) number of locations/subpopulations or v) number of mature individuals, and c) extreme fluctuations in i) extent of occurrence, ii) area of occupancy, iii) number of locations/subpopulations or iv) number of mature individuals.

Finally, this dataset also allows us to reassess some species under criterion C (a small, declining population size, combined with certain other conditions). All of the cases for alterations to Red List status based on this criterion will probably be very species specific and so full details are not gone into here, and will instead be explained in further detail on the respective forum topic. However, the reason behind changes in status based upon this criterion alone is that the rate of decline can no longer be estimated to be at a certain rate (criterion C1, noting that the rate of decline for most, if not all cases will be either suspected or inferred), or the updated rates of forest loss mean that we can change our opinion on the overall population trend (i.e. a population currently stated as decreasing with forest loss as the only threat, may have actually not lost any habitat within the last 3 generations).

As can be expected, this updated data represents a vast, multi-faceted dataset, and it will take a long time to fully decipher all of the species that could, potentially be uplisted or downlisted (as well as all of those that will require minor changes to their criteria string, but without a change in Red List status). We shall be presenting all of the species that are considered to warrant a category change (an uplist or a downlist) in general topic based around a common theme, e.g. uplists based on small Area of Occupancy (criterion B2), and the links to these are provided below.


*Note that the term ‘location’ defines a geographically or ecologically distinct area in which a single threatening event can rapidly affect all individuals of the taxon present. The size of the location depends on the area covered by the threatening event and may include part of one or many subpopulations. 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).



del Hoyo, J.; Collar, N. J. 2014. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Volume 1: Non-passerines. Lynx Edicions and BirdLife International, Barcelona, Spain and Cambridge, UK.

del Hoyo, J.; Collar, N. J. 2016. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Volume 1: Passerines. Lynx Edicions and BirdLife International, Barcelona, Spain and Cambridge, UK.

Hansen M. C.; Potapov, P. V.; Moore, R.; Hancher, M.; Turubanova, S. A.; Tyukavina, A.; Thau, D.; Stehman, S.V.; Goetz, S. J.; Loveland, T. R.; Kommareddy, A.; Egorov, A.; Chini, L.; Justice, C. O.; Townshend, J. R. G. 2013. High-resolution global maps of 21st-century forest cover change. Science 342: 850–853.

IUCN. 2001. IUCN Red List Categories and Criteria: Version 3.1. Gland, Switzerland and Cambridge, UK: IUCN Species Survival Commission.

IUCN. 2012. Guidelines for Application of IUCN Red List Criteria at Regional and National Levels: Version 4.0. Gland, Switzerland and Cambridge, UK: IUCN.

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.


Individual Topics

Uplist following reassessment of A – Expected Oct 2017

Uplist following reassessment of B2 – June 2017

Uplist following reassessment of C – Expected May 2018

Downlist following reassessment of A – Expected May 2018

Downlist following reassessment of B2 – Expected May 2018

Downlist following reassessment of C – Expected May 2018

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One Response to Proposed Status Changes of Forest-dependent Species

  1. Mark O'Brien says:

    Just a reminder. The global forest change map does NOT cover many parts of the Pacific (only Fiji in Polynesia, Palau and Yap in Micronesia). Many areas that it does include as forest cover are mapped as cropped land – but the small-scale and relatively extensive nature of landuse in the region may explain this.
    Out of interest, what is the origin of the list of forest-dependent species? I note it is present on the Datazone, but don’t know the origin or the derivation of that list.

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