Golden-cheeked Warbler (Setophaga chrysoparia): potential revision of Red List status

This discussion was first published as part of the 2017 Red List update. At the time a decision regarding the status of several was pended, but to enable potential reassessment of these species as part of the 2018 Red List update this post remains open and the date of posting has been updated.

Golden-cheeked Warbler (Setophaga chrysoparia) is a Neotropical migrant species that is a breeding endemic to Texas, U.S.A., and overwinters in southern Mexico and Central America. Dependent on juniper-oak woodland during breeding (Lockwood 1996), its Area of Occupancy (AOO) is currently considered to be very small (350 km2) and given habitat loss within its range the species’s AOO, Extent of Occurrence, habitat area/quality and population size are all considered to be in decline. As such it is currently listed as Endangered under criterion B2ab(i,ii,iii,v) (see BirdLife International 2017).

Reviewing this current listing, this Area of Occupancy value appears to be a large underestimation. Records within its breeding range cover a far larger area than this (see eBird 2017), and Mathewson et al. (2012) present multiple estimations of the amount of suitable habitat there is for this species, all of which are >1,000km2 but the most recent was 552,195 hectares (or 5,521.95km2) (SWCA Environmental Consultants 2007 in Mathewson et al. 2012). While this value does not directly relate to an AOO by IUCN guidelines (see IUCN Standards and Petitions Subcommittee 2016) it still strongly suggests that the area where this species breeds is far larger than currently used to assess this species’s Red List status, and potentially does not even approach the threshold for listing as Vulnerable under criterion B2. Therefore, this species requires re-assessing against the other criteria to see whether it warrants maintaining its listing as threatened.

Population figures from the recent Partners in Flight publications (Rosenberg et al. 2016) suggest that the species would not warrant listing under a threatened category based on population size (criteria C and D). The ‘population estimate’ provided in Rosenberg et al. (2016) is 21,000, but it is uncertain whether this refers to total number of individuals or just mature individuals. If this number refers to number of mature individuals, then it would not approach the threshold population size for listing as Vulnerable under criterion C (<10,000 mature individuals). However, if this were to refer to the total number of individuals then this would roughly equate to 14,000 mature individuals and so, given that the species may be considered to consist of only one subpopulation because of its migratory behaviour, then the species could warrant listing as Near Threatened under criterion C2a(ii). This said, the ‘population estimate’ of Rosenberg et al. (2016) appears to be considerably at odds with other population estimates displayed by Mathewson et al. (2012). Mathewson et al. (2012) themselves estimate the number of singing males alone at 262,013 (223,164-301,081) (although depending on model selection range expands to 191,658-301,081). Other estimates of the potential population that could be supported in the available habitat range from 4,822-16,016 pairs (Wahl et al. 1990 in Mathewson et al. 2012) to 228,426 individuals (Rappole et al. 2003). These more recent estimates of Rappole et al. (2003) and Mathewson et al. (2012) then both suggest that the population size would far exceed the 10,000 mature individuals threshold, and so would not even warrant listing as Near Threatened under criterion C.

To the best of our knowledge no quantitative analysis of extinction risk has been conducted for this species, and so it cannot be assessed against criterion E. This leaves only criterion A, which assesses the species against rates of decline. Partners in Flight, in their Appendix, do not provide a species ‘half-life’ or % decline, but earlier in the publication suggest that the species has undergone a decline of >50% over 44 years. As this leaves still a very large range of potential decline over this period, this makes it very difficult to assess the rate of decline over 3 generations (c.11 years). However, as an example, if a decline of 50% over 44 years is used, then this would only equate to a decline of 15.6% over 3 generations, which again would not qualify this species as even Near Threatened.

Thus it appears likely that in the absence of any other information this species may warrant downlisting to Least Concern. However, we do urgently request any further information, particularly regarding the rate of decline over the past 10-15 years and the very large disparity between population size estimates which could at least mean this species may deserve listing as Near Threatened.



BirdLife International. 2017. Species factsheet: Setophaga chrysoparia. Downloaded from on 21/04/2017.

eBird. 2017. eBird: An online database of bird distribution and abundance [web application]. eBird, Cornell Lab of Ornithology, Ithaca, New York. Available: (Accessed: April 21, 2017).

IUCN Standards and Petitions Subcommittee. 2016. Guidelines for Using the IUCN Red List Categories and Criteria. Version 12. Prepared by the Standards and Petitions Subcommittee. Downloadable from

Lockwood, M. W. 1996. Courtship behavior of Golden-cheeked Warblers. Wilson Bulletin 108: 591-592.

Mathewson, H. A.; Groce, J. E.; Mcfarland, T. M.; Morrison, M. L.; Newnam, J. C.; Snelgrove, R. T.; Collier, B. A.; Wilkins, R. N. 2012. Estimating breeding season abundance of golden-cheeked warblers in Texas, USA. The Journal of Wildlife Management 76: 1117-1128.

Rappole, J. H.; King, D. I.; Diez, J. 2003. Winter- vs. breeding-habitat limitation for an endangered avian migrant. Ecological Applications 13: 735-742.

Rosenberg, K. V.; Kennedy, J. A.; Dettmers, R.; Ford, R. P.; Reynolds, D.; Alexander, J. D.; Beardmore, C. J.; Blancher, P. J.; Bogart, R. E.; Butcher, G. S.; Camfield, A. F.; Couturier, A.; Demarest, D. W.; Easton, W. E.; Giocomo, J. J.; Keller, R. H.; Mini, A. E.; Panjabi, A. O.; Pashley, D. N.; Rich, T. D.; Ruth, J. M.; Stabins, H.; Stanton, J.; Will., T. 2016. Partners in Flight Landbird Conservation Plan: 2016 Revision for Canada and Continental United States. Partners in Flight Science Committee.

SWCA Environmental Consultants. 2007. Preliminary deliverable golden-cheeked warbler status review. Texas Department of Transportation, San Antonio, USA.

Wahl, R.; Diamond, D. D.; Shaw, D. 1990. The golden-cheeked warbler: a status review. Texas Parks and Wildlife Department, Austin, USA.

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8 Responses to Golden-cheeked Warbler (Setophaga chrysoparia): potential revision of Red List status

  1. Andy Symes (BirdLife) says:

    Preliminary proposals

    Based on available information, our proposal for the 2017 Red List would be to pend the decision on this species and keep this discussion open until 2017, while leaving the current Red List category unchanged in the 2018 update.

    There is now a period for further comments until the final deadline of 4 August, 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 those in the initial proposal.

    The final 2017 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.

  2. We found 1,771,883 hectares (17,718 sq km) of habitat in this study:

    Diamond, D. D. and C. D. True. 2007. Range-wide modeling of Golden-cheeked Warbler habitat. Final Report to U.S. Fish and Wildlife Service, Austin, Texas.

    Golden-cheeked Warbler Habitat is also being lost within the Range. We found 15,778.9 hecares of conversion of woodland (possible GCWA habitat) to grassland (not habitat), and 5,767,7 hectares of conversion of woodland to urban (not habitat) in a small subset of the range, centered within a single satellite (TM) footprint over Austin and areas to the west and north Time stamp for habitat lass was 2005/2006 to 2014/15. The study citation is:

    Diamond, D.D., L.F. Elliott, and D. German. 2016. Pilot project for up-date of ecological mapping systems of Texas and analysis of habitat change with respect to the Golden-cheeked Warbler. Texas Parks & Wildlife Department, Austin.

    The list of publictaions on golden-cheekd warblers cited above is incomplete, and the author is guilty of cherry-picking to make his case, rather than providing a balanced review of evidence.

    • Andy Symes (BirdLife) says:

      Thank you for providing this additional information and publications.

      “the author is guilty of cherry-picking to make his case, rather than providing a balanced review of evidence.” I’m sorry but this is simply untrue – and indeed the whole point of the forum process is to gather all the relevant information we can in order to ensure that we have an accurate picture before proceeding with any revision to Red List status for this and all species under discussion. We are therefore very grateful to forum contributors for alerting us to any publications or data which may have been accidentally overlooked in the initial proposal. Please note that the discussion explicitly references the fact that there are range of very different published population estimates and that this creates uncertainty over the status of the species. Rest assured that there is no agenda other than to attempt to apply the IUCN Red List criteria as accurately and consistently as possible based on the available evidence.

  3. I have information that clearly demonstrates aggressive GCWA habitat loss over the last 30 years. Here is a summary of our work:

    Over the decades, several different studies have assessed GCWA population size and/or habitat availability at single points in time, but these are inadequate to determine trends over time. Perceived population or habitat changes over time could be due to methodological differences between studies rather than true changes in populations and/or habitat. Therefore, the best way to determine population and/or habitat declines is to use the same methodology across several decades. My co-author and I are the only ones who have done this to assess habitat change for the GCWA over 3 decades. Our results are summarized by a story map at

    In our study area there were both gains and losses in GCWA habitat but the losses substantially exceeded the gains mainly over the last 2 (1990s-2016) of the 3 decades. From 1986 to 2016 high quality habitats decreased from 7% to 4%, low quality habitat declined from 23% to 16% and non-habitat increased from 69% to 81%. Essentially, 43% of high quality and 30% of low quality habitat were lost in only 30 years. Habitat losses were due to development, land modifications and drought. We saw substantial habitat loss after the 2011 drought and its repercussions were still evident 5 years later. Therefore, habitat is clearly diminishing and in turn population numbers likely are also.

    Furthermore, Mathewson et al. (2012) and SWCA Environmental Consultants (2007) do not include the effects of the 2011 drought which I feel are quite substantial. In addition, there is some concern about the methodology in these works and so other research should be included in the assessment. For all these reasons; clear progressive habitat declines exasperated by drought, methodological issues across studies and lack of consensus among researchers, it is pre-mature to downlist the GCWA at this time.

  4. Andy Symes (BirdLife) says:

    Many thanks to all who have provided information so far, both via the forum and by email.

    We appreciate that there are particular sensitivities and concerns around the assessment for this species, and we recognize that many key stakeholders and researchers may have only recently heard about the proposed reassessment. As a result of this, we have received a considerable late flurry of new information, comments and additional references to consider. In order for us to be able to carefully consider all this recently-received information, plus any further information that has not yet been submitted, we have extended the current consultation until the next round of Red List assessments in 2018. In the meantime, the species will continue to be listed as globally Endangered in the 2017 IUCN Red List when it is released this autumn.

    The exact timeline for the 2018 Red List update has yet to be finalised by IUCN, but the forum discussion on this species will remain open for at least the rest of 2017. We will post revised deadlines for comments in 2018 once these have been confirmed by IUCN.

    Please do continue to provide input into the forum discussion – we are very keen to ensure that we have received all relevant information before assessing the implications for the species’s Red List status and recommending any potential change in its global status to IUCN in 2018.

    The title of the forum discussion has been edited from “Golden-cheeked Warbler (Setophaga chrysoparia): downlist to Least Concern?” to “Golden-cheeked Warbler (Setophaga chrysoparia): potential revision of Red List status” to more accurately reflect that there are several Red List categories into which the species could plausibly be categorised.

  5. Chris Harper says:

    For your consideration:

    More information about the golden-cheeked warbler is publicly available here:

    including the most recent (2014) 5-year review for the species:

  6. Jennifer Reidy says:

    I have spent my entire career studying the golden-cheeked warbler. The reason it was listed as endangered, and the reason it continues to require federal protections, is because of habitat loss. GCWA require large blocks of mature (tall, closed-canopy) juniper-oak woodland to reach optimal breeding conditions (high density and productivity). Very importantly, not all woodlands are the same as shown at Fort Hood and the Balcones Canyonlands Preserve, the two biggest protected populations. They show a large gradient in occupancy and density based on landscape and localized vegetation structure. There is currently no reasonable population estimate for the breeding range, either from the early studies in the 1980’s or 1990’s or the Mathewson et al. 2012. The best population estimates provided so far are localized and validated by comparing to known populations of banded birds. They come from Fort Hood, the Balcones Canyonlands Preserve, and Balcones Canyonlands National Wildlife Refuge. These three areas also represent the largest protected areas and cumulatively do not support many birds (7557, 1779, 884 males, respectively or ~10,000 males). Considering the sentiment toward juniper in Texas (ranchers generally hate it), without federal protections, there is no incentive to spare this habitat. Despite federal protections, large amounts of their habitat have already and continue to be destroyed each year, along with processes out of our control such as catastrophic fire, drought, and climate change.

    In summary, we do NOT know how many GCWA there are range-wide because we have no reliable range-wide population estimates to base any conclusions on. We do know that GCWA relies EXCLUSIVELY on juniper-oak woodland to breed in. We do know that this habitat occurs only in central Texas (and occupied woodland area is certainly smaller than the delineated woodland that appears in various publications). We do know that central Texas is one of the fastest growing areas in the U.S. We do know that Texas politicians are hostile toward endangered species. We do know that GCWA serve as a flagship species to protect a fragile ecosystem of other plants and animals and to preserve water quality. This species is incredibly vulnerable to extinction due to habitat loss. Precious little of the breeding range is state or federally owned and all of it is susceptible to climatic forces.

    Please do a more thorough literature review before posing to downgrade a species. Adam Duarte, Rebecca Peak, and I along with our co-authors have contributed several studies on the GCWA in the past 10 years. There are numerous other citations beyond ours as well, but I believe you can find most of them within our literature cited.

    I’m happy to provide further comment or literature. Thank you.

    • Andy Symes (BirdLife) says:

      Hi Jennifer

      Many thanks for these comments. Just to make clear however, the current listing as Endangered under IUCN Red List criteria is entirely dependent on the species having an Area of Occupancy (AOO) in the breeding season of <500 km2.

      Most available information on the species suggests that the AOO is likely to be considerably larger than the threshold of 500km2 (and the estimate currently used in the assessment, of 350km2). For example, the most recent estimates for potential breeding habitat, as quoted in the USFWS five-year review, significantly exceed this threshold. Although not directly comparable to an AOO estimate, they certainly imply that the true AOO value is unlikely to be <500 km2. We are aware that these larger estimates derive from better knowledge rather than a genuine increase in available habitat, but they nevertheless suggest that the current listing as Endangered under criterion B2 is not supported by the information available.

      It may turn out that the species still warrants listing as Endangered, Vulnerable or Near Threatened under this or one of the other Red List criteria, and the forum consultation process is intended to make sure we are aware of all available information in order to establish whether this is the case.

      Andy Symes

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