Archived 2017 topics: Ferruginous Duck (Aythya nyroca): downlist to Least Concern?

BirdLife species factsheet for Ferruginous Duck

The global population size and trend of Ferruginous Duck has been difficult to establish with confidence due to an apparent tendency to shift its breeding distribution in response to interannual fluctuations in water levels across a very large range. Declines have been documented in parts of the range, but evidence from the larger Asian populations is mixed. As a result, the species is currently considered Near Threatened.

For the relatively small proportion of the global population that winters in Europe, the trend reported in the 2015 European Red List of Birds was increasing within the EU 27 and stable for the whole of Europe (BirdLife International 2015). In addition, in China the species is expanding eastwards and increasing, with recent estimates of the breeding population of 1,500-2,000 pairs, and 6,000-8,000 wintering individuals (Zhao and Maming 2014). The suggestion that these two populations may be stable would indicate that any overall rate of decline for the species may no longer approach the thresholds for listing as threatened and that the species may hence warrant listing as Least Concern.

However, there remains considerable uncertainty over the global trend due to significant data gaps throughout the range. While the European wintering population appears to be stable, the European breeding population trend is unknown due to a lack of data from Romania, where it is thought over 60% of this population breeds (BirdLife International 2015). On the basis of the information that was reported (excluding Romania) there appears to be a slight decline across all countries for which long-term trends could be calculated, which is slightly more pronounced when the negative short-term trend for the Croatia population (6% of the European breeding population) is included.

A literature review of West Siberian bird populations (van Impe 2013) indicated that 6 studies reported declines in the breeding population of Ferruginous Duck in Russia, from an estimated 12-14,000 pairs in the 1980s to between 500 and 1,500 pairs in 2003 (Ilyashenko 2011), but more recent trend information appears unavailable.

Trends in wintering populations elsewhere in Asia are also unclear. The Asian Waterbird Census 2008-2015 data demonstrates considerable variation due to the inconsistency in the number of sites surveyed. Over 10,000 individuals were recorded in 2008, 2011 and 2013, while fewer than 3,000 individuals were recorded in 2010 and 2015 (Mundkur et al. 2017). Bangladesh appears to be the key country for wintering for the eastern population, and while effort explains some of count variation between years, there appears to be a genuine multi-year cycle in numbers present in the country. Therefore, the best available data from Asia (which contains the largest flyway population in the world) does not provide any evidence for recent declines, just fluctuations.


The following tale presents the data shown in the Waterbird Population Estimates (Wetlands International 2017b) updated to include data from the AEWA Conservation Status Review 6 (Wetlands International 2017a), along with data from Mundkur et al. (2017).

Population Size (individuals) % total Trend Reference(s)
West Mediterranean/North & West Africa 5,700 – 6,300 2.6 – 3.2 Unknown see Wetlands International (2017a)
Eastern Europe/East Mediterranean & Sahelian Africa 50,000 – 82,000 27.7 – 34.4 Increasing see Wetlands International (2017a)
Western Asia/South-west Asia & North-east Africa 25,000 – 50,000 13.8 – 21.0 Unknown see Wetlands International (2017a)
Remaining Asian Distribution 100,000 42.0 – 55.3 Fluctuating see Wetlands International (2017b); Mundkur et al. (2017)
Total 180,700 – 238,300

Overall, and given the vast size of the range and the species’s apparent low site fidelity, the population trend is essentially uncertain. However, there does not appear to be any evidence suggesting that there is a rapid or moderately rapid decline that approaches 30% (i.e. 25-29%) in three generations (c. 23 years), and the rate of decline is presently estimated at 10-19% over three generations, which in itself is not sufficiently severe to be considered Near Threatened. Therefore, as the species does not presently approach the thresholds for listing as a Threatened species under any criteria, it is proposed that the species be downlisted to Least Concern.

If data from the breeding population in Russia and Romania are available and demonstrate recent negative trends sufficient to be causing a more severe rate of global decline, then maintaining the species as Near Threatened may be justified. Either way, such data would be very useful in supporting the species assessment.


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

Ilyashenko, V. Y. 2011. Principles of compiling a catalogue of rare birds and the Red Data Book of the Russian Federation. Ornitologia 36: 157-187 (Russ.).

Mundkur, T., Langendoen, T. and Watkins, D. (eds.) 2017. The Asian Waterbird Census 2008-2015 – results of coordinated counts in Asia and Australasia. Wetlands International, Ede.

van Impe, J. 2013. Esquisse de l’avifaune de la Sibérie occidentale: une revue bibliographique. Alauda 81(4): 269-296.

Wetlands International. 2017a. “Waterbird Population Estimates”. Retrieved from on Tuesday 23 May 2017. Updated from the AEWA Conservation Status Review 6.

Wetlands International. 2017b. “Waterbird Population Estimates”. Retrieved from on Tuesday 23 May 2017. Current data from

Zhoa, Z. and MaMing, R. 2014. The status of Ferruginous Duck Aythya nyroca breeding and wintering in China. Wildfowl 64: 116-125.

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17 Responses to Archived 2017 topics: Ferruginous Duck (Aythya nyroca): downlist to Least Concern?

  1. Nicky Petkov says:

    Given the lack of knowledge of the actual population in Asia and the fact that most of the extrapolations for the Asian population either rely on numbers and figure quite crudely summed up despite being from different years or simply cite data and numbers that more than 15 years old! In most recent IWC numbers I have seen from Central Asia and SE Asia counts there are not big numbers but mere few hundreds of birds mostly. The fact that there is big numbers observed in China does not compensate for the lack and absence of the thousands of birds counted in the 1990s in other Asian countries at all. I do not see it correct and proper to rely on 1990s numbers as still valid despite there is no evidence of such numbers in the recent years and just add on new big numbers observed in other part of the range. For downlisting the species one should have strong data and evidence for maintaining of the claimed huge population in Asia. Much of the large population as in Danube Delta for example also rely on extrapolation and given the specifics of the species habitat selection and preferences these should be taken with care if not based on a robust habitat selection model, which I doubt has happened. More over I would take care when considering the claim of tens of thousands of pairs in Inner Mongolia, as I remember one similar discussion on the species Red List status when there were claims based on a single visit in June at one lake in Inner Mongolia that it holds thousands of breeding pairs when there was no evidence and information on sex ration and if this is not a gathering of males, which in the past has been recorded in Bulgaria for example with flocks of several thousand birds in June-July along the Danube River, but mostly composed by males. In addition the sum up and calculation for breeding density were not fit for the space available there in this lake and if the claim was correct that the breeding density of the Ferruginous Duck was such then there should have been no other breeding ducks there to have sufficient space for breeding FDs. In my opinion the demand for down listing the species is little premature and based on poor data and evidence that is outdated by over a decade!

  2. Nicola Baccetti says:

    I agree with the previous reviewer that downlisting is premature. Ferruginous Ducks have been recently showing a positive trend in winter in Italy, but the same does not seem to hold for the local breeders and especially for the spring passage of more eastern birds, that until 50-60 years ago represented a massive phenomenon on many Italian wetlands in the month of March. Moreover, local factors that were believed to represent a strong limit until 10-20 years ago haven’t been substantially removed and some of the key sites (e.g. in Sicily) are still at risk.

  3. James Westrip (BirdLife) says:

    There has been some discussion regarding this species on the Duck Specialist Group website, which can be found here;

  4. James Westrip (BirdLife) says:

    Dominik Marchowski (Duck Specialist Group) has provided the following comment:

    Recent assesment in Poland: 100-130 breeding pairs (2009-2013) what is 0.5% of European population and 0.7% of EU population (Chodkiewicz et al. 2015).

    Chodkiewicz T., Kuczyński L., Sikora A., Chylarecki P., Neubauer G., Ławicki Ł., Stawarczyk T. 2015. Assessment of the number of breeding birds in Poland in 2008-2012. Ornis Polonica 56: 149–189. (in Polish with English summary), available @

  5. One of factors being considered in this thread is the new exciting find from China. However Zhao and Maming observations could also factor the prospects of the China wetlands where they have been found, viz. whether any consideration for diverting the wetlands for developments and other potential threats.

  6. Nicky Petkov says:

    I saw this comment, but however the figures missing and most concerned are the figures from Asia! There are no thousands of wintering birds nowadays in any of the CA countries or SE Asia as well. Numbers are at most few hundred birds and the population figures rely on very dubious and/or old figures from Asia to presume safe and stable population when winter (IWC) numbers do not match the figures presumed. The fact that targeted conservation efforts have resulted in a better conservation status in some European countries (and this was result of the threatened conservation status) does not match for the big gap in the data from Asia! I would rather consider uplisting in the light of the old figures from Asia not confirmed by current counts than downlisting to Least Concern as there is lack of evidence for such downlisting for me.

  7. Anup Nayak says:

    I have observed the presence of Ferruginous ducks not recorded earlier in at least 3 widely different places in eastern India over the last 5 years, . This indicates fairly wide distributional range for this bird even in India. Therefore downlisting the species is not a bad idea.

  8. R.K. Birjit Singh says:

    We have observed a decreasing trend of the population of the species in north-east India, particulalry Loktak Ramsar in Manipur and Assam and above missing link and data of SE Asia. Need to have retrospective check back.

  9. Dr. I.R. Gadhvi says:

    Ferrugenous duck is very rare occurance in our region that is saurashtra region of Gujarat state of Western India.
    if anybody observe the data sheet of AWC of this region it would clarify.
    I agree with the previous reviewer that it would be premature dicession to downlist the species

  10. Praveen J says:

    India does not seem to be the best wintering ground for this species if the estimate for 100,000 is valid for ‘Remaining Asian Distribution’.
    As per eBird, Assam is the prominent wintering area for this species where most sites hold a few tens of birds – and rarely counts reaching a couple of hundreds.
    In Northern & Western India, counts greater than 10 has been reported a few times, reaching three figures is extremely rare.
    In summary, though a widely wintering species, no set of sites seem to hold any significant part of this regional population. Hence, it is preferable that status from other countries be checked.

  11. Nicky Petkov says:

    As I have mentioned in my previous comments the huge numbers presumed for Asian population are not supported by recent IWC/AWC data at all. In this respect there should be much more concern if it is not time to consider up-listing instead of down-listing! Down-listing based on data 10 or 20 years old and replicated into today would be for me not only premature, but doubtful as an approach to status assessment.

  12. The Ferruginous Duck is a regular winter visitor to freshwater wetlands of Bangladesh. The Asian Waterbird Census (AWC) count data ( an estimated 80% of the total population occur within the AWC count areas) shows a reduction of less than 50% of its population over the last three generations or 23 years. The species nearly meets A2 (a), but do not satisfy the criteria, hence it is evaluated as Near Threatened in Bangladesh by IUCN Bangladesh in 2015.

  13. Jose Rafael Garrido says:

    Andalucía (south of Spain has a very small breeding population, from two to 10 pairs between 2004-2017, with a stable trend, but wintering population is increasing in the same period, from less 10 birds in 2004 to more 70 during 2014-2017. Obviously, wintering population is not related with our breeding one, so it seems some extra breeding populations are increasing (North Africa could be the answer)

  14. Carol Inskipp and Dr Hem Sagar Baral says:

    In the Nepal national Bird Red Data Book (Inskipp et al. 2016) Ferruginous Duck was assessed as Vulnerable based on the criteria A2acd, D1. The species is locally distributed; mainly a passage migrant, and also a winter visitor. Since the monsoon flooding of 2008 it has sharply declined at Koshi Barrage/KoshiTappu Wildlife Reserve, where it was formerly seen most regularly and in greatest numbers; since 2008 only small numbers have been recorded there. Numbers at other known sites have not changed significantly during the period recorded. The Nepal population was estimated as less than 1,000 birds. The species is seriously threatened by both hunting (illegal in protected areas) and disturbance, and the loss and degradation of wetlands. Recently it has been recorded in a few protected areas. More details of the species’ occurrence in Nepal can be found in Volume 1 national Bird Red Data Book which is available for free download at:
    Inskipp C., Baral H. S., Phuyal S., Bhatt T. R., Khatiwada M., Inskipp, T, Khatiwada A., Gurung S., Singh P. B., Murray L., Poudyal L. and Amin R. (2016) The status of Nepal’s Birds: The national red list series. Zoological Society of London, UK.

  15. Andy Symes (BirdLife) says:

    Preliminary proposals

    Based on available information, our preliminary proposal for the 2017 Red List would be to list:

    Ferruginous Duck as Near Threatened under criterion A2cd+3cd+4cd.

    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 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.

  16. Christoph Zöckler says:

    From my experience over the past 5 years in Northern Myanmar I would also recommend to keep the species as NT. I also agree with many comments on the Asian data to be rather old and not reliably updated. Over the past 15 year the species virtually disappeared from the Ayeyarwaddy River. Eve in 2006 there were hundreds, but today only single birds. There might be a concentration in some more protected wetlands like Lake Indawgyi, where the figures seemed to have change little in the past 15-20 years. The species though has disappeared from other wetlands like Indaw lake and many of these wetlands are not protected and threatened by deforestation habitat change and pollution, hunting and poaching. A more detailed update is planned.

  17. The evident and continuously decreasing of the breeding population is well documented in Lithuania, which is located on the northern border of the species distribution range in Europe. The total breeding population was estimated at 5-10 breeding pairs by 2012 with a short-term trend (2001-2012) up to 50% decreasing rate. If to look at the changes of species abundance since 1980-ies, is less than 10% of the breeding pairs left comparing with numbers 30 years ago in Lithuania. The analogous situation is with changes (reduction) of the distribution range of the species in the country.

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