Archived 2017 topics: Relict Gull (Larus relictus): downlist to Near Threatened?

Relict Gull, Larus relictus, is a migratory gull, breeding at localities in Kazakhstan, Russia, Mongolia and China (e.g. Rubini and Berezovikov 2002, He Fen-qi and Ren Yong-qui 2006). Breeding sites are found in the arid-steppe zone on islands in saline and slightly-saline lakes. These lakes have fluctuating water levels and nesting may not occur if lakes dry up, if islands become attached to the shore or if the water level becomes too high and makes the island too small and overgrown with vegetation. The species migrates away from breeding sites in the non-breeding season, and its non-breeding range is poorly known, though it is documented from South Korea and China at estuarine mud- and sand-flats (P. Holt in litt. 2011, 2012, Q. Bai and M. Xunqiang in litt. 2016), as well as inland on the northern flank of the Qinghai-Tibet plateau, China.

The species is threatened during the breeding season by climate change, as increasing aridisation and vegetation changes have been predicted in its range (Tchebakova et al. 2009). Human disturbance is another threat, for instance Taolimiao-Alashan Nur (formerly thought to hold up to 3,000 pairs [He Fen-qi and Qiao Zhenzhong in litt. 2004]) was recently abandoned, likely a result of increased tourist activity, unsustainable water use and drought (He Fen-qi in litt. 2011). During the non-breeding season pollution and development of coastal areas are thought to be serious threats to the species (P. Holt in litt. 2011).

Its population was estimated at 12,000 individuals by Rose and Scott (1997). However, up to 5,000 pairs have been recorded at Honjian Nur Lake, China (He Fen-qi and Ren Yong-qui 2006) and so the global population size is likely >>10,000 mature individuals. Because the species is migratory there is the possibility that individuals may interact with one another during the non-breeding season, and so the population could be said to contain only one sub-population. However, given the paucity of knowledge regarding the non-breeding distribution of this species, and the presence of an inland non-breeding population, it is tentatively suggested that species consists of more than one sub-population. Population trends are also difficult to determine with some colonies undergoing dramatic declines (Taolimiao-Alashan Nur), while other colonies are increasing (e.g. Honjian Nur Lake), but given the threats that may be affecting this species, it may be conservative to consider the species to be in decline.

Relict Gull is currently listed as Vulnerable under criterion D2 on the basis that it breeds at only a limited number of locations* that could be strongly affected by climate change in the future (see BirdLife International 2017). To qualify as Vulnerable under criterion D2 a species must occur at 5 or fewer locations or have an Area of Occupancy of <20km2, and there be a plausible threat that could drive the species to Critically Endangered or Extinction in a very short time (see IUCN 2001, 2012). However, the number of breeding locations does not meet the threshold for Vulnerable (one locality in Kazakhstan [Rubini and Berezovikov 2002]; one in Russia; several in Mongolia; and at least one in China at Honjian Nur Lake, Shaanxi [He Fen-qi and Ren Yong-qui 2006]), and while its Area of Occupancy has not been directly calculated, it is unlikely to be <20km2. Therefore, Relict Gull likely does not qualify as Vulnerable under criterion D2. Instead, given the number of locations has currently been estimated at 6-10, it is suggested that the species be instead listed as Near Threatened under criterion D2.

We welcome any further information and comments regarding this proposed downlisting.

 

*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).

 

References

BirdLife International. 2017. Species factsheet: Larus relictus. Downloaded from http://www.birdlife.org on 15/03/2017.

He Fen-qi; Ren Yong-qi. 2006. Alternative choosing of breeding sites of those Ordos Relict Gulls. China Nature 4: 16-17.

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.

Rubini, B.; Berezovikov, N. N. 2002. The fluctuation of breeding numbers of Relict Gull Larus relictus on Lake Alakol (SE Kazakhstan): a review of surveys from 1968 to 2001. Acrocephalus 23(115): 185-188.

Tchebakova, N. M.; Parfenova, E.; Soya, A. J. 2009. The effects of climate, permafrost and fire on vegetation change in Siberia in a changing climate. Environmental Ressearch Letters 4.

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5 Responses to Archived 2017 topics: Relict Gull (Larus relictus): downlist to Near Threatened?

  1. Pingback: Globally Threatened Bird Forum: Relict Gull | Birds Korea Blog

  2. Nial Moores says:

    Several bird conservationists within the species’ range seem not to support downlisting of the Relict Gull from Vulnerable to Neat Threatened. I am one of them.

    The argument for possibly down-listing the Relict Gull from Vulnerable to Near Threatened seems to be based largely on the assertion that the species does not meet the requirements for IUCN Criterion D2. This is even though the species breeds at only a limited number of locations that have already been and could be strongly affected by climate change (and mismanagement) in the future. In addition to very real problems at breeding sites, it would therefore seem appropriate to consider in more depth the status of non-breeding habitat, which should in my opinion trigger listing for the species as Vulnerable (or even as Endangered) under one or more of IUCN criteria A1 c); B1 b); B2a) and/ or B2 b).

    Based on present understanding, perhaps all Relict Gull depend on East Asian intertidal habitats in the winter period (~November-March). This assessment is somewhat contrary to BirdLife International’s (2017) assertion, that “there is also evidence that some winter inland on the northern flank of the Qinghai-Tibet plateau, China”. This assertion, unsupported by any reference in the 2017 BirdLife Factsheet for the species, appears to be based on a single record (made at exceptional altitude for the species) in 1989/1990. Even if misidentification or misreporting were not involved, incomplete documentation of that report nonetheless led Duff et al. (1991) to conclude that “we do not know whether the possibility of passage has been fully ruled out”. Notably, there appear to be few if any subsequent winter records of Relict Gull from this or any other inland area, even though large concentrations have recently been well-documented in the coastal zone (e.g. Townshend 2015). In the absence of evidence to the contrary, the Relict Gull should therefore be assessed as a species that is ecologically dependent on coastal wetlands in winter.

    Moreover, the Relict Gull is very locally distributed in winter. All reports of large (or even of medium-sized) flocks in recent years have been from the shores of the Yellow Sea, most especially at a very few sites in Tianjin and Hebei Provinces, Bohai Bay, China. The remainder (perhaps <10% of the total population?) is currently suspected to winter along the east coast of the Korean Peninsula, in the southern part of the Yellow Sea, and along the East China Sea coast. And even within favored coastal wetlands, foraging Relict Gulls are near-confined to tidal-flats with firmer sandy substrates and patches of silt or mud (typically the outer parts of estuaries) which support a high concentration of shellfish, with only a few individuals (mostly First-winters) also found on sandy beaches in bays and close to river-mouths. The species therefore tends to use only a small part of potentially available intertidal habitat.

    In Annex 1 (“Uncertainty”), the IUCN states that, “In cases where there are evident threats to a taxon through, for example, deterioration of its only known habitat, a threatened listing may be justified, even though there may be little direct information on the biological status of the taxon itself.” There is, of course, now plentiful evidence (1) of substantial loss and degradation of intertidal habitats in the Yellow Sea, leading to the conclusion that the habitat itself meets IUCN’s Endangered criteria (Murray et al. 2015); and (2) that this substantial loss and degradation of Yellow Sea intertidal habitat is a major driver of decline in many ecologically-dependent species, most especially migratory shorebirds (e.g. Studd et al. 2017). It therefore seems reasonable to assume that the extremely rapid rate of loss and degradation of Yellow Sea tidal-flats will result in substantial and rapid declines in this specialised and locally distributed gull species – especially as many of the areas preferred by the species are already undergoing or are targeted by reclamation. Indeed, even the site in Tianjin where a single flock of 10,405 (the majority of the world population) were counted in March 2015 is said to be threatened with imminent reclamation (Townshend 2015).

    Although there are perhaps too few count data available to trigger A1 (“an observed, estimated, inferred or suspected population size reduction of ≥ 50% over the last 10 years or three generations, whichever is the longer”), the Relict Gull has already decreased markedly in the Republic of Korea (ROK) in recent decades. Likely to have been overlooked until the 1990s (see Duff et al. 1991), the species appeared at the turn of this century to be regular in winter at 6-8 sites (e.g. Park 2002) – with a maximum of 185 recorded by one team of observers during survey effort along most of the west and south coasts in early 2001 (see Moores 2005). However, there has been rapid and substantial loss and degradation of intertidal habitat in the ROK, as elsewhere within the Yellow Sea and coastal China and Japan (with 60% of the 75% of historical tidal-flat area that has been lost in the ROK being reclaimed in only the past three decades: Birds Korea 2010; Moores 2012; Mackinnon et al. 2012). Reclamation has led to a substantial loss of foraging area including at Song Do, Incheon (where 143 were counted in a small area in 2001); and an estuarine dam, reclamation and increased pollution following the Four Rivers project have also affected the Nakdong Estuary, where at least 40 were counted in the 1990s, with <10 there in all recent winters. In the past five winters there have been probably 50% over three generations.

    In the wintering range, the Relict Gull remains highly threatened by habitat loss, degradation, pollution, and perhaps competition with shellfisheries. The species is also highly threatened by climate change and habitat change in the breeding areas. There is no compelling evidence of recent increase in the population. Rather, a massive recent increase in observer activity has now identified key sites for the species; and we now know that many of these sites are under threat of loss and continuing degradation. Regrettably, a massive population decline over the next three generations is now anticipated – unless the conservation of the species’ habitat is greatly improved.

    References
    Birds Korea. 2010. The Birds Korea Blueprint 2010 for the conservation of the avian biodiversity of the South Korean part of the Yellow Sea. Published by Birds Korea, Oct.2010.

    Duff, D., Bakewell, D. & M. Williams. 1991. The Relict Gull Larus relictus in China and elsewhere. Forktail 6: 43-65.

    IUCN. 2017. The IUCN Red List of Threatened Species. 2001 Categories and Criteria. Version 3.1. Accessed on June 8th 2017 at: http://www.iucnredlist.org/static/categories_criteria_3_1

    MacKinnon J., Verkuil Y. & N. Murray. 2012. IUCN situation analysis on East and Southeast Asian intertidal habitats, with particular reference to the Yellow Sea (including the Bohai Sea).

    Moores, N. 2005. Relict Gull Larus relictus: A Little Known Tidal-flat Specialist. Online article, accessed on June 6th 2017 at: http://www.birdskorea.org/Birds/Miscellaneous/BK-BM-Relict-Gull.shtml

    Moores, N. 2012. The Distribution, Abundance and Conservation of Avian Biodiversity in Yellow Sea Habitats in the Republic of Korea. University of Newcastle, Australia. Unpublished PhD thesis (in English).

    Murray, N., Ma Z. & R. Fuller. 2015. Tidal flats of the Yellow Sea: A review of ecosystem status and anthropogenic threats. Austral Ecology 40, 472–481.

    Park, J-Y. 2002. Current status and distribution of birds in Korea. Department of Biology, Kyung Hee University, Seoul (unpublished thesis, in Korean).

    Studd, C., Kendall, B., Murray, N., Wilson, H., Rogers. D., Clemens, R., Gosbell, K., Hassell, C., Jessop, R., Melville, D., Milton, D., Minton, C., Possingham, H., Riegen, A., Straw, P., Woehler, E. & R. Fuller. 2017. ARTICLE Rapid population decline in migratory shorebirds relying on Yellow Sea tidal mudflats as stopover sites. Nature Communications 8:1-7 · May 2017. Accessed June 8th at: https://www.researchgate.net/publication/316088171_ARTICLE_Rapid_population_decline_in_
    migratory_shorebirds_relying_on_Yellow_Sea_tidal_mudflats_as_stopover_sites

    Townshend, T. 10,000 Relict Gulls. Online article, accessed on June 8th at:
    https://birdingbeijing.com/2015/03/28/10000-relict-gulls/

  3. I’d just like to add the following in terms of ageing the 10,000+ birds recorded at Hangu on 26 March 2015.

    This is a quote from Paul Holt’s trip report:

    “In all we managed to find a few extra birds and the day’s total came to 10,510 in coastal Hangu, Tianjin. These involved a remarkable 10,405 at the Ba Gua Tan site & 105 on the Da Shen Tang mudflats with the vast majority of these, 95, being on the southern portion and just 10 at the middle site. Today’s count represents 87% of the known world population of Relict Gull which stands at 12,000 birds (<10,000 mature adults)(Wetlands International. 2006. Waterbird Population Estimates – Fourth Edition. Wetlands International, Wageningen, The Netherlands).

    A representative sample of the Ba Guan Tan birds (1699 individuals) were aged and this yielded 1424 adult-summers (83.8%), 111 second-summers (6.5%) and 164 first-summers (9.6%). We also saw two leg flagged individuals – one had a plain orange flag on its upper right leg while the other also sported an orange flag on its right leg that bore the white number '1'. Sadly we also saw three oiled birds – two first-summers that had small amounts of oil on their chests and a second summer that was particularly badly oiled."

    This means that the number of mature adults in the flock of 10,405 birds was around 8,719 assuming the sample aged was representative of the whole flock. As far as I know, there were no records around the same time at other locations that would have come close to bumping up the total to over 10,000 mature adults. This species must be one of the most vulnerable of all to the loss of intertidal mudflats along the Yellow Sea, given the reliance of almost the whole population on this area in winter. I have never heard of an inland wintering population before and, without stronger evidence, I am sceptical that it exists at all, especially given the extremely cold inland temperatures in China in winter. I certainly don't support the down-listing.

  4. Shuya Huang says:

    China Biodiversity Conservation and Green Development Foundation (CBCGDF) also does not support downlisting of Relict Gull.

    We have set up our “Community Conservation Area for Relic Gulls at Tianjin”. According to our knowledge, even though the count of mature Relict Gull individuals was marginally over 10,000, it doesn’t necessarily mean that this count number will be stable throughout the years. Many cases, such as catastrophic disaster, disease, unstable age structure, and inadequate food sources, will contribute to dramatically decreasing the number of individuals.

    Also, their future is not optimistic. The major breeding colonies at Taolimiao-Alashan Nur and Hongjian Nur, as well as the major wintering area at Bohai Bay, also have been facing serious declining situations due to human activities etc. Even worse, according to a 2016 news article, the National Protected Area for Relic Gulls at Ordos has died, which will pose more serious problems for this species.
    (news link: http://www.pingshanba.net/f6a1nec620161209c6n475350419.html)

  5. Andy Symes (BirdLife) says:

    Preliminary proposals

    Based on available information, our preliminary proposal for the 2017 Red List would be to list Relict Gull as VU under criterion A3 (suspected rapid future population decline).

    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.

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