This discussion was first published as part of the 2018 Red List update. At the time a decision regarding its status was made to uplist the species to Near Threatened, but to enable potential further reassessment of this species as part of the 2019 Red List update this post remained open and the date of posting has been updated.
Spectacled Eider (Somateria fischeri) is a migratory duck from Russia and Alaska (U.S.A.). It is considered to be made up of three main breeding subpopulations, found around the Yukon-Kuskokwim Delta (Alaska), in Arctic Alaska and along the Arctic coast of eastern Siberia (Sea Duck Joint Venture 2016, D. Solovyeva in litt. 2018). While it spends the breeding season in these areas associated with Arctic and subarctic tundra, lakes, pools and streams (see Carboneras and Kirwan 2018), it is thought that most if not all of the global population comes together in flocks during the non-breeding season in the Bering Sea just south of St. Lawrence Island, Alaska (Larned et al. 2012, D. Solovyeva in litt. 2018).
It had been thought that the Russian and Alaskan populations were of a roughly similar size, with the Yukon-Kuskokwim Delta holding on average 50,000 pairs (see Dau and Kistchinski 1977), however, the population there underwent a massive crash in the late 20th Century, such that by 1992 only 1,721 pairs remained (Stehn et al. 1993). The population in this area has since slightly recovered and potentially stabilised (Sea Duck Joint Venture 2016, Fischer et al. 2017, Swaim 2017), but it is now considered that Russia holds 90% of the breeding population (Warnock 2017, D. Solovyeva in litt. 2018).
In Arctic Alaska the population is not thought to have undergone such severe declines, and clear data about population trends were lacking due to the timing of surveys potentially missing many individuals who leave the breeding grounds early (Stehn et al. 2013). However, more recent surveys have shown the species to potentially be declining there, though these declines appear to be very slight, and not statistically significant (Stehn et al. 2013). There has not been as much survey work conducted throughout the Russian population and so trends have been difficult to determine there. However, recent surveys from Ayopechan Island have shown the population there to be decreasing rapidly (Solovyeva et al. 2017b).
The reasons behind the historical and potential current declines are varied, and still carry some uncertainty over the impact of each. It is thought that predation and hunting can impact the species on breeding grounds (Grand et al. 1998, Flint et al. 2000). For instance, lead shot may have particularly impacted the species in Alaska prior to its banning for wildfowl hunting in 1991 (Flint and Schamber 2010), yet there is now no evidence that lead concentrations at different sites have any impact on survival (Solovyeva et al. 2017a).
Changes in the species community composition may be also having an effect, with a decline in Sabine’s Gull (Xema sabini) and Arctic Tern (Sterna paradisea) (which provide nest protection) and an increase in mammalian predators and Vega Gull (Larus smithsonianus vegae) potentially leading to reduced breeding success (see Solovyeva and Zelenskaya 2016, Solovyeva et al. 2017b). It is possible that these community changes are a result of climate change (D. Solovyeva in litt. 2018).
The greatest effect that climate change may be having on the species is by affecting its wintering habitat, and it is thought that population trends in this species may be being driven by factors in the wintering range (Solovyeva et al. 2017a). Alterations to sea ice distribution can cause habitat shifts that prevent the species from reaching their preferred foraging locations and prey, and this has occurred in almost one third of winters between 1998 and 2011 (Lovvorn et al. 2014). This leads to prey switching and consequently adult body fat can be about a third lower in these years than when these areas have been accessible (Lovvorn et al. 2014). This could therefore be having a major impact on the species.
Given the new information from Russia regarding worrying population trends, we have therefore, re-assessed the species here against all criteria.
Criterion A – As explained above, the population in the Yukon-Kuskokwim Delta declined rapidly but has since recovered and stabilised. There have been non-significant declines in Arctic Alaska, and there have been rapid declines at one site in Russia. There is currently no information regarding population trends from the rest of its Russian range; and this remains a large knowledge gap as Russia contains 90% of the global population (Warnock 2017, D. Solovyeva in litt. 2018).
The time period over which an assessment against Criterion A must be conducted is 3 generations or 10 years, whichever is longest. For this species that would be 3 generations – 25.8 years. Therefore, for past declines, we would have to look at the period after 1992, and so the rapid declines in the Yukon-Kuskokwim Delta population would not be included. Instead, we have seen an increase in this population and a non-significant decline in the other Alaskan population.
If Ayopechan Island is representative for the whole of the Russian range then the overall population trend could be a rapid decline. Declines there have been at a rate of 8% per annum between 2009 and 2016 (Solovyeva et al. 2017b), which could mean that the overall population trend in the past 3 generations was a decline c.39.5% (assuming that overall the other populations are stable, and the population in Russia returned to stability after 2016).
If this is brought forward to look at potential current, ongoing trends, it could be that the species is undergoing a decline that could end up as high as c.79% over 3 generations over the period 2009-2035 (assuming stable Alaskan populations, and declines continue at the same rate in Russia).
However, this does depend on the assumption that trends on Ayopechan Island are representative of the entire of the Russian range, which contains the vast majority of the global population. The main threats to the Ayopechan Island site may not be restricted to just this area, as the spread of Vega Gulls appears to be naturally occurring rather than a site-specific anthropogenic impact (D. Solovyeva in litt. 2018), and so it is possible that the species may be undergoing rapid global declines. Additionally, (and potentially more significantly) Solovyeva et al. (2017a) provide evidence that overall population trends may depend more on conditions at the over-wintering area rather than breeding-site-specific threats. Thus, it is plausible that these trends could be affecting the whole of the Russian population.
However, it still does remain a large inference to assume such massive range-wide declines based on the evidence from one site. Yet without such inference it is currently near impossible to accurately quantify the rate of population decrease, and so assess the species against Criterion A.
Surveys of the wintering flocks in the Bering Sea are planned for March 2019 (K. Martin in litt. 2018), the first since 2009-2010, and these will likely be the best avenue to get a quantification of the overall population trend, as it is thought that the entire global population may over-winter in this area. Therefore, at the moment, it is very difficult to accurately assess the species against this criterion. Even though there is enough evidence to suggest that the species likely warrants a change in Red List category, it is currently difficult to ascertain which category it would warrant uplisting to. Planned future surveys may allow us to get a clearer picture of the species’s status.
Criterion B – The species’s range is far too large to warrant listing under this criterion.
Criterion C – The most recent population estimate based on aerial surveys of winter flocks in the Bering Sea is 369,122 individuals in 2010 (Larned et al. 2012). Therefore, the population size is likely far too large to warrant listing under this criterion.
Criterion D – The species’s population size and range are far too large to warrant listing under this criterion.
Criterion E – To the best of our knowledge, there has been no quantitative analysis of extinction risk carried out for this species. Therefore, it cannot be assessed against this criterion.
The species may therefore warrant uplisting to at least Near Threatened under criterion A if the global population is suspected to be undergoing a moderately rapid population decline over three generations, but the likely rate of this decline, and therefore the appropriate Red List Category under criterion A, are highly uncertain. If the trends reported from a small part of the Russian range are representative for the population there as a whole then Spectacled Eider may warrant uplisting to one of the Threatened categories, but we cannot be confident of this given that data only comes from one site. Fortunately, there is planned a new survey of the non-breeding population in the Bering Sea, which likely represents the vast majority of the global population. Data from this survey would then give a clearer view of the population trend for the species as a whole. A final decision regarding the Red List status of this species may need to wait until the results of this survey are available, but we welcome any further comment in the meantime.
Please note that this topic is not designed to be a general discussion about the ecology of the species, rather a discussion of the species’ Red List status. Therefore, please make sure your comments are relevant to the discussion outlined in the topic.
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