Archived 2015 topics: Razorbill (Alca torda) – uplist from Least Concern to Near Threatened?

Razorbill Alca torda breeds in the temperate N Atlantic and adjacent parts of the Arctic Ocean, on both sides of the Atlantic, as far south as NW France, north as Svalbard and east to NW Russia, wintering along Atlantic coasts as far south as N Africa (Merne & Mitchell 2004). It is currently listed as Least Concern, because when last assessed it was not thought to approach the thresholds for Vulnerable under any of the IUCN Red List criteria.

Globally, it has an extremely large range in both the breeding season (>1 million km2) and in winter (>4 million km2), and hence does not approach the thresholds for Vulnerable under the range size criteria (B and D2). Its population size is also extremely large (c. 610,000–630,000 breeding pairs; Merne & Mitchell 2004), and hence does not approach the thresholds for Vulnerable under the population size criteria (C and D1). Therefore, the only potentially relevant criterion is A, which relates to reductions in population size. Until recently, the population was thought to be declining slowly, but not sufficiently rapidly to approach the threshold for listing as Vulnerable under criterion A (at least a 30% decline over ten years or three generations, whichever is longer).

New data collated from across Europe for the European Red List of Birds (BirdLife International 2015) indicate that the species has recently started to decline more steeply. A combination of official data reported by 27 EU Member States to the European Commission under Article 12 of the EU Birds Directive and comparable data from other European countries, provided by BirdLife Partners and other leading national ornithologists, suggests that the European population has declined markedly since 2005, and is currently estimated and projected to be declining overall at a rate of 25–30% over three generations (c. 41 years, based on a generation length estimated by BirdLife to be 13.6 years). Consequently, the species is now classified as Near Threatened at European level under criterion A4 (BirdLife International 2015).

Based on the latest population estimates (Merne & Mitchell 2004, Berglund & Hentati-Sundberg 2014), Europe holds c. 95% of the global population, so the projected decline in Europe is globally significant. It is driven by recent declines in Iceland, which holds >60% of both the European and global population. There have been two comprehensive surveys of this species in Iceland – the first during 1983-86 (Gardarsson 1995), yielding 378,000 pairs, and the second during 2005-2009 (Gardarsson et al. in press), yielding 313,000 pairs, which suggests a decline of 18% over c. 22 years. However, limited monitoring of a subset of colonies every five years between 1985 and 2005 suggests that the species was stable until 2005, and may only have started to decline since 2005, implying a much steeper rate of decline. This is supported by additional data from Látrabjarg, the largest colony of this species in the world, which declined by 45% in just three years, from 160,000 pairs in 2006 to 89,000 pairs in 2009 (G. Gudmundsson in litt. 2015).

Gardarsson et al. (in press) note that these declines occurred around the same time that the population of sandeels crashed around Iceland. The sandeel is a key species for many seabird species as a food source for raising young, especially in S and W Iceland, and populations of other auks have also declined in concert.

Given the importance of Iceland for this species, and the link between reduced food supply and population decline, which might be exacerbated by regime shift under climate change, it is legitimate to extrapolate recent trends and project a global decline of at least 25–30% over three generations. Therefore, this species appears to qualify for uplisting to globally Near Threatened under criterion A4.

Comments on this proposal are welcome, along with any data regarding recent trends in other regions, and any additional information about the threats currently affecting this species across its range.

References

Berglund, P. A. & Hentati-Sundberg, J. (2014). Arctic Seabirds Breeding in the African-Eurasian Waterbird Agreement (AEWA) Area: Status and Trends 2014. AEWA Conservation Status Report (CSR6) background report. http://www.wetlands.org/Portals/0/PAB%20AEWA%20report%20review%202014.pdf

BirdLife International (2015) European Red List of Birds. Luxembourg: Office for Official Publications of the European Communities. http://www.birdlife.org/datazone/info/euroredlist

Gardarsson, A. (1995). Number and distribution of Common Murre Uria aalge, Thick-billed Murre U. lomvia and Razorbill Alca torda in Iceland. Bliki 16: 47-65. (In Icelandic with an English summary).

Gardarsson, A., Gudmundsson, G.A. & Lilliendahl, K. (in press). The numbers of large auks on the cliffs of Iceland in 2006-2008. Bliki 33. (In Icelandic with an English summary).

Merne, O.J. & Mitchell, P.I. (2004) Razorbill Alca torda. In: Mitchell, P. I., Newton, S. F., Ratcliffe, N. & Dunn, T. E. (eds.) Seabird populations of Britain and Ireland. Poyser, London.

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3 Responses to Archived 2015 topics: Razorbill (Alca torda) – uplist from Least Concern to Near Threatened?

  1. W.R.P. Bourne says:

    It is not certain Razorbills among other seabirds are entirely dependant on sandeels (Marine Pollution Bulletin 13:270-273). A decline of Razorbills in Iceland could be a reflection of the situation where it disperses, where there may be a general decline of small fish available to seabirds due to the recovery of the large fish that also eat them from over-exploitation (“ Seabird fluctuations”. Sea Swallow 62:16.).

  2. Andy Symes (BirdLife) says:

    Preliminary proposals

    Based on available information, our preliminary proposal for the 2015 Red List would be to treat:

    Razorbill as Near Threatened under criterion A4.

    There is now a period for further comments until the final deadline of 31 August, after which the recommended categorisation will be put forward to IUCN.

    The final Red List categories will be published on the BirdLife website in late October and on the IUCN website in November, following further checking of information relevant to the assessments by both BirdLife and IUCN.

  3. Andy Symes (BirdLife) says:

    Recommended categorisation to be put forward to IUCN

    Following further review, there have been no changes to our preliminary proposal for the 2015 Red List status of this species.

    The final categorisation will be published on the BirdLife website in late October and on the IUCN website in November, following further checking of information relevant to the assessment by BirdLife and IUCN.

Comments are closed.