Initial deadline for comments: 31 January 2012.
Yelkouan Shearwater Puffinus yelkouan is endemic to the Mediterranean basin, from Corsica and Sardinia through the central Mediterranean, the Adriatic and the Aegean, with the main breeding colonies concentrated in the central and eastern basins (Borg et al. 2010). The species is known to breed in France, Italy, Malta, Algeria, Tunisia, Croatia, Albania, Greece and Bulgaria. Breeding is assumed in Turkey on offshore islands or mainland cliffs in the Aegean and Mediterranean, but there are very few data on this. A small population may also breed on the eastern Balearic Islands in Spain (Menorca), although the existence of the species here is somewhat controversial, given the taxonomic uncertainty of the birds breeding there.
It is currently listed as Near Threatened under criterion A4b,c,d,e, because when last assessed (in 2010) reports of extremely low breeding success at several key breeding colonies indicated that current declines may accelerate markedly when current breeders approach the end of their life cycle, and may be moderately rapid over three generations. Declines have probably been on-going for many years, and have been projected to continue (Bourgeois and Vidal 2008).
A recent population assessment for the species has estimated the global population size at 15,337-30,519 pairs /46,000-92,000 individuals (Derhé in prep.). The global breeding population for Yelkouan Shearwater was previously estimated at 10,815-53,574 pairs (BirdLife International 2010), although other figures pointed more to a total of 14,700-52,000 pairs (Tucker and Heath 1994) or 100,000 individuals.
There are reports of extremely low breeding success at several important colonies, particularly in Italy (e.g. 0% breeding success on Molara [where rats are present] and 23% on Tavolara [where rats are not present everywhere]; Baccetti et al. 2009). Low breeding success suffered at key colonies could result in an extinction lag and could potentially lead to rapid future population declines.
A lack of data on key sites combined with the absence of long-term regular monitoring at the major breeding colonies (in Italy and Greece) means that it is difficult to determine a global population trend for the species. However, there is evidence of both recent and historical colony extinctions, with nine colonies (comprising around 300-400 breeding pairs) having been reported extinct in the last 60 years (Bourgeois and Vidal 2008). Since 2009, one breeding colony off the south-west corner of Sardinia (San Pietro Island) has been reported as absent, possibly extinct (N. Baccetti in litt.; originally recorded by Schenk and Torre  as numbering 500 pairs).
The trends of populations in Albania, Algeria, Bulgaria, Turkey and Tunisia are currently unknown, but declines are suspected in Croatia (for at least one colony [I. Budinski in litt.]) and Greece (based on long-term trends [J. Fric in litt.]). It has been reported that the species is declining in Italy by 10-50% over 13 years (N. Baccetti in litt.), in France by 6% per year (Oppel et al. 2011) and in Malta by 0-15% over 9 years (Borg and Sultana 2002, Raine et al. 2009, Sultana et al. 2011). In total, these three countries represent around three-quarters of the global population. By combining data for these three countries (see attached spreadsheet) it is predicted that, if the species continues to decline at the current reported rate, the global breeding population will decrease by more than 50% in the next 54 years, i.e. three generations. This projected decline is steeper than that reported by Bourgeois and Vidal (2008) who, on the basis of the data available on population extinctions and declines from the western Mediterranean, estimated that the breeding population may have declined by 12–15% over the past 60 years, which would equate to a decline of c.11–13% over three generations (54 years). However, the authors suggest that the number of birds at sea may have decreased by c.50% over the last 40 years, based on sightings of individuals in marine areas where the species concentrates, which corresponds with the projected population trend estimated here.
Low adult survival has been reported for the species, with adult survival probabilities for breeding Yelkouan Shearwaters across the western Mediterranean currently being too low to maintain stable populations (Oppel et al. 2011). Annual survival probabilities of below 0.9 for French and Maltese colonies were reported between 1969–1994 and 2004–2010, and survival probabilities for non-breeders (0.95, 0.81–1.0) appeared to be higher than for breeders (0.82, 0.70–0.94), but were imprecise partly due to low recapture probabilities (Oppel et al. 2011). It is suspected that immigration of birds may explain why some of these populations have not yet exhibited declines (Bonnaud et al. 2009, 2010). Low adult survival probabilities are likely to be a result of human disturbances, including fisheries bycatch, light pollution and illegal shooting, as well as predation by invasive species (Derhé in prep.).
To explore the impact of uncertainty on the overall trend and category, a number of alternative scenarios were also explored (see attached spreadsheet). When the trend assessments were re-run, only the most optimistic scenarios altered the potential Red List category (from Endangered to Vulnerable or Near Threatened), i.e. assuming Italy is experiencing the minimum decline rate and countries with unknown trends are stable.
This suggests that the species’s global status ought to be revised to Vulnerable under criterion A4b,c,d,e, as it is projected to suffer a rapid population reduction (30-49% decline over three generations). Comments on this proposal and any relevant information (particularly including trend information for additional countries) are invited.
Spreadsheet for reference: Calculating rates of change for Yelkouan Shearwater
Baccetti, N., Capizzi, D., Corbi, F., Massa, B., Nissardi, S., Spano G. and Sposimo, P. (2009) Breeding shearwaters on Italian islands: Population size, island selection and co-existence with their main alien predator, the black rat. Riv. Ital. Orn. 78: 83-100.
BirdLife International (2010) Species factsheet: Puffinus yelkouan. Downloaded from http://www.birdlife.org on 22/11/2011.
Bonnaud, E., Bourgeois, K., Vidal, E., Legrand, J. and Le Corre, M. (2009) How can the Yelkouan shearwater survive feral cat predation? A meta-population structure as a solution? Population Ecology 51: 261–270.
Bonnaud, E., Zarzoso-Lacoste, D., Bourgeois, K., Ruffino, L., Legrand, J. and Vidal, E. (2010) Top-predator control on islands boosts endemic prey but not mesopredator. Animal Conservation 13: 556–567.
Borg, J. J., Raine, H., Raine, A. F. and Barbara, N. (2010) Protecting Malta’s wind chaser: The EU LIFE Yelkouan Shearwater Project Report. Malta: EU LIFE Yelkouan Shearwater Project.
Borg, J. J. and Sultana, J. (2002) Status and distribution of the Breeding Procellariiformes in Malta. Il-Merill 30: 10–15.
Bourgeois, K. and Vidal, E. (2008) The endemic Mediterranean Yelkouan Shearwater Puffinus yelkouan: distribution, threats and a plea for more data. Oryx 42: 187-194.
Derhé, M. A. (in prep.) Population assessment for the Yelkouan Shearwater Puffinus yelkouan. Cambridge, UK: BirdLife International for the European Commission.
Oppel, S., Raine, A. F., Borg, J. J., Raine, H., Bonnaud E., Bourgeois, K. and Breton, A. R. (2011) Is the Yelkouan shearwater Puffinus yelkouan threatened by low adult survival probabilities? Biological Conservation 144: 2255-2263.
Raine, A., Sultana, J. and Gillings, S. (2009) Malta Breeding Bird Atlas 2008. Malta: BirdLife Malta.
Schenk, H. and Torre, A. (1986) Breeding distribution, numbers and conservation of seabirds in Sardinia, 1978-85. Pp. 449–463 in MEDMARAVIS and Monbailliu, X. (Eds) Mediterranean Marine Avifauna: Population Studies and Conservation. Munich, Germany: NATO ASI Series, Vol. G 12.
Sultana, J., Borg, J. J., Gauci, C. and Falzon, V. (2011) The Breeding Birds of Malta. Malta: BirdLife Malta.
Tucker, G. M. and Heath, M. F. (1994) Birds in Europe: their conservation status. BirdLife International Conservation Series no. 3. Cambridge, UK: BirdLife International.