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Balearic Shearwater Puffinus mauretanicus
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This species has a tiny breeding range and a small population which is undergoing an extremely rapid population decline owing to a number of threats, in particular predation at breeding colonies by introduced mammals and at-sea mortality as a result of fisheries by-catch. Population models predict an extremely rapid decline over three generations (54 years), qualifying the species as Critically Endangered. However, this assumption was based on the existence of a population of c. 2,000 breeding pairs, which could have been underestimated according to recent population estimates and records at sea, plus a recent re-evaluation of some colonies (i.e. increased accuracy in the estimates). Updated population viability analysis to re-evaluate the species's status is planned, incorporating recent population estimates and improved demographic data. Should this analysis reveal that the species is declining at a more moderate rate, this species will warrant downlisting.

Taxonomic source(s)
AERC TAC. 2003. AERC TAC Checklist of bird taxa occurring in Western Palearctic region, 15th Draft. Available at: # _the_WP15.xls#.
Brooke, M. de L. 2004. Albatrosses and Petrels Across the World. Oxford University Press, Oxford.
del Hoyo, J.; Collar, N. J.; Christie, D. A.; Elliott, A.; Fishpool, L. D. C. 2014. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Barcelona, Spain and Cambridge UK: Lynx Edicions and BirdLife International.

33 cm. Medium-sized, rather dark shearwater. Upperparts dark brown contrasting slightly with the dirty, variably marked brown-whitish underparts. Most individuals show dusky undertail coverts and armpits. Similar spp. Easily told from Manx Shearwater P. puffinus by lack of strong contrast between upperparts and underparts. Dark individuals could be mistaken for Sooty Shearwater P. griseus but always show a white belly patch and lack the scythe-like wings and heavier flight of that species.

Distribution and population
Puffinus mauretanicus breeds in the Balearic Islands, Spain. In 2009, the breeding population of the Balearic Shearwater was last estimated in 2009 at 3,193 breeding pairs (Arcos 2011a). This figure is significantly larger than previous estimates of 2,000-2,400 pairs recorded in 2005 (Jones et al. 2008) but this is primarily due to increased survey effort (better prospecting of known breeding sites plus discovery of new sites) and does not reflect a genuine increase of the population. The islands of Mallorca have 900 pairs; Cabrera 449 pairs; Menorca 405 pairs; Ibiza 747 pairs and Formentera 692 pairs (Arcos 2011a). The world population was until recently believed to number 8,000-10,000 individuals (Louzao 2006a, Wynn and Yésou 2007), however recent winter at-sea surveys and counts from Gibraltar of post-breeding birds leaving the Mediterranean suggest the total population may in fact lie within in the range 20,000-30,000 individuals (Arcos 2011b). This is supported by a count of at least 16,400 individuals off Valencia in December 2009 (Aleixos 2012). Reasons for the discrepancy between breeding and non-breeding population estimates are unclear, but it is most likely that this species has a particularly large floating population of immatures and non-breeders.

On Cabrera Island, 60% of the colonies have disappeared in the last few decades, while colonies on Formentera have experienced a strong decline in recent years, from more than 1,500 breeding pairs in the early 1990s to less than 1000 pairs in 2001 (Ruiz & Martí 2004) and 692 pairs in 2003-2006 (Arcos 2011a). Population viability analysis has shown that in the presence of environmental and demographic stochasticities, mean extinction time for the world population was estimated at 40.4 years, and mean growth rate showed a 7.4% decrease each year (Oro et al. 2004). However, this model was run using the earlier population estimate of c. 2,000 breeding pairs and so new analysis of extinction risk using the updated population estimate and improved demographic data is required. In winter, it occurs in the Balearic Sea and off the north-east Spanish coast with most of the population traditionally concentrated between Valencia and Catalonia from November to February, although recent data suggest that some birds remain in the Atlantic. For instance, in winter 2007/2008 significant numbers (with a peak count of 710 birds) remained off the coast of Brittany (France), perhaps in response to unusual sea surface temperatures (Plestan et al. 2009). Some birds migrate north in summer to seas off the British Isles and the south of the Scandinavian Peninsula (Wynn et al. 2007). Numbers recorded in the traditional post-breeding quarters have declined since the mid-1990, with a corresponding increase in numbers along the coasts of northern France and south-west U.K (Wynn and Yésou 2007, Wynn et al. 2007) (including an exceptional gathering of 4,600 in the Baie de Lannion, Brittany in August 2010) (D. Andrews in litt. 2010).

Population justification
The breeding population was last estimated in 2009 at 3,193 breeding pairs (CMA 2010). However, winter at-sea surveys along the Iberian Shelf as part of the LIFE project to identify marine Important Bird Areas produced an estimate of 25,000-30,000 individuals (Arcos 2011b), and counts of >18,000 birds past Gibraltar in May-July 2008 were extrapolated to a total of 20,000-25,000 individuals (Arroyo et al. 2011). These data are difficult to reconcile, but a precautionary estimate of 9,000-13,000 mature individuals is considered appropriate (Arcos 2011b, Arcos et al. 2011). This is roughly equivalent to 13,000-20,000 individuals in total.

Trend justification
Using the previous population estimate of 2,000-2,400 breeding pairs, Oro et al. (2004) estimate a mean decline of 7.4% per year and a mean extinction time, as estimated by population viability analysis, of just over 40 years. This equates to an ongoing population decline of more than 80% in three generations (54 years). However, an updated population viability analysis is necessary to re-evaluate the population trend, taking into account the new population estimate and improved demographic data (particularly adult survivability estimates). While the new information on population size could smooth the decreasing trend, adult survival could be even lower than assumed by Oro et al. (2004), given that their analysis did not take into account colonies subject to predation (Arcos 2011a).

It breeds on cliffs and small islets, is very philopatric, and lays only one egg. Adult birds do not commence breeding until their third year (Oro et al. 2004). Breeding takes place between February and June (Ruiz & Martí 2004). When raising young, adult birds form concentrations on the east coast of Spain (Arcos and Oro 2002), where they mostly inhabit the productive continental shelf and associated fronts where high prey concentrations occur around the Ebro Delta (Louzao et al. 2006b). Most birds leave the Mediterranean for a post-breeding moult in the Atlantic coast of southwest Europe, mainly Portugal, northwest Spain and the Bay of Biscay (Ruiz and Martí 2004, Ramírez et al. 2008, Arcos et al. 2009).

This is a long-lived species and therefore immediate threats affect adult mortality rates. Adult survival is the main conservation concern, as this is unusually low for a Procellariiform (Oro et al. 2004). In accordance, the main threats identified are predation by introduced carnivores such as cats, martens and genets in the breeding colonies (Arcos and Oro 2004, Ruiz and Martí 2004, Jones et al. 2008, Arcos 2011a), and fisheries by-catch at sea (Arcos 2011a). The species's gregarious behaviour and its close association with fishing boats means that occasional "mass mortality" is likely to occur when long-line boats fish close to flocks (Arcos et al. 2008), and it appears that bycatch is fairly common but often occurs on an irregular basis, suggesting that estimates derived from observations on a limited number of trips onboard fishing vessels could be largely underestimated (Boue et al. 2013). Increasing evidence on this has been compiled in the last few years, with events of up to a hundred or more birds caught in a single event, in occasions involving other fishing gear such as purse-seiners (ICES 2008, Louzao et al. 2011).

Also due to the congregatory behaviour of the species, acute pollution events, such as oil spills, also pose a very serious threat, as a large number of casualties could result from a spill occurring in a congregation area (Ruiz and Martí 2004, Gutiérrez 2011). Other threats include: the reduction of prey due to fishing overexploitation; a potential reduction in fishing discards (an alternative to the overexploited natural prey) and/or anthropogenic environmental change (Arcos 2011a); habitat degradation and disturbance in the breeding grounds; background pollution (Oro et al. 2008); the development of marine windfarms (Arcos 2011a); and human harvesting (nowadays a relict activity). Predation by Peregrine Falcons in the breeding colonies has also been recently reported (García 2009, Wynn et al. 2010), though this should be considered as a factor of natural mortality that likely has little influence on the decline of the species. The gradual northward movement of the non-breeding population may be affecting adult survival, and this shift may be due to climate change or alterations in fish distributions as a result of fisheries' activities (Yésou 2003, Wynn and Yésou 2007). The recent demographic decline has not yet decreased the species's genetic variability, and connectivity found among colonies at least does not exacerbate the species's extinction risk (Genovart et al. 2007).

Conservation Actions Underway
All breeding sites are currently protected as Special Protection Areas (SPAs) under the Natura 2000 network, with the unique exception of the colony of Punta Prima in Formentera, where new information has revealed that the prevailing colony (50 pp.) lays right outside the SPA (and the overlapping Important Bird Area, IBA) designated for this species. However, the management plans for the Balearic SPAs have not been yet implemented. Management plans are therefore limited to colonies covered by other figures of protection, such as the National Park of Cabrera and the Natural Park of Sa Dragonera. Rat eradication campaigns have been conducted at several colonies, including Cabrera archipelago and Dragonera Island, but less effort has been directed at the most concerning colonies where carnivores are present (e.g. Formentera and Menorca). At sea, the Spanish Government has started the process of SPA designation based on the inventory of marine IBAs conducted by SEO/BirdLife, which, once concluded, will provide protection to the main hotspots for the species in Spanish waters. So far, only a few small coastal sites have been designated as SPAs by the regional governments in Spain. Portugal already has an inventory of marine IBAs, but their designation as SPAs is still pending. Finally, France has also proposed a network of SPAs that include hotspots for the species. Management plans for all the marine SPAs are still pending.

Action Plans for the species have been published at local, national or international level in 1991, 1999, 2004, and 2005 (Jones et al. 2008). A LIFE project for the species ran from 1991-2001 (Ruiz and Martí 2004), and Spain and Portugal had a joint LIFE project running from 2004-2008 aimed at identifying marine IBAs, including for this species (Ramírez et al. 2008, Arcos et al. 2009). A number of actions are currently being implemented through Species Guardians SEO/BirdLife and SPEA as part of BirdLife's Preventing Extinctions programme. Moreover, research on the species is also being conducted by BirdLife partners in collaboration with several research centres, with funding from EC projects LIFE+ INDEMARES (Spain) and Interreg FAME (Portugal, Spain, France, UK and Ireland). Main initiatives include the assessment of bycatch through questionnaires to fishermen, observers on board fishing vessels and conducting of beached bird surveys; and the identification of hotspots at sea through boat surveys, coastal counts and tracking studies (breeding and non-breeding grounds).

Conservation Actions Proposed

Control and eradicate introduced predators (with particular emphasis on carnivores) in breeding colonies identified to be at risk. Thoroughly study the problem of bycatch by long-line fishing and develop awareness campaigns directed at the fishing sector, in order to mitigate this threat, plus assess and implement the appropriate mitigation measures. Ensure effective protection for nesting sites and marine hotspots, and the implementation of monitoring schemes and management plans. Develop a rapid response plan for a potential oil spill close to main feeding and breeding areas. Raise awareness and stop human exploitation. Study small pelagic fish populations in the western Mediterranean and in the Bay of Biscay to assess extent of over-exploitation and how this affects Balearic Shearwaters. Assess the impact of pollutants and heavy metals on this species. Improve understanding of at-sea distribution, including during the non-breeding season.

Related state of the world's birds case studies

Aguilar, J. S. 1999. Species Action Plan for the Balearic Shearwater Puffinus mauretanicus in Europe.

Aleixos, L. 2012. Observación de una excepcional concentración invernal de Pardelas baleares (Puffinus mauretanicus) mediante censo desde la costa en Cullera (Valencia). El Serenet-Revista de la Societat Valenciana d’Ornitologia.

Arcos, J. M. 2011. ¿Cuantas pardelas baleares hay? Discrepancias entre los censos en colonias y en el mar. In: Valeiras, X., Muoz, G., Bermejo, A., Arcos, J.M. y Paterson, A.M. (ed.), Actas del 6 Congreso del GIAM y el Taller internacional sobre la Ecologã­a de Paios y Pardelas en el sur de Europa, pp. 117-121. Boletã­n del Grupo Ibã©rico de Aves Marinas.

Arcos, J. M.; Louzao, M.; Oro, D. 2008. Fishery ccosystem impacts and management in the Mediterranean: seabirds point of view. In: Nielsen, J.; Dodson, J.; Friedland, K.; Hamon, T.; Hughes, N.; Musick, J.; Verspoor, E. (ed.), Proceedings of the Fourth World Fisheries Congress: Reconciling Fisheries with Conservation, pp. 587-596. American Fisheries Society, Symposium 49, Bethesda, MD, USA.

Arcos, J. M.; Oro, D. 2002. Significance of fisheries discards for a threatened Mediterranean seabird, the Balearic Shearwater Puffinus mauretanicus. Marine Ecology Progress Series 239: 209-220.

Arcos, J.M. (compiler). 2011. International species action plan for the Balearic shearwater, Puffinus mauretanicus. SEO/BirdLife & BirdLife International.

Arcos, J.M. & Oro, D. 2004. Pardela balear, Puffinus mauretanicus. In: Madroño, A., González, C. & Atienza, J.C (ed.), Libro Rojo de las Aves de España, pp. 46-50. Dirección General para la Biodiversidad - SEO/BirdLife, Madrid.

Arcos, J.M., Bécares, J., Rodríguez, B. and Ruiz, A. 2009. Áreas Importantes para la Conservación de las Aves marinas en España. LIFE04NAT/ES/000049 . Sociedad Española de Ornitología (SEO/BirdLife), Madrid.

Arcos, J.M., Bécares, J., Rodríguez, B., Ruiz, A. & Oro, D. 2011. How many Balearic shearwaters are out there? Discrepancies between breeding and at sea estimates. Presentation at the 13th MEDMARAVIS Pan-Mediterranean Symposium, Alghero, Sardinia. 14 - 17 October 2011..

Arroyo, G.M., Mateos, M., Muoz, A.R., de la Cruz, A., Cuenca, A.D. y Onrubia, A. 2011. New population estimates of the critically endangered Balearic Shearwater Puffinus mauretanicus. Poster at 13th MEDMARAVIS Pan-Mediterranean Symposium, Alghero, Sardinia. 14 - 17 October de 2011.

Boue, A., Louzao, M., Arcos, J.M., Delord, K., Weimerskirch, H., Cortes, V., Barros, N., Guilford, T., Arroyo, G.M., Oro, D., Andrade, J., Garcia, D., Dalloyau, S., Gonzalez-Solis, J., Newton, S., Wynn, R. and Micol, T. 2013. First Meeting of the Population and Conservation Status Working Group. Recent and current research on Balearic shearwater on colonies and in Atlantic and Mediterranean areas. Agreement on the Conservation of Albatrosses and Petrels, La Rochelle, France.

García, D. 2009. Predation on the endemic Balearic Shearwater Puffinus mauretanicus by Peregrine Falcon Falco peregrinus. Alauda 3: 230-231.

Genovart, M.; Oro, D.; Juste, J.; Bertorelle, G. 2007. What genetics tell us about the conservation of the critically endangered Balearic Shearwater. Biological Conservation 137(2): 283-293.

Gutiérrez, R. 2003. The Balearic Shearwater: apparently heading for extinction. Birding World 16: 260-263.

Gutiérrez, R. 2011. Un vertido de petróleo amenaza el delta del Ebro. Aves y naturaleza: 37.

ICES. 2008. Report of the Working Group on Seabird Ecology (WGSE). ICES CM 2008/LRC:05. Lisbon, Portugal.

Igual, J.M.; Afan, I.; Santana, C.; Oro, D. 2004. Confirmación de cría de la Pardela Balear Puffinus mauretanicus en el islote de Es Bosc, Parque Natural de Cala d'Hort, Ibiza. Anuari Ornitologic de les Balears 19: 11-13.

Jones, H.P., Tershy, B.R., Zavaleta, E.S., Croll, D.A., Keitt, B.S., Finkelstein, M.E. and Howald, G.R. 2008. Severity of the effects of invasive rats on seabirds: a global review. Conservation Biology 22(1): 16-26.

Louzao, M. 2006. Conservation biology of the critically endangered Balearic Shearwater Puffinus mauretanicus: bridging the gaps between breeding colonies and marine foraging grounds. PhD.

Louzao, M., Arcos, J. M., Laneria, K., Beldae, E., Guallartf, J., Sánchez, A., Giménez, M., Maestre, R. and Oro, D. 2011. ["Evidence of the incidental capture of the Balearic Shearwater at sea"]. Proceedings of the 6 CONGRESS of GIAM and the International workshop on petrels and shearwaters ecology at southern Europe. 34: 165-168.

Louzao, M., Hyrenbach, D., Arcos, J.M., Abelló, P., Gil de Sola, L. & Oro, D. 2006. Oceanographic habitat of a critically endangered Mediterranean Procellariiform: implications for the design of Marine Protected Areas. Ecological Applications 16(5): 1683-1695.

Louzao, M.; Arcos, J. M.; Oro, D. 2006. Biologia de la conservació d'un ocell críticament amenaçat: la Baldrijta Puffinus mauretanicus. Anuari Ornitologic de les Balears 21: 43-49.

Mourino, J.; Arcos, F.; Salvadores, R.; Sandoval, A.; Vidal, C. 2003. Status of the Balearic Shearwater (Puffinus mauretanicus) on the Galician coast (NW Iberian peninsula). Scientia Marina 67: 135-142.

Oro, D., Louzao, M., Forero, M.G., Arcos, J.M., Genovart, M., Juste, J. & Igual, J.M. 2008. Investigaciones aplicadas a la conservación de una especie en peligro de extinción (la Pardela Balear en el Parque Nacional de Cabrera): Requerimientos ecológicos, demografía y dinámica de poblaciones. Proyectos de Investigación en Parques Nacionales: 2003-2006. Ministerio de Medio Ambiente, Madrid.

Oro, D.; Aguilar, J. S.; Igual, J. M.; Louzao, M. 2004. Modelling demography and extinction risk in the endangered Balearic shearwater. Biological Conservation 116: 93-102.

Ramírez, I.; Geraldes, P.; Meirinho, A.; Amorim, P.; Paiva, V. 2008. Important Bird Areas for seabirds in Portugal. Sociedade Portuguesa Para o Estudo das Aves, Lisbon.

Rodríguez, A.; McMinn, M. 2007. Gestión de un endemismo en peligro: la Pardela Balear, Puffinus mauretanicus. Anuari Ornitologic de les Balears 22: 77-80.

Ruiz, A.; Martí, R. 2004. La Pardelar balear. SEO/BirdLife, Madrid.

Wynn, R. B.; Josey, S. A.; Martin, A. P.; Johns, D. G.; Yésou, P. 2007. Climate-driven range expansion of a critically endangered top predator in northeast Atlantic waters. Biology Letters 3(5): 529-532.

Wynn, R. B.; McMinn-Grivé, M.; Rodriguez-Molina, A. 2010. The predation of Balearic Shearwaters by Peregrine Falcons. British Birds 103(6): 350-353.

Wynn, R. B.; Yésou, P. undated. Changing status of the Balearic Shearwater (Puffinus mauretanicus) in northwestern European waters.

Yesou, P. 2003. Recent changes in the summer distribution of Balearic Shearwaters (Puffinus mauretanicus) off western France. Scientia Marina 67: 143-148.

Further web sources of information
Detailed regional assessment and species account from the European Red List of Birds (BirdLife International, 2015)

Detailed species account from Birds in Europe: population estimates, trends and conservation status (BirdLife International 2004)

European Union Species Action Plan

Explore HBW Alive for further information on this species

Search for photos and videos, and hear sounds of this species from the Internet Bird Collection

Species Guardian Action Update

Text account compilers
Benstead, P., Bird, J., Calvert, R., Derhé, M., Harding, M., Lascelles, B., O'Brien, A., Peet, N., Symes, A., Martin, R

Andrews, D., Arcos, J., Blasco, J., McMinn, M., Oro, D., Porter, R., Tanner, K.

Recommended citation
BirdLife International (2015) Species factsheet: Puffinus mauretanicus. Downloaded from on 09/10/2015. Recommended citation for factsheets for more than one species: BirdLife International (2015) IUCN Red List for birds. Downloaded from on 09/10/2015.

This information is based upon, and updates, the information published in BirdLife International (2000) Threatened birds of the world. Barcelona and Cambridge, UK: Lynx Edicions and BirdLife International, BirdLife International (2004) Threatened birds of the world 2004 CD-ROM and BirdLife International (2008) Threatened birds of the world 2008 CD-ROM. These sources provide the information for species accounts for the birds on the IUCN Red List.

To provide new information to update this factsheet or to correct any errors, please email BirdLife

To contribute to discussions on the evaluation of the IUCN Red List status of Globally Threatened Birds, please visit BirdLife's Globally Threatened Bird Forums.

Additional resources for this species

ARKive species - Balearic shearwater (Puffinus mauretanicus) 0

Key facts
Current IUCN Red List category Critically Endangered
Family Procellariidae (Petrels, Shearwaters)
Species name author Lowe, 1921
Population size 9000-13000 mature individuals
Population trend Decreasing
Distribution size (breeding/resident) 4,830,000 km2
Country endemic? Yes
Links to further information
- Additional Information on this species
- 2015 European Red List assessment