Volume 44, No. 2

Search by author or title:

Passage patterns of seabirds in October at Cabo Carvoeiro, Portugal, with special reference to the Balearic Shearwater Puffinus mauretanicus


1Division of Natural Sciences, Kristianstad University, SE-29188 Kristianstad, Sweden (
2Köpenhamnsvägen 105D, SE-217 75 Malmö, Sweden
3Largo dos Camarnais, nº 3, 2540-479, Pó, Portugal


ELMBERG, J., HIRSCHFELD, E., CARDOSO, H. & HESSEL, R. 2016. Passage patterns of seabirds in October at Cabo Carvoeiro, Portugal, with special reference to the Balearic Shearwater Puffinus mauretanicus. Marine Ornithology 44: 151 - 156

Received 9 February 2016, accepted 22 April 2016

Date Published: 2016/10/15
Date Online: 2017/02/28
Key words: gannet, seabird migration, seabird monitoring, seawatch, shearwater, skua, tern


Land-based counts of migrating seabirds remain essential to increase knowledge about their numbers and movements. To assess the value of Cabo Carvoeiro (Peniche, Portugal) as a monitoring site in the East Atlantic, we studied seabird species composition, passage patterns and flock size during mid-October 2014. During standardized counts, we observed nearly 8 000 seabirds of 17 species. The ratio of individuals passing in a southerly to southwesterly direction was >96% in all species, showing that genuine migrants were counted. The passage rate (birds/hour) was higher for Northern Gannets Morus bassanus than for any other species, by a factor of approximately 50 (morning mean 906/h, afternoon mean 1 153/h). The globally endangered Balearic Shearwaters Puffinus mauretanicus, Great Skuas Stercorarius skua and Pomarine Skuas S. pomarinus had passage rates of 10–25/h. Flock size distribution in the 11 most numerous species showed that most migrated singly or in groups of two. Flock size was larger in Balearic Shearwaters than in both Cory's Calonectris borealis and Manx Shearwaters P. puffinus. Among skuas, flock size was larger in Pomarine than in Great Skuas. The passage rate of Manx Shearwaters was positively correlated with that of Northern Gannets, Great Skuas and Sandwich Terns Sterna sandvicensis. Northern Gannets showed a positive co-variation with Pomarine Skuas. Balearic and Sooty Shearwaters Ardenna griseus were the only species that did not show any significant co-variation with another species. Morning and afternoon passage rates did not differ significantly in any of the six most numerous species (Northern Gannets, Cory's and Balearic Shearwaters, Great and Pomarine Skuas, and Sandwich Terns), or in Sooty Shearwaters (less numerous). Thus, the passage rates at Cabo Carvoeiro in October of Balearic Shearwaters and five other species were as high or higher than those reported from any other seawatch in Portugal, indicating the international value of seabird monitoring at Cabo Carvoeiro during the autumn migration.


ARCOS, J.M. 2011. International species action plan for the Balearic Shearwater, Puffinus mauretanicus. SEO/BirdLife and BirdLife International.

CROXALL, J.P., BUTCHART, S.H.M., LASCELLE, B., STATTERSFIELD, A.J., SULLIVAN, B., SYMES, A. & TAYLOR, P. 2012. Seabird conservation status, threats and priority actions: a global assessment. Bird Conservation International 22: 1-34.

ELMBERG, J., HIRSCHFELD, E. & CARDOSO, H. 2013. Diurnal seabird movements at Cabo Carvoeiro (Peniche, Portugal): observations in early October 2012. Seabird 26: 24-30.

GENOVART, M., ARCOS, J.M., ÁLVAREZ, D. ET AL. 2016. Demography of the critically endangered Balearic shearwater: the impact of fisheries and time to extinction. Journal of Applied Ecology. doi:10.1111/1365-2664.12622.

GUILFORD, T., WYNN, R., McMINN, M. ET AL. 2012. Geolocators reveal migration and pre-breeding behaviour of the critically endangered Balearic Shearwater Puffinus mauretanicus. PLoS ONE 7(3): e33753.

JONES, A.R., WYNN, R.B., YÉSOU, P. ET AL. 2014. Using integrated land- and boat-based surveys to inform conservation of the Critically Endangered Balearic shearwater Puffinus mauretanicus in northeast Atlantic waters. Endangered Species Research 25: 1-18. doi: 10.3354/esr00611.

LECOQ, M., RAMIREZ, I., GERALDES, P. & ANDRADE, J. 2011. First complete census of Cory's Shearwaters Calonectris diomedea borealis breeding at Berlengas Islands (Portugal), including the small islets of the archipelago. Airo 21: 31-34.

LOUZAO, M., DELORD, K., GARCIA, D., BOUÉ, A. & WEIMERSKIRCH, H. 2012. Protecting persistent dynamic oceanographic features: transboundary conservation efforts are needed for the critically endangered Balearic Shearwater. PLoS ONE 7(5): e35728.

LOUZAO, M., NAVARRO, J., FORRERO, M.G., IGUAL, J.M., GENOVART, M., HOBSON, K.A. & ORO, D. 2011. Exploiting the closest production area: geographical segregation in foraging grounds in a critically endangered seabird. Marine Ecology Progress Series 429: 291-301.

MATEOS-RODRIGUEZ, M., THOMAS, L. & ARROYO, G.M. 2012. The development and use of a method to fill time gaps in migration counts. Condor 114: 513-522.

MOORE, C.C. 2000. Movimentações invulgares de aves marinhas junto ao Cabo Carvoeiro, Outono de 1999 – uma discussão. Pardela 13: 7-10.

MOURIÑO, 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 (suppl. 2): 135-142.

OLIVEIRA, N., BARROS, N., MERINHO, P., GERALDES, I., RAMIREZ, I. & ANDRADE, J. 2014. Relatório RAM em Portugal Continental – 2013. Lisbon, Portugal: Sociedade Portuguesa para o Estudo das Aves.

OLIVEIRA, N., HENRIQUES, A., MIODONSKI, J. ET AL. 2015. Seabird bycatch in Portuguese mainland coastal fisheries: An assessment through on-board observations and fishermen interviews. Global Ecology and Conservation 3: 51-61. 

OPPEL, S., MERINHO, A., RAMIREZ, I., GARDNER, B., O'CONNELL, A.F., MILLER, P.I. & LOUZAO, M. 2011. Comparison of five modelling techniques to predict the spatial distribution and abundance of seabirds. Biological Conservation 156: 94-104.

ORO, D., AGUILAR, J.S., IGUAL, J.M. & LOUZAO, M. 2003. Modelling demography and extinction risk in the endangered Balearic shearwater. Biological Conservation 116: 93-102.

PATERSON, A.M. 1997. Las aves marinas de España y Portugal. Barcelona, Spain: Lynx Edicions.

PÉRON, C. & GRÉMILLET, D. 2013. Tracking through life stages: adult, immature and juvenile autumn migration in a long-lived seabird. PLoS ONE 8(8): e72713.

POOT, M. 2005. Large numbers of staging Balearic Shearwaters Puffinus mauretanicus along the Lisbon coast, Portugal, during the post-breeding period, June 2004. Airo 15: 43-50.

SANDOVAL, R.A., HEVIA, B.R. & FERNÁNDEZ, M.D. 2009. Boletin de la Estación Ornitológica de Estaca de Bares Numero 1 – Año 2008. Dirección Xeral de Conservación da Natureza, Conselleria de Medio Ambiente e Desenvolvemento Sostible da Xunta de Galicia / TERRANOVA Interpretación y Gestión Ambiental S.L. 

SANDOVAL, R.A., HEVIA, B.R. & FERNÁNDEZ, M.D. & VALDERAS, F.A. 2010. Boletin de la Estación Ornitológica de Estaca de Bares Numero 2 – Año 2009. Dirección Xeral de Conservación da Natureza, Conselleria de Medio Ambiente e Desenvolvemento Sostible da Xunta de Galicia / TERRANOVA Interpretación y Gestión Ambiental S.L. 

Seawatching Estaca [Online]. Estaca de Bares, Spain: Seawatching Estaca [Available online at: Accessed 7 June 2016.]

SENGO, R., OLIVEIRA, N., ANDRADE, J., BARROS, N. & RAMIREZ, I. 2012. Três anos de RAM em Portugal Continental (2009 – 2011). Lisbon, Portugal: Sociedade Portuguesa para o Estudo das Aves.

SWATSCHEK, I., RISTOW, D. & WINK, M. 1994. Mate fidelity and parentage in Cory's shearwater Calonectris diomedea – field studies and DNA fingerprinting. Molecular Ecology 3: 259-262.

WALKER, F.J. 1996. Observations of movements of North Atlantic Gannets Morus bassanus from Cape St Vincent, Portugal. Seabird 18: 44-48.

WARHAM, J. 1990. The Petrels. Their ecology and breeding systems. London, UK: Academic Press.

Windguru [Online]. Czech Republic: Windguru. [Available online at: Accessed 7 June 2016.]

YÉSOU, P. 2003. Recent changes in the summer distribution of the Balearic shearwater Puffinus mauretanicus off western France. Scientia Marina 67 (suppl. 2): 143-148.

Search by author or title:

Browse previous volumes: