Common dolphin
Scientific Name: Delphinus delphis (Linnaeus, 1758).
Common Name: Common dolphin.
Classification: Odontoceti, family Delphinidae.
Physical notes: Up to 2.5 m and 200 kg with characteristic tan to pale yellow patches on the sides.
Distribution and habitat use: Tropical to temperate waters worldwide. Primarily coastal species but can be also found in shelf, and oceanic waters, with a preference for upwelling-modified areas with steep sea-bottoms. Resident species, found all year in Sagres.
Group size: Normally seen in groups of 20 to 30 individuals. But depending on the season it can gather in groups of hundreds or even thousands. Group composition and dynamic is very fluid, but usually segregated by gender, age, and reproductive condition.
Life span: 20-35 years.
Gestation period: 10-11 months. Calves are born ca. 1/3 adult size and they reach maturity at 6 – 8 years. Births take place from May till August. Juveniles are weaned after 18 – 20 months.
Diet and Feeding: Wide variety of schooling fish and squid. Cooperative feeding techniques often used to herd prey. They can dive up to 200 m and hold their breath up to 8 minutes.
Typical Behaviour: Highly social and fast swimmers, able to reach over 60 km/h in a short burst. They are extremely interactive and curious with boats, and very enthusiastic with bow and wake riding. They frequently perform variety of acrobatic leaps.
Population: ca. 4-5 million worldwide. Population trend unknown, but there has been significant drop in some areas, such as Portugal (2023) and Mediterranean (2022).
Threats: Habitat degradation, prey depletion, pollution, and by-catch which often lead to death. Although worldwide population is large and widely distributed, in Portugal it may decline by as much as 30% in the next 39 years, based on number of accidental captures and stranding records.
IUCN status: Least concern for overall species worldwide (2020). In Portugal Near Threatened (2023), and Mediterranean sub-population Critically Endangered (2003).
Carwardine, M. (2022). Whales, Dolphins and Porpoises. Bloomsbury Wildlife. London, United kingdom.
Ferreira, M., Eira, C., López, A., & Sequeira, M. (2023). Delphinus delphis golfinho-comum. In Mathias, M. L. (coord.), Fonseca, C., Rodrigues, L., Grilo, C., Lopes-Fernandes, M., Palmeirim, J. M., Santos-Reis, M., Alves, P. C., Cabral, J. A., Ferreira, M., Mira, A., Eira, C., Negrões, N., Paupério, J., Pita, R., Rainho, A., Rosalino, L. M., Tapisso, J. T., & Vingada, J. (eds.): Livro Vermelho dos Mamíferos de Portugal Continental. Fciências.ID, ICNF, Lisboa.
Shirihai, H. (2006). Whales, Dolphins and Seals: A Field Guide to the Marine Mammals of the World. Bloomsbury Wildlife. London, United Kingdom.
Still, R., Harrop, H., Stenton, T., & Dias, L. (2019). Europe’s Sea Mammals Including the Azores, Madeira, the Canary Islands and Cape Verde: A field guide to the whales, dolphins, porpoises and seals. Princeton University Press.