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Distribution – population

Yelkouan Shearwaters breeds in the central and eastern Mediterranean basin, mainly in Greece, Italy, France, and Malta. It is a pelagic seabird, which is closely related to and resembles the Scopoli’s Shearwater, the second pelagic seabird in our country. They have similar habits, with the difference that Yelkouan shearwaters usually fly in flocks, closely formed together, above the waves, while Scopoli’s shearwaters are more solitary. It is estimated that 6,800-13,200 pairs of Yelkouans nest on the islands of the Aegean and Ionian seas, accounting for 35% of the European population.

Most Yelkouan shearwaters remain permanently in the Mediterranean and rarely approach the mainland. The breeding season extends from February to the end of summer. Shearwaters usually nest on the ground in caves and crevices located on steep cliffs and uninhabited islets. Towards late spring, the females lay their single egg of the year, which both parents incubate alternately for about 50 days. It was found for the first time that Yelkouan shearwater pairs breeding in the Eastern Mediterranean take turns incubating their single egg with small and larger trips, going even during spring and summer to the Black Sea in search of food. By the end of summer, fledglings are ready to leave the nest and start their own journey. After the end of the breeding season, thousands of shearwaters leave the Aegean and go to the Black Sea to exploit the rich fishing grounds. In winter, they return to the Aegean, and their breeding season begins with the arrival of spring.

Threats

  • Accidental entanglement in fishing gear: can result in injury or drowning.
  • Hunting by alien predators: Chicks and eggs are vulnerable to being preyed upon by alien invasive species introduced to uninhabited islets by humans, such as rats.
  • Degradation of colonies: Light pollution, noise pollution, and intense human activity on uninhabited islets, especially during the breeding season, can lead to reproductive failure. Additionally, intense lights may disorient young birds leaving their nests, causing them to land on unwanted places.
  • Marine pollution: Like all other marine species, shearwaters often consume plastic debris, mistaking them for food. If ingested, plastic items in the seabirds’ bodies break down and can cause toxic reactions or lead to reduced physical condition, malnutrition, and even death.

Biology – ecology

Diet: A truly pelagic species, spending its entire life in the open sea and returning to land only to breed. A very skilled swimmer with dives occasionally reaching depths of up to 50 meters! Their favorite prey consists of small fish such as anchovies and sardines, but also other marine species such as squid, octopus, and shrimp. They often follow schools of dolphins and whales that push large schools of fish towards the surface when hunting, as well as fishing vessels. This is the reason why a large number of them are caught in fishing gear, especially before they withdraw to their colonies to lay their single egg.

Body length: up to approximately 30-35 cm

Weight: 330-480 grams

Wingspan: 0.70-0.85 meters

Number of eggs/nest: 1 single egg per breeding season!

Distribution: Nests on islands in the Mediterranean. A related species lives in the Balearic Islands, which was previously considered a subspecies; the Balearic Shearwater (Puffinus mauretanicus).

Diving depth: up to 50 meters!

Greek population: 6,800-13,200 pairs

Species