Shearwaters: Comprehensive Guide to the Procellariidae Family
Welcome to the mysterious and fascinating world of shearwaters! These seabirds, members of the Procellariidae family (which also includes petrels), are exceptional pelagic navigators, spending most of their lives on the high seas. Adapted to oceanic life, they are renowned for their characteristic gliding flight, often skimming the waves, and for their nocturnal nesting habits on isolated islands.
This guide provides an overview of the main shearwater species you might encounter, particularly in the Atlantic and Mediterranean. Click on each species to discover in detail their identification, habitat, behavior, diet, and conservation status.
This article was published by the Les-Oiseaux.com team on 23/09/2025.
General Characteristics and Average Measurements
Shearwaters are seabirds characterized by a slender body and long, narrow wings, perfectly adapted for efficient gliding flight over the waves. Although dimensions vary slightly by species, here are average measurements for the shearwater family.
Characteristic
Male
Female
Record / Average
Length
27 – 34 cm
35 – 41 cm
27 – 41 cm (all individuals)
Weight
110 – 200 g
185 – 350 g
Up to 380 g
Wingspan
58 – 65 cm
65 – 80 cm
58 – 80 cm
Life expectancy
Up to 15 years
Up to 15 years
Up to 16 years (in wild)
These data are indicative and can vary considerably among different shearwater species.
General Habitat and Distribution of Shearwaters
Shearwaters are truly pelagic birds, meaning they spend almost their entire lives on the open sea, far from the coast. They only return to land for one single reason: reproduction. Their nesting sites are usually located on isolated oceanic islands, inaccessible coastal cliffs, or islets where they can dig burrows or use rock cavities to lay their eggs, safe from terrestrial predators.
The distribution of shearwaters is vast, covering all oceans of the globe, from temperate regions to tropical and even subarctic waters for some species. In Europe, they are primarily found in the Atlantic Ocean, around archipelagos such as the Azores, Madeira, the Canary Islands, as well as in the Mediterranean Sea. Many species are long-distance migrants, undertaking impressive trans-equatorial journeys to spend the winter in the opposite hemisphere, thus taking advantage of abundant food resources.
General Diet of Shearwaters
Shearwaters are opportunistic and efficient seabirds, feeding almost exclusively on resources offered by the ocean. Their diet primarily consists of small pelagic fish, squid, and various crustaceans. They are excellent hunters, capable of diving beneath the water's surface to catch their prey, although the depth and duration of their dives vary by species and resource availability.
They often hunt in groups, especially by following schools of fish that are driven to the surface by larger marine predators like tuna or cetaceans. This strategy allows them to maximize their catches. Some species may also consume fish waste discarded by fishing boats, although this can expose them to risks.
Migration and Behavior of Shearwaters
Shearwaters are among the most accomplished migratory seabirds. Many species travel thousands of kilometers each year, performing trans-equatorial migrations that connect their breeding sites in one hemisphere with feeding grounds in the opposite hemisphere. For example, the Cory's Shearwater is known to travel from the Southern Hemisphere to the North Pacific, covering over 40,000 kilometers annually — one of the longest migrations of any bird.
Their flight behavior is also remarkable: shearwaters are masters of dynamic soaring, a technique that allows them to exploit wind gradients over the waves to glide for hours with minimal wingbeats. This energy-efficient flight style makes them perfectly adapted to life in the open ocean.
Socially, shearwaters are often seen in large flocks at sea, especially when feeding alongside schools of fish or marine predators such as dolphins and tuna. However, they become secretive and nocturnal at their nesting colonies, returning at night to avoid predation.
Cory's Shearwater (Calonectris borealis)
The largest shearwater in the North Atlantic, famous for its nocturnal calls and extensive migrations. Its plumage is brownish-grey above, white below, with a robust yellow bill.
A Mediterranean shearwater very similar to Cory's Shearwater, but with subtle differences in bill and underwing patterns. It is endemic to the Mediterranean.
Manx Shearwater (Puffinus puffinus)
A classic shearwater of the North Atlantic, easily recognized by its black upperparts and white underparts. It breeds mainly on islands around the British Isles and migrates to South America for the winter.
Shearwaters, like many seabirds, face various threats linked to human activities. As occasional visitors to coastlines, we can all contribute to their protection.
Reduce Plastic Pollution
Plastic waste in the sea is a major threat. Shearwaters can ingest it, obstructing their digestive system, or get entangled. Reduce your single-use plastic consumption and participate in beach clean-ups.
Combat Light Pollution
Artificial light from coasts and boats can disorient young shearwaters during their first nocturnal flight, making them vulnerable to predators or collisions. If you live near a coastline, minimize outdoor lighting during the breeding season.
Support Conservation Efforts
Many organizations work to protect seabirds, particularly by managing breeding colonies, combating introduced species (rats, cats), and reducing accidental captures. Donating or volunteering is valuable support.
Respect Nesting Areas
Shearwater colonies are very sensitive to disturbance. Stay away from marked areas, especially at night. Do not let your pets approach coastal breeding sites.
Report Injured or Oiled Birds
If you find an injured, oiled, or distressed shearwater, do not attempt to handle it. Immediately contact a wildlife rescue center or your local environmental agency.
In conclusion, protecting shearwaters means protecting the balance of our oceans. Every small action counts to ensure the future of these magnificent seabirds.
Frequently Asked Questions (FAQ) about Shearwaters
What is a shearwater?
Shearwaters are pelagic seabirds, members of the Procellariidae family. They are characterized by their tubular nostrils (for excreting salt), long bill, gliding flight close to the water, and often long migrations. They only return to land to breed, usually at night, in burrows or rock cavities to lay their eggs.
Where do shearwaters live?
Shearwaters have a global distribution, covering all oceans, from temperate regions to tropical and even subarctic waters for some species. In Europe, they are mainly found in the Atlantic Ocean, around archipelagos such as the Azores, Madeira, the Canary Islands, as well as in the Mediterranean Sea. Many species are long-distance migrants, undertaking impressive trans-equatorial journeys to spend the winter in the opposite hemisphere, thus taking advantage of abundant food resources.
What do shearwaters eat?
Shearwaters are opportunistic carnivores. Their diet primarily consists of small pelagic fish, squid, and various crustaceans. They are excellent hunters, capable of diving beneath the water's surface to catch their prey, although the depth and duration of their dives vary by species and resource availability. They often hunt in groups, especially by following schools of fish that are driven to the surface by larger marine predators like tuna or cetaceans that congregate prey.
Are shearwaters endangered species?
The conservation status varies by species. For example, Cory's Shearwater is classified as 'Least Concern' globally, but some populations may be locally threatened. In contrast, the Balearic Shearwater is considered 'Critically Endangered', making it Europe's most threatened seabird. Major threats include predation by introduced species (rats, cats) on colonies, accidental capture in fishing gear, light pollution, and plastic pollution.
What is the difference between a shearwater and an Atlantic Puffin?
While both are seabirds, shearwaters and Atlantic Puffins belong to different families and have distinct characteristics. Shearwaters (Procellariidae family) have a more slender body, a more gliding flight, and finer bills. Atlantic Puffins (Alcidae family, like penguins) have a stouter body, short wings used for underwater swimming, and a large, colorful triangular bill, especially visible during the breeding season. They are also better divers than shearwaters.
