Balearic Shearwater Life Cycle: Nest Building To Fledging (and everything in between)

Balearic Shearwater Life Cycle: Nest Building To Fledging (and everything in between)

The Balearic Shearwater, a medium-sized bird in the Procellariidae family of seabirds, carries the scientific name Puffinus mauretanicus. 

Its name, Puffinus, is derived from Neo-Latin, echoing the old English term “puffin”, which referred to the cured remains of hefty fledgling of the Manx shearwater, once considered a delicacy.

The species name mauretanicus is derived from Mauretania, an ancient term for a region now known as Morocco and Algeria. The Balearic shearwater is critically endangered according to the IUCN and ranks among Europe’s most threatened seabird species.

How Long Does A Balearic Shearwater Live?

The Balearic Shearwater, a seabird native to the Balearic Islands, typically has a lifespan of around 12 years. Yet, there are cases where they live longer, with the oldest known one living up to 23 years.

How Fast Can A Balearic Shearwater Fly?

The Balearic Shearwater flies at around 14.7 metres per second while flapping, which works out at around 53km per hour (33mph).

It flies fast with strong wing beats and short glides, about 1 to 3 metres above the water. The wings are held at right angles to the body. 

This bird has a “shearing” flight, dipping side to side with few wing beats, almost touching the water. They look like a flying cross, with dark brown on top and dirty white underneath as it moves.

Are Balearic Shearwaters Aggressive?

Balearic shearwaters are typically not aggressive birds. They are recognised for their social nature, nesting in close proximity to each other and feeding in large groups at sea. 

Unlike certain other bird species, they do not display territorial behaviour and spend minimal time on land, limiting opportunities for aggressive encounters.

What Is A Balearic Shearwater’s Habitat?

The Balearic Shearwater only breeds in the Balearic Islands, making its home on the coastal regions and small islands of Mallorca, Ibiza, Menorca, Formentera, and Cabrera. 

During their breeding period, they primarily feed along the eastern coast of the Iberian Peninsula, especially around the Ebro Delta. 

After breeding, they migrate into the Atlantic and travel north along the Portuguese and north-western Spanish coasts to their regular resting areas in the Bay of Biscay off western France.

How Long Does It Take For A Balearic Shearwater To Build A Nest?

Balearic Shearwater - Puffinus mauretanicus

These birds usually nest in burrows and caves, which they visit only at night to avoid predators. This suggests they might quickly adapt to these natural places instead of building new nests from scratch, indicating a fast nesting process.


Let’s take a look at the lifecycle of Balearic Shearwater eggs, from when they are laid to when they hatch, and what these eggs look like.

When Do Balearic Shearwaters Lay Eggs?

The Balearic Shearwater, a colonial species that returns yearly to its nesting site, breeds in crevices and caves on small islets and cliffs. They lay one egg between March and April, which is incubated for 48-52 days.

How Many Eggs Does A Balearic Shearwater Lay?

Balearic shearwaters typically lay only one egg each breeding season. This single-egg approach is usual among seabirds like shearwaters, as it allows them to devote more resources and effort into raising one chick successfully.

What Do Balearic Shearwater Eggs Look Like?

The eggs of the Balearic Shearwater are white and typically measure about 61 mm by 42 mm (2.4 inches by 1.7 inches). This is a common egg colour among various seabird species.

How Long Do Balearic Shearwater Eggs Take To Hatch?

The Balearic shearwater’s egg is incubated for about 50 to 52 days. Typically, hatching happens in late April to early May. Adults leave their colonies in late June, shortly before the chicks fledge.


We’ll take a closer look at the journey of Balearic Shearwater chicks, starting from how many are born, to when they first open their eyes, and their fledging process.

How Many Chicks Does A Balearic Shearwater Have?

As previously mentioned, Balearic Shearwaters generally produce just one chick per breeding season. With only one egg laid, they are limited to raising a single chick at a time.

When Do Balearic Shearwater Chicks Open Their Eyes?

Balearic Shearwater chicks, being altricial, are born underdeveloped and require significant parental care. Their eyes typically open a few days after hatching, although this timing can vary slightly.

When Do Balearic Shearwater Chicks Fledge?

The time for fledglings to mature is roughly 60 to 70 days, and this phase usually ends in late June. Parents feed the chick for about 15 days, and it fledges 70 days post-hatching.

SEE ALSO: Balearic Shearwater Diet and Size: Feeding Habits, Predators, and Measurements

Frequently Asked Questions

What is the lifespan of a Balearic Shearwater?

The lifespan of a Balearic Shearwater is typically around 12 years, although some can live up to 23 years.

What colour are Balearic Shearwater eggs?

Balearic Shearwater eggs are white in colour.

Are Balearic Shearwaters aggressive?

Balearic Shearwaters are not aggressive; they are known for their social nature and do not display territorial behaviour.

Where is the Balearic Shearwater’s habitat?

The Balearic Shearwater’s habitat is primarily in the Balearic Islands, particularly on coastal regions and small islands like Mallorca, Ibiza, Menorca, Formentera, and Cabrera.

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