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

The Cormorant (Phalacrocorax carbo) is a large, black waterbird commonly seen around the UK’s coastlines and inland water bodies. Known for its striking appearance and distinctive behaviour, including its famous wing-drying posture, the Cormorant is a bird with fascinating adaptations for life in and around water. 

In this article, we’ll learn about the Cormorant’s life cycle from nest building to fledging, giving a detailed insight into this bird’s remarkable journey through their various stages of life!

How Long Does A Cormorant Live?

Cormorants generally live between 10 and 15 years in the wild, although some have been known to survive up to 22 years under favourable conditions. 

Their longevity is influenced by various factors, including food availability, predation, weather, and human activity. These birds face natural threats such as large birds of prey and sometimes foxes, but human-induced threats, such as water pollution, fishing nets, and habitat destruction, also affect their lifespan.

Despite these challenges, Cormorants are resilient and adaptable birds. The availability of fish, their primary diet, and their ability to inhabit both coastal and inland waters gives them an advantage in the wild, allowing them to thrive in diverse environments. 

How Fast Can A Cormorant Fly?

Cormorants can reach speeds of 30 to 35 miles per hour (48 to 56 kilometres per hour) during sustained flight. While they may not be the fastest birds in the sky, their flight capabilities are well-suited to their lifestyle.

These birds are powerful flyers, despite their relatively heavy build. They typically fly low over water, using strong wingbeats to propel themselves forward. Their flight pattern is distinctive, with their long neck stretched out and their large feet trailing behind.

When migrating or moving between feeding grounds, Cormorants often fly in V-shaped formations, similar to geese. This formation helps reduce energy expenditure during long-distance flights.

Are Cormorants Aggressive?

Cormorants are generally not aggressive birds, but they can display territorial behaviour during the breeding season. They are colonial nesters and typically maintain peaceful relationships with their neighbours.

During the breeding season, males may engage in competitive displays and defend their nesting territories from intruders. However, these confrontations rarely escalate beyond threatening postures and vocalisations.

Outside of the breeding season, Cormorants often fish in groups and can be seen sharing roosting sites with other waterbirds, demonstrating their generally sociable nature.

What Is A Cormorant’s Habitat?

Cormorants are highly adaptable birds that thrive in both coastal and inland water environments. They can be found along the entire UK coastline, as well as around inland lakes, reservoirs, and rivers.

These versatile birds prefer areas with good fishing opportunities and suitable roosting sites. They need perches or rocks where they can dry their wings – a necessary behaviour as their feathers are less water-repellent than those of many other waterbirds.

In the UK, Cormorants are present year-round, with numbers boosted in winter by visitors from continental Europe. They’ve successfully adapted to urban environments, becoming a common sight even in city parks with suitable water bodies.

How Long Does It Take For A Cormorant To Build A Nest?

Cormorants are diligent nest builders, taking about 7 to 10 days to construct a suitable nest. Nest building is a collaborative effort between the male and female, with the male gathering materials such as twigs, seaweed, and grass, while the female arranges them to form the nest. These nests are usually built in colonies, and the location can vary depending on the availability of suitable sites.

In coastal areas, Cormorants prefer to nest on rocky outcrops, cliffs, or islands, which offer some protection from predators. Inland, they are known to nest in trees, sometimes building large, bulky nests in the branches above water. In some areas, Cormorants may even nest on the ground, particularly where trees or other elevated surfaces are scarce. Regardless of the location, the nest is typically large and sturdy, built to withstand the elements and house several chicks.

It is also common for Cormorants to reuse their nests from previous years, adding new materials to reinforce them. This behaviour saves energy and ensures the nest remains secure for future breeding seasons.

Eggs

The egg-laying period is a crucial phase in the Cormorant’s annual cycle, marking the beginning of a new generation.

When Do Cormorants Lay Eggs?

Cormorants typically lay eggs between March and May in the UK. The exact timing can vary depending on location and weather conditions, with birds in southern regions often starting earlier than their northern counterparts.

The egg-laying period coincides with the availability of food resources, ensuring that chicks hatch when fish are abundant. This timing is crucial for the survival of the young birds.

How Many Eggs Does A Cormorant Lay?

A cormorant typically lays 3 to 4 eggs per clutch. The eggs are laid at intervals of 2 to 3 days, though incubation usually begins with the first egg.

This staggered laying results in asynchronous hatching, which can create a size hierarchy among chicks. This strategy can be beneficial during times of food scarcity, as it ensures at least some chicks are likely to survive.

What Do Cormorant Eggs Look Like?

Cormorant eggs are pale blue-green in colour, with a chalky white coating that develops shortly after laying. They are oval-shaped and relatively large, measuring approximately 63 to 64 mm in length.

The eggs have a rough, slightly porous texture, which helps regulate moisture and temperature during incubation. As incubation progresses, the eggs often become stained from the nest materials and parental contact.

How Long Do Cormorant Eggs Take To Hatch?

Cormorant eggs typically take 25 to 28 days to hatch. Both parents share incubation duties, carefully tending to their eggs throughout this period.

The parents take turns sitting on the eggs, ensuring they maintain the proper temperature for embryo development. Their dedication during this period is crucial for the successful hatching of their chicks.

Chicks

The development of Cormorant chicks from hatching to fledging is a remarkable process of growth and learning.

How Many Chicks Does A Cormorant Have?

A typical Cormorant brood consists of 3 to 4 chicks, corresponding to the number of eggs laid. The parents feed the chicks through regurgitation, providing them with a steady supply of partially digested fish. 

In years of plentiful fish stocks, most chicks in a brood will survive to fledging, but when food is scarce, competition among siblings can result in the death of the weaker chicks.

When Do Cormorant Chicks Open Their Eyes?

Cormorant chicks are born blind, with their eyes closed. Their eyes typically open within 2 to 3 days after hatching.

This altricial state at birth means they are completely dependent on their parents for warmth, protection, and food during their early days. As their eyes open and develop, they become increasingly aware of their surroundings and better able to beg for food from their parents.

When Do Cormorant Chicks Fledge?

Cormorant chicks typically fledge at around 45 to 55 days after hatching. However, they continue to return to the nest for several weeks afterward, being fed by their parents while they perfect their fishing skills.

The fledging period is a gradual process, with young birds first exploring the areas around the nest before making their first flights. They start practising diving and fishing under their parents’ supervision, gradually becoming more independent.

SEE ALSO: Cormorant Diet and Size: Feeding Habits, Predators, and Measurements

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