Manx Shearwater Diet and Size: Feeding Habits, Predators, and Measurements

Manx Shearwater Diet and Size: Feeding Habits, Predators, and Measurements

The Manx Shearwater (Puffinus puffinus) is a seabird that stays close to the shore and migrates. They are part of the Procellariidae family, which has over twenty kinds of shearwaters. 

They are the most often seen shearwater around the United Kingdom. 

Once in great numbers, their population is now falling due to climate change, severe weather, and food shortages. These seabirds cover large distances but are threatened by these environmental issues.

The Dietary Habits Of The Manx Shearwater

Let’s take a closer look at what the Manx Shearwater eats and how they feed their young.

What Does A Manx Shearwater Eat?

The Manx shearwater eats small fish like sand eels, sprats, and herrings, along with squids, crustaceans, and offal floating on the water. 

It catches food by diving or picking it off the surface, either alone or in small groups. Sometimes, it follows whales but rarely goes after boats or gathers with other shearwater species.

What To Feed A Baby Manx Shearwater? 

Adult Manx shearwaters feed their chicks with fish they’ve partially digested. They travel far, sometimes more than 200 miles, to gather food. The parents catch these fish at sea by diving or skimming the surface, catching herrings, and sprats, along with other sea creatures like squid.

Breeding Habits Of Manx Shearwaters

Manx Shearwater

Manx shearwaters are mostly found at sea throughout the year, returning to land solely for breeding. 

They choose burrows and areas under rocks for nesting and come ashore only at night to steer clear of predators such as great skuas and great black-backed gulls. Sometimes the burrows are previously excavated by European rabbits, though shearwaters can also dig their own.

Their breeding grounds are exclusively on islands, usually devoid of rats that otherwise would prey on them and their eggs and chicks.

Although shearwaters start returning to the breeding sites from March, females often depart again for a few weeks before egg-laying in early May. Males come back to their birth colonies, but up to half of the females may choose different sites. 

Do Manx Shearwaters Mate For Life?

Manx shearwaters are noted for their lifelong monogamous relationships. These seabirds usually stay monogamous, mating for life and returning to the same burrow each breeding season. However, they sometimes part ways after failed breeding attempts.

The Size & Weight Of Manx Shearwaters

Let’s look at the weight of Manx Shearwaters and their size, covering their body length and wingspan.

How Much Does A Manx Shearwater Weigh?

Manx shearwaters generally weigh between 350 and 575 grams, which is around 12 to 20 ounces. On average, a Manx shearwater weighs about 400 grams, or 14 ounces. This range varies due to individual differences and the bird’s health.

How Big Is A Manx Shearwater?

In terms of their size, Manx shearwaters often measure 30 to 38 centimetres long and have wingspans from 76 to 89 centimetres. These dimensions can vary depending on the bird itself and its condition.

Are Manx Shearwaters Under Threat?

Manx Shearwater

Listed on the UK’s Amber Conservation Concern, Manx Shearwaters are at moderate risk. Their nesting places are particularly vulnerable. These birds have adapted to nest underground to protect their eggs from predators. 

However, rats, often accidentally brought to islands, can enter these burrows, causing significant damage.

What Eats A Manx Shearwater?

The Manx shearwater’s lack of agility on land makes them easy prey for large birds, like the great skua and great black-backed gull. Even birds of prey, such as the golden eagle and peregrine falcon, have been noted to kill these adult shearwaters.

Where Can I See Manx Shearwaters In The UK?

Manx shearwaters can be seen in several places across the UK, notably on coastal headlands and islands where they lay their eggs. The most important nesting sites for these birds in the UK are Skomer Islands near Wales, Skokholm, Bardsey, and Rum Island off the west coast of Scotland.

On land, they are hard to notice as they only return to their nests at night, but many gather offshore before nightfall. 

Birdwatchers may also see migrating birds from high points along the west coast in spring and summer, particularly when the wind from the sea brings them closer.

SEE ALSO: Manx Shearwater Life Cycle: Nest Building To Fledging (and everything in between)

Frequently Asked Questions

What are the predators of the Manx Shearwater?

The predators of the Manx Shearwater include large birds such as the great skua and great black-backed gull, as well as birds of prey like the golden eagle and peregrine falcon.

What is the diet of the Manx Shearwater?

The diet of the Manx Shearwater consists of small fish like sand eels, sprats, and herrings, along with squid, crustaceans, and offal floating on the water.

What is the habitat of the Manx Shearwaters?

The habitat of the Manx Shearwaters is primarily at sea, but they return to land, especially coastal headlands and islands, for breeding.

How big are Manx Shearwater birds?

Manx Shearwater birds are typically 30 to 38 centimetres long and have wingspans ranging from 76 to 89 centimetres.

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