Sooty Shearwater Diet and Size: Feeding Habits, Predators, and Measurements
Sooty Shearwaters make a round trip of 40,000 miles (64,000 km) every year as part of their migratory journeys. They spend most of their lives at sea only coming into land to breed once they reach the age of around 9 or 10 years.
In this article we’ll be looking into the dietary habits, breeding habits and the size and weight of these magnificent pelagic seabirds. Keep reading to find out more.
Table of Contents
The Dietary Habits Of The Sooty Shearwater
Sooty Shearwaters spend most of their lives out at sea flying over open waters and their diet reflects this.
What Does A Sooty Shearwater Eat?
Sooty Shearwaters eat fish, squid, jelly fish and crustaceans and can dive up to 225 feet (68 metres) below the surface of the water when hunting for food.
Large flocks of Sooty Shearwaters can often be seen following trawlers. They feed on the offal thrown overboard by the trawlermen.
What To Feed A Baby Sooty Shearwater?
During the first few weeks of their lives, Sooty Shearwater chicks are fed on an oily substance which is regurgitated from both parents’ stomachs. This substance is produced as part of the digestion process when the adult birds consume fish and squid.
The young chicks are not fed regularly and can survive for long periods without any food. In fact, the parents leave the chicks around 7 to 14 days before they fledge and it’s this abandonment that causes the younglings to leave the burrow and fend for themselves.
Breeding Habits Of Sooty Shearwaters
Sooty Shearwaters tend to meet their mates and partner up once they arrive at their breeding grounds. These breeding grounds are located on islands in the southern hemisphere in areas around Australia, New Zealand, Chile and the Falkland Islands.
The breeding season starts around September which is when courtship displays and vocalisations commence. Once paired up, both birds begin the process of either excavating a fresh burrow or tidying up an old disused burrow.
The burrow building/nest building process can take anywhere between a few days to 2 weeks depending on whether the pair have started a new burrow or repurposed an existing one.
Do Sooty Shearwaters Mate For Life?
Sooty Shearwaters are usually monogamous and stay with the same partner every year (as long as they both survive).The pair will typically return to the same area to breed in successive years and typically use the same burrow every year as well.
The Size & Weight Of Sooty Shearwaters
Sooty Shearwaters are large for Shearwaters and just slightly smaller in size than a Herring Gull. Male and female Sooty Shearwaters are roughly the same size.
How Much Does A Sooty Shearwater Weigh?
The average weight of an adult Sooty Shearwater is around 650 to 950 grams. Which is roughly the same weight as the Western Marsh Harrier.
How Big Is A Sooty Shearwater?
An adult Sooty Shearwater is around 40 to 51 cm in length with a wingspan of around 94 to 109 cm. Their large wings are necessary in enabling the Sooty Shearwater to fly the incredibly long migratory journeys.
Are Sooty Shearwaters Under Threat?
According to the International Union for Conservation of Nature (IUCN) the Sooty Shearwater is listed as “Near Threatened”. This means there are concerns about the trends in population numbers as well as the threats they might face although not currently classified as an endangered species.
In New Zealand where these birds are prized as a food source by the Maori population, numbers of up to 250,000 are captured each year. This along with climate change, overfishing and birds getting caught in fishing nets as well as habitat degradation caused by human activity and pollution and predation is contributing to the downward trend in numbers for this species.
What Eats A Sooty Shearwater?
Sooty Shearwaters face predation from stoats, rats, wild pigs and domestic cats which will all take chicks and adults from their burrows. Plus the young fledglings face threats from larger predatory birds like Peregrine Falcons.
As a precautionary measure against predators the Sooty Shearwater enter and leave their nests during the night. Using the cover of darkness to protect them from many predators.
Where Can I See Sooty Shearwaters In The UK?
It is possible to see Sooty Shearwaters in coastal areas of the UK between July and September. These sightings are most likely to occur if there is a strong onshore wind which blows Sooty Shearwaters towards the coasts as they fly towards their breeding grounds in the southern hemisphere.
Typical sightings of Sooty Shearwaters are recorded in coastal areas such as;
- Cornwall
- The Scilly Isles
- Pembrokeshire
- East Yorkshire
- The Isle of Skye
Your best chance of seeing Sooty Shearwaters is from one of the locations above whilst looking out to sea from coastal headlands. They will typically be flying low over the water and usually along with other migrating seabirds.
SEE ALSO: Balearic Shearwater Vs Manx Shearwater: Key Differences Explained
Frequently Asked Questions
The diet of the Sooty Shearwater includes; fish, squid, jelly fish and crustaceans. They can dive to a depth of 225 feet (68 metres) below the surface of the water when hunting for food.
During the first few weeks of their lives, Sooty Shearwater chicks are fed on an oily substance which is regurgitated from both parents’ stomachs. The chicks can survive a surprisingly long time without food and are fed infrequently by their parents.
The average weight of an adult Sooty Shearwater is around 650 to 950 grams.
