Great Shearwater
Ardenna gravis
Visual Identification
Appearance
The Great Shearwater is a large seabird with distinctive brown and white plumage. Its upperparts are dark brown, contrasting sharply with a white underside. The bird has a dark cap extending below the eyes, a white collar, and a dark tail.
Females and males share the same coloring, although the sexes can usually be told apart when alongside males as they are slightly smaller.
Juveniles resemble adults but may have slightly lighter edges to their upper wing coverts. In younger birds, the white collar may also be absent.
Size
Length
43cm to 51cm
Wingspan
100cm to 118cm
Weight
715g to 950g
Colours
Males and females have similar plumage
Primary Colour
Brown White
Secondary Colour
Grey Black
Beak Colour
Grey
Leg Colour
Pink
Habitat and Distribution
Habitats
Woodland
Garden
Wetland
Coastal
Urban
Farmland
Grassland
Desert
Tundra
Rainforest
Mountain
Savanna
Distribution
Great Shearwaters breed on remote islands in the South Atlantic, including Tristan da Cunha and Gough Island. Outside the breeding season, they undertake a trans-equatorial migration, ranging widely across the North and South Atlantic Oceans.
In the Northern Hemisphere summer, they can be observed off the coasts of North America, including the eastern United States and Canada, and in European waters, particularly around the UK and Ireland.
Elevation Range
Sea level to 600 meters
Climate zones
Temperate, Subtropical, Tropical
Distribution Map
This map gives you a rough idea of where you might spot a Great Shearwater. The coloured areas show countries where these birds have been seen.
A few things to keep in mind:
- Birds might not be everywhere in the coloured areas, for example, they may be present around the coast of that country
- Where birds live can change with seasons and available food
- This map is quite simple - it doesn't show exact locations
We're working on making our maps even better! Soon, we hope to show you:
- More detailed maps for bigger countries, including state and region
- How birds move around during different seasons
Distribution by Region
Behaviour and Ecology
Bird Attributes
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Share your thoughtsBird Attributes Explained
Our bird attributes system rates various aspects of a bird's capabilities on a scale of 0-100, based on data from field observations, scientific studies, and expert knowledge.
Attribute Categories:
- Agility: Manoeuvrability, speed, and grace in flight or movement.
- Strength: Physical power, often correlating with size and hunting abilities.
- Adaptability: Ability to thrive in various environments or changing conditions.
- Aggressiveness: Territorial behaviour and assertiveness, particularly during breeding seasons.
- Endurance: Stamina, often seen in migration patterns or foraging behaviours.
Understanding the Ratings:
- 0-20: Very Low
- 21-40: Low
- 41-60: Average
- 61-80: High
- 81-100: Very High
Remember, these attributes are relative to other bird species and don't necessarily indicate superiority.
Hover over the icon next to each attribute for more information.
Tap the icon next to each attribute for more information.
Agility
Reflects the bird's manoeuvrability, speed, and grace in flight or movement.
Exceptional agility, demonstrated by their remarkable gliding abilities and dynamic soaring technique. Great Shearwaters can effortlessly navigate vast oceanic distances, showcasing superb aerial manoeuvrability.
Strength
Indicates the bird's physical power, often correlating with size and hunting abilities.
Considerable strength for their size, evidenced by their ability to dive up to 18 metres deep for prey and withstand the physical demands of long-distance migration. However, they're not as powerful as some larger seabirds.
Adaptability
Represents the bird's ability to thrive in various environments or changing conditions.
Highly adaptable, as shown by their ability to thrive in various oceanic environments across multiple climate zones. Their capacity to drink seawater and migrate over 20,000 km annually further demonstrates their adaptability.
Aggressiveness
Measures the bird's territorial behaviour and assertiveness, particularly during breeding seasons.
Moderately aggressive when necessary, particularly during breeding season or when competing for food. However, they're not known for exceptional aggression compared to other seabirds.
Endurance
Reflects the bird's stamina, often seen in migration patterns or foraging behaviours.
Outstanding endurance, undertaking one of the longest migrations of any bird species. Their ability to cover vast distances using dynamic soaring and survive long periods at sea demonstrates remarkable stamina.
Diet
Great Shearwaters primarily feed on small fish (mackerel and capelin), squid, and crustaceans. Fish offal are also important.
They often hunt by surface-seizing or shallow plunge-diving at least 2 m (6.6 ft) beneath the surface of the water, sometimes following whales or dolphins to catch prey driven to the surface. These birds may also scavenge around fishing vessels.
Behaviour
Great Shearwaters are highly pelagic, spending most of their lives at sea. They are exceptional gliders, using dynamic soaring to cover vast distances with minimal energy expenditure.
These birds often follow ships and gather in large flocks around productive feeding areas, diving to catch prey.
Vocalisation
Great Shearwaters are typically silent at sea but become vocal at breeding colonies. Their calls include a variety of harsh, cackling sounds and wailing notes. A common vocalization is a repeated 'hee-hee-hee' or 'yak-yak-yak', often heard during nighttime activity at nesting sites.
Nesting & Breeding
Great Shearwaters form breeding pairs that often remain together for multiple seasons. They nest in large colonies on remote oceanic islands, typically returning to their breeding grounds in September or October.
Nests are built in burrows or crevices, often lined with grass or feathers. Females lay a single white egg, which both parents incubate for about 55 days.
Chicks fledge after 84-120 days, usually departing the colony between April and May. Parents alternate long foraging trips to feed their single chick.
Conservation and Status
Global Conservation Status
While currently listed as Least Concern, Great Shearwaters face threats from marine pollution, particularly plastic ingestion. Climate change impacts on ocean productivity and nesting sites are potential long-term concerns. Conservation efforts focus on protecting breeding colonies and reducing marine debris.
Birdwatching Tips
- Look for Great Shearwaters from coastal headlands during autumn migration
- Join pelagic birding trips for the best chance of sightings
- Watch for their distinctive gliding flight low over the waves
- Observe them in groups around fishing boats or areas of high marine activity
Additional Information
Quick Facts
Predators
Adult Great Shearwaters have few natural predators at sea, but eggs and chicks are vulnerable to introduced mammals like rats and cats on breeding islands.
Did You Know?
- Great Shearwaters can dive up to 18 meters deep to catch prey.
- They undertake one of the longest migrations of any bird, covering over 20,000 km (over 12,000 miles) annually.
- These birds can drink seawater, expelling excess salt through specialized nasal glands.
References
- 1 3
website: BirdLife International. 2021. Ardenna gravis. The IUCN Red List of Threatened Species 2021: e.T22698201A168963992.
View source - 2
book, 2004: Brooke, M. Albatrosses and Petrels Across the World. Oxford University Press, Oxford, UK.
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