Sandwich Tern
Least ConcernThalasseus sandvicensis
Visual Identification
Sandwich Tern
Appearance
The Sandwich Tern is a medium-sized seabird with a sleek profile. Its plumage is primarily white, with pale grey upper wings and back. The bird sports a distinctive black crest and a long, slender black bill with a yellow tip. The legs are black.
During the breeding season, adults develop a full black cap extending to the nape in a spiky crest. Winter adults show a white forehead and crown.
Females and males are alike with no visual difference, although research shows that females have shorter heads and beaks, and males have longer lower legs and toes than females.
Juveniles have a barred pattern on their upper parts, darker bills and crowns that resemble non-breeding adults.
Size
Length
36cm to 41cm
Wingspan
85cm to 97cm
Weight
210g to 260g
Colours
Males and females have similar plumage
Primary Colour
White Grey
Secondary Colour
Black
Beak Colour
Black Yellow
Leg Colour
Black
Habitat and Distribution
Habitats
Woodland
Garden
Wetland
Coastal
Urban
Farmland
Grassland
Desert
Tundra
Rainforest
Mountain
Savanna
Distribution
Sandwich Terns inhabit coastal areas, preferring sandy or shingle beaches, estuaries, and offshore islands. They are found along the coasts of Europe, Africa, and the Americas, with significant populations in the North Sea and Baltic regions.
During winter, many European birds migrate to the west and south coasts of Africa. In North America, they breed along the Atlantic coast and winter in the Caribbean and South America.
UK colonies are important for the species' European population. They are scattered along the coastline of eastern and southern England, east and west Scotland, the Isle of Man, and parts of north Wales.
Elevation Range
Sea level to 100 meters
Climate zones
Temperate, Subtropical, Tropical
Distribution Map
Distribution by Region
Behaviour and Ecology
Bird Attributes
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Diet
Sandwich Terns primarily feed on small fish such as sand eels, sprats, and herring. They also consume small squid, crustaceans and occasionally insects.
These birds locate prey from the air, then dive rapidly to catch fish just below the water's surface, sometimes submerging completely.
Behaviour
Sandwich Terns are highly social, often seen in large, noisy colonies. They perform elaborate courtship rituals, including aerial displays and fish-offering.
These birds are skilled divers, plunging into the water from heights to catch fish, often hovering briefly before diving.
Vocalisation
The Sandwich Tern's call is a distinctive, harsh 'kirr-ik' or 'kerr-wick'. This loud, grating sound is often heard in flight or when the bird is alarmed. During courtship, males produce a softer, purring 'krurr-rr-rr' sound, accompanied by head-bobbing displays.
A cackling ‘gagaga’ cry is commonly heard from birds on the nest when intruders approach and may also be heard when they are defending foraging grounds.
Nesting & Breeding
Sandwich Terns breed in dense colonies, often alongside other tern species or gulls, between 100 and 4,000 pairs. Pair formation begins in April, with elaborate courtship displays, including aerial acrobatics and fish-presenting.
Nests are simple scrapes in sand or shingle, sometimes lined with vegetation. Females typically lay 1-2 eggs, which are variable in colour and can be pure white to buff-coloured with dark brown spots. Both parents share incubation duties.
Nests are at risk of being washed away by the tide, and in order to add an extra layer of protection, they often defecate around the rim of their nest scrape, with their droppings solidifying into a protective ‘ring’ which then has a greater chance of withstanding heavy rain or flooding.
Eggs hatch after about 21-29 days, and chicks fledge at 28-30 days. Parents continue to feed fledglings for several weeks after they leave the nest.
Lifespan
The Sandwich Tern typically lives for 12 years, with a maximum recorded lifespan of 30.8 years.
Like all birds, lifespan can be affected by factors including predation, habitat quality, disease, and access to food sources.
Conservation and Status
Global Conservation Status
While currently listed as Least Concern globally, Sandwich Terns face threats from habitat loss, disturbance at breeding sites, and climate change impacts on fish populations.
Conservation efforts focus on protecting nesting colonies and managing coastal habitats to ensure suitable breeding grounds.
Birdwatching Tips
- Look for Sandwich Terns along coastal areas, especially near sandy or shingle beaches.
- Listen for their distinctive 'kirr-ik' call, which is louder and harsher than other tern species.
- Observe their unique diving technique, where they plunge straight down with half-closed wings.
- In the UK, visit coastal reserves like Blakeney Point in Norfolk during the summer months.
Additional Information
Quick Facts
Other names:
Cabot's Tern
Family:
LaridaePredators
Main predators include large gulls, skuas, foxes, and rats, which often target eggs and chicks in breeding colonies.
Did You Know?
- Sandwich Terns can live for over 30 years in the wild.
- They were named after Sandwich, Kent, where they were first scientifically described, not after the food item.
- These birds can dive from heights of up to 12 meters to catch fish.
- The United States is home to an estimated 25 to 32 percent of the global population of Sandwich terns, with up to 46,945 breeding pairs.
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References
- 2
website: BirdLife International. 2021. Thalasseus sandvicensis (Europe assessment). The IUCN Red List of Threatened Species 2021: e.T22694591A166282359.
View source - 3 4
report, 2015: Wetlands International
- 1
journalArticle, 2000: Monaghan and Metcalfe, Genome size and longevity, Trends Genet, 16:331-332
View source