Sandwich tern

Latin Sterna sandvicensis (Lath.)
Estonian Tutt-tiir

Also known as: sea swallow, tern.
Status in Estonia
Breeding bird.

Description
The Sandwich tern is a large bird with a long and evenly pointed beak. In summer, the top half is light grey, the lower half is white, and the wings have a wide white rear edge. The outer 4–5 primary feathers darken over the summer, forming a greyish-black wedge on the wing tip. The legs and beak are black, the beak tip is yellow. In winter, the forehead and crown are white with only a narrow dark ‘face mask’ remaining.

Size
Body length 37–43 cm (incl. tail feathers 6–9 cm), wingspan 85–97 cm, body mass 180–300 g.

Similar species
Arctic tern, common tern.

Distribution
It is distributed across a scattered area of Europe; less so in Asia. In Estonia, local distribution is mainly in the Väinameri Sea, in the Gulf of Riga and on Saaremaa’s west coast islands and islets.

Population
Estonia has 800–1100 breeding pairs.

Occurrence in Estonia
It arrives in the spring at the end of April or the beginning of May and usually departs in mid-September, with the last birds leaving in October.

Diet
This bird is piscivorous; it rarely consumes molluscs, chicks, or insects. Kleptoparasitism occurs; fish is stolen from between the beak of another bird (this is only worth it with big fish).

Habitat
It lives on islands and islets and on the coast.

Nesting
Colonies form on level surfaces but less frequently on grassy pebbles. A typical courtship ritual involves the male bird feeding fish to the female bird. The nests are built a few dozen centimetres apart from others. In May or June, the female bird lays 2–3 eggs in a hollow on the ground with thin lining, which are incubated by both parents for 18–23 days. They begin incubating after the first egg is laid, so the chicks hatch at different times and the younger ones frequently die from hunger. Parents often catch dragonflies for their young. The chicks can fly after a bit less than a month.

Conservation status and protection
It belongs to the protected species of category II. The main threat is trampling of nests along the coast.

Distribution and population in Lääne County
The Sandwich tern is an uncommon breeding and migratory bird with a local distribution in Lääne County. In Matsalu National Park, Sandwich terns are often seen in Cape Puise. Sandwich terns are particularly noticeable and loud during the summer months on Cape Põõsaspea.
Sandwich terns nest on small sea islands. Some breeding colonies also remain on the territory of Matsalu National Park.