Sandwich tern

Thalasseus sandvicensis

While similar in size to a black-headed gull, Sandwich terns are easily distinguished by their slender pale wings, short forked tail, crested black head (most visible in the spring and early summer) and long black pointed bill with a yellow tip.

Some people affectionately refer to them as ‘sarnies’ and say it looks like the tips of their bills have been dipped in butter or a dab of mustard.

One of only a handful of bird species to be named after a place in the UK, Sandwich terns are named after Sandwich Bay in Kent. They are regularly seen around the Solent where breeding numbers have remained steady over the last few years thanks to habitat management and community engagement.

Sandwich terns travel here in early March from their winter home in Africa. They head south again in the autumn, some to as far as Namibia or beyond.

All about Sandwich terns

The largest of all terns, measuring about 40cm in length with a wingspan of about a metre. Most distinctively from other terns, their black heads have a spikey crest for the first few months of the breeding season. Their black heads become speckled while they’re incubating their eggs and then turn white before they migrate back to Africa for the winter.

Proportion-wise, they have a front-heavy look, due to their relatively short tail and large head. The bill is also long and thick.

In flight, they reach greater heights than other tern species, and typically travel with their head and bill pointing down.

Feeding

They rarely hover, but you will often find them diving into the sea with a large splash, submerging themselves under for longer than other terns: you might hear a loud ‘smack’ as they enter the water. They hunt for species such as sand eels, sprats and whiting.

Breeding

Despite being the largest tern to breed in the UK, Sandwich terns are surprisingly gentle, so are often found nesting with the more aggressive black-headed gulls to avoid predation.

Their courtship is both elaborate and noisy with pairs lifting high into the sky, often accompanied by several other birds, before executing a fast, downward dive flying very close to each other, or even on occasion touching.

This species will nest exclusively in coastal locations, such as shingle and sandy beaches and islands close to the shore. Once the breeding season has started, around the end of April, the adults will make a scape on the ground with little to no lining for the eggs. Instead, the eggs are camouflaged to blend in with rocks.

The female will lay 1-2 eggs and are incubated by both adults for 21-29 days.

Though the young fly after 28–30 days, they will continue to be cared for by their parents for a further 3 months.

Local spotlight

The Solent remains a stronghold for breeding Sandwich terns.  While these birds are not strictly monogamous, if a pair successfully breeds for 4 years they will probably remain together for life.

Conservation status

UK conservation status is amber as annual productivity is highly variable due mainly to predation.

Sandwich terns are a qualifying feature for the Solent and Southampton Water Special Protection Area and the Chichester and Langstone Harbour Special Protection Area – that means, when the sites were designated, a nationally significant number of the species used the areas.