Sunday 7th May comments: It’s that time of year when the Isle of May starts to change again, as it gets a bit noisier and a bit more pecky…because the Terns are back! The Arctic Tern has mainly grey upperparts and white underparts with distinctive red bill and feet. The head and crown is black and contrasts with the white cheeks. The bird has a deeply forked tail and the birds look very elegant in flight. The species has a circumpolar breeding distribution covering the Arctic and sub-Arctic regions of Europe, Asia and North America and in recent days have just arrived back on the Isle of May.
Arctic Terns are highly migratory and they arrive back in Isle of May waters in late April (but were delayed a little bit this year due to poor weather). In the first two weeks of May pairs will conduct vocal aerial displays over the known breeding grounds and form nightly roosts near the jetty on the island. Soon after copulation and egg laying will begin (usually around 20th-25th May) and Arctic terns are highly aggressive towards any intruders as they will attack humans (and large predators), usually striking the top of the head (and capable of drawing blood). In the Arctic, they have been known to repel Polar bears!
The nest site is usually a depression in the ground and both sexes share incubation duties, sitting on eggs for 22-27 days. The majority of pairs will lay clutches of 2-3 eggs whilst a clutch of four is rare. Once the young hatch they are looked after by both parents and take just 21-24 days to fledge. Arctic Terns are surface feeders, plunging into the sea from a height, catching various small fish and marine invertebrates. Once the chicks are on the wing, the family parties start departing the island from early August and then begin one of the world’s most incredible journeys but more on that later in the season. It’s just good to have them back!
Isle of May National Nature Reserve 