Arctic Tern

Sterna paradisaea

The Arctic tern is a tern in the family Laridae. This bird has a circumpolar breeding distribution covering the Arctic and subarctic regions of Europe, Asia, and North America. The species is strongly migratory, seeing two summers each year as it migrates along a convoluted route from its northern breeding grounds to the Antarctic coast for the southern summer and back again about six months later. Recent studies have shown average annual round-trip lengths of about 70,900 km (38,300 nmi) for birds nesting in Iceland and Greenland, and about 48,700 km (26,300 nmi) for birds nesting in the Netherlands, while an individual from the Farne Islands in Northumberland with a light level geolocator tag covered a staggering 96,000 km (52,000 nmi) in ten months from the end of one breeding season to the start of the next. These are by far the longest migrations known in the animal kingdom. Source

Where it is now

In the last 8 weeks this bird was recorded 154 times across 13 areas (each area is a 5 degree square).

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Movement and weather

Each season it is first heard regularly where daytime highs are around 12°C (typically 10 to 13°C, from 5 areas).

Arrival dates

The week it was first heard regularly in each region, after at least six weeks away. Dates differ from south to north, so a region has a range.

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Figures are effort corrected and come from automatic sound identification, which makes mistakes. How this is measured and how it compares with human observers.