Royal Tern

Thalasseus maximus

The royal tern is a tern in the family Laridae. The species is endemic to the Americas, though vagrants have been identified in Europe. Source

Where it is now

In the last 8 weeks this bird was recorded 44,489 times across 26 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 28°C (typically 25 to 31°C, from 8 areas). That holds across 20° of latitude, which suggests its timing follows temperature more than the calendar.

Over the weeks it was present in the past year, its centre in North America ranged from 17°N in June to 34°N in August, about 1,800 km apart.

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.