Forster's Tern

Sterna forsteri

Forster's tern is a tern in the family Laridae. The genus name Sterna is derived from Old English "stearn", "tern", and forsteri commemorates the naturalist Johann Reinhold Forster. Source

Where it is now

In the last 8 weeks this bird was recorded 3,657 times across 29 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 19°C (typically 15 to 20°C, from 10 areas). That holds across 25° of latitude, which suggests its timing follows temperature more than the calendar.

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.