Hen Harrier

Circus cyaneus

The hen harrier is a bird of prey. It breeds in open areas such as marshes and grasslands in Eurasia and is migratory, moving further south outside of the breeding season. Birds in milder regions, such as France and Great Britain, may be resident year-round, but the higher altitudes are largely deserted in winter. The species is sexually dimorphic; males are smaller and mostly grey and white with black wingtips, whereas females average larger and are predominantly brown and have buff underparts with brown barring. Both sexes have a white rump patch, although it is more noticeable on females and juveniles. Source

Where it is now

In the last 8 weeks this bird was recorded 4,840 times across 25 areas (each area is a 5 degree square).

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Movement and weather

Over the weeks it was present in the past year, its centre in Europe ranged from 52°N in October to 65°N in August, about 1,500 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.