Merlin

Falco columbarius

The merlin is a small species of falcon from the Northern Hemisphere, with numerous subspecies throughout North America and Eurasia. A bird of prey, the merlin breeds in the northern Holarctic; some migrate to subtropical and northern tropical regions in winter. Males typically have wingspans of 53–58 centimetres (21–23 in), with females being slightly larger. They are swift fliers and skilled hunters, which specialize in preying on small birds in the size range of sparrows to doves and medium-sized shorebirds. In recent decades, merlin populations in North America have been significantly increasing, with some merlins becoming so well adapted to city life that they forgo migration; in Europe, populations increased up to about 2000, but have been steady subsequently. The merlin has for centuries been well regarded as a falconry bird. Source

Where it is now

In the last 8 weeks this bird was recorded 30,216 times across 110 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 17°C (typically 5 to 26°C, from 41 areas). That range is wide, so temperature alone does not explain when it turns up.

Over the weeks it was present in the past year, its centre in North America ranged from 42°N in July to 58°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.