Wilson's Warbler

Cardellina pusilla

Wilson's warbler is a small New World warbler. It is greenish above and yellow below, with rounded wings and a long, slim tail. The male has a black crown patch; depending on the subspecies, that mark is reduced or absent in the female. It breeds across Canada and south through the western United States, and winters from Mexico south through much of Central America. It is a very rare vagrant to western Europe. Source

Where it is now

In the last 8 weeks this bird was recorded 28,714 times across 50 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 11 to 23°C, from 42 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 13°N in October to 57°N in June, about 4,900 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.