Least Bittern

Ixobrychus exilis

The least bittern is a small heron, the smallest member of the family Ardeidae found in the Americas. This species was formerly placed in the genus Ixobrychus. Source

Where it is now

In the last 8 weeks this bird was recorded 1,311 times across 37 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 27°C (typically 17 to 31°C, from 10 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 26°N in October to 40°N in May, about 1,600 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.