Big Brown Bat

Eptesicus fuscus

The big brown bat is a species of vesper bat distributed widely throughout North America, the Caribbean, and the northern portion of South America. It was first described as a species in 1796. Compared to other microbats, the big brown bat is relatively large, weighing 15–26 g (0.53–0.92 oz) and possessing a wingspan of 32.5–35 cm (12.8–13.8 in). Source

Where it is now

In the last 8 weeks this bat was recorded 51,769 times across 35 areas (each area is a 5 degree square).

See the Big Brown Bat on the live map

Movement and weather

Over the weeks it was present in the past year, its centre in North America ranged from 39°N in October to 50°N in July, about 1,300 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.

Download every area as CSV

Figures are effort corrected and come from automatic sound identification, which makes mistakes. How this is measured and how it compares with human observers.