Our Wild Neighbors

Big Brown Bat

Eptesicus fuscus

A citizen of Southern Canada

Image of a Big Brown Bat, in flight, seen from a front three-quarter view, mounted on a wooden board.

Description of the animal

  • This bat belongs to the Chiroptera order, the only order of mammals capable of flight.
  • It ranges from 10 to 13 centimetres long. Its wings, fully extended, span between 28 and 33 centimetres.
  • Its body is covered with shiny brown fur.
  • The wings and tail are darker, and consist of a thin membrane of skin stretched over five fingers.
  • It weighs about 16 grams. The Big Brown Bat is about twice as heavy as its cousin, the Little Brown Bat.

Habitat and needs

  • Big Brown Bats are insectivorous.
  • In the summer, they go out to hunt in the twilight.
  • They use echo-location (sonar) to spot their prey, and capture their victims in the folds of their wings.
  • They make their nests on ledges or in natural shelters such as hollow trees or caves.
  • They hibernate from October to May.


  • Human activity has destroyed many of their natural shelters. Sometimes they choose to move into houses.
  • Bats are not dangerous. They have only rarely attacked human beings. All the same, they can carry rabies. If bitten, consult a doctor at once.

Living with them

  • It would be a shame to drive bats away, for their voracious appetites make them a precious ally in reducing the number of insects in your yard.
  • Block any entries to the attic that might allow them to move in. Or, you can build nesting boxes.
  • To eliminate the smell of their droppings (guano), spread sand around the base of nesting sites.

Participating cities where this animal has been seen