Bat Ecology

Print Version (PDF - 23KB)

Fall 2009


The main types of bat found in Ontario are the little brown bat and the big brown bat. The less common species are the eastern pipistrelle, silver-haired, hoary, red, small-footed, and northern long-eared.

Life Cycle:

Breeding usually occurs in late summer or early autumn and the female stores the sperm until the following April when the female ovulates and the egg is fertilized and implanted. The female gives birth 60 to 90 days later. There are usually one or two young. The young usually stay under parental care during June and July. No nest is required, as the young are able to fly and obtain their own food in just three weeks.


The little brown bat has silky reddish-coloured fur and is approximately 4-5 centimetres (cm) long and weighs eight grams. The big brown bat has pale to dark brown fur and is approximately seven cm long and weighs 15-24 grams.



Bats hibernate from November to March. The big brown bat is the most likely species to hibernate in buildings like houses and barns. Little brown bats prefer caves or mines.


Bats are located throughout most of Ontario, preferably near fresh water. Bats select attics for nursery colonies. Bats can squeeze through very tiny spaces (as small as six millimetres) and this is how they access many roosting areas. If people notice excess odour and droppings it means the Bat colonies are large and this can pose a health risk.


Bats eat insects. One bat can consume hundreds of flying insects each night during the summer. They locate food by using echolocation which involves bats sending out signals and when the echo of that signal bounces back to them they can identify where objects are located.


Bats are nocturnal animals. They feed at night and are most active in the second and third hours following sunset. During the day they roost in trees and buildings.



Owls prey on bats at night. During the day, snakes or raccoons may prey on bats while they are roosting.


In North America, bats are carriers of rabies. People should avoid bats seen flying during the day or crawling on the ground. They are most likely sick or injured. As with any animal, if you must handle it, always wear gloves and if possible use forceps or tongs to pick it up. Place it in a sealed container with air holes. If it has come into contact with humans or pets, contact your local health unit for advice if it's alive, or the Canadian Food Inspection Agency if it is dead. Bat bites are not always noticeable. If a bat is found in a bedroom where a person has been sleeping, safely attempt to capture the animal and contact your local health unit immediately for advice.



Natalie Gorman
Ministry of Natural Resources


Disponible en français

Related Links