Bats

Bats help the ecosystem by eating insects – consuming up to half their weight every night. All 16 species of bats in B.C. are protected from being killed and harassed under the Wildlife Act.

Bats can carry fleas, mites, ticks and bat bugs (which are similar in behaviour and appearance to bed bugs). In rare cases they contract rabies – they tend to get sick and die before becoming aggressive. 

Removing Bats from Buildings

If bats are roosting in an area that isn't interfering with human activity, consider leaving them undisturbed. They won't destroy wood, wires or insulation. It is illegal and ineffective to remove bats:

  • Using pesticides
  • Playing loud music
  • Installing ultrasonic devices
  • Scattering mothballs
  • Setting up bright lights

If a bat has entered the living area of your building, try getting them to leave on their own by:

  • Closing interior doors
  • Opening outside doors and windows
  • Turning off the lights

A sleeping bat can be safely picked up by using a pillowcase as a glove. Place it in a safe spot, out of reach of cats.

Prevention

Keeping up with building maintenance is the best way to prevent bats from entering. Do regular inspections and block any entrance points (bats can enter through a dime-sized hole or crack) under eaves or around pipes, vents, doors and windows. Before doing so, make sure there are no bats still inside.

Find out where bats are getting in

  • Listen for squeaks
  • Look for brownish oil stains in walls – evidence that they've been squeezing through small cracks
  • Check for bat droppings (guano) on the ground where they enter and exit
  • At dusk, watch for bats flying out of the suspected entrance to find food
  • Check areas a metre or more off the ground, near wall and roof joints and under loose chimney flashing
  • Check for unscreened louvres and air intakes, gaps in the fascia boards, along the eaves and near dormer windows

Prevent bats from re-entering

Install a one-way escape hatch and leaving it in place for several nights – especially during colder weather when they may be hibernating:

  • Use polypropylene bird netting or fly screen to make a large flap over the escape hole
  • Use duct tape or staples to attach the netting above the exit
  • The netting should hang loosely and extend at least 20 cm on each side and below the exit point

Living with Bats in Buildings

Sometimes it's not possible to evict bats. For example, they frequently roost under wood shakes on roofs or under cedar siding. In these cases, the best option is to learn to live with the bats, especially since they do not damage the building.

Hosting a bat roost is also beneficial to the environment (and to farmers):

  • Ensure that there is no way for bats to find their way into human living quarters
  • Install flooring to cover ceiling joists
  • Cover the flooring with plastic for easy cleanup and removal of bat feces
  • Limit the number of entries by blocking undesirable access points
  • Do any repair work and a seasonal cleanup in late November or December when bats have left their summer roosts

Be careful not to disturb a bat hibernation site. This can cause them to burn off valuable stored energy and die of starvation.

Bat Feces

Bat feces (guano) may be stinky but it also makes an excellent fertilizer for the garden.

In extremely humid environments, guano dust can carry a disease organism that causes a lung infection called histoplasmosis. This is rare in the Pacific Northwest, although it is common in other regions. Always wear a respirator mask when investigating or cleaning a bat roost.