Endangered Bat Colony: Strategy for Protection

Endangered Bat Colony:  Strategy for Protection


Existing derelict house containing the bat colony. Entrance is the square opening to the attic.

The maternity colony of endangered Townsend’s Big-Eared Bats is one of only three known on Vancouver Island.  It has been roosting every summer for at least 15 years (probably longer) in a derelict house in the Qualicum area of Vancouver Island.  The house is in danger of collapsing and, due to financial considerations, the house containing the property is no longer a protected site.  The property will need to be sold in the next year or two.  This means that, most likely, the existing derelict house (if it hasn’t yet collapsed) will be removed to enable the site to be used for residential purposes.  The current owners of the property (a mortgage company which was initially created to provide funding to help support conservation work) are extremely concerned about the ongoing protection of the bats, and do not want to see them put at undue risk, so they have asked NTLCBC to help find a solution.


NTLCBC is currently working with biologists and staff from the BC Ministry of Environment and Climate Change Strategy, who are responsible for the management of threatened species.  Together, we have developed an innovative strategy which, we hope, will ensure a positive future for the bat colony.  PLEASE NOTE:  this approach is experimental – it has never been tried before.  As such, there are some inherent risks (see details below).  However, after much consideration and consultation, we believe it is the best option available to us (and the bats), and that it actually has a very good chance of success.


Step 1:  Construct a new “bat house.”  This new bat house is designed to replicate (as much as possible) the conditions in the attic of the old house, where the bats have been roosting for years.  However, it will be moveable – built in such a way that it can be loaded on to a flat bed truck and relocated as necessary.  This structure was built in early 2019, with the help of a group of dedicated volunteers from the area.

New “bat house” under construction

Completed bat house. Note it is on blocks to enable it to be lifted and moved.

Connection between the new structure and the existing bat house (attic).









Step 2:  Connect the new bat house to the attic of the old house through a short passageway, and allow the bats to move at will between the two structures during the entire nursing season (approximately May to October).  This connection was completed prior to the bats arriving at the site, and through the summer they increasingly began to use the new structure.  This migration was assisted by “seeding” the new structure with a small amount of bat guano from the old house.  As the bats increasingly used the new structure, their own use continued to seed it even further.

Step 3:  Monitor use of the new bat house, as well as ambient environmental conditions.  A motion-controlled video camera and temperature monitors were installed at the beginning of the season, providing environmental data as well as visual proof of the bats’ use of the new structure throughout the summer.

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Click on the above videos of the bats using the new bat house.  Note the bats roosting between the roof joists on the right.  Also note them entering and leaving the structure through the tunnel into the old bat house (attic).


Step 4:  Remove the old house.  Once the colony leaves for the winter (usually be mid t0 late October), we will take down the old house.  At that time we will re-orient the new structure so that its opening is in the same location (and orientation) as the old house (i.e. replacing the old house with the new one).  Hopefully, when the bats return in the spring of next year, they will occupy the new house, recognizing it from its location and its familiar smell – as though nothing has changed.

Step 5:  Relocate the new bat house.  Once the bats are established in their new home (exactly how long that will take is still to be determined), the external opening will be boarded up (early in the day, when all of the bats are inside).  The structure will be carefully lifted on to a flat bed truck and moved to a new site nearby where they will be afforded conservation protection into the future.  Once at the new site, the structure will be opened to allow the bats to come and go.  Hopefully, the bats will simply adjust to their new site with their “home” at the centre of a new range.

Step 6:  Bats return to new site.  After spending much of the season getting oriented at the new location, (and with the new generation of bats born that year knowing no other site) it is hoped that the bats will simply return to the new location in future years.

This strategy, as mentioned has some inherent risks associated with it.  There are still some details of the strategy that are still under discussion, that may help mitigate some of those risks.  Most significantly, the owners of the property have offered to subdivide the site by carving off a small portion at the edge of the property (about 100 feet away from the existing house site) to create a small “conservation area” that would continue to be owned either by the Province or by NTLCBC.  This would allow the owners to sell the remainder of the property unencumbered and recover the funds loaned to the mortgage company by their investors.  The new structure would be relocated to this new area, rather than being taken to a nearby conservation area.  This would significantly increase the potential that the bats would continue to use this facility as it remains in almost exactly the same geographic location.  Consideration of this option is currently underway.  Please check back for further updates.

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