Study and preservation of bats

Grosse Île and the Irish Memorial National Historic Site

Henry, M. 2001. Preservation of bats in historical and natural sites: Recommendations for the management of small brown bat colonies at Grosse Île and the Irish Memorial National Historic Site of Canada. Université de Sherbrooke. Presented to Parks Canada, Québec Field Unit, Québec. 16 p.

In 1997, major colonies of small brown bats, estimated at between 5000 and 7000 individuals, were found in several historic buildings on Grosse Île. However, the restoration of one of these buildings in 1998 (a former lazaretto) saw the dispersal of 2000 bats that lived there. The two remaining colonies on Grosse Île, containing more than 200 females each, are in turn threatened by future restoration projects.

Out of concern for the preservation of the bat population, Parks Canada chose to relocate these colonies to artificial dormitories specially designed for this purpose. Two large dormitories, raised on pilings, were placed at the bats’ disposal, and a third dormitory was integrated in the restored lazarreto’s attic space.

A study of the bat population was carried out in 1999 and 2000 to establish proper management and conservation measures. Various projects have addressed the reproduction and annual migration of females, thermal requirements of reproductive females, and the importance of foraging habitats through the use, among others, of small telemetry transmitters attached to the backs of 50 bats.

The research results show the lactation period causes permanent stress in females. The smallest disturbance of a colony can lead to high infant mortality rates or the complete destruction of the colony. Recommendations for the management of bats aim to avoid the resettlement of colonies, preserve favourable habitats (bodies of water, marshes, clearings and forest edges, broadleaf or mixed and mature forests that offer high insect populations), ensure the monitoring of populations and raise public awareness of the need for their protection.

Installing a telemetry transmitter on a bat Installing a telemetry transmitter on a bat
Preparing an artificial dormitory Preparing an artificial dormitory

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