Grosse Île and the Irish Memorial National Historic Site of Canada

Natural Heritage



Results of Studies

Inventory of floerkea false mermaid population

Marineau, K. 2008. Inventory of false mermaid population. Grosse Île and the Irish Memorial National Historic Site of Canada. Kim Marineau, Consultant for Parks Canada, Québec Field Unit, 18 p. + appendices.

The false mermaid is an endangered plant species in Quebec. Its population on Grosse Île is one of the most northern of the province. Over the last 12 years, the mermaids appear to have been affected by various factors and have experienced a drastic decline.

The inventory carried out in 2008 demonstrates that its population consists of about a thousand individuals only, compared to 5000 in 1996. Measures have been recommended to protect this species, including the installation of exclosures to avoid the plant being trampled and grazed by white-tailed deer.

Monitoring of butternut – nut harvest Monitoring of butternut – nut harvest
© Parks Canada / B. Roberge

Butternut population

Roberge, B. 2008. State of butternut population. Grosse Île and the Irish Memorial National Historic Site of Canada. Parks Canada, Québec Field Unit, 25 p. + appendices.

This study evaluated the population of the butternut on Grosse Île at more than 89 individuals in 2005. Taking into consideration a number of unregistered individuals, the total population of butternut could be as high as 125. Their average diameter is between 21 and 30cm.

The butternut on Grosse Île is found mainly in the following habitats: American birch stands and skunk cabbage (28.1%), swamp alder, dogwood, skunk cabbage and hellaborne areas (24.7%), and stands of red maple, hemlock and white birch (19.1%).

Among the stress factors affecting the butternut on Grosse Île are butternut canker (40.4%), fungus and diseases (4.5%) as well as scratching by white-tailed deer (4.5%).

Taking into consideration its geographical isolation, the possible presence of butternut canker and competition from other nearby species, the small population of butternut on Grosse Île is in a precarious position and could disappear.

Management plan for plants of interest

Vaudry, R. 2003. Management plan for plants of interest. Grosse Île and the Irish Memorial National Historic Site of Canada. Parks Canada, Québec Field Unit, Québec. 53 p. + appendices.

The floral biodiversity of Grosse Île is of particular importance: 600 species exist, several of which are rare plants. Several communities of vegetation make up the flora of the island.

A management plan for plants of interest was developed to preserve and protect Grosse Île. More than 140 species were classified and ranked by priority. Management measures have been developed for each of these identified plants.

Great grey owl at Grosse Île during migration Great grey owl at Grosse Île during migration
© Parks Canada

Wildlife inventory of Grosse Île

Salathé, M., and J.P. Savard. 1993. Wildlife inventory of Grosse Île with emphasis on birds. Report produced by the Wildlife Canadian Service for the Canadian Parks Service. Environment Canada. Parks Canada, Québec Field Unit, Québec. 27 p. + appendices.

An inventory of wildlife resources was carried out on Grosse Île during the summer of 1992. The island was divided into two sectors: the wooded and populated areas. Inventories were conducted along the trails crossing the island. Every bird observed was recorded, while birds observed outside of the census were also noted. Small mammals were sampled using 100 Sherman and Victor type traps. The research allowed us to characterize amphibians and reptiles.

More than 68 species of birds were spotted. The wooded sector of the island was home to 44 species, the most common being the red-eyed vireo, the veery and the Northern wren. The populated sector was home to 33 species, the most common being the song sparrow, European starling and fawn warbler.

Two small species of mammals are found in all habitats of the island, the deer mouse and the meadow vole. Several other types of mammals were also observed.

Two species of reptiles, the garter and ringneck snakes, and six species of amphibians, the green frog and the wood frog were surveyed. Further investigations will be required to characterize all of the wildlife resources on the island.

Installing a telemetry transmitter on a bat Installing a telemetry transmitter on a bat
© Parks Canada

Study and preservation of bats

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.

Preparing an artificial dormitory Preparing an artificial dormitory
© Parks Canada

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.