Monitoring the Mingan Thistle

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Monitoring the Mingan Thistle

The meadow thistle ( Cirsium scariosum ), also known as the "Mingan thistle", is a species at risk. In Canada, it is only observed in a small zone in southern Alberta and British Columbia. It is also found in the region known as La Minganie : 99% of the plants grow in the park. The thistle is considered a threatened species in each of the provinces where it grows.

Mingan Thistle
© Parks Canada / C. Kavanagh

Since 1995, the thistles of the archipelago have been under study. A numbered metallic tag is planted into the ground near each plant. Every year, the plants are counted and measured. The number of leaves is counted, and the locations of the plants are indicated on maps. Such data provides a good idea of the growth and decline of the colonies. It is also used to predict the colonies long-term chances of survival.

Since 1995, 600 plants have been identified on average each year in the entire park. They are grouped into nine colonies that are spread over four islands. The number of plants per colony varies greatly from one year to another, notably owing to weather conditions. They also varies from one colony to another. In 2001, the number of plants per colony varied from 2 to 245. No colony had more than 270 individuals, the minimum required to ensure long-term survival.

A recovery program was started in 2001 to increase the number of plants in the most vulnerable colonies. The method used involves first locating the plants in flower. Then a net must be set up to catch the seeds on the flowers once they have been pollinated by the insects. Finally, the seeds caught in the net are harvested and planted under a metallic grid to protect them from birds and mammals. Tests have shown that the rate of germination is four times higher when the protective grid is used. In 2001, a total of 130 seeds were planted in 3 colonies.

Saving this species depends on all of us. Our role consists of monitoring the Mingan Thistle, re-establishing the most precarious colonies and implementing the necessary measures for the species' survival. Your role : when walking along the seashore, stay within the vegetation-free zone. This way, you will help protect the Mingan thistle as well as other rare plant species. During your activities in the park, stay away from the sectors identified with survey markers and metallic tags. These landmarks indicate the presence of particularly fragile resources.

Your collaboration is essential to ensure the survival of this precious resource, the Mingan thistle.