Thistle monitoring takes to the sky
by Amy Adair
One of the longest-running research projects in Pukaskwa National Park is being updated with 21st century technology. Monitoring of Pitcher’s Thistle populations in Pukaskwa National Park began in 1981. Originally, each plant was marked with a uniquely numbered tag so their life cycle could be observed from tiny seedling to flowering plant. This summer, staff started using a drone to collect aerial photographs of the colonies.
Pitcher’s Thistle is a species at risk that is endemic to the sandy beaches of the Great Lakes, with two of the most northerly populations located in Pukaskwa. Pitcher’s Thistles are inconspicuous silvery rosettes for the majority of their 2 to 11 years of life. During this time they are developing a deep taproot in the shifting, nutrient-poor sands of the Great Lakes' beaches. This taproot stabilizes the plant and provides nutrients for the production of hundreds of wind-borne seeds during the last year of its life.
Drone flying is a popular hobby and useful in many fields of work. However, they also pose risks and can disturb wildlife and visitors. For these reasons, all Parks Canada places are “no drone zones” for recreational use. Please leave your drone at home.
Field Unit Superintendents may authorize limited use of drones for non-recreational purposes such as:
- natural and cultural resource management
- public safety
- law enforcement
- park/site management purposes (including filming and photography for outreach, education and promotional purposes)
Restoration efforts in Pukaskwa National Park were spurred by the burst of a beaver dam upstream from a population of Pitcher’s Thistle in Oiseau Bay. The resulting habitat change and encroaching vegetation restricted the colony’s growth. In 1991, staff collected seeds from this dwindling colony and dispersed them in suitable habitats elsewhere in Oiseau Bay, as well as, at Middle Beach near the Hattie Cove Campground. If you take a hike along Middle Beach today you will be able to see a restored, healthy, and self-sustaining population of these slow-growing thistles.
Each year, Resource Conservation staff count the number of plants growing in each of the colonies in order to track the recovery of these populations. Colonies are also re-seeded periodically to ensure an even age distribution of plants. Aerial photographs are a new addition to Pitcher’s Thistle monitoring and restoration efforts. After marking each plant in the colony with an orange flag, staff are able to take high resolution photographs of the colonies using a drone. These photos easily show the full extent of each colony, as well as the type of habitat Pitcher’s Thistles are growing in successfully. Furthermore, each photo is geo-referenced, allowing for direct comparisons of habitat availability and colony size from year to year.
Drone flights are quick, requiring only about 20 minutes to fly and photograph a complete grid of each colony. They also provide a unique and useful aerial perspective, which otherwise could only be obtained through an expensive helicopter survey. This winter park staff will be investigating additional ways that this technology can contribute to the Ecological Integrity Monitoring Program in Pukaskwa National Park.