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Using Restoration and Management to Recover Pitcher's Thistle and Improve Habitat Conditions for the Great Lakes Population of Piping Plover
Midwest Region, October 15, 2012
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Pitcher's thistle (Cirsium pitcheri) with one flower at full bloom.
Pitcher's thistle (Cirsium pitcheri) with one flower at full bloom. - Photo Credit: U.S. Fish & Wildlife Service
Pitcher's thistle (Cirsium pitcheri)
Pitcher's thistle (Cirsium pitcheri) - Photo Credit: Dr. Timothy Bell

A Great Lakes Restoration Initiative project is benefiting the federally threatened Pitcher’s thistle (Cirsium pitcheri), and the federally endangered Great Lakes piping plover (Charadrius melodus). When completed, the project will increase the size, area occupied, and viability of two restored populations of Pitcher's thistle at Illinois Beach State Park and at the Indiana Dunes National Lakeshore. The primary objective of this project is to meet the recovery goals for Pitcher’s thistle by restoring two viable populations of this species. The secondary objective of this project is to provide habitat management to benefit both Pitcher's thistle and the piping plover by removing invasive plant species that decrease the reproductive potential of both species. These objectives are complementary because the restored thistle populations occur in designated critical habitat for the piping plover.

 

Work began in the spring and fall of 2010 with the planting of over 1,000 Pitcher’s thistle seeds north of the Dead River at Illinois Beach State Park. In addition, a nursery was established in early summer 2010 at Illinois Beach State Park using Pitcher’s thistle plants grown from seed, which were either collected from the wild or produced from gardens at the Chicago Botanic Garden. Twenty juveniles were established in the nursery, and an additional seven juveniles were planted in the vicinity of the seed planting north of the Dead River. Five of the seven transplanted juveniles survived. Survival in the nursery was also very high; however, subsequent monitoring of the spring seed planting indicated low establishment rates. For this reason additional seeds were planted in the fall of 2010 and spring of 2011.

Also during the spring of 2011, a population viability analysis was conducted comparing plants introduced at Illinois Beach in the 1990s from Wisconsin (Kohler-Andrae State Park), Indiana (Indiana Dunes National Lakeshore), and Michigan (Warren Dunes State Park and Saugatuck) seed sources. Annual demographic monitoring data, consisting of survival, growth and reproduction of each transplant, were also used to compare the plants introduced from the three seed sources. Preliminary analysis indicates that the transplants from the three seed sources differed in their demographic characteristics. The plants from the Michigan seed source (Warren Dunes State Park and Saugatuck) had the highest population growth rate, and persisted longer, whereas the opposite was true for the Wisconsin seed source (Kohler-Andrae State Park), with the Indiana Dunes seed source being intermediate. These differences may be a consequence of the difference in fecundity exhibited by the plants from these three seed sources: Michigan has the highest fecundity, Wisconsin the lowest, and Indiana is intermediate.

During July 2011, demographic monitoring and seed collection for Pitcher’s thistle was conducted at Kohler-Andrae State Park. Also in 2011, invasive plant removal was conducted at Illinois Beach State Park, and Pitcher’s thistle seeds were harvested from the nursery at Illinois Beach State Park. In August 2011, demographic monitoring of Pitcher’s thistle was conducted at the reintroduction at Illinois Beach State Park and at Kenosha Dunes Natural Area. Seed from approximately 27 Pitcher’s thistle plants was harvested from Hoffmaster State Park and will be sown within appropriate habitat at Illinois Beach State Park.

In January 2012, a total of 250 Pitcher’s thistle seeds were planted inside and outside of cages in five replicates to test whether small mammals may be eating seeds that are planted. By May 5, 2012, it was evident that germination was significantly higher inside (16 percent) than outside (4 percent) the exclosure. It appears that small mammals are eating the seeds and reducing seedling establishment.

In April 2012, an additional 1,200 seeds and 47 seedlings were planted in exclosures at Illinois Beach State Park, but the 2012 drought has taken its toll.  By August 2012, only five transplants survived. Although efforts to establish a population of Pitcher’s thistle at Illinois Beach State Park has had limited success, the process has provided information on seed survival and introduction techniques that will benefit future efforts.


Contact Info: Cathy Pollack, 847/381-2253 ext. 28, cathy_pollack@fws.gov



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