Midwest Region Conserving the nature of America

Conserving the Nature
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The mission of the U.S. Fish and Wildlife Service is working with others to conserve, protect, and enhance fish, wildlife, plants, and their habitats for the continuing benefit of the American people.




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Species of Concern

Region 3 Decision on the
Status Recommendation for the Hill's Thistle (Cirsium hillii)

We, the U.S. Fish and Wildlife Service, have determined that the Hill's thistle (Cirsium hillii) does not warrant elevation to Candidate Species status. Our decision was based on a rangewide status assessment completed by Mike Penskar (Michigan Natural Features Inventory) and other relevant published and unpublished data for the Hills thistle. Although Hills thistle (Cirsium hillii) does not warrant Candidate Species status at this time, it will remain as a regional "Species of Concern."


"Species of concern" is an informal term that refers to those species which may require some conservation actions but which are not threatened with extinction. The conservation actions needed will vary depending on the health of the populations and types and degree of threats. At one extreme, there may only need to be periodic monitoring of populations and threats to the species and its habitat. At the other extreme, a species eventually may require listing as a Federal threatened or endangered species and become the subject of a Federal recovery program. Species of concern receive are not provided legal protection under the Endangered Species Act, and the use of the term does not necessarily mean that the species will eventually be proposed for listing as a threatened or endangered species. As funding and staffing levels permit, we evaluate Species of Concern to determine the extent of their conservation needs and to determine whether additional legal protection should be sought for them.


Hill's thistle historically and currently occurs in Illinois, Indiana, Iowa, Michigan, Minnesota, Ohio, Wisconsin, and Ontario, Canada. Although its geographical distribution has not changed, populations of Hill's thistle have been extirpated. Despite a decline in the number of populations, 212 (58%) populations persist, 152 (72%) of which are C ranked or higher (secure for at least the next 5 to 10 years), and 39 are A or B-ranked (viable in the long-term). The ranks refer to The Nature Conservancy's Element of Occurrence Ranking Criteria.


Woody succession and outright habitat loss are the primary threats to the species, and could pose a threat to the species' persistence if they go unchecked and intensify. While there is insufficient evidence to show that these ongoing threats currently jeopardize the continued survival of Hill's thistle, they are sufficiently serious to warrant retention on our Species of Concern list.


We recommend that the following management activities be carried out to improve the status of Hill's thistle:


1) Monitoring should continue at several sites across the range, particularly at those sites with unknown status and in Indiana and Iowa where persistence appears tenuous.


2) Protection should be secured, through conservation easements or acquisition, and management initiated/continued for populations classified as A or B-ranked.


3) A rangewide review should be reinitiated within five years to reevaluate the status and trend of Hill's thistle in light of any new information obtained from subsequent monitoring and management efforts.


Questions concerning this species should be directed to our East Lansing, Ecological Services Field Office which has the lead responsibility for data collection and analysis for this species. Questions about the process of listing a species as threatened or endangered should be directed to the Regional Listing Coordinator at 612-713-5346.

February 16, 1999


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