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published and unpublished data for the Hills thistle.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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