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Recovery Strategy for the Hill's Thistle (Cirsium hillii) in Canada

Appendix C: Sites Where Hill's Thistle is Considered Extirpated

Jones (2006) revisited several sites on Manitoulin Island that had historic records for Hill's Thistle that had not been reconfirmed for 10-30 years. She found five sites no longer supported the species. In Michigan, Voss (1996) noted that although there were a number of old records from the southern part of the state, Hill's Thistle might now be extirpated in that area.

COSEWIC (2004) lists six historically known populations, which were considered probably extirpated and several that were considered erroneous. However, some of these populations were investigated and recently relocated (Jalava 2005, 2007, 2008b, pers. comm.). Based on the most recent survey work, sites where Hill's Thistle is in fact no longer present, or has not been found in more than 20 years, are listed below.

Site NameLast Observer*Recent SearchComments
Barrie Island:
Beer Point
Ringius & Wilson, 1976;Not found by Jones, 2006Habitat is overgrown with small cedars
Bear's Rump IslandMorton and Venn, 1987Not found by Jalava, 2007 or Schaefer, 1996 
Cape Croker/Nawash FNVarga 1995 referring to a 'pre-1949 record'Not found by Jalava & Chegano, 2008Extirpated or erroneous record
Clapperton Island: Beattie BayMorton and Venn, 1976Not found by Jones, 2005, 2006Habitat present; species not found
Clapperton Island: Logan BayMorton and Venn, 1976Not found by Jones 2005, 2006Habitat present; species not found
Driftwood Cove AlvarSchaefer, 1996Not found by Jalava, 2007Extirpated or erroneous record
Foxy Prairie: Gore Bay AirportJ.K. Morton, 2005Not found by Jones 2005, 2006Habitat very degraded
Roberts BayMorton and Venn, 1981Not found by Jones, 2006Habitat destroyed by new roads
Sauble Beach SouthJ. Johnson, 1980sGeneral area visited by Jalava, 2008bArea is subdivided with cottages; no habitat found
Vidal Bay: Creasor BightRingius and Wilson, 1976Not found by Jones 1997, 2005Very little habitat present; mostly overgrown
Walpole Island F.N.: Squirrel IslandDodge, 1914Not found by Gaiser, 1966; or Woodliffe and Allen, 1988 
Wasaga Beach: Nottawasaga Bay ShoreA.A. Reznicek 1970s Believed extirpated by recreational development (COSEWIC, 2004)

* Information from Morton and Venn, 2000; COSEWIC, 2004; Jalava, 2008a,b; and Joan Venn, pers. comm.