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

Recovery Feasibility Summary

Recovery of Hill's Thistle in Canada is considered feasible based on the criteria outlined by the Government of Canada (2009).

  1. Individuals of the wildlife species that are capable of reproduction are available now or in the foreseeable future to sustain the population or improve its abundance.
    There are several natural, large, actively reproducing populations of Hill's Thistle in locations with large areas of suitable habitat. This suggests that individuals are capable of reproducing at a rate sufficient to maintain and improve population sizes.

  2. Sufficient suitable habitat is available to support the species or could be made available through habitat management or restoration.
    One of the main threats to Hill's Thistle is filling in of habitat, likely due to fire suppression. However, the most recent burning (at least for habitat in the Bruce Peninsula and Manitoulin Island regions) took place 100 or more years ago, so encroachment is a very slow process. In addition, although habitat patch sizes are shrinking, there are still a large number of sites. Therefore, there is enough habitat which can be restored or improved, and enough time to plan and implement management and restoration actions.

    Reinstating intense, catastrophic wildfire into the human landscape in order to recover Hill's Thistle habitat would be a very difficult thing to do; however, other methods of maintaining existing habitat (e.g. low-level burning, cutting and clearing) may prove effective. This option still needs to be researched.

  3. The primary threats to the species or its habitat (including threats outside Canada) can be avoided or mitigated.
    Many threats can be avoided or mitigated through communications actions to increase awareness about the species, liaising with other groups and agencies, erecting signage, working with management of protected areas, and many other steps.

  4. Recovery techniques exist to achieve the population and distribution objectives or can be expected to be developed within a reasonable timeframe.
    The Nature Conservancy's International Alvar Initiative (IACI) (Reschke et al. 1999) initiated recovery of alvar ecosystems and associated rare species using several of the steps that are now suggested here for Hill's Thistle, and experiences from the IACI show these techniques can be very effective.