Recovery Strategy for the Hill's Thistle in Canada [Final Version] 2011: Critical Habitat

Critical habitat is defined in Section 2(1) of the Species at Risk Act (S.C. 2002, c. 29) as "the habitat that is necessary for the survival or recovery of a listed species and that is identified as the species' critical habitat in the recovery strategy or in an action plan for the species". In a recovery strategy, critical habitat is identified to the extent possible, using the best available information. Ultimately, sufficient critical habitat will be identified to completely support the population and distribution objectives.

Critical habitat has been identified for Hill's Thistle and the amount of critical habitat identified in this recovery strategy contributes to a substantial portion of the targets outlined in objectives 1 and 2 (Section 2.2), but does not fully meet the objectives. In total, 90 critical habitat polygons are identified at 17 sites in the Manitoulin Region (38), the Bruce Peninsula (40), and Wasaga Beach Provincial Park (12). This mapped critical habitat captures an IAO of 56 km², and an Extent of Occurrence of 9,150 km². Per objective 2, critical habitat is also mapped in each of the four core areas the species occupies. Recent surveys funded by the Species at Risk Program have discovered many additional populations of Hill's Thistle. At this time, we do not have adequate information to determine which of those populations should be identified as critical habitat to achieve the objectives. A schedule of studies, which outlines the work required to complete the identification of critical habitat, is included below. In the meantime, implementation of the broad strategies and approaches, as outlined in Section 2.3, will aid in meeting the population and distribution objectives.

Critical habitat was identified from current data on habitat occupied by the species. Confirmed records on the Bruce Peninsula, at Wasaga Beach, and in provincial parks, crown lands⁵, and lands owned by environmental non-governmental organizations (ENGOs) in the Manitoulin Region were all used as the basis of the mapping.

⁵ Crown land is land that is held by the Province of Ontario. Acceptable uses of crown land vary depending on the area but may included recreation, hunting, foresty, mining, or other uses, and may require permits or licences in some cases.

Habitat for Hill's Thistle occurs as patches within several types of open non-forested vegetation, or as openings within successional forest (based on field work by many workers including Reschke et al. 1999; Brownell and Riley 2000; Jalava 2004-2008; Jones 2004-2008; North-South Environmental 2005; vegetation community data from the aforementioned workers is on file at NHIC). In Canada, critical habitat is found within the following vegetation community types, as per the Ecological Land Classification of Ontario (ELC) (Lee et al. 1998):

Bruce Peninsula and Manitoulin Island Region

ALO1-3

Dry-Fresh Little Bluestem Open Alvar Meadow

ALO1-4

Dry-Fresh Poverty Grass Open Alvar Meadow

ALS1-1

Common Juniper Shrub Alvar

ALS1-2

Creeping Juniper-Shrubby Cinquefoil Dwarf Shrub Alvar

ALS1-3

Scrub Conifer-Dwarf Lake Iris Shrub Alvar

ALT1-3

White Cedar-Jack Pine Treed Alvar

ALT1-4

Jack Pine-White Cedar-White Spruce Treed Alvar

Wasaga Beach

TPW1

Dry Black (Red) Oak-White Pine Tallgrass Woodland

TPO1-1

Dry Tallgrass Prairie-Open Sand Barren

FOC1-2

Dry-Fresh White Pine-Red Pine Coniferous Forest

FOM2-1

Dry-Fresh White Pine-Red Oak Mixed Forest
Cultural Meadow/Dry Tallgrass Prairie

These community types often have a distinct boundary where they change from open (suitable) to forest, wetland, or cultural meadow (all unsuitable). Thus, the general areas in which critical habitat patches occur are fairly easy to distinguish in the field and relatively easy to map (methodology below). All known alvar sites on the Bruce Peninsula and at Wasaga Beach have recently been mapped in detail based on a compilation of more than 15 years of field data and observations of satellite imagery (North-South Environmental Inc. 2005; Jalava 2008a).

Critical habitat for the Bruce Peninsula and Wasaga Beach Provincial Park was mapped by Parks Canada in October 2009, and for the Manitoulin Region by Parks Canada in cooperation with staff from Ontario Parks, Ontario Ministry of Natural Resources, Ontario Nature, and the Nature Conservancy Canada in April 2010, based on the following methodology:

Inventory gaps identified by the Recovery Team were surveyed in 2004-2009 to support the identification of critical habitat (Jalava 2004-2008; Jones 2004-2008). All occurrence data for Hill's Thistle for the Bruce Peninsula and Wasaga Beach Provincial Park, and for protected areas in the Manitoulin Region were gathered from all available sources (especially NHIC and BPNP data bases, as well as Wasaga Beach monitoring data). All records were scrutinized and updated in October 2009 and April 2010 by Parks Canada. Only records with coordinates taken on the ground with GPS or localities mapped very precisely in the field on aerial photography were used. Records without GPS coordinates, or not field mapped on air or satellite imagery, or records with only vague locations, were not used to identify critical habitat.

In almost all cases newer georeferenced observations were available and supercede these records.

For the Bruce Peninsula and Wasaga Beach: All occurrence data for Hill's Thistle on the Bruce Peninsula (except those on First Nations lands) and at Wasaga Beach Provincial Park were plotted digitally on 2006 ortho photography with 30 cm resolution (South Western Ontario Orthorectification Project 2006). Suitable alvar community polygons as mapped by Jalava (2008a) were superimposed on this. Field data were available for most records to tell if the plants were spread throughout the vegetation community despite having only a single centroid UTM coordinate.

For the Manitoulin Region: All occurrence data from protected areas were superimposed on Quickbird imagery (6 satellite images at 60 cm resolution with a date range of June 2005 - August 2008). As well, field mapping from hard copies (IACI unpublished field notes 1995 and 1996 on file in NHIC database) was scanned and superimposed on satellite imagery to show field-mapped locations. Again, field data were available to tell if the plants represented a single point or were spread throughout.

For the entire Canadian range: The species occupies edges and openings where substrate and other factors are suitable, and fluctuations of some factors may cause population size to wax and wane. Therefore, some radial distance around the plants (to allow for dispersal and expansion of the population and to provide shelter and edge habitat) must be identified as critical habitat. A radial measure of 30 m around the plants was derived in the field by a core group of the Recovery Team as the distance required to prevent impact to extant populations and habitat. Using GIS software, a 30 m circle was plotted around all single point occurrences. In cases where 30 m circles overlapped, they were joined to form one polygon. In cases where 30 m circles were less than 30 m apart, they were joined if the intervening land contained suitable habitat. In cases where a centroid was provided for a population known to be >50 plants but the locations of individual plants in the habitat were not known, if the suitable habitat patch was larger than a 30 m radius circle, the entire area of suitable habitat was considered critical habitat.

Biophysical attributes of critical habitat for Hill's Thistle in Canada include the following:

• Dry, open ground with little or no immediate canopy cover;
• Trees if present are predominantly coniferous species in a savanna or very open woodland situation;
• Patches of low grasses or sedges, especially Poverty Oat Grass (Danthonia spicata) and Richardson's Sedge (Carex richardsonii), and reindeer lichens (Cladina rangiferina and C. mitis), or Bearberry with scattered shrubs;
• Habitat patches are often found on edges and in openings, especially the edges of alvars and in trails;
• Soils are generally shallow and range from sandy near Lake Huron to silty and slightly alkaline on alvars.

In total, 90 polygons of critical habitat, collectively covering 41 hectares at 17 sites, are identified here. Some sites have more than one polygon. The general locations of critical habitat polygons are depicted in Figures 3, 4 and 5 with detailed maps showing the extent of each critical habitat polygon provided in Appendix D. GIS shapefiles of all critical habitat polygons are maintained by the Federal Government.

Examples of activities that are likely to result in the destruction of Hill's Thistle critical habitat are listed here with the habitat features or properties they are likely to destroy. These activities would be destructive in any part of critical habitat, because they may damage or destroy Hill's Thistle plants, damage or remove the substrate required for growth, introduce competition, or interrupt natural processes that maintain habitat.

Activities that destroy or remove native grassy vegetation:

• Building cottages, houses, and driveways over critical habitat patches
• Building roads across critical habitat
• Limestone/dolostone quarrying or extraction of surface materials such as boulders
• Clearing of ground
• Using critical habitat as landing areas or roads during the logging of adjacent forests

Activities that disturb the extremely shallow soil:

• Driving heavy machinery across critical habitat
• Off-trail ATV or mountain bike use

Activities that reduce native species presence by introducing exotic or potentially invasive species:

• Trucking-in fill dirt and gravel
• Off-trail ATV use as a vector for weeds
• Seeding lawns or planting non-native species
• Planting trees of any kind
• Grazing of livestock
• Feeding hay to livestock in critical habitat

Activities that trample and damage vegetation and soil:

• Off-trail use by hikers at a level that tramples or destroys vegetation
• Camping activities such as placing a tent, fire pit, or latrine on top of critical habitat patches
• Off-trail use of critical habitat for group events.

There are several instances where trail use is beneficial to Hill's Thistle because the light disturbance keeps the ground clear of other vegetation. Threshold levels at which trail usage could become harmful rather than beneficial have not been determined. Thus, it is intended here that in general the use of existing trails and roads within critical habitat may continue. The determination of the point at which trail usage may potentially become harmful and protective action needed is more appropriately handled by land managers on a site by site basis.

This document includes a partial identification of critical habitat for Hill's Thistle. Future identification of critical habitat elsewhere in the range of Hill's Thistle will be undertaken as needed to ensure population and distribution objectives are met, or if the degree of risk affecting the species increases. Table 3 outlines and explains the work required to enable further critical habitat identification and mapping.

Table 3: Schedule of Studies

Figure 4. General Locations of Critical Habitat Polygons on the Bruce Peninsula.

Figure 5. General Locations of Critical Habitat Polygons in the Manitoulin Region.

Figure 6. General Locations of Critical Habitat Polygons at Wasaga Beach.

Critical habitat is identified for a total of 17 Hill's Thistle sites found wholly or partly within protected areas⁶ (national park, provincial park, or property owned by ENGOs or other federal or provincial lands). There are 9 sites on the Bruce Peninsula, 7 sites in the Manitoulin Region, and 1 site at Wasaga Beach in Simcoe County. Some sites contain several critical habitat polygons. The total amount of Hill's Thistle critical habitat identified in the 90 polygons contained within protected areas is 41 hectares (18 ha for the Bruce Peninsula, 15 ha for the Manitoulin Region, and 8 ha for Wasaga Beach). The sites are listed below, with ownership, according to the four core areas.

• Brinkman's Corner (Public Works Canada)
• Bruce Peninsula National Park
• Clarke Property-Baptist Harbour (Ontario Heritage Foundation; Ontario Heritage Trust)
• Dorcas Bay Road (Crown Land)
• Johnston Harbour - Pine Tree Point ANSI (Crown Land)
• Johnston Harbour - Pine Tree Point Provincial Park (Bruce Peninsula National Park)
• Lyal Island (Ontario Nature)
• Rover Property (Nature Conservancy of Canada)
• Williams Property-Baptist Harbour (Escarpment Biosphere Conservancy)

• Macs Bay Conservation Reserve
• Misery Bay Provincial Nature Reserve
• Quarry Bay Nature Reserve (Ontario Nature)
• Queen Elizabeth-Queen Mother M'nidoo M'nissing Provincial Park

• Greene Island (Crown Land)
• Cockburn Island, Wagosh Bay (Nature Conservancy Canada)
• Western Duck Island (Crown Land)

• Wasaga Beach Provincial Park

⁶ The term "Protected Areas" used in the critical maps has no relation to protection requirements under SARA.

Evaluation of the progress toward achieving Hill's Thistle recovery will be reported five years following final posting of this recovery strategy on the Species at Risk Public Registry, and every five years following, as per SARA (s. 46). The success of Hill's Thistle recovery will be evaluated by comparing information from monitoring and inventory with the population and distribution objectives as per Table 4.

Table 4: Performance measures for progress of Hill's Thistle recovery

* This time frame is adopted from the COSEWIC assessment criteria, to account for anomalies within a shorter time frame.

One or more action plans will be completed by December 2015.