Recovery Strategy for the Blanding's Turtle, Nova Scotia Population, in Canada [proposed] 2011: Critical Habitat

Critical habitat is defined in the Species at Risk Act (S.C. 2002, c.29) as "...the habitat that is necessary for the survival or recovery of a listed wildlife species and that is identified as the species' critical habitat in the recovery strategy or in an action plan for the species" (s. 2(1)).

In this recovery strategy, critical habitat is identified for the Blanding's turtle in Nova Scotia to the extent possible, using the best available information. In the province, many of the species' habitats have been determined including nesting sites, overwintering sites and summering sites used for most life stages. For many sites, multiple years of data are available, illustrating both repeated use of sites over time by the species and individual site fidelity.

Critical habitat is identified at all five known sites containing two or more identified individuals (three major populations and two smaller concentrations). Sites containing unconfirmed sightings are not included at this time. Sites containing only one identified turtle were excluded because it is possible that the turtles were moved there by the public. The two small concentrations were included in critical habitat identification at this time based on the precautionary principle; this will be reviewed as more information becomes known about these sites.

The critical habitat identified in this Recovery Strategy is necessary for the recovery of the species, but may not be sufficient to achieve the intermediate or long-term population and distribution objectives for the species due to insufficient understanding of the highly variable habitat attributes and the lack of knowledge of the species' distribution in Nova Scotia. The amount of critical habitat required to support a self-sustaining population of Blanding's turtles in Nova Scotia over the long term is currently unknown. There may be additional viable populations yet to be discovered, which are important to the long term persistence of the population complex. Additionally, critical habitats around the periphery of the known populations may not yet be identified. Critical habitat identified here does not take into account corridors that enable movement between populations which, though infrequent, is necessary to maintain gene flow.

Critical habitat is identified at each of the five sites using a two step process:

• High use areas were identified by mapping turtle locations by categories based on seasonal activity and life-stage and then applying the delineation guidelines identified below.
• The geographic limits of each of the five sites were identified by drawing a polygon that connects all of the high use areas.

Identifying high use areas

Turtle sighting locations were mapped according to seasonal activity (nesting, spring basking, summer, winter, fall travel) and life stages (male, female, juvenile). Following this, high use polygons were delineated using the following guidelines:

• When turtle location(s) were contained within wetlands, the entire wetland was included, as well as the terrestrial and aquatic area that extends 100m around the wetland, even if the turtle locations occurred only in part of the wetland.
• When turtle location(s) were contained within rivers or streams, the extent of the water channel encompassing the turtle locations and 200m upstream and downstream of the outermost extent was included, as well as the terrestrial and aquatic area that extends 100m on either side of the river or stream.
• When turtle locations(s) were contained within lakeshores, the extent of shoreline encompassing the turtle locations and 200m on either side of the outermost extent was included. The lakeshore waterside area within 100m and the terrestrial area within 50m were also included.
• When turtle location(s) were based on inland nesting areas, the entire nesting area was included. If the nesting area occurs along a roadway or other contiguous habitat, the area encompassing the nesting locations and 200m on either side of the outer most extent was included. The terrestrial area between the two outer most extents and within 100m on either side of the roadway or contiguous habitat was included.
• When the turtle location was based on an isolated sighting, a 100m radius around the sighting was included.

The terrestrial areas around identified wetlands are intended to capture additional habitats used by turtles, and include important components of the species' required habitats. This includes vernal pools, treed wetlands, small channels, seasonally flooded areas around the periphery of wetlands, and other areas that may not be identified using traditional wetland polygons. These areas also include terrestrial habitats that may be used by the turtles for travel, basking or refugia. These habitats may be particularly important to hatchling and young juveniles (unpublished data). While knowledge of turtle use of these habitats is somewhat limited in Nova Scotia, use of adjacent terrestrial habitats has been documented elsewhere in the species range. In Maine, for example, Blanding's turtles were found to frequent forested vernal pools in spring (Beaudry et al.2009). These areas are not buffer zones; they are fundamentally part of the critical habitat used by Blanding's turtles and their prey. The identified areas are conservative compared to others identified in the literature, where terrestrial areas of 135m to 1000m are recommended for Blanding's turtles (Bell and Stevens 2006, Hartwig 2004, Semlitch and Bodie 2003).

The lakeshore aquatic areas are identified to account for changes in seasonal water levels. Areas around nesting sites take into account female movements during nesting season and post-emergence movements of hatchlings, which can spend considerable time on land (Camaclang 2007, McNeil et al. 2000, Smith 2003, Standing et al. 2000).

Identifying extent of critical habitat in each site

Critical habitat at each site was identified by linking the outer boundaries of the high use areas together to form a polygon. With the exception of the Kejimkujik population, in places where the line would have bisected a lake, the entire lake was included. This rule was not applied to Kejimkujik Lake, due to the large size of the lake. It is believed that turtles in this population travel primarily along the shoreline rather than across open water (Kydd 2010). For Kejimkujik Lake, lakeside polygons were joined using a 100m waterside area that followed the shoreline. In the Kejimkujik population, three high use areas at the periphery of the population were identified as separate polygons because their relationship to the main population is unknown (Figure 4).

This approach allows for travel among high use areas, unidentified habitats within the population or habitats that are currently unused but may become used in future (e.g. new wetland habitat following creation of a beaver dam; new nesting areas created through disturbance).

Using the above criteria, five sites were identified as critical habitat in Nova Scotia as outlined in Table 4 and illustrated in Figure 4.

* Map square refers to the accompanying map. A low resolution version of this map is presented in Figure 4.

Biophysical attributes

Critical habitat includes all areas within the identified polygons. This encompasses seasonal habitats required for all life stages and the aquatic and terrestrial travel routes between these habitats. Biophysical attributes of habitats used varies considerably with site, season and age-class, and not all are currently identified. Typical biophysical attributes are listed below, although it should be noted that specific attributes for certain life stages (e.g., hatchings) are still unclear. Hence, section 7.2 identifies activities to help better define these attributes and determine the geographic locations of any additional critical habitat.

Biophysical attributes of aquatic habitats used during the active season typically include, but are not limited to, the following (Bourque 2006, Caverhill 2003, Gilhen 1984, McMaster and Herman 2000, Power 1989):

• Wetlands including fens, bogs, ponds, vernal pools, lake coves, streams
• Slow moving water
• Abundant aquatic vegetation
• Overhanging vegetation (e.g. sedges or sweetgale)
• Mid-range water color (100-250 TCU)
• Muddy, organic substrate, not dominated by rocks

Biophysical of overwintering habitats typically include, but are not limited to, the following (Caverhill 2006, McNeil 2002, Newton and Herman 2009, Power 1989):

• Wooded pools or channels, railway trenches, and specific sections of streams or wetlands
• Deep organic substrate
• Undercut banks

Biophysical attributes of nesting habitats include, but are not limited to, the following (Caverhill 2006, McNeil 2002, Power 1989, Standing 1997):

• Natural or human-modified sites such as lakeshore beaches, woodland outcrops, gravel pits and roadsides
• Areas exposed to sunlight
• Areas with exposed substrate such as gravel, soil or sand, in which a turtle can dig a nest

Biophysical attributes of travel routes, include but are not limited to, the following (Camaclang 2007, Kydd 2010, Lefebvre 2010, McNeil 2002, Power 1989):

• A variety of terrestrial habitats including woodland, trails, meadows
• A variety of aquatic habitats including along streams, along lake shores or across lakes, through wetlands, vernal pools

Figure 4: Critical habitat sites for Blanding's Turtle in Nova Scotia. A full resolution version of this map (24 MB).

The critical habitat identified in this recovery strategy is necessary for the survival or recovery of the species, but may be insufficient to achieve the population and distribution objectives for the species due to insufficient understanding of the species' distribution, habitat use and the habitat's biophysical attributes in Nova Scotia.

Destruction of critical habitat would result if part of the critical habitat were degraded, either permanently or temporarily, such that it would not serve its function when needed by the species. Destruction may result from a single or multiple activities at one point in time or from the cumulative effects of one or more activities over time.

The performance indicators presented below provide a way to define and measure progress toward achieving i) the Population and Distribution Objectives (Section 5) and ii) Strategic Direction for Recovery (Section 6.2). Because of the turtle's longevity and slow maturation, achieving the population and distribution objectives is a long-term goal.

i) Population and Distribution Objectives Measures

• Adult survivorship maintained in all known populations.
• Management strategies implemented to mitigate identified site specific threats
• Survivorship estimates updated at least every 5 yrs to refine PVA to ensure that the goal of less than 5% extinction risk is being met

ii) Strategic Direction for Recovery Measures

• Juvenile survivorship maintained or enhanced in all known populations
• Extent of current distribution maintained or increased at all known populations
• Number of nests protected maintained or enhanced in all three populations
• Number of sites under formal habitat protection increased
• Number of landowners employing best practices to protect habitat increased
• Improved awareness of traditional knowledge of turtles and their habitat through number of stories shared

Male fecundity in the population complex assessedStrategic monitoring plan developed by 2014 to enable reassessments of population models

One or more action plans will be completed by December 2014.