Blanding's turtle COSEWIC assessment and status report: chapter 13
Technical Summary
Range of Occurrence in Canada: Southwestern Nova Scotia
Extent and Area Information
Extent of occurrence (EO)(km2)
~900 km2
Specify trend in EO
Declining
Are there extreme fluctuations in EO?
No
Area of occupancy (AO)(km2)
< 100 km2
Specify trend in AO
Declining
Are there extreme fluctuations in AO?
No
Number of known or inferred current locations
3 populations; Kejimkujik National Park, McGowan Lake and Pleasant River.
Specify trend in #
Stable
Are there extreme fluctuations in number of locations?
No
Specify trend in area, extent or quality of habitat
Currently, stable or increasing from restoration efforts.
Population Information
Generation time (average age of parents in the population)
> 40 years
Number of mature individuals
210–245
Total population trend
Likely declining
% decline over the last/next 10 years or 3 generations (> 120 years)
% is unknown, but likely significant
Are there extreme fluctuations in number of mature individuals?
No
Is the total population severely fragmented?
Yes, there is little or no exchange between the 3 populations.
Specify trend in number of populations
Stable
Are there extreme fluctuations in number of populations?
No
List populations with number of mature individuals in each:
Kejimkujik, 66;
McGowan Lake, 79;
Pleasant River, 65-100;
total = 210–245
Threats (actual or imminent threats to populations or habitats)
- Small population size and fragmentation, which increases threats from genetic drift and environmental stochasticity.
- Vulnerability to small increases in adult mortality because of long-lived life history.
- Loss of wetland habitat and surrounding terrestrial habitats.
- Lack of good nest sites and the attractiveness of road shoulders and surfaces to nesting females.
- Expansion of agriculture, forestry and cottage development, which fragment the populations.
- Nest predation and predation of juveniles by skunks, raccoons, and foxes is likely higher than historic rates because of subsidization of raccoons, skunks, decline of the fur market, and increase in edge habitat.
- Collection for the pet trade.
- Alteration of hydrology by human activity.
Rescue Effect (immigration from an outside source): Unlikely
Status of outside population(s)?
USA: Critically Imperiled – South Dakota, Pennsylvania, and Missouri
Imperiled – Minnesota, New York, Massachusetts, Maine, Indiana, and Ohio
Vulnerable – Michigan, New Hampshire, Iowa, Illinois, and Wisconsin
Is immigration known or possible?
No
Would immigrants be adapted to survive in Canada?
Unknown
Is there sufficient habitat for immigrants in Canada?
Not applicable
Is rescue from outside populations likely?
No
Current Status
COSEWIC: Endangered (May 2005)
Nova Scotia Wildlife Protection: Endangered.
Status and Reasons for Designation
Status: Endangered
Alpha-numeric code: B1ab(iii,v)+2ab(iii,v); C2a(i); D1
Reasons for Designation: The three small subpopulations of this species found in central southwest Nova Scotia total fewer than 250 mature individuals. These three subpopulations are genetically distinct from each other and from other Blanding’s turtles in Quebec, Ontario and the United States. Although the largest subpopulation occurs in a protected area, its numbers are still declining. The other subpopulations are also susceptible to increasing habitat degradation, mortality of adults and depredation on eggs and hatchlings.
Applicability of Criteria
Criterion A (Declining Total Population):
Not calculated.
Criterion B (Small Distribution, and Decline or Fluctuation):
Endangered, B1(EO <900 km2) + 2 ( AO < 100 km2) a (<5 locations) b(iii, v).
Criterion C (Small Total Population Size and Decline):
Endangered, C (<2500 mature individuals), 2 (fragmented), i (no population > 250).
Criterion D (Very Small Population or Restricted Distribution):
Endangered D1 (<250 mature individuals).
Criterion E (Quantitative Analysis):
Not applicable.
Range of Occurrence in Canada: Southern and central Ontario and southwestern Québec
Extent and Area Information
Extent of occurrence (EO)(km2)
~73 800 km2
Specify trend in EO
Declining
Are there extreme fluctuations in EO?
No
Area of occupancy (AO)(km2)
< 835 km2
Specify trend in AO
Declining
Are there extreme fluctuations in AO?
No
Number of known or inferred current locations
Many locations. Northern portion of range may consist of many small isolated populations
Specify trend in #
Declining
Are there extreme fluctuations in number of locations?
No
Specify trend in area, extent or quality of habitat
Decline in quality and extent of habitat with increased fragmentation from roads, development and wetland drainage
Population Information
Generation time (average age of parents in the population)
> 40 years
Number of mature individuals
< 10 000
Total population trend
Declining
% decline over the last/next 10 years or 3 generations (> 120 years)
Unknown, but likely substantial because 3 generations would be since ~1885.
Are there extreme fluctuations in number of mature individuals?
No
Is the total population severely fragmented?
Yes, in some parts of their range in the north and around areas with extensive wetland drainage and/or development
Specify trend in number of populations
Declining
Are there extreme fluctuations in number of populations?
No
List populations with number of mature individuals in each:
Unknown
Threats (actual or imminent threats to populations or habitats)
- Vulnerability to small increases in adult mortality because of long-lived life history.
- Loss of wetland habitat and surrounding terrestrial habitats.
- Loss of nesting habitat and the attractiveness of road shoulders and surfaces to nesting females.
- Expansion of development/roads, which fragments populations.
- Nest predation and predation of juveniles by skunks, raccoons, and foxes is likely higher than historic rates because of human subsidization of raccoons, skunks, decline of the fur market, and increase in edge habitat.
- Depredation of eggs and hatchlings by sarcophagid flies is a potential new threat.
- Collection for the pet trade.
- There is some evidence that nests on roadsides have a higher rate of depredation.
- Increased rates of mortality, particularly of nesting females by vehicles, and the expanding road network and concomitant increased traffic density and speed throughout the Ontario/Quebec range.
Rescue Effect (immigration from an outside source): Unlikely
Status of outside population(s)?
USA: Critically Imperiled – South Dakota, Pennsylvania, and Missouri
Imperiled – Minnesota, New York, Massachusetts, Maine, Indiana, and Ohio
Vulnerable – Michigan, New Hampshire, Iowa, Illinois, and Wisconsin
Is immigration known or possible?
Not likely possible and there is no evidence that it does occur
Would immigrants be adapted to survive in Canada?
Yes
Is there sufficient habitat for immigrants in Canada?
Yes
Is rescue from outside populations likely?
No
Current Status
COSEWIC: Threatened (May 2005)
COSSARO (Ontario): Threatened
Status and Reasons for Designation
Status: Threatened
Alpha-numeric code: C2a(i)
Reasons for Designation: The Great Lakes/St. Lawrence population of this species although widespread and fairly numerous is declining. Subpopulations are increasingly fragmented by the extensive road network that criss-crosses all of this turtle’s habitat. Having delayed age at maturity, low reproductive output and extreme longevity make this turtle highly vulnerable to increased rates of mortality of adults. Nesting females are especially susceptible to roadkill because they often attempt to nest on gravel roads or on shoulders of paved roads. Loss of mature females in such a long-lived species greatly reduces recruitment and long-term viability of subpopulations. Another threat is degradation of habitat from development and alteration of wetlands. The pet trade is another serious ongoing threat because nesting females are most vulnerable to collection.
Applicability of Criteria
Criterion A (Declining Total Population):
Not appropriate
Criterion B (Small Distribution, and Decline or Fluctuation):
Not appropriate, possibly not severely fragmented yet and > 10 locations
Criterion C (Small Total Population Size and Decline):
Threatened, C, fewer than 10 000 mature individuals, 2 (continuing decline projected), ai (no population with > 1 000 mature individuals).
Criterion D (Very Small Population or Restricted Distribution):
Not appropriate
Criterion E (Quantitative Analysis):
Not applicable.
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