Blanding's turtle COSEWIC assessment and status report: chapter 13

Technical Summary

Emydoidea blandingii (Nova Scotia Population)

Blanding’s Turtle
Tortue mouchetée

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.

 


Emydoidea blandingii (Great Lakes/St. Lawrence Population)

Blanding’s Turtle
Tortue mouchetée

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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