Kejimkujik National Park and National Historic Site of Canada

Natural Heritage: Research Blanding's Turtle Monitoring and Research

Blanding's Turtle Monitoring

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) has declared the Blanding's turtle a threatened species in Nova Scotia. It is therefore considered a "Species at Risk".

Within Kejimkujik, fieldwork on Blanding's turtles is coordinated by Park Warden Ian Morrison, with special involvement by faculty and students at Acadia, St. Francis Xavier, and Dalhousie universities.

Juvenile Blanding's turtles showing different age classes
© Parks Canada / Peter Hope, 1994

A mark-and-recapture system enables the identification of individual turtles in the Park. A series of notches is cut into the edge of the upper shell of each turtle. The turtle is released unharmed, exactly where it was found. Using this practice, it is possible to determine the areas inhabited by individual turtles and to estimate the size of the population. Currently the population of adult Blanding's turtles in the Park is less than 150 individuals.

Blanding's Turtle Research

A Park Warden holding a young
Blanding's turtle with a radio
transmitter attached to its shell
© Parks Canada / Peter Hope, 1993

Researchers have combined radio-tracking with past studies to provide a picture of adult movements and areas of concentration. The Kejimkujik population appears to concentrate in three areas, but within a season individuals may cover distances of over 1.5 km. Radio-tracking of females revealed that some may even travel up to 3 km to reach a nesting site. It appears that females return to the same beach every time they nest.

By following juveniles fitted with radio transmitters, researchers determined that stillwater brooks, rich in sphagnum moss, provide important habitat for young turtles. Like adults, they frequent highly coloured, acidic waters with peaty soils and mats of sphagnum moss. The concentration of juveniles corresponded to the number of nearby nests. Older juveniles, from 14 to 17 years, were found to move greater distances than younger turtles.

A young Blanding's
turtle with a radio
transmitter on its shell
© Parks Canada / Peter Hope, 1993

The Blanding's turtle is long-lived, but a study conducted by Dr. Tom Herman of Acadia University in 1995 suggests that recruitment into the adult population is low. Young turtles don't mature until they are over 20 years of age. Thirty-one of 48 individuals examined were over 30 yearsof age. Several breeding females in the Park are over 50 years of age and at least one is over 70.

Nest Protection

As a threatened species, the survival of hatchling Blanding's turtles is of concern. For over ten years, Park Wardens have worked to increase hatchling survival by covering all known Blanding's nests.

In recent years, a volunteer program was launched under the direction of Park Wardens. Volunteers assist park staff and researchers to monitor important habitats each night in June during the nesting season. Their observations of turtles and nests improve our understanding of the nesting ecology of the Blanding's turtle.
Female turtles usually return to the same cobble and gravel beaches to nest each year. Once a female has laid her eggs, the nest is immediately covered with a screen to protect it against predators. Results of a predation study conducted in 1997 suggest that such protection promotes hatchling success. Over 80% of that season's uncovered nests were predated, resulting in the emergence of only 12 hatchlings.

Between 1993 and 2000, the number of nests each year ranged from 12 to 23, and yielded between 12 and 106 hatchling Blanding's turtles.

Genetic Variation

A Park Warden holding
a hatchling Blanding's turtle
before its measurements
and weight are recorded
© Parks Canada / Peter Hope, 1999

The Nova Scotia population of the Blanding's turtle has been separated from the species' main range, in central North America, for several thousand years. Within the province, the turtle is found in two areas: Kejimkujik National Park and nearby McGowan Lake. Despite the closeness of these two areas, genetic variation exists between the two Blanding's populations. Recent studies identified an absence of current movement between the two population groups. These findings pose the question whether this lack of movement results from human interference or historical differences in the two populations.

Steve Mockford, a graduate researcher at Dalhousie University, is examining this issue. Since any genetic differences would pre-date human interference, he is using DNA analysis to look for variations between the two groups of turtles. His study also considers whether some clutches of eggs have been fertilized by more than one male. This study is ongoing.

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