Map Turtle Hibernation Patterns Under Scrutiny After Predator Discovery
Research into how northern map turtles hibernate could provide crucial insights for protecting this vulnerable species, according to findings from Carleton University. Professor Grégory Bulté, who has been studying the turtles at Opinicon Lake since 2003, discovered that predators attacked the reptiles during their winter rest period, resulting in significant population loss.
Unusual Hibernation Behavior Makes Turtles Vulnerable
Every autumn, hundreds of northern map turtles engage in unusual behavior for their species. They gather or "aggregate" on the shores of an island in the middle of Opinicon Lake to prepare for underwater hibernation. This mass congregation creates a unique opportunity for researchers but also presents dangers for the turtles themselves.
"I think what happened is that there were hundreds of turtles in one spot," explained Bulté, an associate professor of biology at Carleton University. "Predators could have the little ones that they can just bite through, or they could have the big ones they have to fight with, so they probably just went for the little ones, because they're much easier."
Gruesome Spring Discovery
Bulté typically snorkels in the chilly 6°C to 10°C waters each spring to observe the turtles' dispersal after hibernation. However, on April 21, 2022, just twelve days after the ice melted on the lake, he made a disturbing discovery. Predators—likely river otters—had killed and consumed at least 142 turtles, leaving behind shells and carcasses in the water.
The attack disproportionately affected male turtles, which accounted for approximately three-quarters of the victims. Adult male map turtles are about half the size of adult females, making them easier targets for predators. Bulté estimates this single event wiped out about 10 percent of the lake's map turtle population.
Conservation Implications for Vulnerable Species
Northern map turtles are classified as a Species of Special Concern at both provincial and federal levels in Canada. They typically inhabit large rivers and lakes, including the Ottawa River and Rideau River systems. The incident at Opinicon Lake demonstrates how quickly turtle populations can decline due to their winter behavior patterns.
"The incident showed that a lot of turtles could disappear in a short period of time because of the way they spent their winters," Bulté emphasized. "If Opinicon Lake is typical, that means other lakes with map turtles likely also have only a handful of aggregation sites. Protecting those sites is important when it comes to defending turtle populations."
Long-Term Research Provides Valuable Data
Opinicon Lake, located approximately 100 kilometers south of Ottawa, represents a relatively small body of water for map turtles. However, its manageable size has made it ideal for long-term population tracking. Researchers have implanted some turtles with passive integrated transponders—tiny computer chips similar to those used by veterinarians to identify pets—to monitor their movements and survival rates.
Bulté estimates there are about 1,500 map turtles currently inhabiting Opinicon Lake. Mature females measure approximately 30 centimeters in length and each lays about 15 eggs every summer. The research team continues to monitor how the population recovers from the predator attack and what measures might best protect aggregation sites during vulnerable hibernation periods.
This ongoing study highlights the delicate balance between animal behavior and survival strategies, providing conservationists with critical information about how to protect vulnerable species during their most defenseless periods. The findings suggest that targeted protection of hibernation aggregation sites could be essential for maintaining healthy turtle populations across their range.
