Why the Western Painted Turtle may not be “Revelstoked” about winter

A TRU grad student is studying the effects of hydroelectric dam activity on turtle hibernation patterns

Stretching from Revelstoke to Castlegar is the Arrow Lakes Reservoir, a 230 kilometer-long man-made body of water that was formed by flooding and combining two separate, shorter lakes into one body of water in the 1960s. To power the Hugh Keenleyside Dam in Castlegar, the reservoir’s water levels annually rise and fall by as much as 20 metres, roughly the same height as a five or six-story building.

TRU graduate student Amy Duncan wants to know if these fluctuating water levels pose a threat to the Western Painted Turtle population that resides within the reservoir. The focus of Duncan’s thesis research, which began in January 2013, is to identify patterns between the fluctuating water levels and the overwintering, or hibernating, patterns of the turtle.

MSc student Amy Duncan holds one of the Western Painted Turtles that she is studying. (Natasha Audy/Submitted)

MSc student Amy Duncan holds one of the Western Painted Turtles that she is studying. (Natasha Audy/Submitted)

“I’m working under BC Hydro,” Duncan explained. “The reservoir levels are managed by BC Hydro, and they are interested in knowing how the water levels affect the populations. Because painted turtles are a blue-listed species, or at least this population is, it puts them on a lot of people’s radar. If there are effects, I want to find out what they are.”

In British Columbia, a blue-listed species is a wildlife species that the Ministry of Environment has determined to be at-risk, but not yet endangered or threatened like a red-listed species.

For the painted turtle to overwinter, they require a habitat that will not freeze or become deprived of oxygen. Part of Duncan’s research looks at the effect that water levels have on the turtles’ overwintering habitat. Another aspect of the research involves tracking how the behaviours of the turtles are affected.

“There are two different tactics on how turtles are overwintering,” Duncan explained. “Some of the turtles seem to be congregating [into groups] in different areas, while other turtles don’t have any other turtles around them during the winter. So I’m looking at that.”

To conduct these studies, Duncan is studying three sampled populations of turtles, all of which were located just south of Revelstoke, B.C. The first two populations are located directly in the reservoir, while the third population is located in a nearby pond unaffected by the reservoir’s fluctuations in water levels. This third sample serves as a control group, which helps isolate the reservoir’s fluctuating waters as the independent variable when Duncan compares results between the populations.

The first step in her research was identifying the precise locations that the turtles were using to hibernate.

(Natasha Audy/ Submitted)

(Natasha Audy/ Submitted)

“When I was doing field work, we captured the turtles throughout the spring and summer,” she explained. “When I started, there were already some turtles out there from previous research projects with transmitters on.”

Wireless transmitters attached to the turtles help researchers like Duncan locate and track the turtles from above the water.

“My supervisor, Karl Larson, had a previous student working on the same population of turtles, and he wanted to continue researching them but with a different topic.”

With the transmitters in place, Duncan was able to track the turtles even as the surface of the waters froze over.

“I followed those turtles over the winter, locating them and drilling holes in the ice to take water measurements. In the following spring I tried to recapture the same turtles I had followed. I also captured more turtles and added more transmitters.”

Duncan’s endeavor is ambitious, but she has supporters at her side to help accelerate the progress of her work.

“I’m working with the Okanagan Nation Alliance,” she explained. “They sort of partnered with my industrial sponsor, which is LGL Limited, Environmental Research Associates. Each month I had a field technician from the Okanagan Nation Alliance coming out with me. I also had some volunteers from TRU come and help me do my field work.”

Two years into her project, Duncan says the study has been informative, but also admits it is more complex than she anticipated.

“So far in my results, I have seen a lot of variation. Just between these first two winters, the turtles seem to be doing different things, and the conditions are quite different. This means I have a lot more to look at in my data, but this also means it’s more difficult for me to come to any concrete result. I can’t just say the turtles did the same thing year after year. There is no easy answer, and that’s what I’m struggling with right now.”

With her Master of Science in Environmental Science program coming to an end, she hopes to wrap up her research within the next few months. “The end of April would be my two-year mark for my master’s program, so I hope to be done by then, or be defending my thesis around that time,” she said.

Duncan’s research has already received some public exposure. She has presented her work at various conferences and forums throughout B.C., including the Columbia Mountains Institute of Applied Ecology’s Annual Researchers’ Forum in Revelstoke.

She hopes her research will continue to gain traction within the scientific community in the near future.

“Right now our lab is applying to a conference in France,” she said. “It’s a conservation biology conference. We’re really hoping to make it to that, and I’ll be able to present there.”

Duncan also hopes that the lessons learned through her research will eventually help other researchers get a head start on similar studies in other regions.

“My research will be used locally within the population I studied but, potentially, the results of my research could be used for other conservation management plans in other populations that are affected by anthropogenic use, like reservoirs, or other areas that are affected by humans.”