A pound here or there might not make much of a difference for the average person, but for a Vancouver Island marmot, that extra weight is extra important.
Endangered Vancouver Island marmots can lose up to 30 per cent of their body weight while hibernating, and have about five months to gain that back.
"Vancouver Island marmots, their body weight is tightly linked to their reproductive investment as well as their over-winter survival," said Dr. Brenna Stanford, conservation program manager at the Wilder Institute. "So we're interested in conservation actions that can improve body weight, with hopes to improve these rates out in the wild."
To that end, researchers have teamed up with technicians at Vancouver Island University to make custom smart weigh scales that will monitor how many pounds individual marmots are putting on – and how that can be impacted by supplementing their natural feedings with calorie-dense biscuits.
Stanford said they began a supplemental feeding study with the Marmot Recovery Foundation in 2018 which ran until this past year, involving collecting data on the marmots' weight for several weeks in the spring, and again in the fall. Without the custom scale, researchers have been hiking to the marmots' burrows, live-trapping the marmots using peanut butter bait, then manually taking their weight before releasing them.
The team looped in Vancouver Island University in 2022, with the hope the university's engineers could design something that would allow researchers to observe the weight passively from a remote location across the entire active season.
VIU's engineering technician Devin Ayotte and resource management and protection technician Michael Lester took on the task, designing a special weigh scale to stand against the cold, battery-life challenges and interference from wildlife.
"It's going to be something that's waterproof and dirt-proof and marmot-proof – these things get chewed by animals like bears and marmots," Ayotte said. "We got to make something that's a reliable piece of electronics that has its own power supply, it's got a battery about half the size of a car battery, and to be able to stay out in all conditions from freezing temperatures to a blazing hot sun."
The newest version, to be deployed this summer, contains a tag reader that will identify each individual marmot that steps on the scale through a chip between its shoulder blades, sending that data back to base.
"The marmot has to cross the scale to get out of its den, and it will use the scale as a perch, a vantage point to see around its den," Ayotte explained. "Then we have a micro controller inside that records the weight so the researchers at the Wilder Institute and the Marmot Recovery Foundation can use that data to access the marmot itself."
While the biscuit experimentation may be done with researchers currently analyzing results, Stanford said the use for the remote weigh scales is ongoing. She said researchers will be placing several additional scales this season to observe the marmots' weight to check for poor post-hibernation weight or poor pre-hibernation weight, as well as collect data in how quickly the animals are putting back the weight through the active season.
She said there isn't any concern at this time that the supplemental feeding will result in dependency from the marmots.
"There doesn't seem to be any evidence on that. The marmots will take some biscuits, these high calorie-dense biscuits the [Marmot Recovery Foundation] provides, but we see the marmots foraging and eating plants just like they would normally do as well."
