May 1, 2017

The where and when of grizzly bear food

Using satellite sensors, UCalgary researchers can predict when bears are most likely to be feeding in specific areas.

At one time there were thousands of grizzly bears roaming around Alberta. Today, only about 750 remain and they’re under threat by human activities and climate change.

Alberta’s grizzly bears are about 90 percent vegetarian and they have to cover a lot of ground to find enough to eat. Berries are particularly important – one adult male grizzly can devour up to 200,000 berries a day. It’s critical that the bears stick to an efficient foraging schedule and not waste energy showing up before or after a plant has produced the most food.

Maps have long shown the extent of grizzly habitat in Alberta, but a researcher at UCalgary has developed a better tool to predict grizzly behaviour within that extent – daily maps that monitor the development of plants that provide the grizzlies’ food.

Here in Canada, how fast plants grow is largely dictated by temperature – a horticultural principle well known to back-yard gardeners. “Using satellite remote sensing to measure daily forest temperatures, we can model the timing of nutritional availability in plants that bears eat, things like berries and roots,” says Dr. David Laskin, PhD, from the Department of Geography in UCalgary's Faculty of Arts, who just graduated with his PhD. “So beyond knowing where grizzly bear habitat is, we now also know when.”

Laskin studies phenology – recurring events in nature such as bird migrations, fish spawning or the seasonal emergence of the berries grizzlies like to eat. Since plant growth is sensitive to temperature, Laskin has also explored the potential impacts of climate warming on plant phenology. “A shift in timing of berry development is one of the fingerprints that climate change leaves on the ecosystem,” says Laskin.  “The bears’ foraging schedule is likely to be altered and become more punctuated.”

His maps provide a “dynamic approach” in determining areas of critical bear habitat, an advancement over traditional static maps which are like a snapshot in time. And, knowing when and where the bears are headed is important information to stave off bear-human interactions. “Right now we respond reactively,” says Laskin. “We close trails and campgrounds only after a bear and human have run into each other.”

Laskin, who received an NSERC Vanier award for his research, is working with a number of universities and the fRI Grizzly Bear Program to start applying the maps across Alberta, in order to help make informed decisions about land use management by industry and the public.

“This is a major advancement in environmental monitoring,” says Greg McDermid, associate professor of geography and Laskin’s PhD supervisor. “The fact that these horticultural principles of heat accumulation and plant development can be observed over such huge areas is remarkable. We’ve never seen anything quite like this before.”

Things to remember:

  • Grizzly bear populations in Alberta have drastically declined due to human activity and are listed as a Threatened Species
  • The grizzlies in Alberta are about 90 per cent vegetarian
  • A large male grizzly can eat up to 200,000 berries a day
  • Daily, near-real-time maps using satellite remote sensing show where and when plants are likely to attract grizzlies

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Dr. David Laskin completed his PhD in Geography at the University of Calgary, studying the effects of climate change on forest ecosystem dynamics. Specifically, his research employs multi-scale remote sensing to observe shifts in vegetation phenology to improve current approaches of species habitat modeling. Read more about David

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