It was Labor Day weekend when the so-called Lakeside Female dipped a paw in the tepid west shore waters of Flathead Lake near Rollins and decided to go for a swim.
Grizzly bears aren’t afraid to get wet, and their webbed paws make them more than proficient swimmers, but usually they’re chasing chum rather than swimming laps for pleasure.
This 4-year-old sow was different. Researchers called her the “Lakeside Female” because of where she ranged. She was initially captured with her mother and siblings as a yearling near Bigfork after the family was caught killing chickens in unprotected chicken coops.
State wildlife managers relocated them to the west side of Hungry Horse Reservoir, in the Spotted Bear area east of the Swan Mountains.
Maybe that’s where the Lakeside Female learned to swim, because the next time she emerged was on the west shore of Flathead Lake, meaning she either swam across or walked around the massive lake.
Flathead Lake is essentially an inland sea, the largest natural freshwater lake west of the Mississippi. The lake is approximately 30 miles long, 15 miles across at the widest point, and covers almost 180,000 acres. Its crystal-clear waters are framed by the peaks of the Mission, Swan and Salish mountains.
For a grizzly bear to select a habitat with such a prodigious obstacle smack dab in the middle of it is a little odd, but the Lakeside Female was uniquely ambitious.
“She was a young bear without many experiences in life yet,” said Lori Roberts, a research analyst on the Montana Fish, Wildlife and Parks’ grizzly bear trend monitoring team. “She was just out exploring.”
Like most bears, the Lakeside Female struck out on her own the next spring at the age of 2, and was captured again in June 2010 near Lakeside after the FWP received reports of bear activity in residential areas.
“We figured it would be a black bear because it’s not an area that grizzlies generally frequent, but there was this little sow grizzly bear,” Roberts said. “She wasn’t doing anything too bad so we decided to see where she would go from there.”
The team outfitted the bear with an ARGOS GPS satellite radio programmed to download her coordinates every four hours, and released her in the Island Unit of the Flathead National Forest, west of Lakeside, where she proceeded to spend most of the summer.
And then came the busy Labor Day weekend, when the allure of Flathead Lake draws crowds from all corners and flotillas of boats spend entire days on the water.
The Lakeside Female wanted a piece of the action.
So, she swam from Painted Rocks point near Rollins to the 24-acre Cedar Island, where she spent a leisurely day.
Then she swam about 3 miles southwest to Wild Horse Island, where she wandered around for three days before swimming south about a mile to the foothills northwest of Polson Bay.
After spending several days there, she embarked on an epic crossing to Flathead Lake’s east shore.
That total crossing spanned about 7 miles, but the bear enjoyed a one-day rest break on tiny Bird Island before paddling just north of Skidoo Bay, eventually reaching the east shore on Sept. 7. From there, she wandered east into the Mission Mountain Range, denning up on Kelly Mountain, which overlooks Swan Lake.
“It’s pretty amazing. There had to be boats in the water, there are certainly a lot of houses, but nobody ever reported seeing her,” Roberts said.
The bear’s satellite collar was set to automatically release, and when it did, Roberts was able to recover it after a 15-minute walk from a road in the Swan Lake area.
The bear’s location could be monitored from satellite about once a week while she wore the collar for two years, but the complete information on her movements had to be downloaded from the collar after it was retrieved.
Her watery wanderings came as a surprise to the research team.
Grizzly bears have large home ranges that are often peppered with bodies of water, and crossings on Hungry Horse Reservoir or Lake McDonald aren’t unusual.
But until the Lakeside Female, nothing had approached the distances she swam on Flathead Lake.
“That was the first time that we have ever seen anything like that. We have bears that swim Hungry Horse Reservoir, but we’ve never had one swim Flathead Lake. It told us a lot about how she used that area,” Roberts said. “We don’t have a lot of huge lakes within occupied grizzly habitat.”
Roberts calculated that the bear traveled 1,200 miles on land and water while she was wearing the collar from June 2010 to September 2011.
According to the GPS data, the sow spent a minimum of eight hours in the water swimming during her longest crossing, and probably closer to 12 hours, Roberts said.