Fifty-one grizzly bears mortalities were recorded in the Northern Continental Divide Ecosystem this year, the highest ever recorded since recovery efforts started. Most of the bears are dead, though some ended up in zoos and some were moved to the Cabinet-Yaak ecosystem, where the U.S. Fish and Wildlife Service continues to augment the population there.
Of the 51 bears, 10 were removed by agency biologists, 36 were human caused, four were natural deaths and one was undetermined. The greatest spike in deaths was from collisions with vehicles — 17 bears total died from rig collisions or the surviving young were moved to zoos.
“That’s higher than every previous year,” grizzly bear research biologist Cecily Costello of Montana Fish, Wildlife and Parks said. In an average year three to four deaths are caused by car collisions, she noted.
One collared female that died in a car collision near Marias Pass had a yearling cub. The cub was not counted as a mortality as they often survive without their mother, Costello noted. The sow had a habit of crossing the highway, based on the data from her collar. She frequented both sides of the road, Costello said.
Another collision on Highway 93 south of Ronan killed a sow and two cubs and orphaned a third. Much of Highway 93 is fenced with animal crossings, but that particular stretch is not.
The last bad year for bears was in 2013, when 32 mortalities were noted. One of them was a natural death. From 2014 through 2017, the average mortality has been about 23 bears, according to figures provided by FWP.
Glacier National Park continues to be a relatively safe haven for bears — at least from people. It had just one recorded death — a bear that fell apparently off the trail above Rimrocks and onto the Going-to-the-Sun Road. The fall broke the bear’s back and it had to be killed. The last bear death in Glacier was in 2014.
Despite the high number of mortalities and removals, Costello said that the overall trajectory for the grizzly bear population continues to go up.
“Even with these numbers, the population is growing,” she said. “It’s still a trajectory that positive in the demographic monitoring area.”
But if these high numbers continue over the course of several years, “It might start to be a red flag,” Costello said.
The demographic monitoring area is a 16,000 square mile region along the Continental Divide stretching from the border south to near Missoula where the bear recovery efforts have been focused over decades.
Mortality in the demographic monitoring area was 42 bears this year; 18 were “dependent” bears, or cubs, and 24 were independent bears, meaning they were two years old or older. Ten of those were females, 14 were males.
Even with those deaths, the grizzly population would increase.
But to say bears are numerous would be a misnomer.
The average bear density in the demographic monitoring area is about 24 bears for every 247,000 acres. That’s about one bear for every 10,300 acres.
That’s on par with most of Canada and Alaska, outside of wetter regions, where there’s more food, Costello said. Grizzlies generally don’t live in high densities unless its near a large food source, like a river filled with salmon, Costello noted.
Black bears, which are smaller and require less food resources, can live in densities 10 times higher than that, she said.
There were likely food factors that caused some of this year’s grizzly mortalities. The huckleberry crop in the northern region dried up in the summer drought, but Costello noted that in southern regions, the bears don’t rely as much on hucks and feed on chokecherries and other foods, which did better, despite the dry summer.