Grizzly bear population estimated at about 960

Grizzly bear populations in northwest Montana continue to increase, prompting Montana Fish Wildlife and Parks to prepare for the possibility of the bears being removed from the National Endangered Species List. Added to the list in 1975, the grizzlies in the Northern Continental Divide Ecosystem are estimated at 960 in 2014. The NCDE includes areas around Glacier National Park and the Bob Marshall Wilderness Complex. The NCDE subcommittee of the Interagency Grizzly Bear Committee held its fall meeting in Kalispell last week to discuss grizzly bear recovery.

The Grizzly Bear Conservation Strategy for the NCDE, published in 2013, is being revised to include public comments. Most of the strategy will be revised by the end of the year, said Chris Servheen, grizzly bear recovery coordinator with the U.S. Fish and Wildlife Service. However, the strategy can’t be implemented until the Forest Plan Revision is complete to include habitat standards. The Forest Service expects the revision to be open to public comment in March, Flathead National Forest Planner Joe Krueger said.

Before they can propose delisting grizzlies, all the conditions of the strategy have to be in place with agreement between the agencies involved in bear management. The conditions include determining sustainable mortality limits and ensuring genetic diversity among the grizzlies in the NCDE, Bitterroot Mountains, Yellowstone National Park and Cabinet-Yaaks. Biologists are looking for grizzlies to occasionally migrate between these areas. The Bitterroots currently do not have a sustained grizzly population.

Servheen said that he sees the greater migrations happening within the next 10 or 20 years.

In 2015, there were 22 known grizzly bear deaths in the NCDE. This is close to the average of 19-20 mortalities each year, Servheen said. Human-caused mortalities came to a total of 14 including six killed by vehicles, four were poached, one killed in defense of human life and one mistaken for a different animal while hunting. Bear manager Tim Manley said it was unusual to have so many bears killed on the road, usually there is one annually. Three deaths took place in the Swan Lake area, one on Montana Highway 35, one by Flathead Lake and one on an Indian reservation. Manley said that there were reports of bears feeding on road kills.

Several bear deaths were for FWP management including four bears that had killed livestock and one that had caused property damage. Bear research biologist Lori Roberts keeps track of bears wearing GPS collars in the area as part of trend research. She reported that in 2015 they captured 43 individual bears, but were unable to collar any bears in the Bob Marshall Wilderness due to wildfires. No collared bears died of natural causes this year.

FWP biologist Cecily Costello presented the results of a study on grizzly bear demographics that biologist Rick Mace had worked on since 2004, he recently retired.

Since Mace presented analysis from the study in 2012, they have changed the study to include management bears in the study to increase their sample size. Management bears do have different behavior than bears caught randomly for research. Costello said that they adjusted the rates to account for this. Eighty percent of research bears have never been involved in conflict.

According to the study, on average there are 31.2 mortalities per year, which is an estimate derived from how likely a death is to be reported. Some deaths, such as agency removals, are reported all the time, but some are reported 85 percent of the time such as a vehicle or train collision, defense of life or property and mistaken identity. Then there are deaths that are reported only 15 percent of the time. The infrequently reported deaths are due to poaching or natural causes and are systematically inflated in the study to better capture how grizzlies die.

Female bears currently have a 95 percent survival rate, males have an 85 percent survival rate and cubs are around 60 percent, Costello said. The lowest sustainable survival rate is about 93 percent for females. Also, the starting population size didn’t matter. The study found that given the estimated mortalities, 15 more bears could be killed without seeing a population decline.

Assuming there were 765 bears in 2004, there were 960 bears in the NCDE in 2014, Costello said. Grizzly populations are expected to grow at a rate of 2.33 percent. She noted that this is very close to the death rate, the percentage of mortalities every year is between 2 and 3 percent. Female grizzlies began to have cubs at the mean age of 5.7 years and have 2.1 cubs in each litter.

She also said that the bear population is maturing based on data from the past two decades.

The average age of captured grizzlies is increasing, the oldest was 27 years.