Biologists this week reported a record estimate for female Yellowstone grizzlies with cubs born this year, the lowest mortality since 2009, and an estimated 1,000 bears. Those factors make it more likely that grizzlies of the greater Yellowstone ecosystem could be removed from the endangered species list soon.
Efforts to remove the bear from federal endangered species protection moved forward this week with the submission of an analysis evaluating everything from disease to human encounters to habitat loss that could threaten the future of the bear’s survival.
The threat analysis was recently submitted to the director of the U.S. Fish and Wildlife Services, according to Chris Servheen, grizzly bear recovery coordinator with the service. A decision, based on the analysis, as to whether it’s time to draft a rule removing the bears from federal protection, could be announced any time, Servheen said on Wednesday at the Yellowstone Ecosystem Subcommittee of the Interagency Grizzly Bear Committee meeting in Bozeman, Montana.
Using a statistical model called mark-resight, the grizzly population is estimated at about 1,000 bears, said Frank van Manen, leader of the Interagency Grizzly Bear Study Team. He said this newer way of calculating population is more accurate than previous calculations which suggest a population of 757.
The old method was conservative, something that was important when evaluating a recovering population, van Manen said. The new method is more accurate and is the best available science. The previous method for measuring population was known for being biased-low, he said.
While the population figures derived from the two estimating methods are different, the trend for both methods is the same, showing a stable population since the early 2000s, van Manen said. There is evidence the population isn’t growing, at least in part due to density dependent factors, meaning a population’s growth levels off when it reaches a capacity level for an area. Growth is estimated at zero (stable) to 2 percent.
The trend is at least as important as the actual population numbers, said Chris Colligan, wildlife program coordinator with the Greater Yellowstone Coalition. If both methods show the same trend, it likely doesn’t matter if one number is bigger, he said.
Van Manen agreed. A change in population size simply reflects a change in technique, not a sudden spurt in the bear population.
Colligan said he will evaluate the science behind the new mark-resight method, in particular how it calculates bears seen at army cutworm moth sites. Moth sites were left out of the population estimate using the mark-resight method because bears at the sites are easier to spot than in other places in the ecosystem and many don’t have radio collars.
“Whatever the best available science that gives us the minimum bias is what we’re looking for,” Colligan said.
Bears were found in all 18 management units of the Yellowstone grizzly management area and this year 39 new bears were captured, van Manen reported.
Researchers estimate this is a record year for new cubs. There were an estimated 60 females with cubs of the year, topping last year’s record estimate of 59 females with cubs of the year, according to van Manen.
It also has been a low-mortality year. So far there are 20 known mortalities for 2014, the lowest mortality rate since 2009.
“Things are looking really good for this year,” van Manen said.
Last year there were 29 grizzly bear deaths. Of the deaths this year, 15 were human caused and five were due to natural causes.
Van Manen said he didn’t know why mortalities are low this year. However, the ecosystem provided an abundance of natural food sources including berries, whitebark pine cones, army cutworm moths and truffles, which could help reduce food- and livestock-related conflicts.
There have been no human-bear conflicts in Grand Teton National Park.
In Yellowstone National Park there were 44 human-bear encounters in the backcountry, but zero attacks and only two bluff-charges, said Kerry Gunther, bear biologist in the park. There were no human-caused mortalities in the park. Bears received food rewards only twice. The park had an abundance of winter kill carcasses in the spring and plentiful berries, truffles and whitebark pine cones.
“Our bears are looking really fat and happy,” Gunther said.
Outside of national park boundaries in Wyoming there are more issues as bears expand into new areas, said Dan Bjornlie, large carnivore biologist with Wyoming Game and Fish. There have been 215 conflicts so far this year in Wyoming outside of the parks, and 123 livestock losses in Northwest Wyoming. There were also several incidents of bears getting food from unsecured garbage and attractants like pet or livestock food, Bjornlie said.
Reducing human-bear conflicts is a priority of the Greater Yellowstone Coalition, Colligan said. It recently partnered with the Forest Service to help fund bear boxes at campsites throughout the greater Yellowstone. The coalition is also helping in efforts to protect important habitat.
Colligan said another important factor in considering a delisting of the bear is connectivity, or the natural genetic mixing of the Yellowstone bears and the Northern Continental Divide population near Glacier National park. So far, that genetic mixing has yet to happen.