Bear in the bathroom
Food sources and how they affect grizzlies
Yellowstone grizzly bears are stocking up on food supplies and preparing to enter the next stage of life, which means they may be more visible. Bears consume a wide variety of sustenance throughout the year including army cutworm moths, whitebark pine nuts (WBP), ungulates and cutthroat trout.
Part of the listing and delisting debate involved the livelihood of WBP after a mountain pine beetle insurgency. In 2009, bears were re-listed after a judge concluded their food source supply was not considered in the decision. Fish and Wildlife Services (FWS) appealed this, but bears remained on the Threatened Species list in 2011.
During this time the United States Geological Survey (USGS) tasked the Interagency Grizzly Bear Study Team (IGBST) with looking at the relationship between the grizzly population and the decline of WBP. The mountain pine beetles ravaged cone-producing trees, changed the landscape and made a difference to grizzlie’s diets, but not in a devastating way.
“The findings of that pretty extensive research were that bears so far have been able to adapt to those changes,” Frank van Manen, study team leader since 2012 with IGBST, said. Instead of resorting to WBP, bears transitioned to eating more meat resources, like carcasses, in the fall.
Van Manen and the study team from IGBST found no evidence that grizzly population decline was related to declining WBP. “They were more flexible in food choices than we thought they were,” Danielle Oyler, Education Coordinator for the Montana Bear Education Working Group, said.
Diet choices start to vary even more when bears enter their hyperplasia phase. "In the fall, bears are preparing their dens and putting on as many calories as possible,” Kris Inman, Conservation and Communities Program Coordinator for the Wildlife Conservation Society, explained. Food is the only thing on the bears’ minds as they forage for up to 20 hours per day and consume 15-20 thousand calories, Oyler provided.
Bears are out in the woods more often and for longer periods of time as a result, just like humans, who are trying to soak up the last of the summer hours. The overlap can lead to more human and bear interactions and some negative habituation for bears involving human food sources.
Throughout their feeding season, bears have a map in their head that tells them what food is where, Inman described. They remember places they found food easiest and plan on going back. “They’re generalists. They’ll access whatever food is most readily available. They will find food like your trash can sooner than they might find some other things,” Inman said.
Take the black bear that climbed through a window at Buck’s T4 on Saturday. “It got a food reward somewhere along the line to be bold enough to go through the window,” Inman said. Maybe that food reward was missing outside this time, but the bear was smart enough to know if it made it inside it would likely find another. This is a good reminder for all residents in bear country to close doors and windows when entering and exiting a building.
“Once they become habituated or conditioned to food, to our trash, they become bolder, and once they become bold enough FWP will determine whether they relocate a bear,” Inman said.
Worst case scenario, after tranquilization and relocation, a bear becomes a problem bear, returning to the same area too many times. “Being as resourceful as these animals are, that’s really a challenging thing to deal with,” van Manen said. Inman feels it is a safe assumption to say euthanizing a bear is the worst part of any game warden’s job, especially if something could have been done to prevent it from happening.