Image © Roger Hayden - all rights reserved
Causes of Bear Deaths (Yellowstone)
Grizzly bear mortalities have increased dramatically since roughly 2000, far in excess of anything that can be explained by changes in population size. The most important trend is the substantial increase in mortality that followed hard on the heels of when we lost most whitebark pine in the ecosystem. Grizzly bear conflicts with livestock producers and hunters have surged dramatically since the loss of whitebark pine, which is consistent with a turn by many bears to eating more meat in compensation for loss of pine seeds and cutthroat trout.
Hunters have emerged as the leading cause of grizzly bear mortality. Despite a precipitous drop in the number of hunters in recent decades, there has been a three-fold increase in bear deaths resulting from conflicts with hunters in the last 11 years. What is going on and what can be done about it?
There are many commonsense proactive approaches to preventing conflicts involving livestock – through husbandry practices, livestock guardian dogs, and increased human presence on the landscape. But a few bad actors in a few places contribute to making cattle a leading cause of grizzly bear mortality ecosystem-wide. The Upper Green River area near Pinedale, WY, is one of these places. Instead of trying to co-exist with bears, these ranchers more often pressure agency officials to kill bears.
“Roads probably pose the most imminent threat to grizzly habitat today…The management of roads is the most powerful tool available to balance the needs of bears and all other wildlife with the activities of humans…Any un-roaded land represents important and unique opportunities…Management should seek to maintain these areas as un-roaded wherever possible.”
- US Fish and Wildlife Service, Grizzly Bear Recovery Plan, 1993
Yellowstone grizzly bears are already suffering from the impacts of climate change, which has precipitated the rapid decline of whitebark pine, a key fall food source for the bears. Other foods may be next.