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Absent for 80 years, bears once more roam the eastern Sierra Nevada Mountains and Great Basin
In 1979, a state bear biologist reported that “Nevada has no bear….” Today, 80 years after the last bear sighting, at least 600 black bears roam across the eastern slope of the Sierra Nevada Mountains and western Great Basin Desert. When bears started dispersing from California into Nevada they quickly learned that urban areas were a great source of food in easy to open garbage cans. By the early 1990s WCS staff had recorded a 10-fold increase in homeowner complaints about bears and a 17-fold increase in bears being struck and killed by vehicles. Urban areas of Nevada were rapidly becoming a death-trap for bears moving into the state. WCS field data on bear distribution and movement patterns informed where conservation efforts would have the greatest impact on reducing human-bear conflict and bear mortality. Working with the Nevada Department of Wildlife (NDOW), a combination of deterrents, including using Karelian Bear Dogs to alter the behavior of ‘nuisance’ bears and prevention of human-bear conflicts by investing $3 million in bear-resistant trash cans and dumpsters, has resulted in a 3-fold increase in bears since the late 1990s and a substantial decline in the rate of bear conflicts and mortality. By helping people to live comfortably with wildlife WCS has, once again, rewilded a landscape.
Black bears (Ursus americanus) and grizzly bears (U. arctos) were fairly common in the Great Basin Desert of Nevada until logging to supply gold rush mines with timber support structures, combined with unregulated hunting, drove them to local extinction in the 1930s. Over the next 50 years bear habitat in Nevada gradually recovered. In the 1980s, bears began to move back into the state from California though sightings were still rare events. By the mid-1990s, bears and people were increasingly coming into uncomfortably close proximity. This was unnerving for people watching bears raid their garbage, and deadly for bears hit by traffic. In Lake Tahoe and the Western Great Basin Desert in western Nevada between the early 1990s and early 2000s WCS scientists documented a 10-fold increase in the annual number of complaints about bear encounters and a 17-fold increase in bear deaths after being struck by vehicles. Motivated by a desire to minimize bear-human conflicts and to reduce bear mortality WCS partnered with the Nevada Department of Wildlife to map core habitat patches and connectivity corridors for bears, and study how bear behavior, health and reproduction was influenced by access to human foods and garbage. Results showed that urban bears reach reproductive age earlier than wildland bears and had higher rates of reproduction. Yet this did not result in an increase in the urban bear population as mortality rates, primarily from being struck by vehicles, were higher in all age classes compared to those in wildland bears. This research showed, surprisingly, that urban areas in Nevada were a sink for bears and the primary source for human-bear conflicts. These studies showed clearly that reducing bears’ access to human food waste and deterring bears from taking up residence in urban areas would help minimize human-bear conflicts and bear mortality. Over the last decade, WCS and NDOW along with other partners raised over $3 million to distribute bear-resistant trash cans and dumpsters in the Lake Tahoe Basin, and convinced 6 counties in the area to put in place ordinances requiring home owners and businesses to use bear-resistant garbage containers. Simultaneously, we launched a non-lethal deterrent program to alter the behavior of “nuisance bears” that have lost their fear of people. Karelian Bear Dogs that have an instinct for handling bears safely are used to chase and bark at problem bears until they run away. Using bear dogs has proven more successful than relocating conflict bears, which tend to simply return to their capture locations within days or weeks. Combining targeted prevention and deterrence approaches has resulted in an increase in black bear numbers from around 180 in the late 1990s to over 600 individuals today. Bears are now, once again, roaming across the mountains of Nevada where they had been absent for over 80 years. The Western Great Basin of Nevada is an excellent and replicable example of successful re-colonization by large carnivores, as a result of conservation efforts by WCS and our partners.
The black bear population in the western Great Basin has increased from an estimated 180 individuals in the late 1990s to an estimated 600 individuals today, thanks to a combination of prevention using bear-resistant garbage containers, changes in wildlife management policy, and deterrence using Karelian bear dogs.
By capturing and collaring bears, WCS and our partners have been able to track their movement patterns over time and use this information to map core habitats for both male and female bears. This has allowed us to: 1) identify regions that could support bears as the population expands, and 2) detect key corridors for the safe movement of bears across human-altered landscapes.
WCS research on survival and mortality rates, population size over time, and genetic structure of the expanding bear population is being used by the Nevada Department of Wildlife to guide bear management plans and conservation efforts in Nevada.
By demonstrating the impacts of garbage on bear-human conflict and bear deaths, WCS and NDOW were able to encourage counties in both Nevada and California to enact ordinances requiring that home owners and businesses use bear-resistant garbage cans and dumpsters. Our work also convinced the state of Nevada to pass new laws against the feeding of wildlife. These efforts have resulted in an increase in bear populations without increasing the rate of bear-human conflicts. Many of the lessons learned from this area are being applied to other regions of North America dealing with black bears and grizzly bears, including the Greater Yellowstone Ecosystem.
WCS is currently studying how the increasing bear population is influencing the behavior of other large carnivores such as mountain lions and whether these changes are resulting in increased livestock predation and an economic impact on rural families living with wildlife.
Using a combination of deterrence and prevention, WCS was able to reduce the rate of bear-human conflicts, resulting in a 300% increase in the black bear population since the late 1990s.
Historical range for black bears in the Great Basin of Nevada. With recent range recovery shown as black triangles.
Three black bear cubs in a den in western Nevada.