March 30, 2013
Black Bear Population In Nevada Is Coming Back From The Brink
April Flowers for redOrbit.com - Your Universe Online
One of Nevada's most interesting inhabitants, the black bear, is the focus of a new study from the Wildlife Conservation Society (WCS), the University of Nevada, and the Nevada Department of Wildlife (NDOW). The three agencies pieced together the last 150 years of history for the bear.
The 15-year study was compelled in part by a dramatic increase in human/bear conflicts and a 17-fold increase in bear mortality due to automobile collisions between the early 1990s and mid-2000s. The study, published online in the Journal of Wildlife Management, included a review of the black bear's little-known history in the state.
Over the 15 years of the study, bears were captured both in the wild and at the urban interface because of conflict complaints. Before being released, the captured bears were evaluated for multiple physiological indicators. These included condition, sex, reproductive status, weight, and age. The information gathered allowed the scientists to estimate the population size in the study area to be 262 bears — 171 males and 91 females. The researchers mapped confirmed sightings and points of capture from 1988 to the present. This map was presented in the report to illustrate current population demographics. It will also be used to shape bear management in Nevada.
"It's critical to understand the population dynamics in a given area in order to make informed decisions regarding management," said WCS Conservation Scientist Jon Beckmann. "This includes decisions on everything from setting harvest limits to habitat management to conservation planning in areas where people will accept occupation by bears. We used this long-term study to determine if reported incidences were due to an increasing or expanding bear population, or people moving to where bears are located. The answer is both."
The study encompassed an area locally referred to as the Carson front - reaching from the Carson Range of the Sierra Nevada east to the Virginia Range and Pine Nut Mountains, and from Reno south to Topaz Lake. The urban interfaces of cities and towns of the Lake Tahoe Basin were included because many captures were in response to conflicts in those locations.
The researchers wanted to integrate information on the historical demographics of the black bear, but found that little published scientific research or data was available. The bear's history in Nevada went mostly ignored until 1987 when complaints from sightings and road collisions with vehicles began.
Because of the lack of scientific literature, NDOW biologist Robert McQuivey began searching primary sources. He compiled historical records that included old newspaper articles, pioneer journals dating as far back as 1849, and NDOW records that had long been unavailable. These were reviewed, confirming that black bears were present throughout the state until approximately 1931. The study concludes, "The paucity of historical references after 1931 suggest extirpation of black bears from Nevada's interior mountain ranges by this time."
"The historical records paint a very different picture of Nevada's black bear than what we see today. This new perspective is a good indication of what bear management in this state could involve should the population continue to expand," said Carl Lackey of NDOW.
Overhunting and conflicts with domesticated livestock contributed to the bear's local decline in the Great Basin, however, landscape changes from clear-cutting forests throughout the western and central regions of the state during the mining booms of the late 1800s played an important part as well. The bear population has rebounded, though, as fossil fuels replaced timber as a source for heat and energy, forestry and grazing practices evolved, and reforestation and habitat regeneration occurred in parts of the their former range.
In addition to the current demographics map, the research team created historical maps of black bear distribution within the interior of Nevada during the 1800s and early 1900s, recommending that historical range maps for the species in North America be revised to include the information gathered as part of their study.