Setting up a bear baseline
In the late 1960s, park managers thought that as few as 50 black bears might roam within the Park. At that time, no one guessed that dozens of bears lived a quiet life in the wild for every one that caused trouble with visitors. To eventually come to this conclusion, Dr. Pelton and his students—including van Manen, who was a graduate student in the early 1990s and then full time research ecologist, had to start with a baseline study.
The first step of the baseline was estimating the population. Counting bears was never easy—bears are secretive and active when people aren’t—but researchers adapted their methods over the years. Live trapping of bears took place for 8 weeks each summer and has provided the basis for the long-term study through 2006. When researchers trap bears, they use different methods to track them. These methods changed considerably over time:
Both of these methods provided researchers with an estimate of the total number of bears in the national park, which was around 600 bears in the early 1970s. They witnessed substantial population growth during the early to late 1990s, and now that number is closer to 1600 bears. These methods didn’t give them any information about overall bear home ranges, habitat use, diet, and reproduction, however. To find these answers, which would help wildlife managers make long-term decisions, they continued the baseline study with this technique:
In addition, researchers developed techniques based on information from the long-term study that managers can use to monitor the bear population and their food resources:
The bait station, mast surveys, and DNA collection are good ways to study populations, van Manen explained, because they provide detailed information at different scales—from the entire population to individuals—but they don’t require capturing animals to understand Park-wide trends. The DNA collection and analysis provides the best information but a large obstacle to this form of research is cost. As a result, the Park has not yet switched to this type of population monitoring.
Field Trip Earth offers an in-depth look at what University of Tennessee field research on black bears entails. Go to their site to read about graduate student researchers and watch podcasts of a bear work-up. Click the back arrows to return to this page.
Return to Dispatches from the Field: Issue 3.
Did You Know?
More than 240 species of birds have been found in the park. Sixty species are year-round residents. Nearly 120 species breed in the park, including 52 species from the neo-tropics. Many other species use the park as an important stopover and foraging area during their semiannual migration. More...