Scientists with the Interagency Grizzly Bear Study Team have resumed grizzly bear capture and monitoring operations in Yellowstone National Park as part of long-term efforts to track the species’ recovery in the Greater Yellowstone Ecosystem.
Fieldwork began September 1 and will continue through October 15, according to the U.S. Geological Survey and park officials. The work supports population monitoring and habitat research critical to managing grizzly bears under the Endangered Species Act. Visitors to the park may see bright warning signs posted at major access points near active trap sites. Officials are urging the public to avoid posted areas.
Biologists use natural bait such as road-killed elk or deer to attract grizzly bears. If signs of bear activity are present, they deploy culvert traps or foot snares. Once captured, the bears are sedated and examined.
The IGBST has conducted regular capture operations across the ecosystem since the early 1980s, typically between May and October. The captures are coordinated across multiple jurisdictions, including Yellowstone and Grand Teton national parks and adjacent lands in Montana, Idaho and Wyoming.
Matthew Gould, a biologist and team leader for IGBST, says the Greater Yellowstone grizzly bear population has recovered significantly over the past 40 years, from approximately 250 in the early 1980s to over 1,000 today. “This growth has been accompanied by a notable expansion in occupied range,” Gould wrote in an email to Mountain Journal. “The success of this recovery is due to collaborative efforts among federal, state, and Tribal agencies, landowners, and the public to protect habitat and reduce human-bear conflicts.”
Monitoring is concentrated in the Demographic Monitoring Area, a designated zone used to assess population abundance, distribution, mortality and progress toward recovery goals and is conducted by respective state agencies, all of which are IGBST members. According to Gould, the data collected and research goals are consistent across jurisdictions, both inside and outside of the national parks.
Gould said the two primary objectives of grizzly bear captures are to monitor the status and trend of the GYE grizzly bear population, and to understand habitat use patterns and how land management activities affect the welfare of that population. “While the core goals have remained consistent,” he said, “scientific and conservation priorities have evolved to address the information needs of the IGBST and the Yellowstone Ecosystem Subcommittee member agencies of the Interagency Grizzly Bear Committee.”
Biologists determine the bear’s age and sex, take morphological measurements, record their weight, collect biological samples such as blood and hair for DNA analysis, and assess the individual’s health by evaluating fat reserves and examining the condition of their teeth and claws. “We aim to collar a representative sample of the population and collar individuals after considering their sex, age class, and reproductive status,” Gould said.
The IGBST’s findings are used by YES, a member group of the Interagency Grizzly Bear Committee that oversees policy and management strategies. The 2024 Conservation Strategy outlines the current steps being taken to support long-term grizzly bear recovery and guide potential future delisting decisions.
Public safety during captures remains a key concern, especially during the busy fall season in the parks. Gould said trapping sites are chosen to reduce visitor interactions, and many are in areas that are seasonally or permanently closed to public access. Park officials emphasized that any area marked with grizzly research warning signs should be avoided.
As the fall field season continues, officials ask that the public remain aware of signage and follow all park guidelines to ensure the safety of both humans and bears.
