JACKSON, Wyo. — The Interagency Grizzly Bear Study Team (IGBST) turned 50 years old today!
The IGBST’s 50th anniversary on Tuesday, June 24, marks a milestone for the team of scientists and federal, state and Tribal managers who came together to guide grizzly bear conservation in the Greater Yellowstone Ecosystem (GYE). IGBST members include representatives from the U.S. Geological Survey (USGS); National Park Service (NPS); U.S. Fish and Wildlife Service; U.S. Forest Service; the Eastern Shoshone and Northern Arapaho Tribal Fish and Game Department; and the States of Idaho, Montana and Wyoming.
The grizzly study team was formed by the Department of the Interior as a direct result of controversy surrounding the closure of open pit garbage dumps within Yellowstone National Park (YNP) during the late ’60s and early ’70s.
“People who visited Yellowstone prior to the 1970s, often remember seeing bears along roadsides and within developed areas of the park,” the NPS wrote on its website. “Although observing these animals was very popular with park visitors, it was not good for people or bears.”
In 1970, the park initiated an intensive bear management program to return the grizzly and black bears to feeding on natural food sources and to reduce bear-caused human injuries and property damage, according to the NPS. The measures included installing bear-proof garbage cans and closing garbage dumps in the park.
Since its inception in 1975, the study team has monitored and assessed how grizzlies live, move and adapt across the GYE. YNP wrote via social media that the study team has focused on “solid science” to manage grizzlies and address bear needs.
“Each GPS collar adds to this unmatched body of knowledge — helping us make smarter decisions for this icon of wilderness,” YNP wrote.
The IGBST monitors a minimum of 25 radio-collared adult females annually, and uses radio telemetry signals to track a sample of adult males, according to the USGS.
“By observing radio-collared bears, we document age of first reproduction, average litter size, cub and yearling survival, how often a female produces a litter and causes of mortality,” USGS wrote. “The data allow us to estimate survival among different sex and age classes of bears.”
The IGBST continues to monitor the grizzly’s listing under the Endangered Species Act, trends in population and patterns of habitat use, per USGS. To meet these objectives, the team has focused on three main research areas: females with cubs under a year old, radio-collaring bears and whitebark pine mortality — a high-calorie food resource for grizzly bears.
IGBST reported that GYE grizzly bear populations have gradually expanded their occupied habitat by more than 50%, with an estimated increase from 136 in 1975, to an estimated peak of 1,030 in 2024. As monitored by the IGBST, the criteria used to determine whether the population within the GYE has recovered include estimated population size, distribution of females with cubs and mortality rates. Grizzly bears are still currently listed as a threatened population under the ESA.
