The grizzly bear population at Yellowstone National Park has increased 4-fold over a 25-year period with no loss in genetic diversity, according to a new report. The results strongly suggest that Yellowstone grizzly bears,
Ursus arctos ssp.
, are well on their way to a near full recovery after a huge population drop was reported in the early 1980s. The report, published in Molecular Ecology, represents a collaborative effort among the USGS, Wildlife Genetics International, the University of Montana, and the federal, state and tribal partners of the Interagency Grizzly Bear Study Team. "We already knew the grizzly bear population had been growing since the mid 1980s from our demographic analyses," team leader Frank van Manen, a USGS wildlife biologist, told Discovery News. He added, "This study demonstrated that, in parallel with demographic growth, the effective population size (i.e. the number of individuals contributing genes to the next generation) increased as well." Lead author Pauline Kamath, also from the USGS, echoed that good news, saying that the findings about genetic diversity are a key "indicator of a population's ability to respond to future environmental change."10 Reasons to Visit a National Park Now
Van Manen and his colleagues estimated that there were about 757 grizzly bears in the Greater Yellowstone Ecosystem last year. He said that the 2015 estimate would be announced soon, reporting a slightly lower number. Despite the small drop in number, van Manen said, "Our latest data show evidence of this population nearing carrying capacity: we have documented a decrease in survival of cubs and a slight slowing of reproductive output associated with areas of higher bear densities; we refer to this as density dependence." The region's grizzly bear population was estimated at just 100 in the 1980s and then 450 in the 2000s.Secret Grizzly Bear Feeding Site Discovered
Grizzly bears are "opportunistic omnivores," meaning that they eat almost everything. Van Manen said that they are known to consume over 266 different species at Yellowstone. "Unlike obligate carnivores, such as wolves, grizzly bears typically do not strongly affect any single species," he said. "At higher densities, however, they can affect their own vital rates."Bears Use Wildlife Crossings to Find New Mates
When researchers look for a place to set up a grizzly bear capture location, they seek out evidence of the bears' presence, such as scratches on trees and bear scat. Sometimes traps are set in areas that have no obvious bear sign to determine if indeed bears are present. Once captured, the bears are sedated before they are weighed and measured. Vital signs and other data are also noted. Even the bear feces is often examined as another indicator of health and to determine what the bears are eating.Why Polar Bears Don't Hibernate
Grizzly bears are slow reproducers, since females have a litter of cubs only once every three years. They also often produce their first litter no earlier than age 5 or 6, according to van Manen. "It has taken 40 years of concerted conservation efforts by federal, state, and tribal agencies to get to this point (of conservation success)," he said.Photographing Skinny Polar Bears: First Person
Steve Hillebrand, U.S. Fish and Wildlife Service
The good news about grizzlies has many concerned that the protected status of these Yellowstone bears will be lifted. The Obama administration has been considering such a de-listing since late 2010. Shortly thereafter, a joint federal-state committee recommended that the bears be removed from the Endangered Species Act. Ohio State University researcher Harmony Kristin Szarek pointed out that such decisions do not always come down to scientific data. She explained that "acceptability of a certain level of risk is an ethical or policy decision rather than a scientific decision."
Grizzly bears can pose threats to humans. Their big clawed paws, being measured here, sharp teeth and strength can overwhelm unarmed individuals. In August of this year, for example, 63-year-old Lance Crosby was killed by a female grizzly that was with her cubs. She was later captured and euthanized. Such attacks on humans are still rare, however.Drones Bother Bears, Nearly Triggering Heart Attacks
In this image, USFWS employee Wayne Kasworm is shown with a sedated adult male grizzly bear. The bear lived to tell the tale, as he was just part of a data-gathering survey. Szarek conducted her own survey, but on researchers who have published papers concerning grizzly bears over the past 10 years. The "findings showed little agreement regarding the threats facing the long-term survival of the Greater Yellowstone Ecosystem grizzly bear population," she reported, "but a clear majority believe grizzlies should remain listed as either endangered or threatened."Genetic Islands Are Stranding Big Animals
Doug Smith, National Park Service
Humans are not the only threats to the bears either, as this image indicates. Wolves may stalk cubs and sick or elderly grizzlies. Oregon State Researchers, led by professor William Ripple, determined that the return of wolves to Yellowstone has actually helped the grizzly bears overall. The research shows how intricate and intertwined food chains can be. In this case, the reintroduction of wolves has led to a reduction of elk herds. This, in turn, has resulted in an increase of berry bushes that the grizzly bears like to graze on. Such grazing helps the bears to gain nutrition before going into hibernation. The berry bushes also produce flowers of value to pollinators like butterflies, insects and hummingbirds. They provide food for other small and large mammals, and benefit birds as well.Wolves Help Grizzly Bears Get Berries
Steve Hillebrand, U.S. Fish and Wildlife Service
This grizzly bear is enjoying a relaxed moment, but the months ahead will likely lead to debates over Yellowstone's grizzlies, which are a subspecies of brown bear. Humans have already greatly altered the ecosystem at the national park, and are now left with the challenge of getting the population balances back to healthy levels while also dealing with the reality of human-bear interactions as the bears' numbers increase. "For example, ranchers are experiencing more conflicts with grizzly bear depredation on their livestock and grizzly bears sometimes come into campgrounds and communities" looking for food, van Manen said. Ironically, it is the bears' popularity with tourists that is helping to keep them alive. As van Manen explained, "Grizzly bears are a tremendous draw for tourists and outdoor enthusiasts in the national parks, national forests, and many other areas in the ecosystem. The economic value of bear viewing in the national parks, for example, is substantial."Yellowstone Lesson: What to Do If You Encounter a Bear
The U.S. Fish and Wildlife Service (FWS) says it’s now time to remove Yellowstone grizzly bears from the nation’s endangered and threatened wildlife list.
The agency says the bears have rebounded from an estimated 136 in 1975 to a population of more than 700 today.
“Our proposal today underscores and celebrates more than 30 years of collaboration with our trusted federal, state and tribal partners to address the unique habitat challenges of grizzlies,” said FWS Director Dan Ashe in a press release.
The iconic grizzlies — spread across Yellowstone in Montana, Wyoming, and Idaho — now range over more than 22,500 square miles of the park, FWS said.
Next comes a 60-day comment period on the proposed delisting, in which the public, federal and state agencies, and scientists can weigh in on either side of the proposal.
The FWS notes that even after the bear’s Endangered Species Act protections are removed it will closely monitor the grizzlies’ population and habitat.
“We will continue to be part of a strong monitoring program, implementation of the conservation strategy, and partnership with our state and federal partners,” Ashe said. “We are look forward to hearing from the public about the proposal and consulting with Native American tribes.”