Bears in Torpor at the Minnesota Zoo
Over the winter, a few fuzzy faces will be absent at the Minnesota Zoo. That’s because brown bears and American black bears will be sleeping behind the scenes as they experience the natural, seasonal state of torpor. Torpor is a little different than hibernation and helps northern bear species, like brown bears and black bears, save energy and survive when food is scarce in winter. It takes a large team to care for bears, including veterinarians, veterinary staff, an animal nutritionist, and Zookeepers on the Minnesota Trail and Russia’s Grizzly Coast. During torpor, Zookeepers provide bears ample straw bedding and reduce the lights, temperature, and noise levels in their “bedroom areas”. Snacks such as peanuts and romaine lettuce are provided, and Zookeepers monitor how much food the bears eat, noting if they eat every last bite or leave crumbs behind. As winter thaws and the bears awake, Kappen will be ready with a spring diet that’s akin to that of wild bears. Taking their cues from warming temperatures and increased daylight, the bears will begin to stir. But unlike humans who must move from fast asleep to 60-mph commutes, bears can take their time going from the grogginess of torpor to fully up and active.
Bear Healthcare
Dr. Anne Rivas, DVM, DACZM, serves as Director of Animal Health. Since she joined the Minnesota Zoo in 2021, she’s been hard at work conducting physicals on animals to get a baseline for their condition. During exams, Dr. Rivas and the team use imaging to view the animals’ internal organs, draw fluid for blood tests and urinalysis, give vaccinations, and check and clean teeth. The bears’ health checkup in 2022 detected signs of aging, especially in the 14–16-year-old brown bears who show some symptoms of arthritis. In support of the bears’ health, the team determined it was the right time to encourage the bears to experience torpor instead of staying active all winter. “Our ongoing goal is to provide for their long-term health,” Dr. Rivas says. “By encouraging the bears to go into torpor, there will be many health benefits as they go through the natural cycle of eating in the fall and being sleepy in the winter.”
Bear Weight Management
In addition to using body condition, Zookeepers monitor how much food the bears eat, noting if they eat every last bite or leave crumbs behind. All the data collected—weight, body score, food intake, other observations of behavior—is closely tracked so that Zoo staff can support the bears’ health and wellbeing during torpor and throughout the year. The American black bears on the Medtronic Minnesota Trail will eat more food and put on weight in the fall. In wintertime, they will remain in their dens in a resting state of torpor, during which they will gradually, gently lose weight. Occasionally, keepers can register weight when the bears voluntarily step on a scale. But mostly the team uses body condition scoring, in which they visually assess the bears for where they might have extra fat deposits in key areas of their bodies, like the shoulders and hips. Then they assign them a score on a scale of 1–9, emaciated to obese. “Our bears are 6–7 going into torpor, and we aim for a score of 4–5 coming out,” Kappen says. “This is the normal, seasonal cycle for wild bears.”
Let Sleeping Bears Lie
As winter thaws and the bears awake, Kappen will be ready with a spring diet that’s akin to that of wild bears. Keepers will offer an increasing amount and variety of lower-calorie foods like leafy greens. The black bears especially like cucumbers and tomatoes, she says. Taking their cues from warming temperatures and increased daylight, the bears will begin to stir. But unlike humans who must move from fast asleep to 60-mph commutes, bears can take their time going from the grogginess of torpor to fully up and active. “How long torpor lasts will depend on the environment and weather, but it might be different for each individual bear, too,” Dr. Rivas says. There are no alarm clocks in the bears’ dens. “We won’t rouse them,” she says. “They’ll wake up when they’re ready.”
Minnesota Zoo Bears in Torpor
When the temperatures drop in Minnesota, the bears at the Minnesota Zoo go into a deep sleep. This is known as torpor and it helps the bears survive the cold winter months.
What is Torpor?
Torpor is a type of hibernation in which the body temperature and metabolic rate of the animal drops significantly. This allows the animal to conserve energy and survive the winter when food is scarce. The bears at the Minnesota Zoo are able to go into torpor for up to nine months of the year.
How Do the Bears Survive Torpor?
The bears at the Minnesota Zoo are able to survive torpor because they have adapted to the cold climate. They have thick fur coats that help insulate them from the cold temperatures. They also have an increased amount of fat stored in their bodies, which helps them stay warm.
What Do the Bears Do During Torpor?
During torpor, the bears at the Minnesota Zoo are mostly inactive. They do not eat, drink, or move around much. They spend most of their time sleeping or resting.
How Does the Zoo Help the Bears During Torpor?
The Minnesota Zoo takes special care to make sure the bears are comfortable during torpor. The zoo staff monitors the bears closely and provides them with extra bedding and blankets to keep them warm. They also provide the bears with extra food so they can build up their fat reserves for the winter.
Conclusion
Torpor is a natural process that helps the bears at the Minnesota Zoo survive the cold winter months. The zoo takes special care to make sure the bears are comfortable and well-fed during torpor. By understanding and respecting this natural process, the zoo is able to provide the bears with the best possible care.
