Henry Vilas Zoo Staff Monitored Polar Bear Nora
The zoo is watching for a potential cub after Nora showed a significant weight gain in recent months.
Updated on Oct. 11, 2026 in Pregnancy
Live Poll
Do you trust that accredited zoos prioritize animal welfare in their conservation breeding programs?
Keepers at the Henry Vilas Zoo have been closely monitoring Nora, a polar bear who gained 237 pounds between March and September. She is currently being observed for a potential pregnancy, with an expected birth window of December 2026 or January 2027.
Why it matters
Wildlife experts are tracking the situation closely because polar bear cub mortality rates are higher for first-time mothers. The zoo is providing extra support to ensure the best possible environment for the bear.
Nora gained 237 pounds since March, a metric keepers are monitoring ahead of an estimated birth window in December 2026 or January 2027. Unlike domestic animals, these bears cannot be tested for pregnancy through standard ultrasounds.
The players
Nora
A polar bear born at the Columbus Zoo in 2015 who has resided at several facilities including the Oregon Zoo and Hogle Zoo.
Henry Vilas Zoo
A Madison-based institution currently overseeing Nora's care as part of a national effort to sustain a genetically healthy polar bear population.
The details
Because ultrasound technology is ineffective on polar bears due to their dense insulating fat, staff rely on behavioral observations to track potential progress. To improve monitoring, the zoo recently upgraded the camera systems within Nora's denning suite. Nora moved to the Henry Vilas Zoo as part of a cooperative, coordinated effort to maintain a genetically diverse population of the species.
Timeline
November 6, 2015: Nora was born at the Columbus Zoo and Aquarium.
September 2016: Nora arrived at the Oregon Zoo.
March to September 2026: Nora gained 237 pounds.
December 2026 or January 2027: Estimated birth window for a potential cub.
The Home Front
Nora's presence at the Henry Vilas Zoo follows the rigorous standards of the Species Survival Plan for maintaining genetically diverse populations. This approach is critical for the conservation of vulnerable species in managed care environments.
While there is no action for local residents to take, those following the zoo's updates can watch for official announcements from staff in late December. Keepers remain the sole experts responsible for the bear's intensive care during this period.
The takeaway
Zoo professionals utilize advanced den monitoring to manage animal health when traditional testing methods are not viable. Residents should monitor local zoo updates throughout the winter for news on the potential birth.
Further reading
For more information on family health resources, visit the Pregnancy section.
Live Poll
Do you trust that accredited zoos prioritize animal welfare in their conservation breeding programs?
