How do you know that a groundhog needs only a little oxygen during its winter sleep?

During winter hibernation, groundhogs experience a state of torpor, where their metabolic rate decreases significantly, allowing them to conserve energy. This reduced metabolic rate means they require less oxygen to sustain bodily functions. Additionally, groundhogs are known to have adaptations such as increased muscle mass and specialized breathing patterns that help them efficiently utilize the limited oxygen available during hibernation. Studies have shown that groundhogs can survive with very low oxygen levels during winter sleep, further supporting the idea that they require only a minimal amount of oxygen during this period.