Rabbits are very active during the winter, as the weather and the lack of plants means they have to spend much more of their time searching for food. When not searching for food, rabbits spend much of their time in the warmth of their underground shelters, which they usually line with grass, leaves and sticks to help make it more insulated.
When out in the open during cold weather, rabbits tend to sit still in one place in order to conserve their energy.
Wild rabbits are also forced to change their diet during the winter, eating the bark, sticks and buds of small bushes and trees due to a lack of green vegetation. Rabbits frequently eat their own droppings throughout the year, as their digestive systems are not very efficient at processing food, meaning that there is actually quite a bit of nutrition left in their feces. This habit increases during the winter, as it's important that they extract as much nutrition as possible from their minimal food sources.
Winter is also the time of the year that rabbits are most hunted. Their principal predators are hawks, owls and foxes during winter, but humans often shoot rabbits, both for sport and to protect crops and grazing.