Hibernation usually begins about November and ends around Easter, but is much affected by the weather. Hedgehogs normally wake up several times over winter and often build a new nest. In the spring they commonly spend a few days active then enter hibernation again during a cold snap. Hedgehogs travel about 1-2km each night, males more than females. They return to the same daytime nest for a few days then use another, perhaps returning to an old nest at a later date.
Hedgehogs carry several diseases, but none that are dangerous to humans.
They carry fleas, though not the same sort as found on cats or dogs. The biggest threat to hedgehogs is probably habitat loss, with the change from pastoral farming to arable crops, over the last 30 years. The use of chemicals in gardens and for intensive farming kills the creatures hedgehogs need for food and may also poison them directly. Many are also killed on the roads. Hedgehogs may become locally scarce or even disappear, but nationwide extinction is unlikely.