In the winter months we need to keep an eye out for Hedgehogs who are underweight or too young to survive hibernation. In the Westcountry we only need to begin to be concerned towards the end of November and in December as we have a milder climate than most in the UK. As a general guide Hedgehogs weighing less that 400g at the end of November and less than 500g in December should be taken in to a rescue to be safely overwintered. 

Please only pick up a Hedgehog to weigh it if you are sure it is too small- here is a useful guide on judging weight by eye...