Variation in hibernation patterns of a temperate zone mammal.

Temperate-zone species frequently employ hibernation as a winter energy-saving strategy to overcome periods with unfavourable ambient conditions and low food availability. With winters becoming warmer and seasons becoming less predictable, one question is whether species will show flexibility in the use of hibernation and whether this will be sufficient to keep pace with rapid anthropogenic alteration of the environment. We examined the hibernation pattern of a wild hedgehog population (Erinaceus europaeus) in a semi-rural habitat in the north-west of England that is subject to a mild winter climate. We conducted night surveys across a 1-year study period, collecting population-level activity data on a total of 26 individuals as well as detailed data on hibernation timing and pattern in five individuals tagged with temperature-sensitive VHF tags through the hibernation period. While all five tagged individuals employed hibernation, we found a variation of up to 93 days in the hibernation start date and 47 days in end date between individuals, although the general pattern of hibernation such as average torpor bout duration was similar. Some individuals used shorter torpor bouts over an extended period in combination with extended activity of several days prior to the onset and after termination of hibernation, presumable allowing them to save energy during the colder nights while being able to forage during warmer days when invertebrates were active. This flexibility in hibernation timing suggests that hedgehogs may be able to adapt to changing environmental conditions.