Hibernation - a Variable Feast

Many published statements relating to the 'hibernation period' of the hedgehog convey the impression that hibernation starts and ends of relatively consistent dates. But hibernation is not that simple. Mild weather delays hibernation and young animals (particularly those born in late litters) may anyway remain fully active into December.

Adult hedgehogs will meanwhile have begun to hibernate, with males doing so earlier than females. Males would have several months since the peak of the breeding season in which to fatten up and by September their average body weight is already over 2lb (900g) (females average 3oz / 100 g less). They are fully prepared for hibernation quite early in the autumn. By contrast, females have a strenuous time producing at least one litter, giving them little opportunity to build up fat reserves. Females who have had late litters may still be producing milk (thus actually losing fat), so they are not ready to enter hibernation until after the adult males.

So, age, sex and the weather all influence the timing of these events and climatic differences between different regions of the country also modify the hibernation cycle, making generalisations inappropriate for the country as a whole. Over 1,700 dated records were analysed from different parts of Britain, assuming that the number of hedgehogs recorded by observers represented a rough indication of the active hedgehog population. This showed clearly that hedgehogs emerged from hibernation earlier in the mid south-west than elsewhere. Whereas 42% of the year's hedgehogs had been seen by June in south-west England, only 34% had been recorded by then in London and just 32% in East Anglia. It was a further month before Scotland's hedgehog population achieved a comparable level of activity.

New Zealand hedgehogs experience mild, almost subtropical conditions, especially in North Island. If sighting data are rearranged to permit comparison with the British information, it is evident that 36% of the year's hedgehogs are recorded by June (actually December in New Zealand); a figure which lies between that for south-west England and London. The mild winters also seem to result in more activity during late winter. This may be because, at latitude 40oS (Southern England is 51oN). hedgehogs hardly need to hibernate at all

Little fella I found in the garden were late hibernating , hoping this year they make use of the empty shed at the top of the garden x