Hedgehogs are now hibernating, but will begin to emerge any moment to help control the slugs that are the mushroom hunter and gardener’s hated foes…
Every year bonfire night arrives with a fanfare of government health warnings. Fireworks can maim and blind they scream, yet this is nothing compared to the impact of the evening’s celebrations on one creature in particular.
Hundreds of urchins (to give them their Anglo Saxon name) perish in the flames every year – just the latest in a long line of threats which have seen the creatures drop by 80% in a generation.
Thanks to Beatrix Potter’s Mrs Tiggywinkle, the pointed snout, shiny black eyes and, above all, trademark spines need no introduction. These last are really unusually long, thick, hard hairs and although more thinly distributed than conventional hair, they hide a thick woolly undercoat of normal fur.
Hedgehogs are solitary animals, patrolling a regular territory every night in search of food. The exception, of course, is when they mate in spring. Of course the mere mention of this activity naturally leads to raised eyebrows. The answer is that boars have a very long forward-mounted penis, while the sow’s vagina is unusually far back. She also flattens her spines during the act, but even allowing for this the pair must proceed cautiously.
The babies are born covered with soft white spines in late spring, but these quickly harden and by a fortnight old they can protect themselves by curling into a tight ball. The sow weans them at about a month and they continue to grow rapidly through the summer. This is a critical stage, for it is vital they end the autumn weighing well over 1lb (500g).
Along with dormice, these are one of only two native mammals to go into genuine hibernation. The dormant hedgehog’s body temperature drops to those of its surroundings while its heartbeat slows from 190 to 20 beats per minute and its breathing falls to 10 breaths per minute
All this saves a huge amount of energy when their invertebrate quarry is at its scarcest, but it also means going without food for four months which requires huge energy reserves. They thus eat prodigious quantities of worms, snails, slugs, beetles, grubs, carrion and even fruit throughout the autumn, storing the energy in a thick layer of fat. Then in November or December they find a snug pile of dry vegetation in which to sleep until March.
Unfortunately many – particularly youngsters – perish when their fat reserves run out before spring (only 30% survive their first year). Other threats come from foxes and badgers which can nip through their spiny defences (indeed the doubling in badger numbers since 1980 is probably a significant factor in the population slump). The worse threats undoubtedly come from man: traffic takes a heavy toll, but habitat destruction is the biggest problem – particularly the ripping out of hundreds of thousands of miles of hedges and the increased use of pesticides. Both have drastically reduced food supplies in what were once their rural strongholds.
As a result you are now most likely to meet one in suburbia where the mixture of trees, shrubs, hedges and lawns perfectly mimics their natural woodland edge. Nor are garden walls a problem – for despite their ungainly appearance, they are excellent climbers.
Certainly their presence delights most gardeners. Hedgehogs are not only pretty, but positively benign. Their diet revolves around pests, with slugs and snails particular delicacies so even where they need a little encouragement to visit, they rapidly repay the investment by acting as unpaid pest controllers. Even here, however, there are unexpected risks. Slug pellets are a serious threat, for example, both from direct ingestion and indirectly, when the hog eats a dying gastropod. Also, while they are competent swimmers, ponds and swimming pools can be death traps if there is no way of clambering out.