The spread of patios and decking in gardens is said to be partly to blame. Westminster is working with The Royal Parks, the British Hedgehog Preservation Society and London Zoo to encourage Londoners to create hedgehog friendly gardens and increase biodiversity generally. They say it is particularly important for sheds, piles of debris, hedgerows and compost heaps to be left untouched, if possible, until July, as this is where the animals nest. If a mother hedgehog is disturbed after the birth of her hoglets, she may desert the litter or even eat it.