Almost half of British people have never seen a hedgehog in their garden, according to a survey which suggests a decline in the creatures.

Only 29% of people taking part in this year’s annual wildlife survey for BBC Gardeners’ World magazine had seen a hedgehog in their garden in the past year, down from 32% the previous year. Only 11% of the 2,348 people who took part in the survey said they saw hedgehogs regularly in their gardens and 48% had never seen one.

The hedgehog population is thought to have fallen by 30% since 2003 to fewer than a million in the UK, down from an estimated population of 36m in the 1950s.

The survey suggests people are keen to save the species, which is a friend to gardeners because it feeds on pests such as caterpillars and slugs.

Questioned about which one UK species they would like to save from extinction, 52% said hedgehogs, ahead of other at-risk species such as the sparrow, puffin, mistle thrush and hairy-footed flower bee.

Seven out of 10 people said they would be happy to cut holes in their fences to allow hedgehogs to roam more freely to help halt their demise.

Lucy Hall, the editor of Gardeners’ World, which published the poll in its 25th anniversary edition, said: “The much-loved, humble hog is among gardeners’ most appealing natural allies, but they’re disappearing on our watch.”