Hedgehogs as pets have gained popularity in recent years, but in many parts of the world, they're still wild animals. That includes London, where close to a million of the creatures roam streets, parks, and gardens, seeking out wood and vegetation to take refuge in. Now, Atlas Obscura reports that animal activists are transforming the city into a more hospitable environment for hedgehogs.

Barnes Hedgehogs, a group founded by Michel Birkenwald in the London neighborhood of Barnes four years ago, is responsible for drilling tiny "hedgehog highways" through walls around London. The passages are just wide enough for the animals to climb through, making it easier for them to travel from one green space to the next.

London's wild hedgehog population has seen a sharp decline in recent decades. Though it's hard to pin down accurate numbers for the elusive animals, surveys have shown that the British population has dwindled by tens of millions since the 1950s. This is due to factors like human development and habitat destruction by farmers who aren't fond of the unattractive shrubs, hedges, and dead wood that hedgehogs use as their homes.

When such environments are left to grow, they can still be hard for hedgehogs to access. Carving hedgehog highways through the stone partitions and wooden fences bordering parks and gardens is one way Barnes Hedgehogs is making life in the big city a little easier for its most prickly residents.

[h/t Atlas Obscura]