Slug pellets and pesticides are toxic chemicals intended to kill slugs and other invertebrates. Constant use of pesticides removes these invertebrates from the areas to which they are applied, meaning that hedgehogs and other animals that depend on them for their primary food source will not have sufficient food available. What's more, they can also pose a threat to larger animals—like hedgehogs—that eat poisoned slugs and insects or else ingest the pellets directly. Even products that claim to be hedgehog-friendly may still be cause for concern, as evidenced by the British Hedgehog Preservation Society’s comments on Bio Slug Pellets:
'Recently we have received letters and calls of concern from members and carers who have seen Bio Mini Slug Pellets advertised using pictures of hedgehogs. We are worried that people may think this means the pellets cannot harm hedgehogs. The pellets concerned made by PBI Homes & Gardens contain an ingredient called metaldehyde; we have post-mortem reports of hedgehogs that have died from ingesting this chemical and believe that it does pose a threat to hedgehogs.'
Beyond the threat they pose to hedgehogs and other invertebrate predators, pesticides can also seep into groundwater or run off into surface water where they can cause additional harm.
So if pesticides are so bad for local wildlife, how are you to control the pests that are eating your garden? Hedgehogs will help keep your pest population under control! Just provide them with a shallow bowl of water and a supplemental meat-based food supply to encourage them to visit. Birds are another predator of slugs and can be attracted to your garden with bird seed and water. Beer traps (beer-filled containers sunk into the ground) and grapefruit peels are other pesticide-alternatives.