Wood pigeons can spread disease, as Jean Cloud says (Mailbox, August 31), but it is human habits that give them full opportunity to do that by throwing the remains of pizzas and the like on to our streets – and then the rats join in.

Pigeons come from our woodlands, which have been halved in 50 years, for reasonably-needed houses and roads, sometimes – and, although the thought is still alien to most of us, for growing grain for livestock when animal flesh for a good diet isn't necessary.

A huge boom in the greenhouse gas methane has resulted.

Ladybirds deal with aphids, and snails and slugs would have been taken care of by hedgehogs, if gardeners hadn't allowed them to be so reduced in numbers by chemicals and slug pellets.

Have all the car journeys in recent decades been so necessary? Hundreds of thousands of hedgehogs have had their insect work briskly interrupted under car wheels.

Mr C Neal, Leicester.