Pet peeve

I was annoyed by Mark Winson’s letter (A wildlife catastrophe, December 2017) on cat-proofing bird feeders. He suggests calling a plumber to solve the enormous problem of domestic cat predation on wildlife. What workman and ironmongery does he suggest people use to save small mammals, amphibians and anything else the cat decides to play with?

The only successful method is a solid oak door, firmly shut, which would also save cats from getting squashed on roads.