Wood pigeons nesting in the apple tree

Good morning,

I've noticed a pigeon landing in my apple tree, probably seeking shelter, more so as stormy weather was approaching. But then another one visited, a couple of times, which appeared to be mates. One was coming and going whilst it's pair was resting and making calming sounds.

I noticed, probably the male, now bringing sticks possibly to make a nest. This is what our Persian cat and we don't desire. Natural instincts and parasites will clash.

Any suggestions please?

Marius