what to do about feral cats?

Hi,

I am building a wildlife garden and trying to attract as many birds and wildlife as I can. I am having problems with two feral cats that live inside the drain next to my garden.

They are killing the birds so i want to discourage them from coming here.

I need help finding a safe, non toxic way for getting rid of them. I love cats so I don't want to do anything that can harm/hurt them.

I checked the sonic devices and a forum member advised on water sprays. The problem is that the cats don't come to the garden through the same way. They vary their route so I would need more than one device.


thank you:o)