I don't know about your pigeons, but where I've seen them in use, they don't deter any wild life movement what so ever. Just other day saw squirrel tip toying over garden fence that those spiky strips nailed on top..and big wood pigeons sitting there too.
I think they work (or should) more against humans, trying to climb over the fence.
I've seen different sort of 'spikes' being used against pigeons on building ledges..those are metal strips with row of couple of inches of long needle like spikes pointing all different directions...I try to find for you the 'stuff'...