Hi Francois,
We're thrilled to hear the bird spikes are doing their job! Thanks for the feedback. A little pro tip we've picked up along the way - a good quality glue like Patex No More Nails does the trick when applied to a clean, dry surface. Silicone's a no-go, though, it just doesn't hold up outdoors. And you are 100% right, those holes in the base are perfect for screws or fasteners for extra security.
Thanks again for choosing us. If you need any more bird-proofing tips, just give us a shout!