However, while the spikes look impressive, they don't seem to work. You can see some pictures of how the birds spikes don't work here.
The pigeons took a few weeks to check out the new spikes, but they were able to carefully maneuver between them and to stand around on the platforms, surrounded by a fortress of bird spikes. Admittedly, they do have to avoid the edges of the platforms now, so you can say that they do work if they were simply intended to keep birds away from the edge. I suspect that that wasn't the original purpose because there are now double the amount of spikes as initially installed. The density of the bird spikes should discourage landing on top of them, but all un-spiked areas are fair game.
Yesterday, I noticed the beginning of a pigeon nest in the middle of the bird spike fortress. It's only a small handful of grasses in a circular pattern, but Momma pigeon is already squatting in the middle and occasionally tucking the sparse grasses closer to her. Papa pigeon is patrolling from above to chase away visitors. No one is allowed to use that platform except for his honey wife now.
The platform is quite open and I'll be able to see the nest clearly all of the time. I wonder if I'll get to see some real eggs and real newborn pigeons this year! That would be a real treat.