[goldenkey]

I use these plastic spikes. [1] Not even sure if you can call them spikes, moreso just protrusions. They aren't sharp at all so they don't impale the pigeon, only stop it from roosting. They work really well because the pigeons just aren't comfortable sitting on them.

I agree with you about sharp metal spikes. Those are really terrible and I feel bad for any bird that gets injured by those.

[1] https://www.amazon.com/Bird-X-Plastic-Polycarbonate-Spikes-A...

[honopu]

These spikes are in a nook above the office at work. They help hold the bird nest there perfectly, and actually seem to make nesting easier. I could see them keeping away large birds, but for their intended use case, they just made it easier for nests to be put where they otherwise might not stay.

That said, I don't mind it, watching the birds is fun.

[goldenkey]

That's pretty funny. For me, they work pretty good against the pigeons. Honestly, if it were sparrows or some other type of bird making a nest in them, I don't know if I would care too much. Pigeons are pretty large and make big poops.