[rglullis]

If you want the low-tech solution, here is a recipe that definitely resolved it for me:

- One big spoon of cinnamon

- One big spoon of chilli peppers

- Half a bottle of cheap, cleaning vinegar

Spray it in all the places that the pigeons want to land. I am doing that once a week and it is enough to keep them away. If you clean your whole balcony with it, you might be able to go through most of the spring - when I think they really get annoying because they are looking for a place to make a nest.

[andai]

This is interesting, I was under the impression that chili peppers specifically evolved (spiciness) to be edible by birds but not mammals. Maybe that's an adaptation specific to tropical birds?

[MontyCarloHall]

You are correct; birds are not sensitive to capsaicin [0]. Seems this is specifically confirmed for pigeons [1].

Perhaps the cinnamon or vinegar are the true repellents?

[0] https://pubmed.ncbi.nlm.nih.gov/11853675/

[1] https://pubmed.ncbi.nlm.nih.gov/3797018/

[Conlectus]

Adding on: Though there is no consensus, I believe that is now the less-popular theory for the origin of spiciness. It seems instead to be a form of pesticide and fungicide.

Evidence for this is that pepper varieties tend to be spicier in wetter environments, where the biological resources spent on producing capsaicin to fight fungus are more valuable than preserving them in case of drought.

Source: https://sitn.hms.harvard.edu/flash/2012/issue131b/

[realo]

Another low tech solution:

feed them occasionally on your balcony… birds are smart and they will not poo in their food plate.

Cooked pasta works well, nothing will be left when they leave.

[michaelcampbell]

Hard disagree, or our pigeons are especially daft. (To be fair, ours are wild Mourning Doves), but they crap all over the food and water receptacles we have out for a variety of birds.

[imperistan]

I was under the impression that birds have no sphincter so they can't control when they poop. Is this not true?

[geoduck14]

Some birds do, some don't.

Source: my pet duck didn't have a sphincter.

Pro tip: don't get a pet duck

[MerelyMortal]

Wouldn't it then always slowly leak out rather than become one big glop?

[geoduck14]

This is cool alright, but can I program a Rasberry Pi to spray it?

[perfopt]

No water? Just mix in vinegar?