To prevent birds from making their needs, it is good as well as it is prohibitive for them to sit on the railings and take walks on them and to avoid the Pap Pap with their feet...
Note: As we said, the birds are cunning even at the 1 meter of needles I had written about, and whenever I smoke them, they enter the balcony taking the needles (a specific pigeon happened to come 30 times a day while I was chasing it away, it was playing and it was nerve-wracking) and to add here so that they don't come completely, it needs a net or in combination with special tapes, windmills, and floor needles, only this way we will avoid them.
Basically, the whole neighborhood is filled with repellents because this year is something else and they have driven us crazy.