Throwing out the question

[bktheirregular]

So I've got this small balcony off my bedroom, with a shed-cabinet-thing, about three feet tall and four wide and three deep, with a double door that won't latch closed. And apparently word's gotten out to the local pigeon community that the shed would make a nice nesting place. This despite my having disposed of one nest already.

As a newcomer to fending off wildlife ... how would you go about dissuading pigeons? (Bearing in mind that I may not have the resources in Athens that one would have stateside, and also that I don't have any guns to shoot them with.)