There's nothing wrong with inviting a little wildlife to your home, but there are some places you just don't want birds invading your space. Keep them away with a simple mirror.If you have trouble with birds nesting on your porch (and thus dirtying up with sticks, mud, and... well, you know), weblog Jammer(six) shares a simple solution:
Our final (and effective!) trick was to attach small mirrors just above each of the columns to scare the birds away whenever they tried to land up there. This worked surprisingly well – I guess the phrase "bird brains" has a basis in truth! We used small mirrors from the cosmetic aisle, though I'm planning on switching them out for something less conspicuous.
Every year around this time the birds come back, and I often see them flying up under the porch roof looking for a place to nest. However, whenever they try to land on top of one of the columns, they inevitably see their own reflection, get tricked into thinking another bird is already up there, and head out in search of unoccupied space.
This trick is pretty well documented, though it's more likely that the bird doesn't like shiny or weirdly reflective objects that play tricks with the light and cast weird shadows. Either way, if you're sick of birds nesting in all the wrong places, you can probably keep them away with a cheap little mirror (or even an old broken one). Hit the link to read more.
How to Stop Birds From Nesting On Your Porch [Jammer(six)]