How do you stop a bird nesting in your flower box?

most birds especially in the wild make their own nest with what they can find on the ground eg twigs, moss,leaves but alot of bigger birds or birds that were kept inside would use earth,damp holes or moss peat where ever they find it. cover the moss peat with small pebbles or cover around your flowers with a paper or cloth or somthing porous. you could also over fill your flower box with flowers or greenery to hide the moss peat good luck