Many people in apartments and flats enjoy their balcony, whether it be for al fresco dining, growing plants, a seating area and more. The last thing that you want is debris and droppings caused by birds spoiling all of your hard work. Pigeons, amongst other birds, are the most common threat to the cleanliness of your balcony and therefore a solution is almost necessary if you want an area to grow plants or have your lunch.
The most humane and economical method of prevention is netting; some forms are almost undetectable when looking out at the vista, yet strong enough to keep out a range of creatures. You can the preventative measures against destruction to your property, without allowing the aesthetics to be compromised. You will need a decent quality net and a mesh size suitable to you needs; the smaller the size of the animals you want to keep out, the smaller the size of the hole (standard is around 10mm x 10mm for keeping out most birds)
You will mostly find that net comes in either extruded or knotted/knitted. The extruded netting is usually of polyethylene construction and is the weaker of the two. It is still expected to last a number of seasons if treated correctly, but will deteriorate more quickly than some other forms of netting. The knotted style is stronger because it is built with multiple strands, creating a weave that increases the tensile strength
In terms of installation you have a range of options; most of them can be altered depending on the size, shape and contours of your balcony. The first is to build or adapt a frame; starting from scratch you can use timber or perhaps steel poles to create a structure that fits on top of your balcony. There are also items such as crop cages and garden frames which you may be able to change in order to fit your needs. With steel frames the poles will fit through the mesh holes to secure it; for wood you can staple, cable tie or nail it on.
You can also attach the netting to the building itself. I will include some pictures of this below: