A wood box works ideally for birds, if you need a larger shelter you can make on large like a chicken coop and place perches inside for the birds to rest on
a pigeon shelter provides safety and place for pigeon. For constructing sheltor use grass convered roundly and just tie with soft thread, don't remove the pigeon shelter whereever you see.
A good pigeon shelter would be a pigeon loft, similar to a chicken coop. you'll need fencing, and a roof, and you'll need to make sure to keep it clean.
