Concrete is gonna be really hard to clean unless completely smooth n you don't mind scraping n hosing off a lot. just put one inch mesh on bottom of coop (helps let poop etc fall through and keeps pigeons cleaner n dryer), n keep pen one n a half to four feet off ground. Homing Pigeons are great partly because they were such good heroes/tools in wars etc. they are delicious eating if needing to cull (waste not want not, n better end than many have..). that poop n those feathers are best natural fertilizer there is supposedly (worms looove the feathers). the poop can also be used to make boom booms, and was in ol days by some before black powder (I've seen used to make lil fireworks with copper sulpate i think was..), pigeons were farmed by some specifically for poop for various things, and still are in developing places in communities that value them for that and ability to come home after foraging for own food and water, and harvest meat and feathers etc also (gotta love discovery channels), and eggs valued for ceremonial dishes in some cultures.
