Flooring suggestions for chicken run area needed

[loblackw]

We are new to the urban garden scene, and on a whim decided our little backyard beach garden could use a few hens. We have three total - a Buff Orpington, Barred Rock and Ameraucana. The girls have a nice little home but the flooring has some pebble like stones that get scattered as the girls are out during the day. Is it ok to have these stones scattered out, or should I buy some soil/compost/mulch and put that down instead? My goal is to have something that will keep the flies and other pests at bay since we are on an island in south Texas and the heat is going to be something else!
Thanks

 

[Eggcessive]

For an outdoor run I like sand. I can run a small rake over it and sweep any poops into a dustpan (even an old dollar store broom works well.) Even if it's not cleaned often the droppings kind of crumble into the sand. I use sand right out of my creek bed.

 

[loblackw]

Thank you for your response! The ground is a mix of soil and sand so maybe I need to just sift the rocks out.