We had a couple of inches of rain on top of a couple of inches of snow on frozen solid ground. Run off has made a wet, muddy mess of our run. The coop floor is dry after I removed the bottom layer of moist pine shavings. I'd like to dry out the muddy run but wondering what to use? More sand on top? Gravel? I'd like not to have birds get wet feet and they seem only now to want to be in their messy run. Also, any harm in them getting wet feet?