I have some creek gravel in one of our dry creeks and was wondering if it would make a good substitute for straw. Right now it is just dirt and straw. When it rains, if I dont add to it my poor birds end up all muddy. I figure if I out enough gravel in I can even spray it out to keep it clean. Another added bonus is the added grit to their food. Has anyone done this? Will it be hard on their feet? Any feedback would be appreciated.