My runs get all the midday and late day hot sun, but for nearly a week now it's either cloudy and very humid, temps in the 90's, or it's raining. This morning I noticed fuzzy stuff, mold or mildew?, growing in the pens. First, will this hurt the birds, is it something I should worry about, or is it ok to just leave it knowing that when things start to dry up the sun will kill it?