What a difference. Since I got my ducks last year and built them a pen in September, I have been using dried oak leaves for their bedding. I use the "deep litter" method where I dump out about 8-10 inches of leaves. I turn it every day to every other day, topdress with additional leaves as needed, probably about every 5 to 7 days, and generally shovel it all out about every 4 weeks. I have access to bazillions of bags of oak leaves in the fall -- many of the trees around here are oaks, and people bag them all up and put them out to the curb for municipal composting. I was able to gather well over 500 bags of leaves last year for my garden, as well as probably 100 to 120 for the birds, which I stored in all of my various nooks and crannies in garages, sheds, greenhouses. Well, I ran out last week, and now have to use straw until October. Yuck -- guess what -- they stink now! Apparently, the low pH and high tannin content of the oak leaves was great at keeping down the growth of bacteria in the litter. Straw not so much -- all of the sudden I have an odor problem with the duck pen. The ducks don't seem to mind, but I do.