A common problem for composters is keeping others from sorting through the pile. A big warm heap of edible material tempts a wide variety of animals, from rats to bears to flies. Some of these, if well behaved, don’t cause much problem. Others cannot be tolerated.
We have trouble with ravens. They like to dig through our compost piles. This wouldn’t be too seriously, generally. They never dig too deeply, I suppose the bacteria and other microorganisms they bring with them contribute much to the composting/curing process. But, they make a big mess, throwing the compost and biofilter around, and our compost must stay within the confines of the bin.
We’re not sure what brings the ravens to the pile, but we suspect it might be egg shells. All birds apparently seek calcium, to aid in egg development, and there’s probably no better source than other birds’ eggshells. We roast ours in the vent of the oven, or on the wood stove, then crumble them small before adding them to the compost, but the ravens still sort through our pile, and we can’t tolerate that.
I recently built a lid for the compost bin, to exclude the ravens.
I made a 7-foot square frame of cedar 1X1, stretched hardware cloth across it, and added a brace on each corner. This seems like it will work nicely.
Our bins are 6 feet square. I probably should have made the frame a bit smaller than 7 feet, but I wanted to ensure overlap. It extends well beyond the outer edges of the bin; it’s incredibly ungainly to move, and since I used hardware cloth left over from building the compost sifter (see Our Home-Built Archaeology-Style Shaker Sifter) I could have messed around a lot less in piecing it all together to cover the frame. I sewed the different pieces together with baling wire.
Nevertheless, it’s done and in place, preventing the raiding parties to which our local raven couple have become accustomed. I’ve covered the old compost pile for now. When the trees go dormant this winter, I’ll cut fresh spruce boughs to heap over that pile, and will switch the lid to the new compost pile (see Time For a New Compost Bin). The ravens will have to look elsewhere for their treats.