Depending on where you live, you will need to keep various animals out of your compost. Creatures attracted to a compost pile may include rodents, cats, dogs, foxes, raccoons, coyotes, badgers, and javelina. In some regions, even bears may appear in backyards as development spreads into their ranges and normal food supplies become scarce.
People are the ones usually encroaching on the animals' territory — don't blame them for seeking food.
When wild creatures tangle with humans, the animals are usually the losers, so it's better to deter them from the get-go rather than try to change their routine once they've discovered there's a regular food supply in your backyard. You can do this by eliminating specific ingredients from your compost and by using bins that prevent animal access (or at least make it more difficult).
Don't put meat, fish, bones, dairy products, grease, or oil in your compost bin. This simple step reduces the likelihood of midnight prowlers rooting through your pile. Avoid using blood meal as a nitrogen source or accelerator to speed up the composting process. Its scent, though not particularly noticeable to humans, may attract unwanted critters to the pile, including your family dog. Cover kitchen scraps or vegetable garden trimmings with an 8-inch layer of dry brown materials, such as leaves, straw, or organic matter that's in the process of decomposing. Using two or three side-by-side bins makes this easy. Pitchfork or shovel material stockpiled in one bin onto the freshly added scraps in a second bin.
Manufacturers of compost bins know that animals can be pretty smart when it comes to gaining access to the contents of your bin, so they design their bins with specific features that help keep animals out. The following bin styles and features inhibit unwanted access:
Fully enclosed bins (including solid bottoms) with securely latched lids.
Tumblers resting on aboveground supports.
Small aeration holes or holes covered with wire mesh
When building your own bins or modifying less secure manufactured bins, these ideas may help you prevent pests from gaining access:
Cover aeration holes with hardware cloth or wire mesh to prevent rodents from squeezing through. (Rodents chew plastic mesh.)
Build wood bins with tight mesh wire sides and hinged, fiberglass or wood lids.
Place heavy covers (such as wood shipping palettes) on the top of large open bins to block easy access.
Set bricks on top of easy-to-remove lids.