Bear-Proof Composting

One product, with a limit worth understanding. The Wildlife Management Institute (WMI), a nonprofit, runs a program with the Southeastern Association of Fish and Wildlife Agencies (SEAFWA) that tests products with captive black bears. Products must stay functional through at least 60 minutes of bear contact, according to WMI's program announcement. WMI's approved-products page lists a Grizzly Guard Composter under its garbage containers, food storage lockers, and recycling units section. Our records attribute it to Teton Bear Products. We did not find a certification number or date for it in the page text we could read, so check the WMI page itself for the current listing and details.

Two things this is not. It is not an IGBC certification: the Interagency Grizzly Bear Committee tests with captive grizzlies, and we found no composter in our transcription of the IGBC full list. And it is not a sign that every composter marketed as bear-resistant has been tested. We did not find certification for any other composter, and we do not name uncertified brands here. Vermont Fish & Wildlife says some tumblers are bear-proof but does not say which ones. Treat "bear-resistant" on a retail listing as the seller's claim unless it points to a WMI or IGBC listing. Our verification page explains how we check, and the certified products database covers what is listed for trash.

No two agency lists are identical, so here is each one, attributed:

• BearWise: keep out meat, grease, bones, unwashed eggshells, and large amounts of sweet fruit scraps or rinds. It also says to avoid composting where bears visit often, since food odors attract them.
• Vermont Fish & Wildlife: leave out meat, bones, and seafood leftovers, which it says do not break down quickly and are strong wildlife attractants. Where food scraps are banned from the trash, it says people who compost at home can put these in the trash, and that they can be kept frozen until trash day.
• N.C. Wildlife Resources Commission: keep pasta and oils out.
• Colorado Parks & Wildlife: keep meat and fruit scraps off mulch and compost piles.

On smell, Vermont suggests about three parts brown material (dried leaves, yard debris, wood chips, shredded paper) to one part green (kitchen scraps, vegetables, a small amount of fruit). If the pile smells, it says to turn it, add more browns, or put a layer of wood shavings or sawdust on top. We found no agency that says odor control makes a pile bear-proof; it lowers the draw.

An open heap is the option none of these sources recommend. Colorado says to use an enclosed system if you compost. BearWise says to use an electric fence or an enclosed, bear-resistant composter. Vermont says to either surround the compost with electric fencing or keep it in a hard, durable container with a lid that is hard for a bear to open, and that some tumblers are bear-proof.

Read "bear-resistant" here the way the agencies use it: a design description, not a certification. The sources we read do not rank or describe specific bin designs. If you want a tested option, the WMI-listed composter above is the one we found. Otherwise the agency-backed fallback is fencing.

BearWise lists compost among the attractants an electric fence can protect, alongside garbage, chickens, beehives, and gardens. The N.C. Wildlife Resources Commission also names compost piles and notes that standard 4-foot and 6-foot fences are easy for bears to climb. These are BearWise's general fence specifications, not numbers written only for compost:

• Energizer: at least 6,000 volts and at least 0.5 joules (0.7 joules where grizzlies are present). BearWise says a lower rating may work depending on location and soil, so check with your state agency.
• Wires: a minimum of 3 strands, with 5 or 6 better. Lowest wire 7 to 9 inches above ground, highest 36 to 42 inches, spaced 8 to 10 inches apart.
• Material: metal wire or polywire. BearWise warns polytape can flatten against a bear's coat and fail to make contact.
• Grounding: a galvanized steel rod driven six feet deep, with multiple rods if you cannot reach that depth or the soil is dry. Use plastic insulators so wires do not ground out on posts.
• Energizer placement: keep it out of a bear's reach.

For persistent bears, Vermont says adding food scent to the wires will discourage them. North Carolina says to check HOA, community, or county rules before installing electric wire, and that it can be switched off when people or pets need access. The N.C. Wildlife Resources Commission says to install electric fencing only where safety measures protect children and adults, so read the full source before you build. We cover this in more depth in our electric fence guide.

Vermont's advice, from a 2022 release: if bears are active nearby, take food scraps to a drop-off station (it points to a statewide directory and to local solid waste districts) rather than composting at home. If you are having a bear problem, it says to delay starting a new pile until it is resolved and to keep scraps frozen or take them to a collection site in the meantime. BearWise likewise says to avoid composting where bears visit often. For what to do when a bear is in your yard, see our guide to keeping bears away, and for trash, our trash guide. For other yard attractants, see bear-proof bird feeders.