there’s nothing more dismaying than walking into your garden and finding missing plants, holes and mounds of soil heaped in random piles. the marauder is gone and you’re left wondering what critter made the mess and how you can fix things so it doesn’t happen again. here are some simple actions that will help you gather clues, identify the animal and take precautions.
for critter identity, first prize is seeing the animal with your own eyes. most of the garden-variety animals, like raccoons, skunks and rats, are nocturnal, which can make this difficult. however, there are inexpensive motion-activated video cameras on the market that can capture a shot of them in action and send it to a smart phone. this won’t help, of course, if the animal is snaking their way through a tunnel in the soil.
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some of the most annoying and common pests are pocket gophers, voles and moles. they leave mounds of soil throughout the garden, and if you push the soil away, the entry or exit hole may not be obvious. mole mounds are circular, 6 to 24 inches wide and 8 inches high. the pocket gopher burrows 6 to 12 inches below the surface and leaves mounds that are horseshoe or crescent-shaped, with the plugged hole on the side. voles create a maze of runways to and from burrow openings, which are 1½ to 2 inches in diameter.
chipmunks, rats and ground squirrels dig burrows through the soil and don’t leave mounds near their exit hole for identification. the holes can be as small as an inch wide or as large as 2 inches across. many times, the location of their exits can help with identification. rat holes tend to be under or near structures, piles of deadfall and under or near trash. ground squirrel holes can be out in the open, with little to no cover.
raccoons and skunks are diggers and leave random refuse piles as they explore your garden. they’re looking for worms, grubs, snails, frogs and spiders using their sharp claws to dig shallow holes in the soil and mulch. these critters are known to roll back sod and grassy areas looking for their dinner, and can be quite destructive.
other clues for identification include animal tracks. bring your camera and flashlight and bend low to look at the soil and hardscape for muddy imprints. if you have a recurring problem, you can set up a “track trap” by clearing the ground and dusting it with flour or some other innocuous white powder. as the animal walks through the garden, the powder is picked up on their feet and deposited as a footprint in undusted areas. review information on the uc integrated pest management site on garden and landscape pests, which may include sketches of tracks for comparison.
another clue animals leave behind is scat or poop. you can easily look for two qualities — size and content. large scat with hair and bone is more likely to be from a coyote, bobcat or fox. smaller yet substantial poop is more likely raccoon, skunk or opossum. rats leave behind large black, cylindrical grains of scat.
there are some precautions that you can take to reduce the chance the critters will pick your garden as their home. animals are seeking food and water. and while you can’t remove the grubs and worms they are hunting for, you can eliminate sources of attraction. pet food left outside, bird feeders and seed spillage, trash and unsecure composters can lure these pests to your garden. pick up dropped fruit and exclude pests from your vegetable garden with fencing. use a tight bungee cord on the lid to your green can.
don’t provide the animals with a comfy place to live. check for open spaces under buildings, decks and other structures. use 10 gauge ¼- to 1/3-inch fencing to block entrances, burying the mesh at least 6 inches deep and 12 inches outward. clean up around your home and garden, thinning vegetation that can be used as cover for dens and nests.
once you have identified the critter digging in your garden, you can find out ways to deter and eliminate the pest from your garden through our integrated pest management pest pages at ipm.ucanr.edu and clicking on landscape pests.
the uc marin master gardener column is written by uc marin master gardeners, who are sponsored by the university of california cooperative extension. for questions about gardening, plant pests or diseases, call +61404532026 from 9 a.m. to noon, and 1 to 4 p.m. weekdays, bring in samples or pictures to 1682 novato blvd., suite 150b, novato, or email email@example.com