WEEKLY ARTICLES

MANAGING GOPHERS

1. Take advantage of natural predators

Gophers are the main course for several kinds of other animals, particularly owls.  Since the gopher regularly comes above ground to gather food at night, nocturnal predators such as owls are able to pick them off and owls are even known to feed primarily on gophers, sometimes several each night.

To encourage owls, build an owl house:  Sink a 4 x 4 inch pole four feet into the ground and build a nesting box, to be attached at the top of the pole (to extend to 12 feet above ground level.  The nesting box should be 16-24 inches on each side, with landing dowels, an entry hole 6 inches in diameter in front, several 5/8 inch drainage holes at the bottom together with a clean out panel, and four ¾ inch air holes on the side. 

Click here for a good example of Barn Owl Nest Box Plans. 

If placed in the sun, as opposed to under a tree, a slanted roof should be provided on the top of the box, extending several inches over the front and back to give the owls shade. Care should be taken not to place the nesting box in an area of intense vehicle or foot traffic since owls will not visit such noisy sites.  Although barn owls reside wherever people do, they need peace and quiet during daylight hours, which is their nap time.

Recommended Site Characteristics for Barn Owl Nest Box Placement:

At least 25 acres of contiguous, good quality hunting habitat (pastures, hay fields, fields that have been fallow for at least 3 years, grassy marshlands) available within ½ mile radius of the nest box site (about 5% of the land area within this radius).  Within a 5 mile radius an additional 200 acres of good hunting habitat for dispersing birds is preferable.

Several natural nesting and roosting opportunities (e.g. hollow trees, old barns, old bridges) within 2 mile radius.

Dense forest should not exceed 50% of the habitat in a 2 mile radius, to decrease risk of Great Horned Owl predation.

A low density of well-traveled paved roads within ½ mile radius.

Rodenticides are not used in and around buildings and nearby orchards and fields.

A reasonable expectation that the amount of foraging habitat will not decline over the next 5 years.

Notes on Barn Owl Nest Box Placement:

Boxes should be located in or on structures so that birds have unrestricted, year-round access.  Avoid erecting nesting boxes on trees or telephone posts due to high predation risks (unless providing a predator baffle).

Preferably there should be little human disturbance around the nest box, although barn owls will nest in barns being used for regular and routine farm activities.

Boxes should be fastened on the outside or inside of farm structures at least 20 feet off the ground, preferably with the entrance facing directly to the outside and towards hunting habitat.

If affixed to the inside of a barn, a 6" by 6" hole should be cut in the side of the barn and the nest box attached so that birds fly directly into the box from outside.

Place the box so that the nest exit faces towards hunting habitat.

2.  Use “gopher resistant” plants

As yet, there are no good studies on the non-preference of one plant over another but there is plenty of informal input on the subject.  The plants listed below are “gopher-resistant” according to many home gardeners. That is, if other food is abundant, gophers will leave these plants alone. This does not mean that gophers never eat these plants -- only that gophers prefer other food if it's available.

Acer palmatum   Japanese Maple

Amaryllis belladonna   Naked Ladies

Arbutus   Strawberry Tree

Begonia semperflorens   Fibrous Begonia

Buddleja   Butterfly bush

Callistemon   Bottlebrush

Ceanothus   California Lilac

Citrus limonia   Lemon

Dietes   Fortnight lily

Digitalis   Foxglove

Escallonia   Escallonia

Eucalyptus   Eucalyptus

Euonymus   Euonymus

Fraxinus   Ash

Grevillea   Grevillea

Heteromeles   Toyon, California Holly

Heuchera   Coral bells

Hydrangea   Hydrangea

Lantana   Lantana

Lavandula   Lavender

Michelia   Banana Shrub

Morus   Mulberry

Nandina   Heavenly Bamboo

Narcissus   Daffodil

Nepeta   Catnip, Catmints

Nierembergia   Cupflower

Nerium   Oleander

Penstemon   Beardtongue

Persea   Avocado

Prunus armeniaca   Apricot

Punica   Pomegranate

Rhaphiolepis   Indian Hawthorn

Rosmarinus   Rosemary

Salvia   Salvia

Vinca   Trailing Periwinkle

3.  Use a “repellent” plant.

Of the many plants that have been recommended as gopher repellents, only one has actually shown some repulsive qualities:  Melilotus indica, sold as “GopherStopper”™

It's a somewhat weedy-looking legume that should be sown on the periphery of the property.  It is somewhat toxic, so keep it away from pets, farm animals and horses.  It’s available from:

            S&S Seeds

            Albright Seed Company

            Peaceful Valley Farms

            Rincon-Vitova

4. Exclude them

For raised vegetable beds, it is possible to keep gophers out by putting in some sort of physical barrier, such as aviary hardware cloth of small mesh.

If you want to install a barrier of this kind it should go at least two feet deep in the soil, with the raised bed wall itself at least one foot above ground, so that gophers cannot climb over it.  The underground fence should be of ¼- or ½-inch wire mesh.  

"Gopher cages" are not effective in the long run when used for planting trees, shrubs and landscape plants in general.  In fact, in many cases the cages can hinder the growth of the plants.

5. Trap them

Trapping is possibly the most effective method for managing gophers, especially on small areas (large areas require more persistence with traps).  Commercially available gopher traps include the Macabee® (my favorite), the Victor® Gopher Getter, the Death Klutch®-1, and the box-type trap (e.g. Black Hole®).  Instructions on setting are usually provided by the manufacturer.

Trapping can be the most time-consuming and difficult way to control gophers but it’s the closest thing to guaranteed gopher control in a home garden. 

The benefit to trapping is that you definitely know you’ve got the gopher.

The trap must be placed in the gopher burrow.

In order to be effective you are going to have to do some digging, and obviously if the gophers are in your lawn this cure could be worse than the critter in its effect on the appearance of the lawn.  You need to dig down – carefully so as to not allow the tunnel to collapse -- until you expose a main tunnel, and place the trap delicately in the runway.  Better results are with two traps, one facing each direction of the gopher run to intercept the gopher from whichever way he comes.

The best success is had when tunnels are left slightly open -- lodging a loose wad of weeds or sod into the opening allowing a slight window.  The gopher, which absolutely abhors changes in its burrow, detects the light and comes back to fill the new window.

Some trappers close off the tunnel completely with a board or sod. 

Traps should be attached to a stake with a wire or chain.  Generally, 3 or 4 traps per 1,000 square feet are needed for trapping to be reasonably efficient.

You may have to experiment with trap type and placement.

Trapping is most effective when gophers are pushing up new mounds, generally in spring and fall.  If a trap is not visited within two days, move it to a new location. 

On large areas, it’s a good idea to place colored flags at set locations.

In spring and early summer when gophers are mating or when young may be present, it is a good idea to reset traps in the same location after the first gopher is caught.

When you do catch some gophers with the traps, do not handle them with your bare hands.  Most rodents have parasites on them such as fleas that you do not want on you.  Use gloves and place the dead animal into a plastic bag for disposal.

Just because you have eliminated all the gophers from your property does not mean that new ones won't move in very quickly.  They are territorial, and once some ground is rendered free and clear of the competition new gophers may take over the vacated area, even moving into the burrow system left by a departed comrade.  (By the way, the notion that leaving a dead gopher in its burrow to scare off potential new squatters doesn’t hold water because of this territorial imperative.)

Gopher management needs to be an ongoing process, particularly on large properties.

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