Pocket gopher
| Pocket gophers Temporal range: Early Oligocene - Recent
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| Family: | Geomyidae Bonaparte, 1845
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Cratogeomys | |
The pocket gophers are burrowing rodents of the family Geomyidae. These are the "true" gophers. Several ground squirrels of the family Sciuridae are often called gophers as well, despite the fact that they are not true gophers.. The name "Pocket Gopher" on its own is used for a number of subspecies of the family. Pocket gophers, despite being largely a pest, are a symbol of the U.S. state of Minnesota, sometimes called "The Gopher State".
Distribution
Pocket Gophers are widely distributed in North America, extending into Central America.
Appearance
Gophers are heavily built, and most are moderately large. They usually weigh a few hundred grams. A few species reach weights approaching 1 kg. Most gophers have brown fur which often closely matches the color of the soil in which they live. Their most characteristic feature is their large cheek pouches. The pocket in their name comes from these pouches. These pouches are fur-lined, and can be turned inside out. They extend from the side of the mouth well back onto the shoulders. They have small eyes and a short, hairy tail which they use to feel around tunnels when they walk backwards.
Behavior
All pocket gophers are burrowers. They are larder hoarders, and their cheek pouches are used for transporting food back to their burrows. Gophers can collect large hoards. Their presence is unambiguously announced by the appearance of mounds of fresh dirt about 20 cm in diameter. These mounds will often appear in vegetable gardens, lawns, or farms, as gophers like moist soil. They also enjoy feeding on vegetables. For this reason, some species are considered agricultural pests. They may also damage trees in forests. Although they will attempt to flee when threatened, they may attack other animals, including cats and humans, and can inflict serious bites with their long, sharp teeth.
Classification
There has been much debate among taxonomists about which races of pocket gopher should be recognised as full species, and the following list cannot be regarded as definitive.
Some sources also list a genus Hypogeomys, with one species, but this genus name is normally used for the Malagasy Giant Rat, which belongs to the family Nesomyidae.
Pest Management
 | This page or section needs to be cleaned up. (January 2007) |
Gopher trapping
Gopher traps can be employed to kill them. These traps are very effective and need not be baited. To deploy the trap, a hole must be dug in a fresh gopher mound to uncover the tunnel. The cocked trap is inserted jaws-first so that the entire trap is within the tunnel, and then it is covered with dirt. The gopher will push against the trigger plate in order to reacquire access to the hole which has been blocked. In doing so, it will position its body directly above the jaws. When the jaws close, they will break the gopher's spine in the best case or merely maim the animal in the worst case. This method of gopher control is allowable in certified organic operations as there are no non-organic chemicals used. Mounds made by moles are different, with the dirt being more finely broken up, and gopher traps are ineffective against moles.
To make your traps more effective, realize that the mound is always set off a foot or two from the main run. Dig (or probe with a thin rod) until you locate the tunnel going in both directions; then put a trap in each hole. Cover with dirt, as above, and wait 24 hours. Gophers are very sensitive to light, and will fill in their tunnels and abandon them if they perceive any light, so it is important to cover all openings where light might come in after setting a trap. Placing a board larger than the hole over the opening and covering all edges around it with dirt will seal off light so that the gopher does not abandon the tunnel.
Gopher gas poisoning, poison baiting, concussion
Another non-organically certified, but more humane, method of gopher extermination is to inject toxic gases such as aluminum phosphide into the tunnels. The aluminum phosphide pellets react with moisture in the soil to produce phosphine gas (not phosgene) While this method has created controversy from aluminum phosphide being a federally registered pesticide with known hazards to human health, with proper safety precautions, this poison is easy to use, and causes no secondary poisoning of predators or carrion eaters as do some poison baits. The gophers die quickly underground.
Zinc phosphide bait is delivered in a compressed grain pellet. The phosphide creates phosphine gas in the gopher's stomach.
Gopher gassers and automotive type flares are sometimes used. They are ignited and placed in the burrows. The fumes kill the gopher.
Poison baits require the gopher to eat the bait. They include barley, wheat, and milo grains, sometimes with raisins, coated with strychnine. The disadvantages of poisoned baits include the following: The gopher must find and eat the bait. If the bait molds or rots, the gopher wont eat it. If a gopher eats a non-lethal dose and just gets sick, it will never eat it again (bait shy). Strychnine poisoned gophers may wander above ground in an intoxicated stupor, making themselves easy targets for predators. Resulting secondary poisoning of pets and predators, including owls, would prove to be counterproductive. A loss of predators means more gophers. Hence, these baits must be used with extreme caution.
A concussion method kills gophers instantly with a shock wave. Specialized equipment used by trained operators wearing personal protective equipment injects a mixture of propane and oxygen into the gopher burrow. An igniter on the end of the injection probe explodes the fuel mixture, destroying not only the gophers, but the burrows as well. This method is obviously not suited for urban residential areas, but rather to agricultural situations. The destruction of the burrows by this method prevents loss of irrigation water, prevents injury from collapse of the burrow underfoot (human, equine, etc.), and may make any re-infestation more quickly noticeable. Killing animals with explosives is illegal in some jurisdictions, such as the State of Colorado, USA.
--pechaney 04:36, 12 May 2007 (UTC)