Pocket gopher
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Cratogeomys |
The pocket gophers are burrowing rodents of the family Geomyidae. These are the "true" gophers, though several ground squirrels of the family Sciuridae are often called gophers also. The name "Pocket Gopher" on its own may be used to refer to any of a number of subspecies of the family. Pocket gophers, despite being largely a pest, are a symbol of the U.S. state of Minnesota.
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[edit] Distribution
Pocket Gophers are widely distributed in North America, extending into Central America.
[edit] Appearance
Gophers are heavily built, and most are moderately large, weighing 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, from which the word "pocket" in their name derives. 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.
[edit] 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.
[edit] 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.
- Family Geomyidae
- Genus Cratogeomys; some authors treat this genus as a subgenus of Pappogeomys.
- Yellow-faced Pocket Gopher (Cratogeomys castanops)
- Smoky Pocket Gopher (C. fumosus)
- Llano Pocket Gopher (C. gymnurus)
- Merriam´s Pocket Gopher (C. merriami)
- Querétaro Pocket Gopher (C. neglectus)
- Naked-nosed Pocket Gopher (C. tylorhinus)
- Zinser´s Pocket Gopher (C. zinseri)
- Genus Geomys - eastern pocket gophers; principally found in the south-western United States, east of the Sierra Nevada mountains.
- Geomys arenarius; two subspecies, the Desert and White Sands Pocket Gophers
- Attwater's Pocket Gopher (G. attwateri)
- Plains Pocket Gopher (G. bursarius); two subspecies
- Jones' Pocket Gopher (G. knoxjonesi)
- Geomys personatus; 5 subspecies including the Texas, Davis, Maritime and Carrizo Springs Pocket Gophers
- Geomys pinetis; 4 subspecies, the Southeastern, Cumberland Island, Sherman's and Goff's Pocket Gophers
- Geomys texensis; 2 subspecies, including the LLano Pocket Gopher
- Genus Orthogeomys - giant pocket gophers or taltuzas; found in Mexico and Central America.
- Chiriqui Pocket Gopher (Orthogeomys cavator)
- Cherrie´s Pocket Gopher (O. cherriei)
- Oaxacan Pocket Gopher (O. cuniculus)
- Darien Pocket Gopher (O. dariensis)
- Giant Pocket Gopher (O. grandis)
- Variable Pocket Gopher (O. heterodus)
- Hispid Pocket Gopher (O. hispidus)
- Big Pocket Gopher (O. lanius)
- Nicaraguan Pocket Gopher (O. matagalpae)
- Thaeler´s Pocket Gopher (O. thaeleri)
- Underwood´s Pocket Gopher (O. underwoodi)
- Genus Pappogeomys; found in Mexico.
- Alcorn´s Pocket Gopher (Pappogeomys alcorni)
- Buller´s Pocket Gopher (P. bulleri)
- Genus Thomomys - western pocket gophers; widely distributed in North America, extending into the northwestern US, Canada and the southeastern US.
- Thomomys bottae; many subspecies, including the Botta's, Fish Spring, Bonneville, Clear Lake, San Antonio, Pistol River, Mount Ellen, Guadalupe, Limpia, Mearns', Stansbury Island, Antelope Island, Cebolleta, Salinas, Skull Valley, Swasey Springs, Harquahala and Limpia Greek Pocket Gophers.
- Camas Pocket Gopher (T. bulbivorus)
- Wyoming Pocket Gopher (T. clusius)
- Idaho Pocket Gopher (T. idahoensis)
- Mazama Pocket Gopher (T. mazama); several subspecies including the Western, Gold Beach, Olympic, and Tacoma Pocket Gophers.
- Mountain Pocket Gopher (T. monticola)
- Northern Pocket Gopher (T. talpoides); very widely distributed; several subspecies including the Cheyenne Northern Pocket Gopher
- Townsend´s Pocket Gopher (T. townsendii)
- Southern Pocket Gopher (T. umbrinus)
- Genus Zygogeomys
- Michoacan Pocket Gopher or Tuza (Zygogeomys trichopus)
- Genus Cratogeomys; some authors treat this genus as a subgenus of Pappogeomys.
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.
[edit] Pest Management
[edit] 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.
[edit] Gopher gas poisoning and poison baiting
Another non-organically certified method of gopher extermination is to inject toxic nerve gases such as aluminum phosphide into the tunnels. This is also often followed with the insertion of poison bait pellets in to the central nest areas for longer term control. This method has created controversy as aluminum phosphide is a federally registered pesticide with known hazards to human health.
[edit] External links
- Article on the Animal Diversity Web site
- eNature flashcard with image (southeastern pocket gopher)
- eNature flashcard with image (western pocket gopher)
