   Woodrats - September 23, 1998 Jeff Schalau, County Director, Agent, Agriculture & Natural Resources Arizona Cooperative Extension, Yavapai County Have you ever been hiking across the countryside and noticed a two to three-foot tall pile of sticks, pine cones, cactus, and cow dung inside a bush or under a rock overhang? Maybe you looked at it more closely and discovered an entrance heavily fortified by cactus spines. This is the nest of the woodrat (also known as the packrat). The woodrat can be distinguished from other rats by it's fur covered tail and light-colored underparts and feet. Three species can be found in central Arizona: the whitethroat woodrat, Mexican woodrat, and Stephens woodrat. Each has a slightly different food/habitat preference, but if you garden near the edges of civilization, you will likely have encounters with woodrats. Historically, these nocturnal rodents have become known for their attraction to shiny, interesting objects. When they encounter a cartridge casings, coin, soda can tab, or article of jewelry, they will carry it until they encounter another, more interesting object leaving behind the old and departing with the new. This behavior also earned them the name "trade rat." Woodrat nests are occupied over many generations and in some cases many thousand years. Most often, they are built at the base of a tree, center of a cactus, or small cave. However, they can also be underneath houses or in the engine compartment of parked cars. At the center of a woodrat nest is the midden: a central living and food storage area. Woodrats are not meticulous housekeepers such that these middens have accumulated layers of urine and feces. In these layers, paleoecologists study long-term changes in plant communities by identifying pollen types and other debris found in the midden. In fact, indigenous people once robbed their nests in search of pinyon nuts. Their menu varies from cactus, juniper berries, acorns, and pinyon nuts to leaves, plant shoots, flowers and fruit. These latter dietary preferences usually introduce urban dwellers to woodrats. Yavapai County Cooperative Extension receives at least three calls per month about these urban invaders. A few of the calls in recent memory are: cleanly clipped lilac tips missing and small piles of leaves nearby, pansy flowers being nipped off every morning, and ripe tomatoes being mysteriously transported to a nearby wood pile. This behavior is usually enough to inspire residents to seek more information and, in some cases, declare all out war. Each individual resident will have to assess their situation when considering woodrat control measures. In native or xeriscape situations, they may not cause noticeable impact. Woodrats do climb small branches but may not climb a large tree trunk. Low branches are perfect ladders to desirable tree parts. Sheet metal barriers at least two feet tall can be effective at preventing damage in gardens or individual plants. Control measures, such as traps or toxicants, may be appropriate if plant damage is heavy. They can be permanently excluded from buildings by constructing a barrier at the entrance point. Probably the most humane control is to use a live trap and relocate the offender. If you choose this option, contact Arizona Game and Fish before releasing the animal. Residents may consider destroying the nest to dissuade these uninvited guests. Use cation: Hantavirus can be carried by woodrats. Learn about infection risks before disturbing woodrat nests. Finally, it should be said that all native animals (including birds and insects) were here before we were. We should try to be good neighbors and tolerate their activities. The University of Arizona Cooperative Extension has publications and information on managing many other vertebrate pests and Hantavirus. If you have other gardening questions, call the Master Gardener line in the Cottonwood office at 646-9113 or E-mail us at mgardener@kachina.net and be sure to include your address and phone number. |