   Porcupines in Arizona - July 10, 2002 Jeff Schalau, County Director, Agent, Agriculture & Natural Resources Arizona Cooperative Extension, Yavapai County A mysterious pine tree sample was recently brought to the Cottonwood Cooperative Extension office from the Camp Verde area. The sample was a 1-2 inch diameter branch that had patches of bark removed as if they had been cut with a razor-sharp utility knife. In between each patch, a narrow strip (1/8") of bark was left creating a mosaic pattern. The girdling had killed the branch. There appeared to be faint tooth marks. However, sap had oozed out and covered most of the bare wood surface. What caused this? Well, you've seen the title of this article. Porcupines are not common in the Verde Valley, but they are here. Some dog owners can probably attest to this. Porcupines prefer coniferous forests, but sometimes wander to lower elevation riparian areas. They eat herbaceous plants, inner tree bark, twigs, leaves, and show a preference for Ponderosa pine, aspen, cottonwood, and willow. Trees with thin, smooth bark are preferred over those with rough, thick bark. It is interesting to note that their feeding habits indirectly benefit other wildlife species. Clipped twigs that fall to the ground are used by deer and other mammals during winter months. In addition, the damage they do to trees exposes the sapwood. This allows insects, fungi, and birds to feed on the decaying wood. Other wildlife species then use these tree cavities for shelter and reproduction. Porcupines are active year-round and are primarily nocturnal. They usually rest in a tree during the day. They also use caves, rockslides, thick timber, or slash piles for protective shelter. Porcupines breed in fall, and after a seven month gestation period, usually produce one offspring in spring. The young are capable of eating plant material within a week of birth and they generally stay with the female through the summer. Survival rates of young are usually high. Predators do a fairly good job keeping porcupine populations in check. Some predators in our area include coyotes, bobcats, mountain lions, black bears, and great horned owls. The literature mentions that coyotes are noted for eating the quills. How they maneuver these through their digestive tracts is not known, but they have been noted in scat. In agricultural and residential areas, porcupines cause a variety of unwanted damage. Fruit and ornamental trees, sweet corn, alfalfa, and small grains are often attacked. They have also been known to chew on hand tools handles in search of salt and buildings in search of plywood resins. They also pose a significant threat to domestic dogs, which never learn to leave them alone. The best strategy to prevent damage from porcupines is exclusion. Fences, climbing barriers, and cages around plants are commonly used. For gardens, 18 inch tall poultry wire with a smooth electric wire 1.5 inches above the top is effective. Also, a simple smooth electric wire 4-6 inches above ground can provide adequate protection. Of course, porcupines are not the only pests to exclude from your garden. Javelina, wood rats, deer, elk, etc. must also be considered. Trees can be protected by wrapping the trunk with 30" wide aluminum flashing (this makes it difficult to climb) or creating a sheet metal barrier that they cannot climb around that is fixed to the trunk. Live trapping is the best solution to persistent porcupines. These can be baited with salt soaked cloth, sponge, or piece of wood. Do not shoot or lethally trap a porcupine without first calling the Arizona Game and Fish Department. They should also be able to provide you with a suitable release site for live-trapped animals (at least 25 miles from your current location). You may also simply call a licensed wildlife damage control person to handle this for you. The University of Arizona Cooperative Extension has publications and information on gardening and pest control. If you have other gardening questions, call the Master Gardener line in the Cottonwood office at 646-9113 or E-mail us at mgardener@verdeonline.com and be sure to include your address and phone number. Find past Backyard Gardener columns or submit column ideas at the Backyard Gardener web site: http://ag.arizona.edu/yavapai/anr/hort/byg/. |