   A Beaver's Tale - March 17, 1999 Jeff Schalau, County Director, Agent, Agriculture & Natural Resources Arizona Cooperative Extension, Yavapai County If you live along the riparian corridor of the Verde River or one of its tributaries, then you may be better acquainted with beavers than your upland neighbors. This can be good or bad. It's a good thing if you enjoy viewing wildlife and do not have an orchard, pond, ditch diversion, or stand of young trees. Otherwise these rodents may be the most unwelcome neighbors you ever had. They don't call beavers "eager" and "busy" for nothing. They can really have serious effects on the landscape. Beavers are the largest rodents in Arizona and carry unique equipment for life in the water. Their broad, paddle-like tail and webbed hind feet make them strong swimmers. Their ears have valves that allow them to exclude water when diving. All beavers have long, dense fur, but the Arizona populations have the lightest color of any in North America. Their heavy incisors give them a means to convert standing timber into kindling. They are nocturnal, and may be observed at fairly close range (they have poor eyesight). In terms of ecosystem health and water quality, beavers once played an important role in riparian areas. Their dams slow the flow of water and allow sediment to settle out. This allows soils to build up behind the dams rather than wash downstream. Their dams also trap organic debris that acts as a sponge to retain water on-site. Beaver ponds also create habitat for other aquatic life. They also create prime mosquito breeding areas. By the way, malaria was not uncommon in Arizona during the last century. Beavers have one to eight young per litter. They build two types of dens: stick houses in the stream or pool and bank houses burrowed along the stream. In the Verde Valley, most are the burrow variety. The entrance is underwater and leads to an enlarged cavity above the high water line. Beavers feed on leaves, twigs and bark of many woody species including cottonwood, willow, aspen, salt cedar, as well as cattail, and other tuberous aquatic plant roots. Like other rodents, they must chew to wear away the constantly growing incisors. Human conflicts such as dams, ditches and other stream channel modifications make life difficult for beavers. So did the fashion trend of using beaver pelts to make hats. Fur trappers came to the Verde Valley in the mid-1800's and significantly reduced beaver populations. In many parts of Arizona, including the Verde Valley, beavers were eventually extirpated (made locally extinct). Today, the Arizona Game and Fish Department has successfully reintroduced beavers. Once again we have beavers in our midst and human conflicts that accompany them. If you suspect beaver damage, then positively identify the cause before attempting control measures. Look for tracks on the stream bank or tooth marks on the stumps. Their presence is usually obvious. To control damage on a few trees, wrap trees with hardware cloth (heavy galvanized screen) to a height of 36 inches. You can see examples of this at the outlet of Montezuma Well. If this is impractical, then build an electric fence about 6-8 inches above the ground. The fence should completely encircle any route between the water and target species. I have seen this work along Oak Creek in Cornville. In other states, lethal traps and dynamiting are often used to control beavers. Do not trap or dynamite beavers in Arizona under ant circumstances. Even live trapping is illegal without express permission from Arizona Game and Fish Department. If you live in the uplands, take a trip down to the river and observe some beavers or just impress your friends by using fancy terms like "extirpate." The University of Arizona Cooperative Extension has publications and information on encouraging wildlife in you garden as well as controlling unwanted pests. 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. |