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Idaho Fish and Game

Leave Forest Homes

Idahoans who provide their own homes with the comfort of wood heat might think of their neighbors while cutting a winter wood supply. With the soaring costs of propane, natural gas and electricity, thousands of Idahoans are out and about collecting wood for heating. Saving money is one of the biggest reasons for heating with wood. Many firewood collectors do not recognize the value of the partially or completely dead standing trees they see in the forest. These woodland features, called snags, support a complex system of life. By understanding a little about snags, people who appreciate Idaho's wildlands come to value them and leave some here and there, changing their woodcutting habits to benefit wildlife. In Idaho, about 50 species of birds and 25 species of mammals nest, roost, forage or take shelter in snags. Artificial snags are now being placed in many places that have lost snags. At Wolf Lodge Bay on Lake Coeur d'Alene in the Idaho Panhandle, artificial snags create hunting perches for bald eagles which frequent the area in the late winter to feed on kokanee salmon, as many of the natural snags have been removed during road construction in the area. Plants and invertebrates also benefit from snags which eventually fall and provide watershed protection and the nutrients that create rich forest soils. Many of the snags woodcutters fell are left on the ground because they are too far decayed to make good firewood. This only speeds up the process of the snag becoming a soil enhancement by dropping it before or while it provided a home for wildlife. Before dropping a snag, look for any fungal growth on the main trunk. If you see any, there are better, more solid trees around to heat your home as this snag has already begun to decay and will soon be a home for wildlife. Look for any signs of current wildlife use such as nesting cavities or signs of roosting. Woodpecker holes indicate there are many insects already inhabiting the tree, and insects are the last thing you want to bring into your home. Leaving such trees standing will benefit wildlife. Large diameter snags remain standing longer than smaller ones, so they are good choices to leave for wildlife. Snags measuring 15 inches in diameter or larger at breast height are valuable to wildlife and will remain standing longer than most of us will if we leave them. While large diameter snags can provide homes for more species of wildlife, leaving snags of a variety of diameters will benefit more species. Woodpeckers typically use trees at least 15 inches in diameter, raccoons use trees in the 24 inch diameter range and black bears will use snags 40 inches in diameter and larger. When cutting wood on the national forest, you might even notice trees bearing a sign saying "Wildlife Tree," an indication the Forest Service has observed wildlife use of this particular dead tree. Such trees should always remain undisturbed as there are likely several species of birds or mammals using this particular snag. A snag's species is also important. Ponderosa pine, western larch, and Douglas fir make for good and durable snags, as do cottonwood and aspen because they normally grow in riparian areas already conducive to wildlife habitation. Leaving one snag per acre was once the recommendation of many forest biologists. However, it appears that additional snags of varying heights and diameters may provide further benefits to wildlife. When cutting wood, look first for trees that have uprooted and are horizontal on the ground. Where legal, cut live trees which are crowded and subordinate to those around them for firewood, then let them season. (Cutting enough wood so one winter's supply has a full year to season is a good plan because dry, checked wood provides more heat while burning cleaner.) Fish and Game has produced a nongame leaflet called "Dead Trees and Living Creatures: The Snag Ecology of Idaho." The leaflet describes many of the benefits of snags to wildlife and describes the ways many different species of wildlife that use snags. The publication is available free at any Fish and Game office.