by Randy Kreil
ND Outdoors - March 1994
At the risk of sounding like Andy Rooney, have you ever noticed how neat and organized people are in North Dakota? Stop and think about the last time you saw a farmstead that wasn't laid out with everything running exactly east to west or north to south. The buildings are always perpendicular to the shelter-belt, grain bins, county road and drive-way. Angles, curves or serpentine landscaping are rarely found and if they are its a safe bet the house is less than 20 years old.
This kind of structured neatness is typical of hardworking European descendants who homesteaded the prairies of Dakota.
This commitment to organization is even more evident in our urban communities. Try to think of an area in your towns where the streets don't run east to west or north to south. Every town has a few of these areas but they are often confusing and hard to navigate.
The point of all this is, humans are neat, organized creatures. This trait can have a detrimental effect on the rest of our nonhuman neighbors. There is no more easily recognizable, but almost always overlooked example of this concept than the way we look at dead trees.
Dead or dying trees are looked upon as something that must be removed because they are ugly, hazardous and are only useful as a source of firewood. In our neat, organized world this probably makes sense to most people. But if you're a red-headed woodpecker, bluebird, kingfisher, great blue heron or chipmunk that same dead or dying tree might be your idea of a fine restaurant or a good place to raise a family.
The value of dead and dying trees as wildlife habitat is often overlooked but is in reality very important. Over 85 species of North American birds are cavity nesters and several dozen mammals also use holes in trees for burrows and rearing of young. Typically, nearly 40 percent of birds found in Midwestern forested areas are cavity nesters. In some areas of the northern plains, such as North Dakota, it may be even more. North Dakota Cavity Users
Cavity nesting birds are just what the name implies; birds that nest in holes or cavities in dead, weakened or living trees. These can originate naturally by rot or decay, breakage of limbs or trunks, insects, fire, and windfalls. Cavities are attractive to birds and other animals for a variety of reasons including protection from predators, insulation from temperature extremes, and shelter from the elements.
Cavities are also created by certain species of birds such as woodpeckers. These birds are called primary cavity nesters, meaning they make their own holes or enlarge natural holes to fit their needs. Primary cavity nesters also benefit other bids called secondary cavity nesters that require holes in which to nest but are unable to create cavities themselves. Woodpeckers often make partial or incomplete holes which they don't use. These cavities, along with naturally occurring holes, are used by secondary nesters such as bluebirds, nuthatches and wood ducks.
In addition to providing nesting habitat for cavity nesting birds, dead trees are used by great blue herons, cormorants, hawks and eagles as secure above-the-ground nest sites. Bats (see also bat) readily use the spaces under loose bark of dead trees as places to raise young and gain protection from the elements of light of day. Chipmunks, squirrels, raccoons, and weasels all will use holes in trees for raising young, hibernating or protection from the weather.
Dead and dying trees also serve as perches for feeding birds including kingfishers, hawks and insect eaters such as great-crested flycatchers and bluebirds. Foraging areas for insect-eating birds are another function of dead, decadent, and dying trees. Woodpeckers, brown creepers, nuthatches and wrens all patrol the bark, branches and trunks of trees for insects.
Over the years many forested areas found along prairie streams and rivers were cut for fuel or construction materials. Still other areas were degraded by intense livestock grazing. As woodlands became old and decadent they were cut down and no replacement forests grew.
This had a tremendous effect on wildlife throughout the country. There was a time in the late 1890s and early 1900s that wood ducks were in serious trouble in the United States. The mass cutting of forests, and in particular dead trees, resulted in the elimination of nesting sites.
Bluebirds suffered in a similar fashion, their predicament made worse by intense competition for nest sites. The introduction of English sparrows and starlings, which are also cavity nesters, created a situation where bluebirds, purple martins and other native species were being displaced by these nonnative invaders.
Other cavity nesting birds were also affected but did not get the attention that more popular species received. They lost nest sites, feeding areas and breeding territories just like wood ducks and bluebirds. In the 1950s, people across the country began to recognize the problems facing cavity nesters and began a program of building, erecting and maintaining artificial nest boxes. These efforts helped restore wood duck, bluebird and purple martin populations, as well as being beneficial to less recognized cavity nesting species.
More importantly, people began to regard dead and dying trees as more than a nuisance eyesore and cheap fuel. Old wood lots were left standing, clearing of large areas of river bottom and native forest was less frequent, and individual dead trees were allowed to remain in back yards and homesteads.
In recent times, natural resource agencies have taken a different approach to management of dead trees. In our agency we have discontinued unregulated public wood cutting on our wildlife management areas in an effort to protect those species of wildlife that use these areas.
Wood cutting is allowed when it helps us achieve a wildlife management objective. For example, we allow wood cutting in areas identified for aspen forest regeneration. It provides the public a wood source and helps us clear specific areas in an effort to enhance wildlife habitat. On the other hand the elimination of wood cutting on Oahe WMA saved a great blue heron rookery.
The State Water Commission incorporates wildlife considerations into its snagging and clear projects designed for flood control. They realize not only the value of dead and dying trees to wildlife, but also the bank stabilization and sediment reduction values offered by trees along the water course.
There are a number of things that need to be considered when discussing management recommendations for dead trees. First, you don't need to save every dead and dying tree. There is no steadfast rule describing how many you need in a given area. It all depends on the situation.
A complex of old trees, old live trees, young healthy trees, saplings, seedlings and thick ground cover is a sign of a good healthy forested area. Strive for a variety of tree and shrub types. Remember, bare trees are only one component of habitat.
Some trees, such as Siberian elm, are too small and brittle to have usable cavities. Other trees may be in bad locations, like over your house, or in a high use area. A tree is only a hazard if it is in a location where it could cause harm or damage. In this case common says you may want to remove it.
In other situations, trees with only a few dead branches may provide benefits for a long time before the tree itself is dead. Consider pruning the tree in such a way as to leave a portion that could be used by cavity nesting birds or a squirrel.
There are a number of ways in which you can help ensure the continued existence of the wide array of wildlife species that use dead and dying trees. It doesn't matter if you live in the country or in town. Everyone can contribute.
2) Decide if the tree in your yard is a hazard to you, your neighbors or overhead powerlines. If the tree is in a position that will not cause any serious problems if it is blown down in a windstorm, then consider removing parts that are hazardous and keeping it for its wildlife value. Besides, there won't be any leaves to rake.
3) Another area you should investigate before deciding to leave a tree is local ordinances, both safety and pest control. Obviously if the tree is carrying a disease that can be spread to other healthy trees, then you should reconsider your plan.
4) If you have a dead tree that is safe to keep in your back yard, consider drilling some holes in the trunk. Remember, many of the secondary cavity nesters cannot make their own holes. Typically, birds in urban areas are secondary cavity nesters. You could also use the dead tree as a location for your back yard feeders.
5) Put up nest boxes for desirable species such as squirrels, purple martins, wrens and chickadees. Make sure, however, that your efforts are not done in by aggressive English sparrows.
6) Put your cat on a leash! House cats are responsible for hundreds of millions of songbird deaths each year. A Wisconsin study estimates deaths of songbirds in that state alone reaches over 20 million each year. Don't attract birds to nest and feed in your yard if you don't leash your cat.
1) Leave old wood lots standing. Many of the 80 to 100-year-old homestead wood lots provide excellent habitat for bluebirds, woodpeckers and other cavity nesters.
2) Protect river and stream band forested areas. By excluding overly intensive livestock use, clearing and extensive fire-wood cutting you not only save living and dead trees for wildlife, you also help yourself by reducing bank erosion and sediment runoff.
3) When renovating field and farmstead shelterbelts, leave several large dead trees per acre or per quarter mile. This provide some habitat for a variety of birds and animals during the period when the new trees are growing.
4) Participate in various state and federal agency programs that work with and provide incentives to landowners to protect, restore and create wildlife habitat.
Things are not always what they seem. At first glance a dead or dying tree seems like a tragic loss of a valuable resource. But on further inspection it becomes clear that a dead tree is simply a part of nature. And as a part of nature it serves an important purpose that isn't always obvious to us.
Dead trees and dead parts of trees are critically important to birds and mammals for nesting, rearing of young, feeding and as shelter. With a little forethought and tolerance we can maintain our organized, structured lifestyle and at the same time provide wildlife the habitat it needs to survive. In the long run, we'll be the better for it.
For a Related Source
Randy Kreil is responsible for the Department's nongame wildlife program. (Technical advice for this article was provided by Craig Foss, community forestry coordinator for the North Dakota State Forest Service.) Return ND Outdoors Magazine.