Vigorous, living trees provide wildlife with food and shelter, but what about dead or dying trees-or even logs? Just as they did when they were healthy and living, dead and dying trees are critical elements of habitat for many animals. Trees are like any Irving thing. They have Infancy, youth, maturity, old age, and death. And, as a tree ages and eventually dies, changes in Its bark, wood, and other parts create habitat for animals suited to each stage In the life and death of the tree. Dead trees are called “snags”, and when snags fall to the ground they are then called “logs”.
How Do Snags Help Wildlife?
Animals find shelter in snags. Cavities that have formed in the heart of a tree from disease or from the loss of limbs provides a place to nest for woodpeckers, nuthatches, chickadees, bluebirds, some owls, wrens, tree swallows, and many other birds as well as raccoons and squirrels. Snakes use tree cavities to shed their skin. Inside a tree, the snake is well hidden during this very vulnerable time. Existing cavities can form at any time during the maturity of a tree but woodpeckers can actively excavate a nesting cavity in the soft wood of a dead tree. When they move out of their hole other animals can enlarge the entrance hole and move In.
Bats may also roost in tree cavities Some bat species prefer to roost under the loose bark of a dead tree. The brown creeper, a small forest bird, will nest under loose bark. Ospreys, some hawks, and great homed owls will nest or use nests built on the tops of very tail snags Cavities and loose bark can also serve a safe place to hibernate or metamorphize in the case of moths or butterflies.
Snags are very attractive to Insects which help to decompose the various parts of trees. These insects are eagerly sought by birds, reptiles, and mammals. The fungi which grows on dying trees Is also eaten by animals. Besides using snags to find food, some animals use cavities and loose bark to store food. Snags, with their stripped and bare branches, also serve as great look-out perches for hawks, eagles, vultures and other carnivorous birds which are large enough to find it awkward to perch on leafy branches. Mockingbirds will use a bare branch as a singing stage.
How Do Logs Help Wildlife?
When a snag falls down and becomes a log, a whole new ecosystem Is created. Tiny soil organisms, which add to soil nutrients through their metabolism, begin to decompose the log, only to be preyed upon by other organisms and Insects, which also eat the bacteria and fungi which add to the decomposition process And, these insects in turn provide food for all kinds of animals. Pileated woodpeckers, for example, can sometimes be found hammering a log apart with a powerful beak which has evolved for this purpose.
Within the log, the woodpecker finds ants, beetles and termites. What the pileated leaves behind In the gap It has made in the log, other birds can now easily reach. Holes in logs can become traps for rain water which can become a place to drink or bathe. The rotting wood Itself is wet because of chemical changes. This wetness In turn attracts salamanders and tree frogs. Logs tat have fallen in rivers and ponds provide resting areas for birds and turtles and sate havens for fish. Logs can even become “nurseries” the seeds d other trees, providing all the moisture and nutrients to make a healthy, new tree. Ferns and other forest plants also on rotting logs.
Snags and Logs in Your Backyard
If you are lucky enough to have a small woodlot locate the snags or dying trees that are there, as well as the logs and other fallen woody debris. Diseased or dying trees or trees with hollow insides may have bracket fungi clinging to the bark. Noticeable populations of beetles can also indicate a dying tree. Trees that are dying begin to lose their leaves, then the small branches that support the leaves, then the larger branches and so on until there is only a single trunk left. This eventually falls to the ground. Trees may fall before this point and begin the cycle of a log earlier in the decaying process.
In fact, you can never have too many snags or logs to suit your wildlife neighbors. One pair of woodpeckers can use more than ten snags. But, you will need to decide which to keep and which to remove based on their height and their distance from your home. If a snag is likely to fall and hit your home, your neighbors’ homes, or any other personal property of value, remove it. But save any and all snags that are not potentially dangerous. Try to also save as much fallen woody debris, including logs, as possible.
This serves as important habitat for ground-dwelling birds, mammals, and reptiles. “Cleaning” up the forest floor actually removes a whole layer of habitat which in turn causes local extinction of all the animals which depend on it. Cleaning up the forest floor should be limited to small dry branches if it is done at all. Try to always keep the larger logs and branches where they have fallen
Enhancing Your Snags and Logs
- If you do not have a forested property, it is possible to bring small logs in as part of your landscape. Logs placed in a backyard are especially useful if they are shaded most of the time and are positioned perpendicular to the line of a slope so that the soil moving down the slope is trapped against the log. The soil that accumulates next to the log will begin foster soil organisms which will break down the lo>, and help make it more useful to larger animals.
- Snags and logs can be improved for wildlife by encouraging vines to grow on them. Virginia creeper, greenbriar and trumpet vine can be used as food and shelter for the animals using your snags and logs.
- If you have a pond, a log partially submerged will help make the water more accessible to small animals and can serve as a resting area for turtles, frogs, and birds.
- It is possible to create a fallen tree or log by cutting a living tree about 3/4 through the trunk and pushing it over. Called a ‘hinge tree’, this can provide food and shelter for ground-dwelling animals, like bob-white quail.
- It is also possible to create a snag by ‘girdling’ the tree. Girdling involves cutting a band between one and six inches wide through the bark and completely around the tree. This prevents water and nutrients from moving up the bark from the ground to the leaves and eventually kills the tree.
- Beware of termites which can be brought into your house when you bring decaying logs into your yard. Keep decaying logs far away from your home and exclude them altogether from small yards. Check with your community association or local government about the legalities of having decaying logs in your backyard.